@article{VerchHirschmuellerMuelleretal.2018, author = {Verch, Ronald and Hirschm{\"u}ller, Anja and M{\"u}ller, Juliane and Baur, Heiner and Mayer, Frank and M{\"u}ller, Steffen}, title = {Is in-toing gait physiological in children?}, series = {Gait \& posture}, volume = {66}, journal = {Gait \& posture}, publisher = {Elsevier}, address = {Clare}, issn = {0966-6362}, doi = {10.1016/j.gaitpost.2018.08.019}, pages = {70 -- 75}, year = {2018}, abstract = {Research question: This study aimed to establish reference values in 1-14 year old healthy children and to implement FPA-percentile curves for daily clinical use. Methods: 5910 healthy children performed at least 3 repetitions of barefoot walking over an instrumented walkway using a pressure measurement platform. The FPA [degrees] was extracted and analyzed by age and gender (mean +/- standard deviation; median with percentiles, MANOVA (age, gender) and Wilcoxon-Signed-Rank test for intra-individual side differences (alpha = 0.05). Results: FPA maximum was observed in 2-year-old children and diminished significant until the age of 4 to moderate out-toeing. For ages 5-14, no statistically significant differences in FPA values were present (p > 0.05). MANOVA confirmed age (p < 0.001) and gender (p < 0.001) as significant FPA influencing factors, without combined effect (p > 0.05). In every age group, right feet showed significantly greater out-toeing (p < 0.05). Significance: Percentile values indicate a wide FPA range in children. FPA development in young children shows a spontaneous shift towards moderate external rotation (age 2-4), whereby in-toeing <= 1-5 degrees can be present, but can return to normal. Bilateral in-toeing after the age of four and unilateral in-toeing after the age of seven should be monitored.}, language = {en} } @article{WochatzEngelMuelleretal.2020, author = {Wochatz, Monique and Engel, Tilman and M{\"u}ller, Steffen and Mayer, Frank}, title = {Alterations in scapular kinematics and scapular muscle activity after fatiguing shoulder flexion and extension movements}, series = {Medicine and science in sports and exercise : MSSE}, volume = {52}, journal = {Medicine and science in sports and exercise : MSSE}, number = {17}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/01.mss.0000676540.02017.2c}, pages = {274 -- 274}, year = {2020}, abstract = {Repetitive overhead motions in combination with heavy loading were identified as risk factors for the development of shoulder pain. However, the underlying mechanism is not fully understood. Altered scapular kinematics as a result of muscle fatigue is suspected to be a contributor. PURPOSE: To determine scapular kinematics and scapular muscle activity at the beginning and end of constant shoulder flexion and extension loading in asymptomatic individuals. METHODS: Eleven asymptomatic adults (28±4yrs; 1.74±0.13m; 74±16kg) underwent maximum isokinetic loading of shoulder flexion (FLX) and extension (EXT) in the sagittal plane (ROM: 20- 180°; concentric mode; 180°/s) until individual peak torque was reduced by 50\%. Simultaneously 3D scapular kinematics were assessed with a motion capture system and scapular muscle activity with a 3-lead sEMG of upper and lower trapezius (UT, LT) and serratus anterior (SA). Scapular position angles were calculated for every 20° increment between 20-120° humerothoracic positions. Muscle activity was quantified by amplitudes (RMS) of the total ROM. Descriptive analyses (mean±SD) of kinematics and muscle activity at begin (taskB) and end (taskE) of the loading task was followed by ANOVA and paired t-tests. RESULTS: At taskB activity ranged from 589±343mV to 605±250mV during FLX and from 105±41mV to 164±73mV during EXT across muscles. At taskE activity ranged from 594±304mV to 875±276mV during FLX and from 97±33mV to 147±57mV during EXT. Differences with increased muscle activity were seen for LT and UT during FLX (meandiff= 141±113mV for LT, p<0.01; 191±153mV for UT, p<0.01). Scapula position angles continuously increased in upward rotation, posterior tilt and external rotation during FLX and reversed during EXT both at taskB and taskE. At taskE scapula showed greater external rotation (meandiff= 3.6±3.7°, p<0.05) during FLX and decreased upward rotation (meandiff= 1.9±2.3°, p<0.05) and posterior tilt (meandiff= 1.0±2.1°, p<0.05) during EXT across humeral positions. CONCLUSIONS: Force reduction in consequence of fatiguing shoulder loading results in increased scapular muscle activity and minor alterations in scapula motion. Whether even small changes have a clinical impact by creating unfavorable subacromial conditions potentially initiating pain remains unclear.}, language = {en} } @misc{BaurHirschmuellerJahnetal.2008, author = {Baur, Heiner and Hirschm{\"u}ller, Anja and Jahn, Michael and M{\"u}ller, Steffen and Mayer, Frank}, title = {Therapeutic efficiency and biomechanical effects of sport insoles in female runners}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {624}, issn = {1866-8364}, doi = {10.25932/publishup-43552}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435525}, pages = {4}, year = {2008}, language = {en} } @article{MuellerMuellerStolletal.2016, author = {M{\"u}ller, Juliane and M{\"u}ller, Steffen and Stoll, Josefine and Rector, Michael V. and Baur, Heiner and Mayer, Frank}, title = {Influence of Load on Three-Dimensional Segmental Trunk Kinematics in One-Handed Lifting: A Pilot Study}, series = {Journal of applied biomechanics}, volume = {32}, journal = {Journal of applied biomechanics}, publisher = {Human Kinetics Publ.}, address = {Champaign}, issn = {1065-8483}, doi = {10.1123/jab.2015-0227}, pages = {520 -- 525}, year = {2016}, abstract = {Stability of the trunk is relevant in determining trunk response to different loading in everyday tasks initiated by the limbs. Descriptions of the trunk's mechanical movement patterns in response to different loads while lifting objects are still under debate. Hence, the aim of this study was to analyze the influence of weight on 3-dimensional segmental motion of the trunk during 1-handed lifting. Ten asymptomatic subjects were included (29 ± 3 y; 1.79 ± 0.09 m; 75 ± 14 kg). Subjects lifted 3× a light and heavy load from the ground up onto a table. Three-dimensional segmental trunk motion was measured (12 markers; 3 segments: upper thoracic area [UTA], lower thoracic area [LTA], lumbar area [LA]). Outcomes were total motion amplitudes (ROM;[°]) for anterior flexion, lateral flexion, and rotation of each segment. The highest ROM was observed in the LTA segment (anterior flexion), and the smallest ROM in the UTA segment (lateral flexion). ROM differed for all planes between the 3 segments for both tasks (P < .001). There were no differences in ROM between light and heavy loads (P > .05). No interaction effects (load × segment) were observed, as ROM did not reveal differences between loading tasks. Regardless of weight, the 3 segments did reflect differences, supporting the relevance of multisegmental analysis.}, language = {en} } @inproceedings{EngelMuellerMuelleretal.2013, author = {Engel, Tilman and M{\"u}ller, Juliane and M{\"u}ller, Steffen and Reschke, Antje and Kopinski, Stephan and Mayer, Frank}, title = {Validity and reliability of a new customised split-belt treadmill provoking unexpected walking perturbations}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {45}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {462 -- 462}, year = {2013}, language = {en} } @inproceedings{WochatzKopinskiEngeletal.2014, author = {Wochatz, Monique and Kopinski, Stephan and Engel, Tilman and M{\"u}ller, Steffen and Mayer, Frank}, title = {Flexion-extension ratio of trunk peak torque measures and antagonistic activity in males and females}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {46}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {148 -- 148}, year = {2014}, language = {en} } @inproceedings{KopinskiEngelMuelleretal.2013, author = {Kopinski, Stephan and Engel, Tilman and M{\"u}ller, Steffen and Mayer, Frank}, title = {Torque-EMG relationship of lower back muscles - a pilot study}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {45}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {7 -- 8}, year = {2013}, language = {en} } @article{MuellerEngelKopinskietal.2017, author = {M{\"u}ller, Juliane and Engel, Tilman and Kopinski, Stephan and Mayer, Frank and M{\"u}ller, Steffen}, title = {Neuromuscular trunk activation patterns in back pain patients during one-handed lifting}, series = {World journal of orthopedics}, volume = {8}, journal = {World journal of orthopedics}, number = {2}, publisher = {Baishideng Publishing Group}, address = {Pleasanton}, issn = {2218-5836}, doi = {10.5312/wjo.v8.i2.142}, pages = {142 -- 148}, year = {2017}, abstract = {AIM To analyze neuromuscular activity patterns of the trunk in healthy controls (H) and back pain patients (BPP) during one-handed lifting of light to heavy loads. METHODS RESULTS Seven subjects (3m/4f; 32 +/- 7 years; 171 +/- 7 cm; 65 +/- 11 kg) were assigned to BPP (pain grade >= 2) and 36 (13m/23f; 28 +/- 8 years; 174 +/- 10 cm; 71 +/- 12 kg) to H (pain grade <= 1). H and BPP did not differ significantly in anthropometrics (P > 0.05). All subjects were able to lift the light and middle loads, but 57\% of BPP and 22\% of H were not able to lift the heavy load (all women) chi(2) analysis revealed statistically significant differences in task failure between H vs BPP (P = 0.03). EMG-RMS ranged from 33\% +/- 10\%/30\% +/- 9\% (DL, 1 kg) to 356\% +/- 148\%/283\% +/- 80\% (VR, 20 kg) in H/BPP with no statistical difference between groups regardless of load (P > 0.05). However, the EMG-RMS of the VR was greatest in all lifting tasks for both groups and increased with heavier loads. CONCLUSION Heavier loading leads to an increase (2-to 3-fold) in trunk muscle activity with comparable patterns. Heavy loading (20 kg) leads to task failure, especially in women with back pain.}, language = {en} } @article{MuellerBaurHirschmuelleretal.2006, author = {M{\"u}ller, Steffen and Baur, Heiner and Hirschmueller, Anja and Mayer, Frank}, title = {Validit{\"a}t des COP-Verlaufes zur Quantifizierung der funktionalen Gangentwicklung bei Kindern}, year = {2006}, abstract = {Functional gait development in children is discussed controversially. Differentiated information about the roll- over process of the foot, represented by the "Center of Pressure" (COP), are still missing. The purpose of the study was the validation of the COP-path to quantify the functional gait development of children. Plantar pressure distribution was measured barefoot with an individual speed on a walkway (tartan) - in 255 children aged between 2 and 15 years. The medial and lateral area enclosed between the COP-path and the bisection of plantar angle (A(med), A(lat), Sigma: A(ml)) was calculated from plantar pressure data. Furthermore, the duration of the COP-path in the heel (COPtimeF), midfoot (COPtimeM) and forefoot (COPtimeV) was analysed. The load distribution under the medial and lateral forefoot was also calculated. The variation coefficient (VC) was calculated as a measure of interindividual variability. The medio-lateral divergency of the COP (Aml) initially decreases with advancing age (-20.2\%), followed by a continuous increase (+27.2\%). No changes in VC (A(med), A(lat), and A(ml)) appeared during age-related development. COPtimeM remains constant in all children over time. In contrast to COPtimeM, Cop(time)F decreases from youngest to oldest children (-31.0\%), and COPtimeV increases (+41.7\%). After initial descent up to 8 years of age, VC (COPtimeF, COPtimeM, COPtimeV) remains constant. The mediolateral load under the forefoot did not change. The COP-Path is able to characterise the functional gait development of children. VC values indicate high individual variability of gait pattern. In this context, age-based standard values should be critically discussed}, language = {de} } @phdthesis{Mueller2008, author = {M{\"u}ller, Steffen}, title = {Die belastungsspezifische neuromuskul{\"a}re Antwort bei Athleten mit Tendinopathie der Achilles- oder Patellarsehne : Analysen der funktionalen und therapeutischen Effekte eines sensomotorischen Trainings}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-940793-18-8}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16454}, school = {Universit{\"a}t Potsdam}, pages = {II, 137}, year = {2008}, abstract = {Tendinopathien der Achilles- oder Patellarsehne sind h{\"a}ufig in Sportarten mit zahlreichen repetitiven Belastungen im Dehnungs-Verk{\"u}rzungs-Zyklus der unteren Extremit{\"a}t zu finden. Sowohl eine m{\"o}glicherweise alterierte belastungsspezifische neuromuskul{\"a}re Antwort (NMA), als auch funktional begr{\"u}ndete Therapiemaßnahmen mit m{\"o}glichen positiven Effekten sind aktuell ungekl{\"a}rt. Ziel der Arbeit war deshalb die Untersuchung der belastungsspezifischen neuromuskul{\"a}ren Antwort bei Athleten mit Tendinopathie der Achilles- oder Patellarsehne im Vergleich zu beschwerdefreien Athleten. Zus{\"a}tzlich sollten m{\"o}gliche funktionale und therapeutische Effekte eines sensomotorischen Trainings im randomisierten, kontrollierten und prospektiven Studiendesign {\"u}berpr{\"u}ft werden. 51 Sportler mit unilateraler Tendinopathie (Achilles-/Patellarsehne n = 35/16) und 33 gesunde Sportler wurden zur Beurteilung der belastungsspezifischen neuromuskul{\"a}ren Antwort eingeschlossen. Zur Kl{\"a}rung der Effekte eines sensomotorischen Trainings im L{\"a}ngsschnitt konnten 26 Sportler mit Tendinopathie randomisiert zu einer Kontrollgruppe (n = 14) und einer Therapiegruppe mit sensomotorischem Training (n = 12) zugeordnet werden. Nach einer ersten biomechanischen Messung M1 (Belastungssituationen: Lauf-, Stabilisations-, Kraftbelastung) und der Erhebung der subjektiven Schmerzsymptomatik folgte eine 8-w{\"o}chige Therapiephase mit einer abschließenden Re-Test-Messung M2 identisch zu M1. Das sensomotorische Training war auf die gesamte untere Extremit{\"a}t ausgerichtet und wurde nach Einweisung regelm{\"a}ßig kontrolliert. Die Erfassung der NMA erfolgte {\"u}ber die Quantifizierung der muskul{\"a}ren Aktivit{\"a}t (EMG). Zus{\"a}tzlich wurde die Kinetik (z.B. Maximalkraft) belastungsspezifisch erfasst. Eine reduzierte NMA konnte f{\"u}r die Sportler mit Tendinopathie {\"u}ber ver{\"a}nderte EMG-Zeit- und Amplitudenmessgr{\"o}ßen, eine reduzierte aktive Stabilisationsf{\"a}higkeit und Maximalkraft (p < 0,05) nachgewiesen werden. In Abh{\"a}ngigkeit der Lokalisation (Achilles-/Patellarsehen) bzw. der Seite (Beschwerdeseite/gesunde Seite) ergaben sich keine relevanten Differenzen. Das sensomotorische Training zeigte eine Optimierung der NMA (z.B. erh{\"o}hte Maximalkraft) bei Tendinopathie der Achilles- oder Patellarsehne. Die {\"U}berpr{\"u}fung der Beschwerdesymptomatik wies in allen Schmerz-Scores nach der Therapie reduzierte Werte und damit einen positiven therapeutischen Effekt gegen{\"u}ber der Kontrollgruppe auf. Zusammenfassend kann eine systematisch reduzierte NMA bei Lauf-, Stabilisations- und Kraftbelastung der Sportler mit Tendinopathie nachgewiesen werden. Das sensomotorische Training ist funktional und therapeutisch als effiziente Therapiemaßnahme zu erachten.}, language = {de} } @article{MuellerHadzicMugeleetal.2017, author = {M{\"u}ller, Juliane and Hadzic, Miralem and Mugele, Hendrik and Stoll, Josefine and M{\"u}ller, Steffen and Mayer, Frank}, title = {Effect of high-intensity perturbations during core-specific sensorimotor exercises on trunk muscle activation}, series = {Journal of biomechanics}, volume = {70}, journal = {Journal of biomechanics}, publisher = {Elsevier}, address = {Oxford}, issn = {0021-9290}, doi = {10.1016/j.jbiomech.2017.12.013}, pages = {212 -- 218}, year = {2017}, abstract = {Core-specific sensorimotor exercises are proven to enhance neuromuscular activity of the trunk. However, the influence of high-intensity perturbations on training efficiency is unclear within this context. Sixteen participants (29 +/- 2 yrs; 175 +/- 8 cm; 69 +/- 13 kg) were prepared with a 12-lead bilateral trunk EMG. Warm-up on a dynamometer was followed by maximum voluntary isometric trunk (flex/ext) contraction (MVC). Next, participants performed four conditions for a one-legged stance with hip abduction on a stable surface (HA) repeated randomly on an unstable surface (HAP), on a stable surface with perturbation (HA + P), and on an unstable surface with perturbation (HAP + P). Afterwards, bird dog (BD) was performed under the same conditions (BD, BDP, BD + P, BDP + P). A foam pad under the foot (HA) or the knee (BD) was used as an unstable surface. Exercises were conducted on a moveable platform. Perturbations (ACC 50 m/sec(2);100 ms duration;10rep.) were randomly applied in the anterior-posterior direction. The root mean square (RMS) normalized to MVC (\%) was calculated (whole movement cycle). Muscles were grouped into ventral right and left (VR;VL), and dorsal right and left (DR;DL). Ventral Dorsal and right-left ratios were calculated (two way repeated-measures ANOVA;alpha = 0,05). Amplitudes of all muscle groups in bird dog were higher compared to hip abduction (p <= 0.0001; Range: BD: 14 +/- 3\% (BD;VR) to 53 +/- 4\%; HA: 7 +/- 2\% (HA;DR) to 16 +/- 4\% (HA;DR)). EMG-RMS showed significant differences (p < 0.001) between conditions and muscle groups per exercise. Interaction effects were only significant for HA (p = 0.02). No significant differences were present in EMG ratios (p > 0.05). Additional high-intensity perturbations during core-specific sensorimotor exercises lead to increased neuromuscular activity and therefore higher exercise intensities. However, the beneficial effects on trunk function remain unclear. Nevertheless, BD is more suitable to address trunk muscles.}, language = {en} } @article{MayerBonaventuraCasseletal.2012, author = {Mayer, Frank and Bonaventura, Klaus and Cassel, Michael and M{\"u}ller, Steffen and Weber, Josefine and Scharhag-Rosenberger, Friederike and Carlsohn, Anja and Baur, Heiner and Scharhag, J{\"u}rgen}, title = {Medical results of preparticipation examination in adolescent athletes}, series = {British journal of sports medicine : the journal of sport and exercise medicine}, volume = {46}, journal = {British journal of sports medicine : the journal of sport and exercise medicine}, number = {7}, publisher = {BMJ Publ. Group}, address = {London}, issn = {0306-3674}, doi = {10.1136/bjsports-2011-090966}, pages = {524 -- 530}, year = {2012}, abstract = {Background Preparticipation examinations (PPE) are frequently used to evaluate eligibility for competitive sports in adolescent athletes. Nevertheless, the effectiveness of these examinations is under debate since costs are high and its validity is discussed controversial. Purpose To analyse medical findings and consequences in adolescent athletes prior to admission to a sports school. Methods In 733 adolescent athletes (318 girls, 415 boys, age 12.3+/-0.4, 16 sports disciplines), history and clinical examination (musculoskeletal, cardiovascular, general medicine) was performed to evaluate eligibility. PPE was completed by determination of blood parameters, ECG at rest and during ergometry, echocardiography and x-rays and ultrasonography if indicated. Eligibility was either approved or rated with restriction. Recommendations for therapy and/or prevention were given to the athletes and their parents. Results Historical (h) and clinical (c) findings (eg, pain, verified pathologies) were more frequent regarding the musculoskeletal system (h: 120, 16.4\%; c: 247, 33.7\%) compared to cardiovascular (h: 9, 1.2\%; c: 23, 3.1\%) or general medicine findings (h: 116, 15.8\%; c: 71, 9.7\%). ECG at rest was moderately abnormal in 46 (6.3\%) and severely abnormal in 25 athletes (3.4\%). Exercise ECG was suspicious in 25 athletes (3.4\%). Relevant echocardiographic abnormalities were found in 17 athletes (2.3\%). In 52 of 358 cases (14.5\%), x-rays led to diagnosis (eg, Spondylolisthesis). Eligibility was temporarily restricted in 41 athletes (5.6\%). Three athletes (0.4\%) had to be excluded from competitive sports. Therapy (eg, physiotherapy, medication) and/or prevention (sensorimotor training, vaccination) recommendations were deduced due to musculoskeletal (t:n = 76,10.3\%; p:n = 71,9.8\%) and general medicine findings (t:n = 80, 10.9\%; p:n = 104, 14.1\%). Conclusion Eligibility for competitive sports is restricted in only 5.5\% of adolescent athletes at age 12. Eligibility refusals are rare. However, recommendations for therapy and prevention are frequent, mainly regarding the musculoskeletal system. In spite of time and cost consumption, adolescent preparticipation before entering a career in high-performance sports is supported.}, language = {en} } @article{CasselMuellerCarlsohnetal.2012, author = {Cassel, Michael and M{\"u}ller, Steffen and Carlsohn, Anja and Baur, Heiner and Jerusel, N. and Mayer, Frank}, title = {Intra- and interrater variability of sonographic investigations of patella and achilles tendons}, series = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, volume = {26}, journal = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, number = {1}, publisher = {Thieme}, address = {Stuttgart}, issn = {0932-0555}, doi = {10.1055/s-0031-1281839}, pages = {21 -- 26}, year = {2012}, abstract = {Background: Clinical examinations of tendon disorders routinely include ultrasound examinations, despite the fact that availability of data concerning validity criteria of these measurements are limited. The present study therefore aims to evaluate the reliability of measurements of Achilles- and Patella tendon diameter and in the detection of structural adaptations. Materials and Methods: In 14 healthy, recreationally active subjects both asymptomatic Achilles (AT) and patella tendons (PT) were measured twice by two examiners in a test-retest design. Besides the detection of anteroposterior (a.p.-) and mediolateral (m.l.-) diameters, areas of hypoechogenicity and neovascularisation were registered. Data were analysed descriptively with calculation of test-retest variability (TRV), intraclass-correlation coefficient (ICC) and Bland and Altman's plots with bias and 95\% limits of agreement (LOA). Results: Intra- and interrater differences of AT- and PT-a.p.-diameter varied from 0.2 - 1.2 mm, those of AT- and PT-m.l-diameter from 0.7-5.1 mm. Areas of hypoechogenicity were visible in 24\% of the tendons, while 15\% showed neovascularisations. Intrarater AT-a.p.-diameters showed sparse deviations (TRV 4.5-7.4\%; ICC 0.60-0.84; bias -0.05-0.07 mm; LOA-0.6-0.5 to -1.1 - 1.0 mm), while interrater AT- and PT-m.l.-diameters were highly variable (TRV 13.7-19.7\%; ICC 0.11-0.20; bias -1.4-4.3 mm; LOA-5.5-2.7 to -10.5 - 1.9 mm). Conclusion: Our results suggest that the measurement of AT- and PT-a.p.-diameters is a reliable parameter. In contrast, reproducibility of AT- and PT-m.l.-diameters is questionable. The study corroborates the presence of hypoechogenicity and neovascularisation in asymptomatic tendons.}, language = {de} } @article{BaurHirschmuellerMuelleretal.2012, author = {Baur, Heiner and Hirschm{\"u}ller, Anja and M{\"u}ller, Steffen and Cassel, Michael and Mayer, Frank}, title = {Is EMG of the lower leg dependent on weekly running mileage?}, series = {International journal of sports medicine}, volume = {33}, journal = {International journal of sports medicine}, number = {1}, publisher = {Thieme}, address = {Stuttgart}, issn = {0172-4622}, doi = {10.1055/s-0031-1286250}, pages = {53 -- 57}, year = {2012}, abstract = {Neuromuscular activity of the lower leg is dependent on the task performed, speed of movement and gender. Whether training volume influences neuromuscular activity is not known. The EMG of physically active persons differing in running mileage was analysed to investigate this. 55 volunteers were allocated to a low (LM: < 30 km), intermediate (IM: > 30 km \& < 45 km) or high mileage (HM: > 45 km) group according to their weekly running volume. Neuromuscular activity of the lower leg was measured during running (3.33 m.s(-1)). Mean amplitude values for preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle. Higher activity in the gastrocnemius group was observed in weight acceptance in LM compared to IM (+30\%) and HM (+25\%) but lower activity was present in the push-off for LM compared to IM and HM. For the peroneal muscle, differences were present in the push-off where HM showed increased activity compared to IM (+24\%) and LM (+60\%). The tibial muscle revealed slightly lower activity during preactivation for the high mileage runners. Neuromuscular activity differs during stance between the high and intermediate group compared to low mileage runners. Slight adaptations in neuromuscular activation indicate a more target-oriented activation strategy possibly due to repetitive training in runners with higher weekly mileage.}, language = {en} } @inproceedings{IntziegianniCasselMuelleretal.2012, author = {Intziegianni, Konstantina and Cassel, Michael and M{\"u}ller, Steffen and Mayer, Frank}, title = {Ultrasound evaluation of the patellar tendon cross-sectional area and its relation to maximum force}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {44}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {714 -- 714}, year = {2012}, language = {en} } @inproceedings{MuellerCasselMuelleretal.2014, author = {M{\"u}ller, Steffen and Cassel, Michael and M{\"u}ller, Juliane and Stoll, Josefine and Baur, Heiner and Mayer, Frank}, title = {Trunk strength in adolescent athletes with Spondylolisthesis with/without back pain during training: Pilot study}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {46}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {642 -- 642}, year = {2014}, language = {en} } @misc{MuellerMuellerStolletal.2017, author = {M{\"u}ller, Steffen and M{\"u}ller, Juliane and Stoll, Josefine and Prieske, Olaf and Cassel, Michael and Mayer, Frank}, title = {Incidence of back pain in adolescent athletes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-101874}, pages = {5}, year = {2017}, abstract = {Background Recently, the incidence rate of back pain (BP) in adolescents has been reported at 21\%. However, the development of BP in adolescent athletes is unclear. Hence, the purpose of this study was to examine the incidence of BP in young elite athletes in relation to gender and type of sport practiced. Methods Subjective BP was assessed in 321 elite adolescent athletes (m/f 57\%/43\%; 13.2 ± 1.4 years; 163.4 ± 11.4 cm; 52.6 ± 12.6 kg; 5.0 ± 2.6 training yrs; 7.6 ± 5.3 training h/week). Initially, all athletes were free of pain. The main outcome criterion was the incidence of back pain [\%] analyzed in terms of pain development from the first measurement day (M1) to the second measurement day (M2) after 2.0 ± 1.0 year. Participants were classified into athletes who developed back pain (BPD) and athletes who did not develop back pain (nBPD). BP (acute or within the last 7 days) was assessed with a 5-step face scale (face 1-2 = no pain; face 3-5 = pain). BPD included all athletes who reported faces 1 and 2 at M1 and faces 3 to 5 at M2. nBPD were all athletes who reported face 1 or 2 at both M1 and M2. Data was analyzed descriptively. Additionally, a Chi2 test was used to analyze gender- and sport-specific differences (p = 0.05). Results Thirty-two athletes were categorized as BPD (10\%). The gender difference was 5\% (m/f: 12\%/7\%) but did not show statistical significance (p = 0.15). The incidence of BP ranged between 6 and 15\% for the different sport categories. Game sports (15\%) showed the highest, and explosive strength sports (6\%) the lowest incidence. Anthropometrics or training characteristics did not significantly influence BPD (p = 0.14 gender to p = 0.90 sports; r2 = 0.0825). Conclusions BP incidence was lower in adolescent athletes compared to young non-athletes and even to the general adult population. Consequently, it can be concluded that high-performance sports do not lead to an additional increase in back pain incidence during early adolescence. Nevertheless, back pain prevention programs should be implemented into daily training routines for sport categories identified as showing high incidence rates.}, language = {en} } @article{MuellerMuellerStolletal.2016, author = {M{\"u}ller, Steffen and M{\"u}ller, Juliane and Stoll, Josefine and Prieske, Olaf and Cassel, Michael and Mayer, Frank}, title = {Incidence of back pain in adolescent athletes}, series = {BMC sports science, medicine \& rehabilitation}, volume = {8}, journal = {BMC sports science, medicine \& rehabilitation}, publisher = {BioMed Central}, address = {London}, issn = {2052-1847}, doi = {10.1186/s13102-016-0064-7}, pages = {5}, year = {2016}, abstract = {Background Recently, the incidence rate of back pain (BP) in adolescents has been reported at 21\%. However, the development of BP in adolescent athletes is unclear. Hence, the purpose of this study was to examine the incidence of BP in young elite athletes in relation to gender and type of sport practiced. Methods Subjective BP was assessed in 321 elite adolescent athletes (m/f 57\%/43\%; 13.2 ± 1.4 years; 163.4 ± 11.4 cm; 52.6 ± 12.6 kg; 5.0 ± 2.6 training yrs; 7.6 ± 5.3 training h/week). Initially, all athletes were free of pain. The main outcome criterion was the incidence of back pain [\%] analyzed in terms of pain development from the first measurement day (M1) to the second measurement day (M2) after 2.0 ± 1.0 year. Participants were classified into athletes who developed back pain (BPD) and athletes who did not develop back pain (nBPD). BP (acute or within the last 7 days) was assessed with a 5-step face scale (face 1-2 = no pain; face 3-5 = pain). BPD included all athletes who reported faces 1 and 2 at M1 and faces 3 to 5 at M2. nBPD were all athletes who reported face 1 or 2 at both M1 and M2. Data was analyzed descriptively. Additionally, a Chi2 test was used to analyze gender- and sport-specific differences (p = 0.05). Results Thirty-two athletes were categorized as BPD (10\%). The gender difference was 5\% (m/f: 12\%/7\%) but did not show statistical significance (p = 0.15). The incidence of BP ranged between 6 and 15\% for the different sport categories. Game sports (15\%) showed the highest, and explosive strength sports (6\%) the lowest incidence. Anthropometrics or training characteristics did not significantly influence BPD (p = 0.14 gender to p = 0.90 sports; r2 = 0.0825). Conclusions BP incidence was lower in adolescent athletes compared to young non-athletes and even to the general adult population. Consequently, it can be concluded that high-performance sports do not lead to an additional increase in back pain incidence during early adolescence. Nevertheless, back pain prevention programs should be implemented into daily training routines for sport categories identified as showing high incidence rates.}, language = {en} } @article{BaurHirschmuellerCasseletal.2010, author = {Baur, Heiner and Hirschm{\"u}ller, Anja and Cassel, Michael and M{\"u}ller, Steffen and Mayer, Frank}, title = {Gender-specific neuromuscular activity of the M. peroneus longus in healthy runners : a descriptive laboratory study}, issn = {0268-0033}, doi = {10.1016/j.clinbiomech.2010.06.009}, year = {2010}, abstract = {Background: Gender-specific neuromuscular activity for the ankle (e.g., peroneal muscle) is currently not known. This knowledge may contribute to the understanding of overuse injury mechanisms. The purpose was therefore to analyse the neuromuscular activity of the peroneal muscle in healthy runners. Methods: Fifty-three male and 54 female competitive runners were tested on a treadmill at 3.33 m s(-1). Neuromuscular activity of the M. peroneus longus was measured by electromyography and analysed in the time domain (onset of activation, time of maximum of activation, total time of activation) in \% of stride time in relation to touchdown (= 1.0). Additionally, mean amplitudes for the gait cycle phases preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle. Findings: Onset of activation (mean; female: 0.86/male: 0.90, p<0.0001) and time of maximum of activation (female: 1.13/male: 1.16, p<0.0001) occurred earlier in female compared to male and the total time of activation was longer in women (female: 0.42/male: 0.39, p=0.0036). In preactivation, women showed higher amplitudes (+ 21\%) compared to men (female: 1.16/male: 0.92, p<0.0001). Activity during weight acceptance (female: 2.26/male: 2.41, p = 0.0039) and push-off (female: 0.93/male: 1.07, p = 0.0027) were higher in men. Interpretation: Activation strategies of the peroneal muscle appear to be gender-specific. Higher preactivation amplitudes in females indicate a different neuromuscular control in anticipation of touchdown ("pre-programmed activity"). These data may help interpret epidemiologically reported differences between genders in overuse injury frequency and localisation.}, language = {en} } @article{BaurMuellerHirschmuelleretal.2011, author = {Baur, Heiner and M{\"u}ller, Steffen and Hirschm{\"u}ller, Anja and Cassel, Michael and Weber, Josefine and Mayer, Frank}, title = {Comparison in lower leg neuromuscular activity between runners with unilateral mid-portion Achilles tendinopathy and healthy individuals}, series = {Journal of electromyography and kinesiology}, volume = {21}, journal = {Journal of electromyography and kinesiology}, number = {3}, publisher = {Elsevier}, address = {Oxford}, issn = {1050-6411}, doi = {10.1016/j.jelekin.2010.11.010}, pages = {499 -- 505}, year = {2011}, abstract = {Neuromuscular control in functional situations and possible impairments due to Achilles tendinopathy are not well understood. Thirty controls (CO) and 30 runners with Achilles tendinopathy (AT) were tested on a treadmill at 3.33 m s(-1) (12 km h(-1)). Neuromuscular activity of the lower leg (tibialis anterior, peroneal, and gastrocnemius muscle) was measured by surface electromyography. Mean amplitude values (MAV) for the gait cycle phases preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle. MAVs of the tibialis anterior did not differ between CO and AT in any gait cycle phase. The activation of the peroneal muscle was lower in AT in weight acceptance (p = 0.006), whereas no difference between CO and AT was found in preactivation (p = 0.71) and push-off (p = 0.83). Also, MAVs of the gastrocnemius muscle did not differ between AT and CO in preactivity (p = 0.71) but were reduced in AT during weight acceptance (p = 0.001) and push-off (p = 0.04). Achilles tendinopathy does not seem to alter pre-programmed neural control but might induce mechanical deficits of the lower extremity during weight bearing (joint stability). This should be addressed in the therapy process of AT.}, language = {en} } @misc{MayerScharhagRosenbergerCarlsohnetal.2011, author = {Mayer, Frank and Scharhag-Rosenberger, Friederike and Carlsohn, Anja and Cassel, Michael and M{\"u}ller, Steffen and Scharhag, J{\"u}rgen}, title = {The intensity and effects of strength training in the elderly}, series = {Deutsches {\"A}rzteblatt international : a weekly online journal of clinical medicine and public health}, volume = {108}, journal = {Deutsches {\"A}rzteblatt international : a weekly online journal of clinical medicine and public health}, number = {21}, publisher = {Dt. {\"A}rzte-Verl.}, address = {Cologne}, issn = {1866-0452}, doi = {10.3238/arztebl.2011.0359}, pages = {359 -- U30}, year = {2011}, abstract = {Background: The elderly need strength training more and more as they grow older to stay mobile for their everyday activities. The goal of training is to reduce the loss of muscle mass and the resulting loss of motor function. The dose-response relationship of training intensity to training effect has not yet been fully elucidated. Methods: PubMed was selectively searched for articles that appeared in the past 5 years about the effects and dose-response relationship of strength training in the elderly. Results: Strength training in the elderly (> 60 years) increases muscle strength by increasing muscle mass, and by improving the recruitment of motor units, and increasing their firing rate. Muscle mass can be increased through training at an intensity corresponding to 60\% to 85\% of the individual maximum voluntary strength. Improving the rate of force development requires training at a higher intensity (above 85\%), in the elderly just as in younger persons. It is now recommended that healthy old people should train 3 or 4 times weekly for the best results; persons with poor performance at the outset can achieve improvement even with less frequent training. Side effects are rare. Conclusion: Progressive strength training in the elderly is efficient, even with higher intensities, to reduce sarcopenia, and to retain motor function.}, language = {en} } @misc{MuellerStollCasseletal.2017, author = {M{\"u}ller, Steffen and Stoll, Josefine and Cassel, Michael and Mayer, Frank}, title = {Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-395261}, pages = {9}, year = {2017}, abstract = {In the context of back pain, great emphasis has been placed on the importance of trunk stability, especially in situations requiring compensation of repetitive, intense loading induced during high-performance activities, e.g., jumping or landing. This study aims to evaluate trunk muscle activity during drop jump in adolescent athletes with back pain (BP) compared to athletes without back pain (NBP). Eleven adolescent athletes suffering back pain (BP: m/f: n = 4/7; 15.9 ± 1.3 y; 176 ± 11 cm; 68 ± 11 kg; 12.4 ± 10.5 h/we training) and 11 matched athletes without back pain (NBP: m/f: n = 4/7; 15.5 ± 1.3 y; 174 ± 7 cm; 67 ± 8 kg; 14.9 ± 9.5 h/we training) were evaluated. Subjects conducted 3 drop jumps onto a force plate (ground reaction force). Bilateral 12-lead SEMG (surface Electromyography) was applied to assess trunk muscle activity. Ground contact time [ms], maximum vertical jump force [N], jump time [ms] and the jump performance index [m/s] were calculated for drop jumps. SEMG amplitudes (RMS: root mean square [\%]) for all 12 single muscles were normalized to MIVC (maximum isometric voluntary contraction) and analyzed in 4 time windows (100 ms pre- and 200 ms post-initial ground contact, 100 ms pre- and 200 ms post-landing) as outcome variables. In addition, muscles were grouped and analyzed in ventral and dorsal muscles, as well as straight and transverse trunk muscles. Drop jump ground reaction force variables did not differ between NBP and BP (p > 0.05). Mm obliquus externus and internus abdominis presented higher SEMG amplitudes (1.3-1.9-fold) for BP (p < 0.05). Mm rectus abdominis, erector spinae thoracic/lumbar and latissimus dorsi did not differ (p > 0.05). The muscle group analysis over the whole jumping cycle showed statistically significantly higher SEMG amplitudes for BP in the ventral (p = 0.031) and transverse muscles (p = 0.020) compared to NBP. Higher activity of transverse, but not straight, trunk muscles might indicate a specific compensation strategy to support trunk stability in athletes with back pain during drop jumps. Therefore, exercises favoring the transverse trunk muscles could be recommended for back pain treatment.}, language = {en} } @article{MuellerStollCasseletal.2017, author = {M{\"u}ller, Steffen and Stoll, Josefine and Cassel, Michael and Mayer, Frank}, title = {Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain}, series = {Frontiers in physiology}, volume = {8}, journal = {Frontiers in physiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2017.00274}, year = {2017}, abstract = {In the context of back pain, great emphasis has been placed on the importance of trunk stability, especially in situations requiring compensation of repetitive, intense loading induced during high-performance activities, e.g., jumping or landing. This study aims to evaluate trunk muscle activity during drop jump in adolescent athletes with back pain (BP) compared to athletes without back pain (NBP). Eleven adolescent athletes suffering back pain (BP: m/f: n = 4/7; 15.9 ± 1.3 y; 176 ± 11 cm; 68 ± 11 kg; 12.4 ± 10.5 h/we training) and 11 matched athletes without back pain (NBP: m/f: n = 4/7; 15.5 ± 1.3 y; 174 ± 7 cm; 67 ± 8 kg; 14.9 ± 9.5 h/we training) were evaluated. Subjects conducted 3 drop jumps onto a force plate (ground reaction force). Bilateral 12-lead SEMG (surface Electromyography) was applied to assess trunk muscle activity. Ground contact time [ms], maximum vertical jump force [N], jump time [ms] and the jump performance index [m/s] were calculated for drop jumps. SEMG amplitudes (RMS: root mean square [\%]) for all 12 single muscles were normalized to MIVC (maximum isometric voluntary contraction) and analyzed in 4 time windows (100 ms pre- and 200 ms post-initial ground contact, 100 ms pre- and 200 ms post-landing) as outcome variables. In addition, muscles were grouped and analyzed in ventral and dorsal muscles, as well as straight and transverse trunk muscles. Drop jump ground reaction force variables did not differ between NBP and BP (p > 0.05). Mm obliquus externus and internus abdominis presented higher SEMG amplitudes (1.3-1.9-fold) for BP (p < 0.05). Mm rectus abdominis, erector spinae thoracic/lumbar and latissimus dorsi did not differ (p > 0.05). The muscle group analysis over the whole jumping cycle showed statistically significantly higher SEMG amplitudes for BP in the ventral (p = 0.031) and transverse muscles (p = 0.020) compared to NBP. Higher activity of transverse, but not straight, trunk muscles might indicate a specific compensation strategy to support trunk stability in athletes with back pain during drop jumps. Therefore, exercises favoring the transverse trunk muscles could be recommended for back pain treatment.}, language = {en} } @article{IntziegianniCasselKoenigetal.2015, author = {Intziegianni, Konstantina and Cassel, Michael and K{\"o}nig, Niklas and M{\"u}ller, Steffen and Fr{\"o}hlich, Katja and Mayer, Frank}, title = {Ultrasonography for the assessment of the structural properties of the Achilles tendon in asymptomatic individuals: An intra-rater reproducibility study}, series = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, volume = {23}, journal = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0959-3020}, doi = {10.3233/IES-150586}, pages = {263 -- 270}, year = {2015}, abstract = {BACKGROUND: Reproducible measurements of tendon structural properties are a prerequisite for accurate diagnosis of tendon disorders and for determination of their mechanical properties. Despite the widely used application of Ultrasonography (US) in musculoskeletal assessment, its operator dependency and lack of standardization influences the consistency of the measurement. OBJECTIVE: To evaluate the intra-rater reproducibility of a standardized US method assessing the structural properties of the Achilles tendon (AT). METHODS: Sixteen asymptomatic participants were positioned prone on an isokinetic dynamometer with the knee extended and ankle at 90. flexion. US was used to assess AT-length, cross-sectional area (CSA), and AT-elongation during isometric plantarflexion contraction. The intra-rater reproducibility was assessed by ICC (2.1), Test-Retest Variability (TRV, \%), Bland-Altman analyses (Bias +/- LoA [1.96*SD]), and Standard-Error of Measurement (SEM). RESULTS: Measurements of AT-length demonstrated an ICC of 0.93, TRV of 4.5 +/- 3.9\%, Bias +/- LoA of -2.8 +/- 25.0 mm and SEM of 6.6 mm. AT-CSA showed an ICC of 0.79, TRV of 8.7 +/- 9.6\%, Bias +/- LoA of 1.7 +/- 19.4 mm(2) and SEM of 5.3 mm(2). AT-elongation revealed an ICC of 0.92, TRV of 12.9 +/- 8.9\%, Bias +/- LoA of 0.3 +/- 5.7 mm and SEM of 1.5 mm. CONCLUSIONS: The presented methodology allows a reproducible assessment of Achilles tendon structural properties when performed by a single rater.}, language = {en} } @misc{AppiahDwomohMuellerHadzicetal.2017, author = {Appiah-Dwomoh, Edem Korkor and M{\"u}ller, Steffen and Hadzic, Miralem and Mayer, Frank}, title = {Star Excursion Balance Test in young athletes with back pain}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400441}, pages = {11}, year = {2017}, abstract = {The Star Excursion Balance Test (SEBT) is effective in measuring dynamic postural control (DPC). This research aimed to determine whether DPC measured by the SEBT in young athletes (YA) with back pain (BP) is different from those without BP (NBP). 53 BP YA and 53 NBP YA matched for age, height, weight, training years, training sessions/week and training minutes/session were studied. Participants performed 4 practice trials after which 3 measurements in the anterior, posteromedial and posterolateral SEBT reach directions were recorded. Normalized reach distance was analyzed using the mean of all 3 measurements. There was no statistical significant difference (p > 0.05) between the reach distance of BP (87.2 ± 5.3, 82.4 ± 8.2, 78.7 ± 8.1) and NBP (87.8 ± 5.6, 82.4 ± 8.0, 80.0 ± 8.8) in the anterior, posteromedial and posterolateral directions respectively. DPC in YA with BP, as assessed by the SEBT, was not different from NBP YA.}, language = {en} } @article{AppiahDwomohMuellerMayer2019, author = {Appiah-Dwomoh, Edem Korkor and M{\"u}ller, Steffen and Mayer, Frank}, title = {Is there an association between variables of static and dynamic postural control in adolescent athletes with back pain?}, series = {German Journal of Exercise and Sport Research}, volume = {49}, journal = {German Journal of Exercise and Sport Research}, number = {2}, publisher = {Springer}, address = {New York}, issn = {2509-3142}, doi = {10.1007/s12662-019-00573-6}, pages = {150 -- 155}, year = {2019}, abstract = {An association between static and dynamic postural control exists in adults with back pain. We aimed to determine whether this association also exists in adolescent athletes with the same condition. In all, 128 athletes with and without back pain performed three measurements of 15s of static (one-legged stance) and dynamic (star excursion balance test) postural control tests. All subjects and amatched subgroup of athletes with and without back pain were analyzed. The smallest center of pressure mediolateral and anterior-posterior displacements (mm) and normalized highest reach distance were the outcome measures. No association was found between variables of the static and dynamic tests for all subjects and the matched group with and without back pain. The control of static and dynamic posture in adolescent athletes with and without back pain might not be related.}, language = {en} } @phdthesis{Mueller2018, author = {M{\"u}ller, Steffen}, title = {Relevance of back bain and validity of neuromuscular diagnostics in adolescent athletes}, address = {Potsdam}, school = {Universit{\"a}t Potsdam}, pages = {135}, year = {2018}, language = {en} } @article{MuellerStollMuelleretal.2017, author = {M{\"u}ller, Steffen and Stoll, Josefine and Mueller, Juliane and Cassel, Michael and Mayer, Frank}, title = {Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain}, series = {Frontiers in physiology}, volume = {8}, journal = {Frontiers in physiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2017.00274}, pages = {124 -- 132}, year = {2017}, abstract = {In the context of back pain, great emphasis has been placed on the importance of trunk stability, especially in situations requiring compensation of repetitive, intense loading induced during high-performance activities, e.g., jumping or landing. This study aims to evaluate trunk muscle activity during drop jump in adolescent athletes with back pain (BP) compared to athletes without back pain (NBP). Eleven adolescent athletes suffering back pain (BP: m/f: n = 4/7; 15.9 +/- 1.3 y; 176 +/- 11 cm; 68 +/- 11 kg; 12.4 +/- 10.5 h/we training) and 11 matched athletes without back pain (NBP: m/f: n = 4/7; 15.5 +/- 1.3 y; 174 +/- 7 cm; 67 +/- 8 kg; 14.9 +/- 9.5 h/we training) were evaluated. Subjects conducted 3 drop jumps onto a force plate (ground reaction force). Bilateral 12-lead SEMG (surface Electromyography) was applied to assess trunk muscle activity. Ground contact time [ms], maximum vertical jump force [N], jump time [ms] and the jump performance index [m/s] were calculated for drop jumps. SEMG amplitudes (RMS: root mean square [\%]) for all 12 single muscles were normalized toMIVC (maximum isometric voluntary contraction) and analyzed in 4 time windows (100 ms pre- and 200 ms post-initial ground contact, 100 ms pre- and 200 ms post-landing) as outcome variables. In addition, muscles were grouped and analyzed in ventral and dorsal muscles, as well as straight and transverse trunk muscles. Drop jump ground reaction force variables did not differ between NBP and BP (p > 0.05). Mm obliquus externus and internus abdominis presented higher SEMG amplitudes (1.3-1.9-fold) for BP (p < 0.05). Mm rectus abdominis, erector spinae thoracic/lumbar and latissimus dorsi did not differ (p > 0.05). The muscle group analysis over the whole jumping cycle showed statistically significantly higher SEMG amplitudes for BP in the ventral (p = 0.031) and transverse muscles (p = 0.020) compared to NBP. Higher activity of transverse, but not straight, trunk muscles might indicate a specific compensation strategy to support trunk stability in athletes with back pain during drop jumps. Therefore, exercises favoring the transverse trunk muscles could be recommended for back pain treatment.}, language = {en} } @article{RectorIntziegianniMuelleretal.2017, author = {Rector, Michael V. and Intziegianni, Konstantina and M{\"u}ller, Steffen and Mayer, Frank and Cassel, Michael}, title = {Reproducibility of an ankle joint rotation correction method for assessment of Achilles tendon elongation}, series = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, volume = {25}, journal = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, number = {1}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0959-3020}, doi = {10.3233/IES-160644}, pages = {47 -- 52}, year = {2017}, abstract = {BACKGROUND: The Achilles tendon (AT) requires optimal material and mechanical properties to function properly. Calculation of these properties depends on accurate measurement of input parameters (i.e. tendon elongation). However, the measurement of AT elongation with ultrasound during maximum voluntary isometric contraction (MVIC) is overestimated by ankle joint rotation (AJR). Methods to correct the influence of this rotation on AT elongation exist, yet their reproducibility in clinical settings is unknown. OBJECTIVE: To evaluate the test-retest reproducibility of AT elongation during MVIC after AJR correction. METHODS: Ten participants attended test and retest measurements where they performed plantar-flexion MVIC on a dynamometer. Simultaneously, ultrasound recorded AT elongation as the displacement of the medial gastrocnemius-myotendinous junction, while an electrogoniometer measured AJR. The ankle was then passively rotated to the AJR achieved during MVIC and AT elongation again determined. Elongation was corrected by subtracting this passive AT elongation from the total AT elongation during MVIC. Reproducibility was evaluated using ICC (2.1), test-retest variability (TRV, \%), Bland-Altman analyses (Bias +/- LoA [1.96*SD]) and standard error of the measurement (SEM). RESULTS: Corrected AT elongation reproducibility exhibited an ICC = 0.79, SEM = 0.2 cm and TRV = 20 +/- 19\%. Bias +/- LoA were determined to be 0.0 +/- 0.8 cm. CONCLUSIONS: Using this ultrasound and electrogoniometer-based method, corrected AT elongation can be assessed reproducibly.}, language = {en} } @article{KoenigReschkeWolteretal.2013, author = {K{\"o}nig, Niklas and Reschke, Antje and Wolter, Martin and M{\"u}ller, Steffen and Mayer, Frank and Baur, Heiner}, title = {Plantar pressure trigger for reliable nerve stimulus application during dynamic H-reflex measurements}, series = {Gait \& posture}, volume = {37}, journal = {Gait \& posture}, number = {4}, publisher = {Elsevier}, address = {Clare}, issn = {0966-6362}, doi = {10.1016/j.gaitpost.2012.09.021}, pages = {637 -- 639}, year = {2013}, abstract = {In dynamic H-reflex measurements, the standardisation of the nerve stimulation to the gait cycle is crucial to avoid misinterpretation due to altered pre-synaptic inhibition. In this pilot study, a plantar pressure sole was used to trigger the stimulation of the tibialis nerve with respect to the gait cycle. Consequently, the intersession reliability of the soleus muscle H-reflex during treadmill walking was investigated. Seven young participants performed walking trials on a treadmill at 5 km/h. The stimulating electrode was placed on the tibial nerve in the popliteal fossa. An EMG was recorded from the soleus muscle. To synchronize the stimulus to the gait cycle, initial heel strike was detected with a plantar pressure sole. Maximum H-reflex amplitude and M-wave amplitude were obtained and the Hmax/Mmax ratio was calculated. Data reveals excellent reliability, ICC = 0.89. Test-retest variability was 13.0\% (+/- 11.8). The Bland-Altman analysis showed a systematic error of 2.4\%. The plantar pressure sole was capable of triggering the stimulation of the tibialis nerve in a reliable way and offers a simple technique for the evaluation of reflex activity during walking.}, language = {en} } @article{MuellerMuellerBauretal.2013, author = {M{\"u}ller, Juliane and M{\"u}ller, Steffen and Baur, Heiner and Mayer, Frank}, title = {Intra-individual gait speed variability in healthy children aged 1-15 years}, series = {Gait \& posture}, volume = {38}, journal = {Gait \& posture}, number = {4}, publisher = {Elsevier}, address = {Clare}, issn = {0966-6362}, doi = {10.1016/j.gaitpost.2013.02.011}, pages = {631 -- 636}, year = {2013}, abstract = {Introduction: Gait speed is one of the most commonly and frequently used parameters to evaluate gait development. It is characterized by high variability when comparing different steps in children. The objective of this study was to determine intra-individual gait speed variability in children. Methods: Gait speed measurements (6-10 trials across a 3 m walkway) were performed and analyzed in 8263 children, aged 1-15 years. The coefficient of variation (CV) served as a measure for intra-individual gait speed variability measured in 6.6 +/- 1.0 trials per child. Multiple linear regression analysis was conducted to evaluate the influence of age and body height on changes in variability. Additionally, a subgroup analysis for height within the group of 6-year-old children was applied. Results: A successive reduction in gait speed variability (CV) was observed for age groups (age: 1-15 years) and body height groups (height: 0.70-1.90 m). The CV in the oldest subjects was only one third of the CV (CV 6.25 +/- 3.52\%) in the youngest subjects (CV 16.58 +/- 10.01\%). Up to the age of 8 years (or 1.40 m height) there was a significant reduction in CV over time, compared to a leveling off for the older (taller) children. Discussion: The straightforward approach measuring gait speed variability in repeated trials might serve as a fundamental indicator for gait development in children. Walking velocity seems to increase to age 8. Enhanced gait speed consistency of repeated trials develops up to age 15.}, language = {en} } @inproceedings{ReschkeMuellerMuelleretal.2013, author = {Reschke, Antje and M{\"u}ller, Juliane and M{\"u}ller, Steffen and Engel, Tilman and Mayer, Frank}, title = {Three-dimensional spine kinematics during perturbed treadmill walking - a pilot study}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {45}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {172 -- 172}, year = {2013}, language = {en} } @inproceedings{HainMuellerMuelleretal.2013, author = {Hain, Gerrit and M{\"u}ller, Juliane and M{\"u}ller, Steffen and Reschke, Antje and Mayer, Frank}, title = {Reliability of an in-vivo 3-segmental kinematic trunk model in a one-handed lifting task}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {45}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {174 -- 174}, year = {2013}, language = {en} } @unpublished{BaurHoffmannReichmuthetal.2012, author = {Baur, Heiner and Hoffmann, Jan and Reichmuth, Anne and M{\"u}ller, Steffen and Mayer, Frank}, title = {Influence of carbon fiber foot orthoses on plantar pressure distribution in cycling}, series = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, volume = {26}, journal = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, number = {1}, publisher = {Thieme}, address = {Stuttgart}, issn = {0932-0555}, pages = {12 -- 17}, year = {2012}, abstract = {Background: Several equipment interventions like optimizing seat position or optimizing shoe/insole/pedal interface are suggested to reduce overuse injury in cycling. Data analyzing clinical or biomechanical effects of those interventions is sparse. Foot orthoses out of carbon fiber are one possibility to alter the interface between foot and pedal. The aim of this study was therefore to analyze plantar pressure distribution in carbon fiber foot orthoses in comparison to standard insoles of commercially available cycling shoes. Materials and Methods: 11 pain-free triathletes (Age: 29 +/- 9, 1.77 +/- 0.04 m, 68 5 kg) were tested on a cycle ergometer at 60 and 90 rotations per minute (rpm) at workloads of 200 and 300 Watts. Subjects wore in randomized order a cycling shoe with its standard insole (control condition CO) or the shoe with carbon fiber foot orthoses (Condition CA). Mean peak pressure out of 30 movement cycles were extracted for the total foot and specific foot regions (rear, mid, fore foot (medial, central, lateral) and toe region). Three-factor ANOVAs (factor foot orthoses, rpm, workload) for repeated measures (alpha = 0.05) were used to analyze the main question of a foot orthoses effect on peak in-shoe plantar pressure. Results: Peak pressures in the total foot were in a range of 70-75 kPa for 200 Watts (W) (300 W: 85-110 kPa). The carbon fiber foot orthoses reduced peak pressures by -4,1\% compared to the standard insole (p = 0,10). In the foot regions rear(-16,6\%, p<0.001), mid (-20,0\%, p<0.001) and fore foot (-5.9\%, p < 0.03)CA reduced peak pressure compared to CO. In the toe region, peak pressure was higher in CA (+16,2\%) compared to CO (p<0,001). The lateral fore foot showed higher peak pressures in CA (+34\%) and CO (+59\%) compared to medial and central fore foot. Conclusion: Carbon fiber can serve as a suitable material for foot orthoses manufacturing in cycling. Plantar pressures do not increase due to the stiffness of the carbon. Individual customization may have the potential to reduce peak pressure in certain foot areas.}, language = {de} } @article{MuellerCarlsohnMuelleretal.2012, author = {M{\"u}ller, Steffen and Carlsohn, Anja and M{\"u}ller, Juliane and Baur, Heiner and Mayer, Frank}, title = {Static and dynamic foot characteristics in children aged 1-13 years a cross-sectional study}, series = {Gait \& posture}, volume = {35}, journal = {Gait \& posture}, number = {3}, publisher = {Elsevier}, address = {Clare}, issn = {0966-6362}, doi = {10.1016/j.gaitpost.2011.10.357}, pages = {389 -- 394}, year = {2012}, abstract = {The aim of this study was to acquire static and dynamic foot geometry and loading in childhood, and to establish data for age groups of a population of 1-13 year old infants and children. A total of 10,382 children were recruited and 7788 children (48\% males and 52\% females) were finally included into the data analysis. For static foot geometry foot length and foot width were quantified in a standing position. Dynamic foot geometry and loading were assessed during walking on a walkway with self selected speed (Novel Emed X, 100 Hz, 4 sensors/cm(2)). Contact area (CA), peak pressure (PP), force time integral (FTI) and the arch index were calculated for the total, fore-, mid- and hindfoot. Results show that most static and dynamic foot characteristics change continuously during growth and maturation. Static foot length and width increased with age from 13.1 +/- 0.8 cm (length) and 5.7 +/- 0.4 cm (width) in the youngest to 24.4 +/- 1.5 cm (length) and 8.9 +/- 0.6 cm (width) in the oldest. A mean walking velocity of 0.94 +/- 0.25 m/s was observed. Arch-index ranged from 0.32 +/- 0.04 [a.u.] in the one-year old to 0.21 +/- 0.13 [a.u.] in the 5-year olds and remains constant afterwards. This study provides data for static and dynamic foot characteristics in children based on a cohort of 7788 subjects. Static and dynamic foot measures change differently during growth and maturation. Dynamic foot measurements provide additional information about the children's foot compared to static measures.}, language = {en} } @article{BaurHirschmuellerMuelleretal.2011, author = {Baur, Heiner and Hirschm{\"u}ller, Anja and M{\"u}ller, Steffen and Mayer, Frank}, title = {Neuromuscular activity of the peroneal muscle after foot orthoses therapy in runners}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {43}, journal = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, number = {8}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, doi = {10.1249/MSS.0b013e31820c64ae}, pages = {1500 -- 1506}, year = {2011}, abstract = {BAUR, H., A. HIRSCHMULLER, S. MULLER, and F. MAYER. Neuromuscular Activity of the Peroneal Muscle after Foot Orthoses Therapy in Runners. Med. Sci. Sports Exerc., Vol. 43, No. 8, pp. 1500-1506, 2011. Purpose: Foot orthoses are a standard option to treat overuse injury. Biomechanical data providing mechanisms of foot orthoses' effectiveness are sparse. Stability of the ankle joint complex might be a key factor. The purpose was therefore to analyze neuromuscular activity of the musculus peroneus longus in runners with overuse injury symptoms treated with foot orthoses. Methods: A total of 99 male and female runners with overuse injury symptoms randomized in a control group (CO) and an orthoses group (OR) were analyzed on a treadmill at 3.3 m.s(-1) before and after an 8-wk foot orthoses intervention. Muscular activity of the musculus peroneus longus was measured and quantified in the time domain (initial onset of activation (T-ini), time of maximal activity (T-max), total time of activation (T-tot)) and amplitude domain (amplitude in preactivation (A(pre)), weight acceptance (A(wa)), push-off (A(po))). Results: Peroneal activity in the time domain did not differ initially between CO and OR, and no effect was observed after therapy (T-ini: CO = -0.88 +/- 0.09, OR = -0.88 +/- 0.08 / T-max: CO = 0.14 +/- 0.06, OR = 0.15 +/- 0.06 / T-tot: CO = 0.40 +/- 0.09, OR = 0.41 +/- 0.09; P > 0.05). In preactivation (Apre), muscle activity was higher in OR after intervention (CO = 0.97 +/- 0.32, 95\% confidence interval = 0.90-1.05; OR = 1.18 +/- 0.43, 95\% confidence interval = 1.08-1.28; P = 0.003). There was no group or intervention effect during stance (A(wa): CO = 2.33 +/- 0.66, OR = 2.33 +/- 0.74 / A(po): CO = 0.80 +/- 0.41, OR = 0.88 +/- 0.40; P > 0.05). Conclusions: Enhanced muscle activation of the musculus peroneus longus in preactivation suggests an altered preprogrammed activity, which might lead to better ankle stability providing a possible mode of action for foot orthoses therapy.}, language = {en} } @inproceedings{CarlsohnWeberMuelleretal.2012, author = {Carlsohn, Anja and Weber, Josefine and M{\"u}ller, Juliane and Stuwe, Anja and M{\"u}ller, Steffen and Mayer, Frank}, title = {Dietary intake to reduce body mass before competition in german judo athletes}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {44}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {109 -- 109}, year = {2012}, language = {en} } @inproceedings{MuellerWeberOttoetal.2012, author = {M{\"u}ller, Juliane and Weber, Josefine and Otto, Christoph and M{\"u}ller, Steffen and Mayer, Frank}, title = {Effects of six-month trunk stability exercises on low back pain prevalence in young athletes}, series = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, volume = {44}, booktitle = {Medicine and science in sports and exercise : official journal of the American College of Sports Medicine}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {0195-9131}, pages = {601 -- 601}, year = {2012}, language = {en} } @article{HirschmuellerBaurMuelleretal.2011, author = {Hirschm{\"u}ller, Anja and Baur, Heiner and M{\"u}ller, Steffen and Helwig, Peter and Dickhuth, Hans-Hermann and Mayer, Frank}, title = {Clinical effectiveness of customised sport shoe orthoses for overuse injuries in runners a randomised controlled study}, series = {British journal of sports medicine : the journal of sport and exercise medicine}, volume = {45}, journal = {British journal of sports medicine : the journal of sport and exercise medicine}, number = {12}, publisher = {BMJ Publ. Group}, address = {London}, issn = {0306-3674}, doi = {10.1136/bjsm.2008.055830}, pages = {959 -- 965}, year = {2011}, abstract = {Background and objectives Treatment of chronic running-related overuse injuries by orthopaedic shoe orthoses is very common but not evidence-based to date. Hypothesis Polyurethane foam orthoses adapted to a participant's barefoot plantar pressure distribution are an effective treatment option for chronic overuse injuries in runners. Design Prospective, randomised, controlled clinical trial. Intervention 51 patients with running injuries were treated with custom-made, semirigid running shoe orthoses for 8 weeks. 48 served as a randomised control group that continued regular training activity without any treatment. Main outcome measures Evaluation was made by the validated pain questionnaire Subjective Pain Experience Scale, the pain disability index and a comfort index in the orthoses group (ICI). Results There were statistically significant differences between the orthoses and control groups at 8 weeks for the pain disability index (mean difference 3.2; 95\% CI 0.9 to 5.5) and the Subjective Pain Experience Scale (6.6; 2.6 to 10.6). The patients with orthoses reported a rising wearing comfort (pre-treatment ICI 69/100; post-treatment ICI 83/100) that was most pronounced in the first 4 weeks (ICI 80.4/100). Conclusion Customised polyurethane running shoe orthoses are an effective conservative therapy strategy for chronic running injuries with high comfort and acceptance of injured runners.}, language = {en} } @article{MuellerStollMuelleretal.2012, author = {M{\"u}ller, Steffen and Stoll, Josefine and M{\"u}ller, Juliane and Mayer, Frank}, title = {Validity of isokinetic trunk measurements with respect to healthy adults, athletes and low back pain patients}, series = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, volume = {20}, journal = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0959-3020}, doi = {10.3233/IES-2012-00482}, pages = {255 -- 266}, year = {2012}, abstract = {Background: Isokinetic measurements are widely used to assess strength capacity in a clinical or research context. Nevertheless, the validity of isokinetic measures for identifying strength deficits and the evaluation of therapeutic process regarding different pathologies is yet to be established. Therefore, the purpose of this review is to evaluate the validity of isokinetic measures in a specific case: that of muscular capacity in low back pain (LBP). Methods: A literature search (PubMed; ISI Web of Knowledge; The Cochrane Library) covering the last 10 years was performed. Relevant papers regarding isokinetic trunk strength measures in healthy and patients with low back pain (PLBP) were searched. Peak torque values [Nm] and peak torque normalized to body weight [Nm/kg BW] were extracted for healthy and PLBP. Ranked mean values across studies were calculated for the concentric peak torque at 60 degrees/s as well as the flexion/extension (F/E) ratio. Results: 34 publications (31 flexion/extension; 3 rotation) were suitable for reporting detailed isokinetic strength measures in healthy or LBP (untrained adults, adolescents, athletes). Adolescents and athletes were different compared to normal adults in terms of absolute trunk strength values and the F/E ratio. Furthermore, isokinetic measures evaluating therapeutic process and isokinetic rehabilitation training were infrequent in literature (8 studies). Conclusion: Isokinetic measurements are valid for measuring trunk flexion/extension strength and F/E ratio in athletes, adolescents and (untrained) adults with/without LBP. The validity of trunk rotation is questionable due to a very small number of publications whereas no reliable source regarding lateral flexion could be traced. Therefore, isokinetic dynamometry may be utilized for identifying trunk strength deficits in healthy adults and PLBP.}, language = {en} } @article{MuellerMayerBauretal.2011, author = {M{\"u}ller, Steffen and Mayer, Patrizia and Baur, Heiner and Mayer, Frank}, title = {Higher velocities in isokinetic dynamometry a pilot study of new test mode with active compensation of inertia}, series = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, volume = {19}, journal = {Isokinetics and exercise science : official journal of the European Isokinetic Society}, number = {2}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0959-3020}, doi = {10.3233/IES-2011-0398}, pages = {63 -- 70}, year = {2011}, abstract = {Isokinetic dynamometry is a standard technique for strength testing and training. Nevertheless reliability and validity is limited due to inertia effects, especially for high velocities. Therefore in a first methodological approach the purpose was to evaluate a new isokinetic measurement mode including inertia compensation compared to a classic isokinetic measurement mode for single and multijoint movements at different velocities. Isokinetic maximum strength measurements were carried out in 26 healthy active subjects. Tests were performed using classic isokinetic and new isokinetic mode in random order. Maximum torque/force, maximum movement velocity and time for acceleration were calculated. For inter-instrument agreement Bland and Altman analysis, systematic and random error was quantified. Differences between both methods were assessed (ANOVA alpha = 0.05). Bland and Altman analysis showed the highest agreement between the two modes for strength and velocity measurements (bias: < +/- 1.1\%; LOA: < 14.2\%) in knee flexion/extension at slow isokinetic velocity (60 degrees/s). Least agreement (range: bias: -67.6\% +/- 119.0\%; LOA: 53.4\% 69.3\%) was observed for shoulder/arm test at high isokinetic velocity (360 degrees/s). The Isokin(new) mode showed higher maximum movement velocities (p < 0.05). For low isokinetic velocities the new mode agrees with the classic mode. Especially at high isokinetic velocities the new isokinetic mode shows relevant benefits coupled with a possible trade-off with the force/torque measurement. In conclusion, this study offers for the first time a comparison between the 'classical' and inertia-compensated isokinetic dynamometers indicating the advantages and disadvantages associated with each individual approach, particularly as they relate to medium or high velocities in testing and training.}, language = {en} } @article{HirschmuellerKonstantinidisBauretal.2011, author = {Hirschm{\"u}ller, Anja and Konstantinidis, Lukas and Baur, Heiner and M{\"u}ller, Steffen and Mehlhorn, Alexander and Kontermann, Julia and Grosse, Ulrich and S{\"u}dkamp, Norbert P. and Helwig, Peter}, title = {Do changes in dynamic plantar pressure distribution, strength capacity and postural control after intra-articular calcaneal fracture correlate with clinical and radiological outcome?}, series = {Injury : international journal of the care of the injured}, volume = {42}, journal = {Injury : international journal of the care of the injured}, number = {10}, publisher = {Elsevier}, address = {Oxford}, issn = {0020-1383}, doi = {10.1016/j.injury.2010.09.040}, pages = {1135 -- 1143}, year = {2011}, abstract = {Fractures of the calcaneus are often associated with serious permanent disability, a considerable reduction in quality of life, and high socio-economic cost. Although some studies have already reported changes in plantar pressure distribution after calcaneal fracture, no investigation has yet focused on the patient's strength and postural control. Method: 60 patients with unilateral, operatively treated, intra-articular calcaneal fractures were clinically and biomechanically evaluated >1 year postoperatively (physical examination, SF-36, AOFAS score, lower leg isokinetic strength, postural control and gait analysis including plantar pressure distribution). Results were correlated to clinical outcome and preoperative radiological findings (Bohler angle, Zwipp and Sanders Score). Results: Clinical examination revealed a statistically significant reduction in range of motion at the tibiotalar and the subtalar joint on the affected side. Additionally, there was a statistically significant reduction of plantar flexor peak torque of the injured compared to the uninjured limb (p < 0.001) as well as a reduction in postural control that was also more pronounced on the initially injured side (standing duration 4.2 +/- 2.9 s vs. 7.6 +/- 2.1 s, p < 0.05). Plantar pressure measurements revealed a statistically significant pressure reduction at the hindfoot (p = 0.0007) and a pressure increase at the midfoot (p = 0.0001) and beneath the lateral forefoot (p = 0.037) of the injured foot. There was only a weak correlation between radiological classifications and clinical outcome but a moderate correlation between strength differences and the clinical questionnaires (CC 0.27-0.4) as well as between standing duration and the clinical questionnaires. Although thigh circumference was also reduced on the injured side, there was no important relationship between changes in lower leg circumference and strength suggesting that measurement of leg circumference may not be a valid assessment of maximum strength deficits. Self-selected walking speed was the parameter that showed the best correlation with clinical outcome (AOFAS score). Conclusion: Calcaneal fractures are associated with a significant reduction in ankle joint ROM, plantar flexion strength and postural control. These impairments seem to be highly relevant to the patients. Restoration of muscular strength and proprioception should therefore be aggressively addressed in the rehabilitation process after these fractures.}, language = {en} } @article{MuellerMuellerStolletal.2014, author = {M{\"u}ller, Juliane and M{\"u}ller, Steffen and Stoll, Josefine and Baur, Heiner and Mayer, Frank}, title = {Trunk extensor and flexor strength capacity in healthy young elite athletes aged 11-15 Years}, series = {Journal of strength and conditioning research : the research journal of the NSCA}, volume = {28}, journal = {Journal of strength and conditioning research : the research journal of the NSCA}, number = {5}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {1064-8011}, doi = {10.1519/JSC.0000000000000280}, pages = {1328 -- 1334}, year = {2014}, abstract = {Mueller, J, Mueller, S, Stoll, J, Baur, H, and Mayer, F. Trunk extensor and flexor strength capacity in healthy young elite athletes aged 11-15 years. J Strength Cond Res 28(5): 1328-1334, 2014-Differences in trunk strength capacity because of gender and sports are well documented in adults. In contrast, data concerning young athletes are sparse. The purpose of this study was to assess the maximum trunk strength of adolescent athletes and to investigate differences between genders and age groups. A total of 520 young athletes were recruited. Finally, 377 (n = 233/144 M/F; 13 +/- 1 years; 1.62 +/- 0.11 m height; 51 +/- 12 kg mass; training: 4.5 +/- 2.6 years; training sessions/week: 4.3 +/- 3.0; various sports) young athletes were included in the final data analysis. Furthermore, 5 age groups were differentiated (age groups: 11, 12, 13, 14, and 15 years; n = 90, 150, 42, 43, and 52, respectively). Maximum strength of trunk flexors (Flex) and extensors (Ext) was assessed in all subjects during isokinetic concentric measurements (60 degrees center dot s(-1); 5 repetitions; range of motion: 55 degrees). Maximum strength was characterized by absolute peak torque (Flex(abs), Ext(abs); N center dot m), peak torque normalized to body weight (Flex(norm), Ext(norm); N center dot m center dot kg(-1) BW), and Flex(abs)/Ext(abs) ratio (RKquot). Descriptive data analysis (mean +/- SD) was completed, followed by analysis of variance (alpha = 0.05; post hoc test [Tukey-Kramer]). Mean maximum strength for all athletes was 97 +/- 34 N center dot m in Flex(abs) and 140 +/- 50 N center dot m in Ext(abs) (Flex(norm) = 1.9 +/- 0.3 N center dot m center dot kg(-1) BW, Ext(norm) = 2.8 +/- 0.6 N center dot m center dot kg(-1) BW). Males showed statistically significant higher absolute and normalized values compared with females (p < 0.001). Flex(abs) and Ext(abs) rose with increasing age almost 2-fold for males and females (Flex(abs), Ext(abs): p < 0.001). Flex(norm) and Ext(norm) increased with age for males (p < 0.001), however, not for females (Flex(norm): p = 0.26; Ext(norm): p = 0.20). RKquot (mean +/- SD: 0.71 +/- 0.16) did not reveal any differences regarding age (p = 0.87) or gender (p = 0.43). In adolescent athletes, maximum trunk strength must be discussed in a gender- and age-specific context. The Flex(abs)/Ext(abs) ratio revealed extensor dominance, which seems to be independent of age and gender. The values assessed may serve as a basis to evaluate and discuss trunk strength in athletes.}, language = {en} } @article{MuellerMuellerEngeletal.2016, author = {M{\"u}ller, Juliane and M{\"u}ller, Steffen and Engel, Tilman and Reschke, Antje and Baur, Heiner and Mayer, Frank}, title = {Stumbling reactions during perturbed walking: Neuromuscular reflex activity and 3-D kinematics of the trunk - A pilot study}, series = {Journal of biomechanics}, volume = {49}, journal = {Journal of biomechanics}, publisher = {Elsevier}, address = {Oxford}, issn = {0021-9290}, doi = {10.1016/j.jbiomech.2015.09.041}, pages = {933 -- 938}, year = {2016}, abstract = {Stumbling led to an increase in ROM, compared to unperturbed gait, in all segments and planes. These increases ranged between 107 +/- 26\% (UTA/rotation) and 262 +/- 132\% (UTS/lateral flexion), significant only in lateral flexion. EMG activity of the trunk was increased during stumbling (abdominal: 665 +/- 283\%; back: 501 +/- 215\%), without significant differences between muscles. Provoked stumbling leads to a measurable effect on the trunk, quantifiable by an increase in ROM and EMG activity, compared to normal walking. Greater abdominal muscle activity and ROM of lateral flexion may indicate a specific compensation pattern occurring during stumbling. (C) 2015 Elsevier Ltd. All rights reserved.}, language = {en} } @article{EichlerRabeSalzwedeletal.2017, author = {Eichler, Sarah and Rabe, Sophie and Salzwedel, Annett and M{\"u}ller, Steffen and Stoll, Josefine and Tilgner, Nina and John, Michael and Wegschneider, Karl and Mayer, Frank and V{\"o}ller, Heinz}, title = {Effectiveness of an interactive telerehabilitation system with home-based exercise training in patients after total hip or knee replacement}, series = {Trials}, volume = {18}, journal = {Trials}, publisher = {BioMed Central}, address = {London}, issn = {1745-6215}, doi = {10.1186/s13063-017-2173-3}, pages = {1 -- 7}, year = {2017}, abstract = {Background Total hip or knee replacement is one of the most frequently performed surgical procedures. Physical rehabilitation following total hip or knee replacement is an essential part of the therapy to improve functional outcomes and quality of life. After discharge from inpatient rehabilitation, a subsequent postoperative exercise therapy is needed to maintain functional mobility. Telerehabilitation may be a potential innovative treatment approach. We aim to investigate the superiority of an interactive telerehabilitation intervention for patients after total hip or knee replacement, in comparison to usual care, regarding physical performance, functional mobility, quality of life and pain. Methods/design This is an open, randomized controlled, multicenter superiority study with two prospective arms. One hundred and ten eligible and consenting participants with total knee or hip replacement will be recruited at admission to subsequent inpatient rehabilitation. After comprehensive, 3-week, inpatient rehabilitation, the intervention group performs a 3-month, interactive, home-based exercise training with a telerehabilitation system. For this purpose, the physiotherapist creates an individual training plan out of 38 different strength and balance exercises which were implemented in the system. Data about the quality and frequency of training are transmitted to the physiotherapist for further adjustment. Communication between patient and physiotherapist is possible with the system. The control group receives voluntary, usual aftercare programs. Baseline assessments are investigated after discharge from rehabilitation; final assessments 3 months later. The primary outcome is the difference in improvement between intervention and control group in 6-minute walk distance after 3 months. Secondary outcomes include differences in the Timed Up and Go Test, the Five-Times-Sit-to-Stand Test, the Stair Ascend Test, the Short-Form 36, the Western Ontario and McMaster Universities Osteoarthritis Index, the International Physical Activity Questionnaire, and postural control as well as gait and kinematic parameters of the lower limbs. Baseline-adjusted analysis of covariance models will be used to test for group differences in the primary and secondary endpoints. Discussion We expect the intervention group to benefit from the interactive, home-based exercise training in many respects represented by the study endpoints. If successful, this approach could be used to enhance the access to aftercare programs, especially in structurally weak areas.}, language = {en} } @misc{EichlerRabeSalzwedeletal.2017, author = {Eichler, Sarah and Rabe, Sophie and Salzwedel, Annett and M{\"u}ller, Steffen and Stoll, Josefine and Tilgner, Nina and John, Michael and Wegschneider, Karl and Mayer, Frank and V{\"o}ller, Heinz}, title = {Effectiveness of an interactive telerehabilitation system with home-based exercise training in patients after total hip or knee replacement}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403702}, pages = {7}, year = {2017}, abstract = {Background Total hip or knee replacement is one of the most frequently performed surgical procedures. Physical rehabilitation following total hip or knee replacement is an essential part of the therapy to improve functional outcomes and quality of life. After discharge from inpatient rehabilitation, a subsequent postoperative exercise therapy is needed to maintain functional mobility. Telerehabilitation may be a potential innovative treatment approach. We aim to investigate the superiority of an interactive telerehabilitation intervention for patients after total hip or knee replacement, in comparison to usual care, regarding physical performance, functional mobility, quality of life and pain. Methods/design This is an open, randomized controlled, multicenter superiority study with two prospective arms. One hundred and ten eligible and consenting participants with total knee or hip replacement will be recruited at admission to subsequent inpatient rehabilitation. After comprehensive, 3-week, inpatient rehabilitation, the intervention group performs a 3-month, interactive, home-based exercise training with a telerehabilitation system. For this purpose, the physiotherapist creates an individual training plan out of 38 different strength and balance exercises which were implemented in the system. Data about the quality and frequency of training are transmitted to the physiotherapist for further adjustment. Communication between patient and physiotherapist is possible with the system. The control group receives voluntary, usual aftercare programs. Baseline assessments are investigated after discharge from rehabilitation; final assessments 3 months later. The primary outcome is the difference in improvement between intervention and control group in 6-minute walk distance after 3 months. Secondary outcomes include differences in the Timed Up and Go Test, the Five-Times-Sit-to-Stand Test, the Stair Ascend Test, the Short-Form 36, the Western Ontario and McMaster Universities Osteoarthritis Index, the International Physical Activity Questionnaire, and postural control as well as gait and kinematic parameters of the lower limbs. Baseline-adjusted analysis of covariance models will be used to test for group differences in the primary and secondary endpoints. Discussion We expect the intervention group to benefit from the interactive, home-based exercise training in many respects represented by the study endpoints. If successful, this approach could be used to enhance the access to aftercare programs, especially in structurally weak areas.}, language = {en} } @article{MuellerEngelMuelleretal.2017, author = {M{\"u}ller, Juliane and Engel, Tilman and M{\"u}ller, Steffen and Stoll, Josefine and Baur, Heiner and Mayer, Frank}, title = {Effects of sudden walking perturbations on neuromuscular reflex activity and three-dimensional motion of the trunk in healthy controls and back pain symptomatic subjects}, series = {PLoS one}, volume = {12}, journal = {PLoS one}, number = {3}, publisher = {PLoS}, address = {Lawrence, Kan.}, issn = {1932-6203}, doi = {10.1371/journal.pone.0174034}, pages = {11}, year = {2017}, abstract = {Background Back pain patients (BPP) show delayed muscle onset, increased co-contractions, and variability as response to quasi-static sudden trunk loading in comparison to healthy controls (H). However, it is unclear whether these results can validly be transferred to suddenly applied walking perturbations, an automated but more functional and complex movement pattern. There is an evident need to develop research-based strategies for the rehabilitation of back pain. Therefore, the investigation of differences in trunk stability between H and BPP in functional movements is of primary interest in order to define suitable intervention regimes. The purpose of this study was to analyse neuromuscular reflex activity as well as three-dimensional trunk kinematics between H and BPP during walking perturbations. Methods Eighty H (31m/49f;29±9yrs;174±10cm;71±13kg) and 14 BPP (6m/8f;30±8yrs;171±10cm;67±14kg) walked (1m/s) on a split-belt treadmill while 15 right-sided perturbations (belt decelerating, 40m/s2, 50ms duration; 200ms after heel contact) were randomly applied. Trunk muscle activity was assessed using a 12-lead EMG set-up. Trunk kinematics were measured using a 3-segment-model consisting of 12 markers (upper thoracic (UTA), lower thoracic (LTA), lumbar area (LA)). EMG-RMS ([\%],0-200ms after perturbation) was calculated and normalized to the RMS of unperturbed gait. Latency (TON;ms) and time to maximum activity (TMAX;ms) were analysed. Total motion amplitude (ROM;[°]) and mean angle (Amean;[°]) for extension-flexion, lateral flexion and rotation were calculated (whole stride cycle; 0-200ms after perturbation) for each of the three segments during unperturbed and perturbed gait. For ROM only, perturbed was normalized to unperturbed step [\%] for the whole stride as well as the 200ms after perturbation. Data were analysed descriptively followed by a student´s t-test to account for group differences. Co-contraction was analyzed between ventral and dorsal muscles (V:R) as well as side right:side left ratio (Sright:Sleft). The coefficient of variation (CV;\%) was calculated (EMG-RMS;ROM) to evaluate variability between the 15 perturbations for all groups. With respect to unequal distribution of participants to groups, an additional matched-group analysis was conducted. Fourteen healthy controls out of group H were sex-, age- and anthropometrically matched (group Hmatched) to the BPP. Results No group differences were observed for EMG-RMS or CV analysis (EMG/ROM) (p>0.025). Co-contraction analysis revealed no differences for V:R and Srigth:Sleft between the groups (p>0.025). BPP showed an increased TON and TMAX, being significant for Mm. rectus abdominus (p = 0.019) and erector spinae T9/L3 (p = 0.005/p = 0.015). ROM analysis over the unperturbed stride cycle revealed no differences between groups (p>0.025). Normalization of perturbed to unperturbed step lead to significant differences for the lumbar segment (LA) in lateral flexion with BPP showing higher normalized ROM compared to Hmatched (p = 0.02). BPP showed a significant higher flexed posture (UTA (p = 0.02); LTA (p = 0.004)) during normal walking (Amean). Trunk posture (Amean) during perturbation showed higher trunk extension values in LTA segments for H/Hmatched compared to BPP (p = 0.003). Matched group (BPP vs. Hmatched) analysis did not show any systematic changes of all results between groups. Conclusion BPP present impaired muscle response times and trunk posture, especially in the sagittal and transversal planes, compared to H. This could indicate reduced trunk stability and higher loading during gait perturbations.}, language = {en} } @misc{MuellerEngelMuelleretal.2017, author = {M{\"u}ller, Juliane and Engel, Tilman and M{\"u}ller, Steffen and Stoll, Josefine and Baur, Heiner and Mayer, Frank}, title = {Effects of sudden walking perturbations on neuromuscular reflex activity and three-dimensional motion of the trunk in healthy controls and back pain symptomatic subjects}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-394931}, pages = {11}, year = {2017}, abstract = {Background Back pain patients (BPP) show delayed muscle onset, increased co-contractions, and variability as response to quasi-static sudden trunk loading in comparison to healthy controls (H). However, it is unclear whether these results can validly be transferred to suddenly applied walking perturbations, an automated but more functional and complex movement pattern. There is an evident need to develop research-based strategies for the rehabilitation of back pain. Therefore, the investigation of differences in trunk stability between H and BPP in functional movements is of primary interest in order to define suitable intervention regimes. The purpose of this study was to analyse neuromuscular reflex activity as well as three-dimensional trunk kinematics between H and BPP during walking perturbations. Methods Eighty H (31m/49f;29±9yrs;174±10cm;71±13kg) and 14 BPP (6m/8f;30±8yrs;171±10cm;67±14kg) walked (1m/s) on a split-belt treadmill while 15 right-sided perturbations (belt decelerating, 40m/s2, 50ms duration; 200ms after heel contact) were randomly applied. Trunk muscle activity was assessed using a 12-lead EMG set-up. Trunk kinematics were measured using a 3-segment-model consisting of 12 markers (upper thoracic (UTA), lower thoracic (LTA), lumbar area (LA)). EMG-RMS ([\%],0-200ms after perturbation) was calculated and normalized to the RMS of unperturbed gait. Latency (TON;ms) and time to maximum activity (TMAX;ms) were analysed. Total motion amplitude (ROM;[°]) and mean angle (Amean;[°]) for extension-flexion, lateral flexion and rotation were calculated (whole stride cycle; 0-200ms after perturbation) for each of the three segments during unperturbed and perturbed gait. For ROM only, perturbed was normalized to unperturbed step [\%] for the whole stride as well as the 200ms after perturbation. Data were analysed descriptively followed by a student´s t-test to account for group differences. Co-contraction was analyzed between ventral and dorsal muscles (V:R) as well as side right:side left ratio (Sright:Sleft). The coefficient of variation (CV;\%) was calculated (EMG-RMS;ROM) to evaluate variability between the 15 perturbations for all groups. With respect to unequal distribution of participants to groups, an additional matched-group analysis was conducted. Fourteen healthy controls out of group H were sex-, age- and anthropometrically matched (group Hmatched) to the BPP. Results No group differences were observed for EMG-RMS or CV analysis (EMG/ROM) (p>0.025). Co-contraction analysis revealed no differences for V:R and Srigth:Sleft between the groups (p>0.025). BPP showed an increased TON and TMAX, being significant for Mm. rectus abdominus (p = 0.019) and erector spinae T9/L3 (p = 0.005/p = 0.015). ROM analysis over the unperturbed stride cycle revealed no differences between groups (p>0.025). Normalization of perturbed to unperturbed step lead to significant differences for the lumbar segment (LA) in lateral flexion with BPP showing higher normalized ROM compared to Hmatched (p = 0.02). BPP showed a significant higher flexed posture (UTA (p = 0.02); LTA (p = 0.004)) during normal walking (Amean). Trunk posture (Amean) during perturbation showed higher trunk extension values in LTA segments for H/Hmatched compared to BPP (p = 0.003). Matched group (BPP vs. Hmatched) analysis did not show any systematic changes of all results between groups. Conclusion BPP present impaired muscle response times and trunk posture, especially in the sagittal and transversal planes, compared to H. This could indicate reduced trunk stability and higher loading during gait perturbations.}, language = {en} } @misc{AppiahDwomohMuellerMayer2018, author = {Appiah-Dwomoh, Edem Korkor and M{\"u}ller, Steffen and Mayer, Frank}, title = {Reproducibility of Static and Dynamic Postural Control Measurement in Adolescent Athletes with Back Pain}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {470}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-417526}, pages = {8}, year = {2018}, abstract = {Static (one-legged stance) and dynamic (star excursion balance) postural control tests were performed by 14 adolescent athletes with and 17 without back pain to determine reproducibility. The total displacement, mediolateral and anterior-posterior displacements of the centre of pressure in mm for the static, and the normalized and composite reach distances for the dynamic tests were analysed. Intraclass correlation coefficients, 95\% confidence intervals, and a Bland-Altman analysis were calculated for reproducibility. Intraclass correlation coefficients for subjects with (0.54 to 0.65), (0.61 to 0.69) and without (0.45 to 0.49), (0.52 to 0.60) back pain were obtained on the static test for right and left legs, respectively. Likewise, (0.79 to 0.88), (0.75 to 0.93) for subjects with and (0.61 to 0.82), (0.60 to 0.85) for those without back pain were obtained on the dynamic test for the right and left legs, respectively. Systematic bias was not observed between test and retest of subjects on both static and dynamic tests. The one-legged stance and star excursion balance tests have fair to excellent reliabilities on measures of postural control in adolescent athletes with and without back pain. They can be used as measures of postural control in adolescent athletes with and without back pain.}, language = {en} } @article{AppiahDwomohMuellerMayer2018, author = {Appiah-Dwomoh, Edem Korkor and M{\"u}ller, Steffen and Mayer, Frank}, title = {Reproducibility of Static and Dynamic Postural Control Measurement in Adolescent Athletes with Back Pain}, series = {Rehabilitation Research and Practice}, volume = {2018}, journal = {Rehabilitation Research and Practice}, publisher = {Hindawi}, address = {New York}, issn = {2090-2875}, doi = {10.1155/2018/8438350}, pages = {1 -- 8}, year = {2018}, abstract = {Static (one-legged stance) and dynamic (star excursion balance) postural control tests were performed by 14 adolescent athletes with and 17 without back pain to determine reproducibility. The total displacement, mediolateral and anterior-posterior displacements of the centre of pressure in mm for the static, and the normalized and composite reach distances for the dynamic tests were analysed. Intraclass correlation coefficients, 95\% confidence intervals, and a Bland-Altman analysis were calculated for reproducibility. Intraclass correlation coefficients for subjects with (0.54 to 0.65), (0.61 to 0.69) and without (0.45 to 0.49), (0.52 to 0.60) back pain were obtained on the static test for right and left legs, respectively. Likewise, (0.79 to 0.88), (0.75 to 0.93) for subjects with and (0.61 to 0.82), (0.60 to 0.85) for those without back pain were obtained on the dynamic test for the right and left legs, respectively. Systematic bias was not observed between test and retest of subjects on both static and dynamic tests. The one-legged stance and star excursion balance tests have fair to excellent reliabilities on measures of postural control in adolescent athletes with and without back pain. They can be used as measures of postural control in adolescent athletes with and without back pain.}, language = {en} } @article{MuellerMuellerStolletal.2017, author = {M{\"u}ller, Juliane and M{\"u}ller, Steffen and Stoll, Josefine and Fr{\"o}hlich, K. and Otto, Christoph and Mayer, Frank}, title = {Back pain prevalence in adolescent athletes}, series = {Scandinavian journal of medicine \& science in sports}, volume = {27}, journal = {Scandinavian journal of medicine \& science in sports}, publisher = {Wiley}, address = {Hoboken}, issn = {0905-7188}, doi = {10.1111/sms.12664}, pages = {448 -- 454}, year = {2017}, abstract = {The research aimed to investigate back pain (BP) prevalence in a large cohort of young athletes with respect to age, gender, and sport discipline. BP (within the last 7days) was assessed with a face scale (face 1-2=no pain; face 3-5=pain) in 2116 athletes (m/f 61\%/39\%; 13.3 +/- 1.7years; 163.0 +/- 11.8cm; 52.6 +/- 13.9kg; 4.9 +/- 2.7 training years; 8.4 +/- 5.7 training h/week). Four different sports categories were devised (a: combat sports, b: game sports; c: explosive strength sport; d: endurance sport). Analysis was described descriptively, regarding age, gender, and sport. In addition, 95\% confidence intervals (CI) were calculated. About 168 (8\%) athletes were allocated into the BP group. About 9\% of females and 7\% of males reported BP. Athletes, 11-13years, showed a prevalence of 2-4\%; while prevalence increased to 12-20\% in 14- to 17-year olds. Considering sport discipline, prevalence ranged from 3\% (soccer) to 14\% (canoeing). Prevalences in weight lifting, judo, wrestling, rowing, and shooting were 10\%; in boxing, soccer, handball, cycling, and horse riding, 6\%. 95\% CI ranged between 0.08-0.11. BP exists in adolescent athletes, but is uncommon and shows no gender differences. A prevalence increase after age 14 is obvious. Differentiated prevention programs in daily training routines might address sport discipline-specific BP prevalence.}, language = {en} } @article{BaurMuellerHirschmuelleretal.2006, author = {Baur, Heiner and M{\"u}ller, Steffen and Hirschm{\"u}ller, Anja and Huber, Georg and Mayer, Frank}, title = {Reactivity, stability, and strength performance capacity in motor sports}, series = {British journal of sports medicine : the journal of sport and exercise medicine}, volume = {40}, journal = {British journal of sports medicine : the journal of sport and exercise medicine}, publisher = {BMJ Publ. Group}, address = {London}, issn = {0306-3674}, doi = {10.1136/bjsm.2006.025783}, pages = {906 -- 910}, year = {2006}, abstract = {Background: Racing drivers require multifaceted cognitive and physical abilities in a multitasking situation. A knowledge of their physical capacities may help to improve fitness and performance. Objective: To compare reaction time, stability performance capacity, and strength performance capacity of elite racing drivers with those of age-matched, physically active controls. Methods: Eight elite racing drivers and 10 physically active controls matched for age and weight were tested in a reaction and determination test requiring upper and lower extremity responses to visual and audio cues. Further tests comprised evaluation of one-leg postural stability on a two-dimensional moveable platform, measures of maximum strength performance capacity of the extensors of the leg on a leg press, and a test of force capacity of the arms in a sitting position at a steering wheel. An additional arm endurance test consisted of isometric work at the steering wheel at + 30 degrees and -30 degrees where an eccentric threshold load of 30 N.m was applied. Subjects had to hold the end positions above this threshold until exhaustion. Univariate one way analysis of variance (alpha = 0.05) including a Bonferroni adjustment was used to detect group differences between the drivers and controls. Results: The reaction time of the racing drivers was significantly faster than the controls ( p = 0.004). The following motor reaction time and reaction times in the multiple determination test did not differ between the groups. No significant differences (p> 0.05) were found for postural stability, leg extensor strength, or arm strength and endurance. Conclusions: Racing drivers have faster reaction times than age-matched physically active controls. Further development of motor sport-specific test protocols is suggested. According to the requirements of motor racing, strength and sensorimotor performance capacity can potentially be improved.}, language = {en} } @misc{CasselIntziegianniRischetal.2017, author = {Cassel, Michael and Intziegianni, Konstantina and Risch, Lucie and M{\"u}ller, Steffen and Engel, Tilman and Mayer, Frank}, title = {Physiological Tendon Thickness Adaptation in Adolescent Elite Athletes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-403823}, pages = {8}, year = {2017}, abstract = {Increased Achilles (AT) and Patellar tendon (PT) thickness in adolescent athletes compared to non-athletes could be shown. However, it is unclear, if changes are of pathological or physiological origin due to training. The aim of this study was to determine physiological AT and PT thickness adaptation in adolescent elite athletes compared to non-athletes, considering sex and sport. In a longitudinal study design with two measurement days (M1/M2) within an interval of 3.2 ± 0.8 years, 131 healthy adolescent elite athletes (m/f: 90/41) out of 13 different sports and 24 recreationally active controls (m/f: 6/18) were included. Both ATs and PTs were measured at standardized reference points. Athletes were divided into 4 sport categories [ball (B), combat (C), endurance (E) and explosive strength sports (S)]. Descriptive analysis (mean ± SD) and statistical testing for group differences was performed (α = 0.05). AT thickness did not differ significantly between measurement days, neither in athletes (5.6 ± 0.7 mm/5.6 ± 0.7 mm) nor in controls (4.8 ± 0.4 mm/4.9 ± 0.5 mm, p > 0.05). For PTs, athletes presented increased thickness at M2 (M1: 3.5 ± 0.5 mm, M2: 3.8 ± 0.5 mm, p < 0.001). In general, males had thicker ATs and PTs than females (p < 0.05). Considering sex and sports, only male athletes from B, C, and S showed significant higher PT-thickness at M2 compared to controls (p ≤ 0.01). Sport-specific adaptation regarding tendon thickness in adolescent elite athletes can be detected in PTs among male athletes participating in certain sports with high repetitive jumping and strength components. Sonographic microstructural analysis might provide an enhanced insight into tendon material properties enabling the differentiation of sex and influence of different sports.}, language = {en} } @article{CasselIntziegianniRischetal.2017, author = {Cassel, Michael and Intziegianni, Konstantina and Risch, Lucie and M{\"u}ller, Steffen and Engel, Tilman and Mayer, Frank}, title = {Physiological Tendon Thickness Adaptation in Adolescent Elite Athletes}, series = {Frontiers in physiology}, volume = {8}, journal = {Frontiers in physiology}, publisher = {Frontiers}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2017.00795}, pages = {1 -- 8}, year = {2017}, abstract = {Increased Achilles (AT) and Patellar tendon (PT) thickness in adolescent athletes compared to non-athletes could be shown. However, it is unclear, if changes are of pathological or physiological origin due to training. The aim of this study was to determine physiological AT and PT thickness adaptation in adolescent elite athletes compared to non-athletes, considering sex and sport. In a longitudinal study design with two measurement days (M1/M2) within an interval of 3.2 ± 0.8 years, 131 healthy adolescent elite athletes (m/f: 90/41) out of 13 different sports and 24 recreationally active controls (m/f: 6/18) were included. Both ATs and PTs were measured at standardized reference points. Athletes were divided into 4 sport categories [ball (B), combat (C), endurance (E) and explosive strength sports (S)]. Descriptive analysis (mean ± SD) and statistical testing for group differences was performed (α = 0.05). AT thickness did not differ significantly between measurement days, neither in athletes (5.6 ± 0.7 mm/5.6 ± 0.7 mm) nor in controls (4.8 ± 0.4 mm/4.9 ± 0.5 mm, p > 0.05). For PTs, athletes presented increased thickness at M2 (M1: 3.5 ± 0.5 mm, M2: 3.8 ± 0.5 mm, p < 0.001). In general, males had thicker ATs and PTs than females (p < 0.05). Considering sex and sports, only male athletes from B, C, and S showed significant higher PT-thickness at M2 compared to controls (p ≤ 0.01). Sport-specific adaptation regarding tendon thickness in adolescent elite athletes can be detected in PTs among male athletes participating in certain sports with high repetitive jumping and strength components. Sonographic microstructural analysis might provide an enhanced insight into tendon material properties enabling the differentiation of sex and influence of different sports.}, language = {en} } @article{BaritelloKhajooeiEngeletal.2020, author = {Baritello, Omar and Khajooei, Mina and Engel, Tilman and Kopinski, Stephan and Quarmby, Andrew James and M{\"u}ller, Steffen and Mayer, Frank}, title = {Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass}, series = {BMC sports science, medicine and rehabilitation}, volume = {12}, journal = {BMC sports science, medicine and rehabilitation}, number = {1}, publisher = {BioMed Central}, address = {London}, issn = {2052-1847}, doi = {10.1186/s13102-020-00168-x}, pages = {14}, year = {2020}, abstract = {Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (\%MVIC). Differences between conditions for RMS\%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p <= 0.05; Bonferroni adjusted alpha = 0.008). Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS\%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.}, language = {en} } @article{WochatzRabeEngeletal.2021, author = {Wochatz, Monique and Rabe, Sophie and Engel, Tilman and M{\"u}ller, Steffen and Mayer, Frank}, title = {Scapular kinematics during unloaded and maximal loaded isokinetic concentric and eccentric shoulder flexion and extension movements}, series = {Journal of electromyography \& kinesiology : official journal of the International Society of Electrophysiology and Kinesiology}, volume = {57}, journal = {Journal of electromyography \& kinesiology : official journal of the International Society of Electrophysiology and Kinesiology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1050-6411}, doi = {10.1016/j.jelekin.2021.102517}, pages = {8}, year = {2021}, abstract = {Characterization of scapular kinematics under demanding load conditions might aid to distinguish between physiological and clinically relevant alterations. Previous investigations focused only on submaximal external load situations. How scapular movement changes with maximal load remains unclear. Therefore, the present study aimed to evaluate 3D scapular kinematics during unloaded and maximal loaded shoulder flexion and extension. Twelve asymptomatic individuals performed shoulder flexion and extension movements under unloaded and maximal concentric and eccentric loaded isokinetic conditions. 3D scapular kinematics assessed with a motion capture system was analyzed for 20° intervals of humeral positions from 20° to 120° flexion. Repeated measures ANOVAs were used to evaluate kinematic differences between load conditions for scapular position angles, scapulohumeral rhythm and scapular motion extent. Increased scapular upward rotation was seen during shoulder flexion and extension as well as decreased posterior tilt and external rotation during eccentric and concentric arm descents of maximal loaded compared to unloaded conditions. Load effects were further seen for the scapulohumeral rhythm with greater scapular involvement at lower humeral positions and increased scapular motion extent under maximal loaded shoulder movements. With maximal load applied to the arm physiological scapular movement pattern are induced that may imply both impingement sparing and causing mechanisms.}, language = {en} } @article{KirchheckerTroegerMuellerBakeetal.2015, author = {Kirchhecker, Sarah and Tr{\"o}ger-M{\"u}ller, Steffen and Bake, Sebastian and Antonietti, Markus and Taubert, Andreas and Esposito, Davido}, title = {Renewable pyridinium ionic liquids from the continuous hydrothermal decarboxylation of furfural-amino acid derived pyridinium zwitterions}, series = {Green chemistry}, volume = {8}, journal = {Green chemistry}, number = {17}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9262}, doi = {10.1039/c5gc00913h}, pages = {4151 -- 4156}, year = {2015}, abstract = {Fully renewable pyridinium ionic liquids were synthesised via the hydrothermal decarboxylation of pyridinium zwitterions derived from furfural and amino acids in flow. The functionality of the resulting ionic liquid (IL) can be tuned by choice of different amino acids as well as different natural carboxylic acids as the counterions. A representative member of this new class of ionic liquids was successfully used for the synthesis of ionogels and as a solvent for the Heck coupling.}, language = {en} } @article{KirchheckerTroegerMuellerBakeetal.2015, author = {Kirchhecker, Sarah and Tr{\"o}ger-M{\"u}ller, Steffen and Bake, Sebastian and Antonietti, Markus and Taubert, Andreas and Esposito, Davide}, title = {Renewable pyridinium ionic liquids from the continuous hydrothermal decarboxylation of furfural-amino acid derived pyridinium zwitterions}, series = {Green chemistry : an international journal and green chemistry resource}, volume = {17}, journal = {Green chemistry : an international journal and green chemistry resource}, number = {8}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9262}, doi = {10.1039/c5gc00913h}, pages = {4151 -- 4156}, year = {2015}, abstract = {Fully renewable pyridinium ionic liquids were synthesised via the hydrothermal decarboxylation of pyridinium zwitterions derived from furfural and amino acids in flow. The functionality of the resulting ionic liquid (IL) can be tuned by choice of different amino acids as well as different natural carboxylic acids as the counter-ions. A representative member of this new class of ionic liquids was successfully used for the synthesis of ionogels and as a solvent for the Heck coupling.}, language = {en} } @misc{KirchheckerTroegerMuellerBakeetal.2015, author = {Kirchhecker, Sarah and Tr{\"o}ger-M{\"u}ller, Steffen and Bake, Sebastian and Antonietti, Markus and Taubert, Andreas and Esposito, Davido}, title = {Renewable pyridinium ionic liquids from the continuous hydrothermal decarboxylation of furfural-amino acid derived pyridinium zwitterions}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81390}, year = {2015}, abstract = {Fully renewable pyridinium ionic liquids were synthesised via the hydrothermal decarboxylation of pyridinium zwitterions derived from furfural and amino acids in flow. The functionality of the resulting ionic liquid (IL) can be tuned by choice of different amino acids as well as different natural carboxylic acids as the counterions. A representative member of this new class of ionic liquids was successfully used for the synthesis of ionogels and as a solvent for the Heck coupling.}, language = {en} } @article{PrieskeMuehlbauerMuelleretal.2013, author = {Prieske, Olaf and M{\"u}hlbauer, Thomas and M{\"u}ller, Steffen and Kr{\"u}ger, Tom and Kibele, Armin and Behm, David George and Granacher, Urs}, title = {Effects of surface instability on neuromuscular performance during drop jumps and landings}, series = {European journal of applied physiology}, volume = {113}, journal = {European journal of applied physiology}, number = {12}, publisher = {Springer}, address = {New York}, issn = {1439-6319}, doi = {10.1007/s00421-013-2724-6}, pages = {2943 -- 2951}, year = {2013}, abstract = {The purpose of this study was to investigate the effects of surface instability on measures of performance and activity of leg and trunk muscles during drop jumps and landings. Drop jumps and landings were assessed on a force plate under stable and unstable (balance pad on top of the force plate) conditions. Performance measures (contact time, jump height, peak ground reaction force) and electromyographic (EMG) activity of leg and trunk muscles were tested in 27 subjects (age 23 +/- A 3 years) during different time intervals (preactivation phase, braking phase, push-off phase). The performance of drop jumps under unstable compared to stable conditions produced a decrease in jump height (9 \%, p < 0.001, f = 0.92) and an increase in peak ground reaction force (5 \%, p = 0.022, f = 0.72), and time for braking phase (12 \%, p < 0.001, f = 1.25). When performing drop jumps on unstable compared to stable surfaces, muscle activity was reduced in the lower extremities during the preactivation, braking and push-off phases (11-25 \%, p < 0.05, 0.48 a parts per thousand currency sign f a parts per thousand currency sign 1.23). Additionally, when landing on unstable compared to stable conditions, reduced lower limb muscle activities were observed during the preactivation phase (7-60 \%, p < 0.05, 0.50 a parts per thousand currency sign f a parts per thousand currency sign 3.62). Trunk muscle activity did not significantly differ between the test conditions for both jumping and landing tasks. The present findings indicate that modified feedforward mechanisms in terms of lower leg muscle activities during the preactivation phase and/or possible alterations in leg muscle activity shortly after ground contact (i.e., braking phase) are responsible for performance decrements during jumping on unstable surfaces.}, language = {en} } @misc{MuellerCarlsohnMuelleretal.2016, author = {M{\"u}ller, Steffen and Carlsohn, Anja and M{\"u}ller, Juliane and Baur, Heiner and Mayer, Frank}, title = {Influence of Obesity on Foot Loading Characteristics in Gait for Children Aged 1 to 12 Years}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-90108}, year = {2016}, abstract = {Background Overweight and obesity are increasing health problems that are not restricted to adults only. Childhood obesity is associated with metabolic, psychological and musculoskeletal comorbidities. However, knowledge about the effect of obesity on the foot function across maturation is lacking. Decreased foot function with disproportional loading characteristics is expected for obese children. The aim of this study was to examine foot loading characteristics during gait of normal-weight, overweight and obese children aged 1-12 years. Methods A total of 10382 children aged one to twelve years were enrolled in the study. Finally, 7575 children (m/f: n = 3630/3945; 7.0 +/- 2.9yr; 1.23 +/- 0.19m; 26.6 +/- 10.6kg; BMI: 17.1 +/- 2.4kg/m(2)) were included for (complete case) data analysis. Children were categorized to normalweight (>= 3rd and <90th percentile; n = 6458), overweight (>= 90rd and <97th percentile; n = 746) or obese (>97th percentile; n = 371) according to the German reference system that is based on age and gender-specific body mass indices (BMI). Plantar pressure measurements were assessed during gait on an instrumented walkway. Contact area, arch index (AI), peak pressure (PP) and force time integral (FTI) were calculated for the total, fore-, mid-and hindfoot. Data was analyzed descriptively (mean +/- SD) followed by ANOVA/Welch-test (according to homogeneity of variances: yes/no) for group differences according to BMI categorization (normal-weight, overweight, obesity) and for each age group 1 to 12yrs (post-hoc Tukey Kramer/Dunnett's C; alpha = 0.05). Results Mean walking velocity was 0.95 +/- 0.25 m/s with no differences between normal-weight, overweight or obese children (p = 0.0841). Results show higher foot contact area, arch index, peak pressure and force time integral in overweight and obese children (p< 0.001). Obese children showed the 1.48-fold (1 year-old) to 3.49-fold (10 year-old) midfoot loading (FTI) compared to normal-weight. Conclusion Additional body mass leads to higher overall load, with disproportional impact on the midfoot area and longitudinal foot arch showing characteristic foot loading patterns. Already the feet of one and two year old children are significantly affected. Childhood overweight and obesity is not compensated by the musculoskeletal system. To avoid excessive foot loading with potential risk of discomfort or pain in childhood, prevention strategies should be developed and validated for children with a high body mass index and functional changes in the midfoot area. The presented plantar pressure values could additionally serve as reference data to identify suspicious foot loading patterns in children.}, language = {en} } @article{MuellerCarlsohnMuelleretal.2016, author = {M{\"u}ller, Steffen and Carlsohn, Anja and M{\"u}ller, Juliane and Baur, Heiner and Mayer, Frank}, title = {Influence of Obesity on Foot Loading Characteristics in Gait for Children Aged 1 to 12 Years}, series = {PLoS one}, volume = {11}, journal = {PLoS one}, number = {2}, publisher = {Public Library of Science}, address = {Lawrence, Kan.}, issn = {1932-6203}, doi = {10.1371/journal.pone.0149924}, year = {2016}, abstract = {Background Overweight and obesity are increasing health problems that are not restricted to adults only. Childhood obesity is associated with metabolic, psychological and musculoskeletal comorbidities. However, knowledge about the effect of obesity on the foot function across maturation is lacking. Decreased foot function with disproportional loading characteristics is expected for obese children. The aim of this study was to examine foot loading characteristics during gait of normal-weight, overweight and obese children aged 1-12 years. Methods A total of 10382 children aged one to twelve years were enrolled in the study. Finally, 7575 children (m/f: n = 3630/3945; 7.0 +/- 2.9yr; 1.23 +/- 0.19m; 26.6 +/- 10.6kg; BMI: 17.1 +/- 2.4kg/m(2)) were included for (complete case) data analysis. Children were categorized to normalweight (>= 3rd and <90th percentile; n = 6458), overweight (>= 90rd and <97th percentile; n = 746) or obese (>97th percentile; n = 371) according to the German reference system that is based on age and gender-specific body mass indices (BMI). Plantar pressure measurements were assessed during gait on an instrumented walkway. Contact area, arch index (AI), peak pressure (PP) and force time integral (FTI) were calculated for the total, fore-, mid-and hindfoot. Data was analyzed descriptively (mean +/- SD) followed by ANOVA/Welch-test (according to homogeneity of variances: yes/no) for group differences according to BMI categorization (normal-weight, overweight, obesity) and for each age group 1 to 12yrs (post-hoc Tukey Kramer/Dunnett's C; alpha = 0.05). Results Mean walking velocity was 0.95 +/- 0.25 m/s with no differences between normal-weight, overweight or obese children (p = 0.0841). Results show higher foot contact area, arch index, peak pressure and force time integral in overweight and obese children (p< 0.001). Obese children showed the 1.48-fold (1 year-old) to 3.49-fold (10 year-old) midfoot loading (FTI) compared to normal-weight. Conclusion Additional body mass leads to higher overall load, with disproportional impact on the midfoot area and longitudinal foot arch showing characteristic foot loading patterns. Already the feet of one and two year old children are significantly affected. Childhood overweight and obesity is not compensated by the musculoskeletal system. To avoid excessive foot loading with potential risk of discomfort or pain in childhood, prevention strategies should be developed and validated for children with a high body mass index and functional changes in the midfoot area. The presented plantar pressure values could additionally serve as reference data to identify suspicious foot loading patterns in children.}, language = {en} } @misc{BaritelloKhajooeiEngeletal.2020, author = {Baritello, Omar and Khajooei, Mina and Engel, Tilman and Kopinski, Stephan and Quarmby, Andrew and M{\"u}ller, Steffen and Mayer, Frank}, title = {Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {1}, issn = {1866-8364}, doi = {10.25932/publishup-50936}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-509366}, pages = {16}, year = {2020}, abstract = {Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (\%MVIC). Differences between conditions for RMS\%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p <= 0.05; Bonferroni adjusted alpha = 0.008). Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS\%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.}, language = {en} } @phdthesis{TroegerMueller2018, author = {Tr{\"o}ger-M{\"u}ller, Steffen}, title = {Truly sustainable imidazolium ionics}, school = {Universit{\"a}t Potsdam}, pages = {158}, year = {2018}, language = {de} }