TY - JOUR A1 - Müller, Juliane A1 - Hadzic, Miralem A1 - Mugele, Hendrik A1 - Stoll, Josefine A1 - Müller, Steffen A1 - Mayer, Frank T1 - Effect of high-intensity perturbations during core-specific sensorimotor exercises on trunk muscle activation JF - Journal of biomechanics N2 - 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. KW - Split-belt treadmill KW - EMG KW - Core stability KW - MiSpEx Y1 - 2017 U6 - https://doi.org/10.1016/j.jbiomech.2017.12.013 SN - 0021-9290 SN - 1873-2380 VL - 70 SP - 212 EP - 218 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Rector, Michael V. A1 - Intziegianni, Konstantina A1 - Müller, Steffen A1 - Mayer, Frank A1 - Cassel, Michael T1 - Reproducibility of an ankle joint rotation correction method for assessment of Achilles tendon elongation JF - Isokinetics and exercise science : official journal of the European Isokinetic Society N2 - 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. KW - Ultrasonography KW - Achilles tendon KW - reproducibility KW - isokinetic KW - ankle joint rotation Y1 - 2017 U6 - https://doi.org/10.3233/IES-160644 SN - 0959-3020 SN - 1878-5913 VL - 25 IS - 1 SP - 47 EP - 52 PB - IOS Press CY - Amsterdam ER - TY - GEN A1 - De Witt Huberts, Jessie A1 - Niederer, Daniel A1 - Wippert, Pia-Maria A1 - Mayer, Frank T1 - The effects of a new practical and synergetic multimodal treatment for chronic back pain on pain-related cognitions and wellbeing T2 - Psychosomatic medicine Y1 - 2017 SN - 0033-3174 SN - 1534-7796 VL - 79 IS - 4 SP - A22 EP - A23 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - GEN A1 - Puschmann, Anne-Kathrin A1 - Beck, Heidrun A1 - Schiltenwolf, Marcus A1 - Wippert, Pia-Maria A1 - Mayer, Frank T1 - Distress in a longitudinal study of a population with nonspecific low back pain T2 - Psychosomatic medicine Y1 - 2017 SN - 0033-3174 SN - 1534-7796 VL - 79 SP - A20 EP - A21 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Risch, Lucie A1 - Cassel, Michael A1 - Mayer, Frank T1 - Acute effect of running exercise on physiological Achilles tendon blood flow JF - Scandinavian journal of medicine & science in sports N2 - Sonographically detectable intratendinous blood flow (IBF) is found in 50%-88% of Achilles tendinopathy patients as well as in up to 35% of asymptomatic Achilles tendons (AT). Although IBF is frequently associated with tendon pathology, it may also represent a physiological regulation, for example, due to increased blood flow in response to exercise. Therefore, this study aimed to investigate the acute effects of a standardized running exercise protocol on IBF assessed with Doppler ultrasound (DU) Advanced dynamic flow in healthy ATs. 10 recreationally active adults (5 f, 5m; 29 +/- 3years, 1.72 +/- 0.12m, 68 +/- 16kg, physical activity 206 +/- 145minute/wk) with no history of AT pain and inconspicious tendon structure performed 3 treadmill running tasks on separate days (M1-3) with DU examinations directly before and 5, 30, 60, and 120minutes after exercise. At M1, an incremental exercise test was used to determine the individual anaerobic threshold (IAT). At M2 and M3, participants performed 30-minute submaximal constant load tests (CL1/CL2) with an intensity 5% below IAT. IBF in each tendon was quantified by counting the number of vessels. IBF increased in five ATs from no vessels at baseline to one to four vessels solely detectable 5minutes after CL1 or CL2. One AT had persisting IBF (three vessels) throughout all examinations. Fourteen ATs revealed no IBF at all. Prolonged running led to a physiological, temporary appearance of IBF in 25% of asymptomatic ATs. To avoid exercise-induced IBF in clinical practice, DU examinations should be performed after 30minutes of rest. KW - advanced dynamic flow KW - doppler ultrasound KW - hyperemia KW - neovascularization KW - sonography Y1 - 2017 U6 - https://doi.org/10.1111/sms.12874 SN - 0905-7188 SN - 1600-0838 VL - 28 IS - 1 SP - 138 EP - 143 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Müller, Juliane A1 - Engel, Tilman A1 - Kopinski, Stephan A1 - Mayer, Frank A1 - Müller, Steffen T1 - Neuromuscular trunk activation patterns in back pain patients during one-handed lifting JF - World journal of orthopedics N2 - 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. KW - Lifting KW - Core KW - Trunk KW - EMG KW - MISPEX Y1 - 2016 U6 - https://doi.org/10.5312/wjo.v8.i2.142 SN - 2218-5836 VL - 8 IS - 2 SP - 142 EP - 148 PB - Baishideng Publishing Group CY - Pleasanton ER - TY - JOUR A1 - Risch, Lucie A1 - Wochatz, Monique A1 - Messerschmidt, Janin A1 - Engel, Tilman A1 - Mayer, Frank A1 - Cassel, Michael T1 - Reliability of evaluating achilles tendon vascularization assessed with doppler ultrasound advanced dynamic flow JF - Journal of ultrasound in medicine N2 - The reliability of quantifying intratendinous vascularization by high-sensitivity Doppler ultrasound advanced dynamic flow has not been examined yet. Therefore, this study aimed to investigate the intraobserver and interobserver reliability of evaluating Achilles tendon vascularization by advanced dynamic flow using established scoring systems. Methods-Three investigators evaluated vascularization in 67 recordings in a test-retest design, applying the Ohberg score, a modified Ohberg score, and a counting score. Intraobserver and interobserver agreement for the Ohberg score and modified Ohberg score was analyzed by the Cohen kappa and Fleiss kappa coefficients (absolute), Kendall tau b coefficient, and Kendall coefficient of concordance (W; relative). The reliability of the counting score was analyzed by intraclass correlation coefficients (ICC) 2.1 and 3.1, the standard error of measurement (SEM), and Bland-Altman analysis (bias and limits of agreement [LoA]). Results-Intraobserver and interobserver agreement (absolute/relative) ranged from 0.61 to 0.87/0.87 to 0.95 and 0.11 to 0.66/0.76 to 0.89 for the Ohberg score and from 0.81 to 0.87/0.92 to 0.95 and 0.64 to 0.80/0.88 to 0.93 for the modified Ohberg score, respectively. The counting score revealed an intraobserver ICC of 0.94 to 0.97 (SEM, 1.0-1.5; bias, -1; and LoA, 3-4 vessels). The interobserver ICC for the counting score ranged from 0.91 to 0.98 (SEM, 1.0-1.9; bias, 0; and LoA, 3-5 vessels). Conclusions-The modified Ohberg score and counting score showed excellent reliability and seem convenient for research and clinical practice. The Ohberg score revealed decent intraobserver but unexpected low interobserver reliability and therefore cannot be recommended. KW - advanced dynamic flow KW - intratendinous blood flow KW - musculoskeletal KW - reliability KW - ultrasound Y1 - 2017 U6 - https://doi.org/10.1002/jum.14414 SN - 0278-4297 SN - 1550-9613 VL - 37 IS - 3 SP - 737 EP - 744 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Wippert, Pia-Maria A1 - Puschmann, Anne-Katrin A1 - Drießlein, David A1 - Arampatzis, Adamantios A1 - Banzer, Winfried A1 - Beck, Heidrun A1 - Schiltenwolf, Marcus A1 - Schmidt, Hendrik A1 - Schneider, Christian A1 - Mayer, Frank T1 - Development of a risk stratification and prevention index for stratified care in chronic low back pain. Focus: yellow flags (MiSpEx network) JF - Pain reports N2 - Introduction: Chronic low back pain (LBP) is a major cause of disability; early diagnosis and stratification of care remain challenges. Objectives: This article describes the development of a screening tool for the 1-year prognosis of patients with high chronic LBP risk (risk stratification index) and for treatment allocation according to treatment-modifiable yellow flag indicators (risk prevention indices, RPI-S). Methods: Screening tools were derived from a multicentre longitudinal study (n = 1071, age >18, intermittent LBP). The greatest prognostic predictors of 4 flag domains ("pain," "distress," "social-environment," "medical care-environment") were determined using least absolute shrinkage and selection operator regression analysis. Internal validity and prognosis error were evaluated after 1-year follow-up. Receiver operating characteristic curves for discrimination (area under the curve) and cutoff values were determined. Results: The risk stratification index identified persons with increased risk of chronic LBP and accurately estimated expected pain intensity and disability on the Pain Grade Questionnaire (0-100 points) up to 1 year later with an average prognosis error of 15 points. In addition, 3-risk classes were discerned with an accuracy of area under the curve = 0.74 (95% confidence interval 0.63-0.85). The RPI-S also distinguished persons with potentially modifiable prognostic indicators from 4 flag domains and stratified allocation to biopsychosocial treatments accordingly. Conclusion: The screening tools, developed in compliance with the PROGRESS and TRIPOD statements, revealed good validation and prognostic strength. These tools improve on existing screening tools because of their utility for secondary preventions, incorporation of exercise effect modifiers, exact pain estimations, and personalized allocation to multimodal treatments. KW - Back pain prognosis KW - Back pain diagnosis KW - Pain screening KW - PROGRESS/TRIPOD KW - Prediction of disability/intensity KW - Yellow flags KW - Exercise Y1 - 2017 U6 - https://doi.org/10.1097/PR9.0000000000000623 VL - 9 SP - 1 EP - 11 PB - Wolters Kluwer Health CY - Riverwoods, IL ER - TY - JOUR A1 - Müller, Steffen A1 - Stoll, Josefine A1 - Mueller, Juliane A1 - Cassel, Michael A1 - Mayer, Frank T1 - Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain JF - Frontiers in physiology N2 - 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. KW - SEMG-pattern KW - back pain KW - pre-activity KW - drop jump KW - neuromuscular KW - trunk KW - performance KW - young athletes Y1 - 2017 U6 - https://doi.org/10.3389/fphys.2017.00274 SN - 1664-042X VL - 8 SP - 124 EP - 132 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Cassel, Michael A1 - Intziegianni, Konstantina A1 - Risch, Lucie A1 - Mueller, Steffen A1 - Engel, Tilman A1 - Mayer, Frank T1 - Physiological Tendon Thickness Adaptation in Adolescent Elite Athletes: A Longitudinal Study JF - Frontiers in physiology N2 - 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 (cy = 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 (Ml: 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. KW - Achilles and patellar tendon KW - training adaptation KW - sonography KW - young athletes KW - non-athletes Y1 - 2017 U6 - https://doi.org/10.3389/fphys.2017.00795 SN - 1664-042X VL - 8 SP - 599 EP - 611 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Wippert, Pia-Maria A1 - Puschmann, Anne-Katrin A1 - Arampatzis, Adamantios A1 - Schiltenwolf, Marcus A1 - Mayer, Frank T1 - Diagnosis of psychosocial risk factors in prevention of low back pain in athletes (MiSpEx) JF - BMJ Open Sport & Exercise Medicine N2 - Background Low back pain (LBP) is a common pain syndrome in athletes, responsible for 28% of missed training days/year. Psychosocial factors contribute to chronic pain development. This study aims to investigate the transferability of psychosocial screening tools developed in the general population to athletes and to define athlete-specific thresholds. Methods Data from a prospective multicentre study on LBP were collected at baseline and 1-year follow-up (n=52 athletes, n=289 recreational athletes and n=246 non-athletes). Pain was assessed using the Chronic Pain Grade questionnaire. The psychosocial Risk Stratification Index (RSI) was used to obtain prognostic information regarding the risk of chronic LBP (CLBP). Individual psychosocial risk profile was gained with the Risk Prevention Index – Social (RPI-S). Differences between groups were calculated using general linear models and planned contrasts. Discrimination thresholds for athletes were defined with receiver operating characteristics (ROC) curves. Results Athletes and recreational athletes showed significantly lower psychosocial risk profiles and prognostic risk for CLBP than non-athletes. ROC curves suggested discrimination thresholds for athletes were different compared with non-athletes. Both screenings demonstrated very good sensitivity (RSI=100%; RPI-S: 75%–100%) and specificity (RSI: 76%–93%; RPI-S: 71%–93%). RSI revealed two risk classes for pain intensity (area under the curve (AUC) 0.92(95% CI 0.85 to 1.0)) and pain disability (AUC 0.88(95% CI 0.71 to 1.0)). Conclusions Both screening tools can be used for athletes. Athlete-specific thresholds will improve physicians’ decision making and allow stratified treatment and prevention. Y1 - 2017 U6 - https://doi.org/10.1136/bmjsem-2017-000295 SN - 2055-7647 VL - 3 IS - 1 ER - TY - JOUR A1 - Wochatz, Monique A1 - Rabe, Sophie A1 - Wolter, Martin A1 - Engel, Tilman A1 - Mueller, Steffen A1 - Mayer, Frank T1 - Muscle activity of upper and lower trapezius and serratus anterior during unloaded and maximal loaded shoulder flexion and extension JF - International Biomechanics N2 - Altered scapular muscle activity is mostly described under unloaded and submaximal loaded conditions in impingement patients. However, there is no clear evidence on muscle activity with respect to movement phases under maximum load in healthy subjects. Therefore, this study aimed to investigate scapular muscle activity under unloaded and maximum loaded isokinetic shoulder flexion and extension in regard to the movement phase. Fourteen adults performed unloaded (continuous passive motion [CPM]) as well as maximum loaded (concentric [CON], eccentric [ECC]) isokinetic shoulder flexion (Flex) and extension (Ext). Simultaneously, scapular muscle activity was measured by EMG. Root mean square was calculated for the whole ROM and four movement phases. Data were analyzed descriptively and by two-way repeated measures ANOVA. CPMFlex resulted in a linear increase of muscle activity for all muscles. Muscle activity during CONFlex and ECCFlex resulted in either constant activity levels or in an initial increase followed by a plateau in the second half of movement. CPMExt decreased with the progression of movement, whereas CONExt and ECCExt initially decreased and either levelled off or increased in the second half of movement. Scapular muscle activity of unloaded shoulder flexion and extension changed under maximum load showing increased activity levels and an altered pattern over the course of movement. KW - shoulder KW - scapular muscle activity KW - isokinetic testing KW - electromyography Y1 - 2017 U6 - https://doi.org/https://doi.org/10.1080/23335432.2017.1364668 VL - 4 IS - 2 SP - 68 EP - 76 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Müller, Juliane A1 - Müller, Steffen A1 - Stoll, Josefine A1 - Fröhlich, K. A1 - Otto, Christoph A1 - Mayer, Frank T1 - Back pain prevalence in adolescent athletes JF - Scandinavian journal of medicine & science in sports N2 - 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. KW - Young athletes KW - back pain KW - prevalence KW - types of sports Y1 - 2017 U6 - https://doi.org/10.1111/sms.12664 SN - 0905-7188 SN - 1600-0838 VL - 27 SP - 448 EP - 454 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Martinez-Valdes, Eduardo Andrés A1 - Negro, F. A1 - Laine, C. M. A1 - Falla, D. A1 - Mayer, Frank A1 - Farina, Dario T1 - Tracking motor units longitudinally across experimental sessions with high-density surface electromyography JF - The Journal of Physiology N2 - A new method is proposed for tracking individual motor units (MUs) across multiple experimental sessions on different days. The technique is based on a novel decomposition approach for high-density surface electromyography and was tested with two experimental studies for reliability and sensitivity. Experiment I (reliability): ten participants performed isometric knee extensions at 10, 30, 50 and 70% of their maximum voluntary contraction (MVC) force in three sessions, each separated by 1 week. Experiment II (sensitivity): seven participants performed 2 weeks of endurance training (cycling) and were tested pre-post intervention during isometric knee extensions at 10 and 30% MVC. The reliability (Experiment I) and sensitivity (Experiment II) of the measured MU properties were compared for the MUs tracked across sessions, with respect to all MUs identified in each session. In Experiment I, on average 38.3% and 40.1% of the identified MUs could be tracked across two sessions (1 and 2 weeks apart), for the vastus medialis and vastus lateralis, respectively. Moreover, the properties of the tracked MUs were more reliable across sessions than those of the full set of identified MUs (intra-class correlation coefficients ranged between 0.63-0.99 and 0.39-0.95, respectively). In Experiment II, similar to 40% of the MUs could be tracked before and after the training intervention and training-induced changes in MU conduction velocity had an effect size of 2.1 (tracked MUs) and 1.5 (group of all identified motor units). These results show the possibility of monitoring MU properties longitudinally to document the effect of interventions or the progression of neuromuscular disorders. Y1 - 2016 U6 - https://doi.org/10.1113/JP273662 SN - 0022-3751 SN - 1469-7793 VL - 595 SP - 1479 EP - 1496 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Wahmkow, Gunnar A1 - Cassel, Michael A1 - Mayer, Frank A1 - Baur, Heiner T1 - Effects of different medial arch support heights on rearfoot kinematics JF - PLoS one N2 - Background Foot orthoses are usually assumed to be effective by optimizing mechanically dynamic rearfoot configuration. However, the effect from a foot orthosis on kinematics that has been demonstrated scientifically has only been marginal. The aim of this study was to examine the effect of different heights in medial arch-supported foot orthoses on rear foot motion during gait. Methods Nineteen asymptomatic runners (36±11years, 180±5cm, 79±10kg; 41±22km/week) participated in the study. Trials were recorded at 3.1 mph (5 km/h) on a treadmill. Athletes walked barefoot and with 4 different not customized medial arch-supported foot orthoses of various arch heights (N:0 mm, M:30 mm, H:35 mm, E:40mm). Six infrared cameras and the `Oxford Foot Model´ were used to capture motion. The average stride in each condition was calculated from 50 gait cycles per condition. Eversion excursion and internal tibia rotation were analyzed. Descriptive statistics included calculating the mean ± SD and 95% CIs. Group differences by condition were analyzed by one factor (foot orthoses) repeated measures ANOVA (α = 0.05). Results Eversion excursion revealed the lowest values for N and highest for H (B:4.6°±2.2°; 95% CI [3.1;6.2]/N:4.0°±1.7°; [2.9;5.2]/M:5.2°±2.6°; [3.6;6.8]/H:6.2°±3.3°; [4.0;8.5]/E:5.1°±3.5°; [2.8;7.5]) (p>0.05). Range of internal tibia rotation was lowest with orthosis H and highest with E (B:13.3°±3.2°; 95% CI [11.0;15.6]/N:14.5°±7.2°; [9.2;19.6]/M:13.8°±5.0°; [10.8;16.8]/H:12.3°±4.3°; [9.0;15.6]/E:14.9°±5.0°; [11.5;18.3]) (p>0.05). Differences between conditions were small and the intrasubject variation high. Conclusion Our results indicate that different arch support heights have no systematic effect on eversion excursion or the range of internal tibia rotation and therefore might not exert a crucial influence on rear foot alignment during gait. Y1 - 2017 U6 - https://doi.org/10.1371/journal.pone.0172334 SN - 1932-6203 VL - 12 IS - 3 PB - PLoS CY - Lawrence, Kan. ER - TY - JOUR A1 - Eichler, Sarah A1 - Rabe, Sophie A1 - Salzwedel, Annett A1 - Mueller, Steffen A1 - Stoll, Josefine A1 - Tilgner, Nina A1 - John, Michael A1 - Wegscheider, Karl A1 - Mayer, Frank A1 - Völler, Heinz T1 - Effectiveness of an interactive telerehabilitation system with home-based exercise training in patients after total hip or knee replacement: study protocol for a multicenter, superiority, no-blinded randomized controlled trial JF - Trials N2 - 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. KW - Telerehabilitation KW - Home-based KW - Total hip replacement KW - Total knee replacement KW - Exercise therapy KW - Aftercare Y1 - 2017 U6 - https://doi.org/10.1186/s13063-017-2173-3 SN - 1745-6215 VL - 18 PB - BioMed Central CY - London ER - TY - JOUR A1 - Eichler, Sarah A1 - Rabe, Sophie A1 - Salzwedel, Annett A1 - Müller, Steffen A1 - Stoll, Josefine A1 - Tilgner, Nina A1 - John, Michael A1 - Wegschneider, Karl A1 - Mayer, Frank A1 - Völler, Heinz T1 - Effectiveness of an interactive telerehabilitation system with home-based exercise training in patients after total hip or knee replacement BT - Study protocol for a multicenter, superiority, no-blinded randomized controlled trial JF - Trials N2 - 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. KW - Telerehabilitation KW - Home-based KW - Total hip replacement KW - Total knee replacement KW - Exercise therapy KW - Aftercare Y1 - 2017 U6 - https://doi.org/10.1186/s13063-017-2173-3 SN - 1745-6215 VL - 18 SP - 1 EP - 7 PB - BioMed Central CY - London ER - TY - JOUR A1 - Engel, Tilman A1 - Mueller, Juliane A1 - Kopinski, Stephan A1 - Reschke, Antje A1 - Mueller, Steffen A1 - Mayer, Frank T1 - Unexpected walking perturbations: Reliability and validity of a new treadmill protocol to provoke muscular reflex activities at lower extremities and the trunk JF - Journal of biomechanics N2 - Instrumented treadmills offer the potential to generate standardized walking perturbations, which are particularly rapid and powerful. However, technical requirements to release adequate perturbations regarding timing, duration and amplitude are demanding. This study investigated the test-retest reliability and validity of a new treadmill perturbation protocol releasing rapid and unexpected belt perturbations to provoke muscular reflex responses at lower extremities and the trunk. Fourteen healthy participants underwent two identical treadmill walking protocols, consisting of 10 superimposed one-sided belt perturbations (100 ms duration; 2 m/s amplitude), triggered by a plantar pressure insole 200 ms after heel contact. Delay, duration and amplitude of applied perturbations were recorded by 3D-motion capture. Muscular reflex responses (within 200 ms) were measured at lower extremities and the trunk (10-lead EMG). Data was analyzed descriptively (mean +/- SD). Reliability was analyzed using test-retest variability (TRV%) and limits of agreement (LoA, bias +/- 1.96*SD). Perturbation delay was 202 14 ms, duration was 102 +/- 4 ms and amplitude was 2.1 +/- 0.01 m/s. TRV for perturbation delay, duration and amplitude ranged from 5.0% to 5.7%. LoA reached 3 +/- 36 ms for delay, 2 +/- 13 ms for duration and 0.0 +/- 0.3 m/s for amplitude. EMG amplitudes following perturbations ranged between 106 +/- 97% and 909 +/- 979% of unperturbed gait and EMG latencies between 82 +/- 14 ms and 106 +/- 16 ms. Minor differences between preset and observed perturbation characteristics and results of test-retest analysis prove a high validity with excellent reliability of the setup. Therefore, the protocol tested can be recommended to provoke muscular reflex responses at lower extremities and the trunk in perturbed walking. (C) 2017 Elsevier Ltd. All rights reserved. KW - Perturbation KW - Stumbling KW - Gait KW - Treadmill KW - Reliability KW - MiSpEx Y1 - 2017 U6 - https://doi.org/10.1016/j.jbiomech.2017.02.026 SN - 0021-9290 SN - 1873-2380 VL - 55 SP - 152 EP - 155 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Müller, Steffen A1 - Stoll, Josefine A1 - Cassel, Michael A1 - Mayer, Frank T1 - Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain JF - Frontiers in physiology N2 - 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. KW - SEMG-pattern KW - back pain KW - pre-activity KW - drop jump KW - neuromuscular KW - trunk KW - performance KW - young athletes Y1 - 2017 U6 - https://doi.org/10.3389/fphys.2017.00274 SN - 1664-042X VL - 8 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Cassel, Michael A1 - Intziegianni, Konstantina A1 - Risch, Lucie A1 - Müller, Steffen A1 - Engel, Tilman A1 - Mayer, Frank T1 - Physiological Tendon Thickness Adaptation in Adolescent Elite Athletes BT - A Longitudinal Study JF - Frontiers in physiology N2 - 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. KW - Achilles and patellar tendon KW - training adaptation KW - sonography KW - young athletes KW - non-athletes Y1 - 2017 U6 - https://doi.org/10.3389/fphys.2017.00795 SN - 1664-042X VL - 8 SP - 1 EP - 8 PB - Frontiers CY - Lausanne ER - TY - JOUR A1 - Martinez-Valdes, Eduardo Andrés A1 - Falla, Deborah A1 - Negro, Francesco A1 - Mayer, Frank A1 - Farina, Dario T1 - Differential Motor Unit Changes after Endurance or High-Intensity Interval Training JF - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine N2 - Purpose Using a novel technique of high-density surface EMG decomposition and motor unit (MU) tracking, we compared changes in the properties of vastus medialis and vastus lateralis MU after endurance (END) and high-intensity interval training (HIIT). Methods Sixteen men were assigned to the END or the HIIT group (n = 8 each) and performed six training sessions for 14 d. Each session consisted of 8-12 x 60-s intervals at 100% peak power output separated by 75 s of recovery (HIIT) or 90-120 min continuous cycling at similar to 65% VO2peak (END). Pre- and postintervention, participants performed 1) incremental cycling to determine VO2peak and peak power output and 2) maximal, submaximal (10%, 30%, 50%, and 70% maximum voluntary contraction [MVC]), and sustained (until task failure at 30% MVC) isometric knee extensions while high-density surface EMG signals were recorded from the vastus medialis and vastus lateralis. EMG signals were decomposed (submaximal contractions) into individual MU by convolutive blind source separation. Finally, MU were tracked across sessions by semiblind source separation. Results After training, END and HIIT improved VO2peak similarly (by 5.0% and 6.7%, respectively). The HIIT group showed enhanced maximal knee extension torque by similar to 7% (P = 0.02) and was accompanied by an increase in discharge rate for high-threshold MU (50% knee extension MVC) (P < 0.05). By contrast, the END group increased their time to task failure by similar to 17% but showed no change in MU discharge rates (P > 0.05). Conclusions HIIT and END induce different adjustments in MU discharge rate despite similar improvements in cardiopulmonary fitness. Moreover, the changes induced by HIIT are specific for high-threshold MU. For the first time, we show that HIIT and END induce specific neuromuscular adaptations, possibly related to differences in exercise load intensity and training volume. KW - HIGH-DENSITY SURFACE EMG KW - MOTOR UNIT DECOMPOSITION KW - MOTOR UNIT TRACKING KW - MOTOR UNIT DISCHARGE RATE KW - MOTOR UNIT ADAPTATION KW - NEUROMUSCULAR ADAPTATION Y1 - 2017 U6 - https://doi.org/10.1249/MSS.0000000000001209 SN - 0195-9131 SN - 1530-0315 VL - 49 SP - 1126 EP - 1136 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Wochatz, Monique A1 - Rabe, Sophie A1 - Wolter, Martin A1 - Engel, Tilman A1 - Mueller, Steffen A1 - Mayer, Frank T1 - Reproducibility of scapular muscle activity in isokinetic shoulder flexion and extension JF - Journal of electromyography and kinesiology N2 - Repetitive overhead movements have been identified as a main risk factor to develop shoulder complaints with scapular muscle activity being altered. Reliable assessment of muscle activity is essential to differentiate between symptomatic and asymptomatic individuals. Therefore, the present study aimed to investigate the intra-and inter-session reliability of scapular muscle activity during maximal isokinetic shoulder flexion and extension. Eleven asymptomatic adults performed maximum effort isokinetic shoulder flexion and extension (concentric and eccentric at 60 degrees/s) in a test-retest design. Muscle activity of the upper and lower trapezius and serratus anterior was assessed by sEMG. Root Mean Square was calculated for whole ROM and single movement phases of absolute and normalized muscle activity. Absolute (Bland-Altman analysis (Bias, LoA), Minimal detectable change (MDC)) and relative reliability parameters (Intraclass correlation coefficient (ICC), coefficient of variation (CV)/test-retest variability (TRV)) were utilized for the evaluation of reproducibility. Intra-session reliability revealed ICCs between 0.56 and 0.98, averaged CVs of 18% and average MDCs of 81 mV. Inter-session reliability resulted in ICCs between 0.13 and 0.93, averaged TRVs of 21%, average MDCs of 15% and systematic and random error between -8 +/- 60% and 12 +/- 36%. Scapular muscle activity assessed in overhead movements can be measured reliably under maximum load conditions, though variability is dependent on the movement phase. Measurement variability does not exceed magnitudes of altered scapular muscle activities as reported in previous studies. Therefore, maximum load application is a promising approach for the evaluation of changes in scapular control related to pathologies. (C) 2017 Elsevier Ltd. All rights reserved. Y1 - 2017 U6 - https://doi.org/10.1016/j.jelekin.2017.04.006 SN - 1050-6411 SN - 1873-5711 VL - 34 SP - 86 EP - 92 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Müller, Juliane A1 - Engel, Tilman A1 - Müller, Steffen A1 - Stoll, Josefine A1 - Baur, Heiner A1 - Mayer, Frank T1 - Effects of sudden walking perturbations on neuromuscular reflex activity and three-dimensional motion of the trunk in healthy controls and back pain symptomatic subjects JF - PLoS one N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1371/journal.pone.0174034 SN - 1932-6203 VL - 12 IS - 3 PB - PLoS CY - Lawrence, Kan. ER - TY - GEN A1 - Chaparro, Camilo G. A. Perez A1 - Zech, Philipp A. A1 - Heinzel, Stephan A1 - Mayer, Frank A1 - Wolfarth, Bernd A1 - Rapp, Michael A. A1 - Heissel, Andreas T1 - Effects Of Aerobic & Resistance Training On Cardiorespiratory Fitness In People Living with HIV. A Meta-analysis T2 - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine Y1 - 2017 U6 - https://doi.org/10.1249/01.mss.0000519265.28705.86 SN - 0195-9131 SN - 1530-0315 VL - 49 SP - 842 EP - 842 PB - Lippincott Williams & Wilkins CY - Philadelphia ER -