@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{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{MartinezValdesNegroLaineetal.2017,
  author    = {Martinez-Valdes, Eduardo Andr{\´e}s and Negro, F. and Laine, C. M. and Falla, D. and Mayer, Frank and Farina, Dario},
  title     = {Tracking motor units longitudinally across experimental sessions with high-density surface electromyography},
  series = {The Journal of Physiology},
  volume    = {595},
  journal   = {The Journal of Physiology},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0022-3751},
  doi       = {10.1113/JP273662},
  pages     = {1479 -- 1496},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@misc{PuschmannBeckSchiltenwolfetal.2017,
  author    = {Puschmann, Anne-Kathrin and Beck, Heidrun and Schiltenwolf, Marcus and Wippert, Pia-Maria and Mayer, Frank},
  title     = {Distress in a longitudinal study of a population with nonspecific low back pain},
  series = {Psychosomatic medicine},
  volume    = {79},
  journal   = {Psychosomatic medicine},
  publisher = {Lippincott Williams \& Wilkins},
  address   = {Philadelphia},
  issn      = {0033-3174},
  pages     = {A20 -- A21},
  year      = {2017},
  language  = {en}
}
@misc{DeWittHubertsNiedererWippertetal.2017,
  author    = {De Witt Huberts, Jessie and Niederer, Daniel and Wippert, Pia-Maria and Mayer, Frank},
  title     = {The effects of a new practical and synergetic multimodal treatment for chronic back pain on pain-related cognitions and wellbeing},
  series = {Psychosomatic medicine},
  volume    = {79},
  journal   = {Psychosomatic medicine},
  number    = {4},
  publisher = {Lippincott Williams \& Wilkins},
  address   = {Philadelphia},
  issn      = {0033-3174},
  pages     = {A22 -- A23},
  year      = {2017},
  language  = {en}
}
@article{RischCasselMayer2017,
  author    = {Risch, Lucie and Cassel, Michael and Mayer, Frank},
  title     = {Acute effect of running exercise on physiological Achilles tendon blood flow},
  series = {Scandinavian journal of medicine \& science in sports},
  volume    = {28},
  journal   = {Scandinavian journal of medicine \& science in sports},
  number    = {1},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0905-7188},
  doi       = {10.1111/sms.12874},
  pages     = {138 -- 143},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{RischWochatzMesserschmidtetal.2017,
  author    = {Risch, Lucie and Wochatz, Monique and Messerschmidt, Janin and Engel, Tilman and Mayer, Frank and Cassel, Michael},
  title     = {Reliability of evaluating achilles tendon vascularization assessed with doppler ultrasound advanced dynamic flow},
  series = {Journal of ultrasound in medicine},
  volume    = {37},
  journal   = {Journal of ultrasound in medicine},
  number    = {3},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0278-4297},
  doi       = {10.1002/jum.14414},
  pages     = {737 -- 744},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@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{WochatzRabeWolteretal.2017,
  author    = {Wochatz, Monique and Rabe, Sophie and Wolter, Martin and Engel, Tilman and Mueller, Steffen and Mayer, Frank},
  title     = {Muscle activity of upper and lower trapezius and serratus anterior during unloaded and maximal loaded shoulder flexion and extension},
  series = {International Biomechanics},
  volume    = {4},
  journal   = {International Biomechanics},
  number    = {2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {https://doi.org/10.1080/23335432.2017.1364668},
  pages     = {68 -- 76},
  year      = {2017},
  abstract  = {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.},
  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}
}