TY  - JOUR
A1  - Wochatz, Monique
A1  - Engel, Tilman
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Alterations in scapular kinematics and scapular muscle activity after fatiguing shoulder flexion and extension movements
JF  - Medicine and science in sports and exercise : MSSE
N2  - 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.
Y1  - 2020
U6  - https://doi.org/10.1249/01.mss.0000676540.02017.2c
SN  - 0195-9131
SN  - 1530-0315
VL  - 52
IS  - 17
SP  - 274
EP  - 274
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Henschke, Jakob
A1  - Kaplick, Hannes
A1  - Wochatz, Monique
A1  - Engel, Tilman
T1  - Assessing the validity of inertial measurement units for shoulder kinematics using a commercial sensor-software system
BT  - a validation study
JF  - Health science reports
N2  - Background and Aims Wearable inertial sensors may offer additional kinematic parameters of the shoulder compared to traditional instruments such as goniometers when elaborate and time-consuming data processing procedures are undertaken. However, in clinical practice simple-real time motion analysis is required to improve clinical reasoning. Therefore, the aim was to assess the criterion validity between a portable "off-the-shelf" sensor-software system (IMU) and optical motion (Mocap) for measuring kinematic parameters during active shoulder movements. Methods 24 healthy participants (9 female, 15 male, age 29 +/- 4 years, height 177 +/- 11 cm, weight 73 +/- 14 kg) were included. Range of motion (ROM), total range of motion (TROM), peak and mean angular velocity of both systems were assessed during simple (abduction/adduction, horizontal flexion/horizontal extension, vertical flexion/extension, and external/internal rotation) and complex shoulder movements. Criterion validity was determined using intraclass-correlation coefficients (ICC), root mean square error (RMSE) and Bland and Altmann analysis (bias; upper and lower limits of agreement). Results ROM and TROM analysis revealed inconsistent validity during simple (ICC: 0.040-0.733, RMSE: 9.7 degrees-20.3 degrees, bias: 1.2 degrees-50.7 degrees) and insufficient agreement during complex shoulder movements (ICC: 0.104-0.453, RMSE: 10.1 degrees-23.3 degrees, bias: 1.0 degrees-55.9 degrees). Peak angular velocity (ICC: 0.202-0.865, RMSE: 14.6 degrees/s-26.7 degrees/s, bias: 10.2 degrees/s-29.9 degrees/s) and mean angular velocity (ICC: 0.019-0.786, RMSE:6.1 degrees/s-34.2 degrees/s, bias: 1.6 degrees/s-27.8 degrees/s) were inconsistent. Conclusions The "off-the-shelf" sensor-software system showed overall insufficient agreement with the gold standard. Further development of commercial IMU-software-solutions may increase measurement accuracy and permit their integration into everyday clinical practice.
KW  - diagnostic techniques and procedures
KW  - kinematics
KW  - shoulder joint
KW  - validation study
KW  - wearable devices
Y1  - 2022
U6  - https://doi.org/10.1002/hsr2.772
SN  - 2398-8835
VL  - 5
IS  - 5
SP  - 1
EP  - 11
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - GEN
A1  - Molnar, Marco
A1  - Kok, Manor
A1  - Engel, Tilman
A1  - Kaplic, Hannes
A1  - Mayer, Frank
A1  - Seel, Thomas
T1  - A method for lower back motion assessment using wearable 6D inertial sensors
T2  - 21st International Conference on Information Fusion (FUSION)
N2  - Low back pain (LBP) is a leading cause of activity limitation. Objective assessment of the spinal motion plays a key role in diagnosis and treatment of LBP. We propose a method that facilitates clinical assessment of lower back motions by means of a wireless inertial sensor network. The sensor units are attached to the right and left side of the lumbar region, the pelvis and the thighs, respectively. Since magnetometers are known to be unreliable in indoor environments, we use only 3D accelerometer and 3D gyroscope readings. Compensation of integration drift in the horizontal plane is achieved by estimating the gyroscope biases from automatically detected initial rest phases. For the estimation of sensor orientations, both a smoothing algorithm and a filtering algorithm are presented. From these orientations, we determine three-dimensional joint angles between the thighs and the pelvis and between the pelvis and the lumbar region. We compare the orientations and joint angles to measurements of an optical motion tracking system that tracks each skin-mounted sensor by means of reflective markers. Eight subjects perform a neutral initial pose, then flexion/extension, lateral flexion, and rotation of the trunk. The root mean square deviation between inertial and optical angles is about one degree for angles in the frontal and sagittal plane and about two degrees for angles in the transverse plane (both values averaged over all trials). We choose five features that characterize the initial pose and the three motions. Interindividual differences of all features are found to be clearly larger than the observed measurement deviations. These results indicate that the proposed inertial sensor-based method is a promising tool for lower back motion assessment.
KW  - Inertial measurement units
KW  - joint angle estimation
KW  - human motion analysis
KW  - low back pain
KW  - back motion assessment
KW  - avoid magnetometers
KW  - validation against optical motion capture
KW  - drift correction
Y1  - 2018
SN  - 978-0-9964-5276-2
SP  - 799
EP  - 806
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Mueller, Juliane
A1  - Martinez-Valdes, Eduardo Andrés
A1  - Stoll, Josefine
A1  - Mueller, Steffen
A1  - Engel, Tilman
A1  - Mayer, Frank
T1  - Differences in neuromuscular activity of ankle stabilizing muscles during postural disturbances
BT  - a gender-specific analysis
JF  - Gait & posture
N2  - The purpose was to examine gender differences in ankle stabilizing muscle activation during postural disturbances. Seventeen participants (9 females: 27 +/- 2yrs., 1.69 +/- 0.1 m, 63 +/- 7 kg; 8 males: 29 +/- 2yrs., 1.81 +/- 0.1 m; 83 +/- 7 kg) were included in the study. After familiarization on a split-belt-treadmill, participants walked (1 m/s) while 15 right-sided perturbations were randomly applied 200 ms after initial heel contact. Muscle activity of M. tibialis anterior (TA), peroneus longus (PL) and gastrocnemius medialis (GM) was recorded during unperturbed and perturbed walking. The root mean square (RMS; [%]) was analyzed within 200 ms after perturbation. Co-activation was quantified as ratio of antagonist (GM)/agonist (TA) EMG-RMS during unperturbed and perturbed walking. Time to onset was calculated (ms). Data were analyzed descriptively (mean +/- SD) followed by three-way-ANOVA (gender/condition/muscle; alpha= 0.05). Perturbed walking elicited higher EMG activity compared to normal walking for TA and PL in both genders (p < 0.000). RMS amplitude gender comparisons revealed an interaction between gender and condition (F = 4.6, p = 0.049) and, a triple interaction among gender, condition and muscle (F = 4.7, p = 0.02). Women presented significantly higher EMG-RMS [%] PL amplitude than men during perturbed walking (mean difference = 209.6%, 95% confidence interval = -367.0 to -52.2%, p < 0.000). Co-activation showed significant lower values for perturbed compared to normal walking (p < 0.000), without significant gender differences for both walking conditions. GM activated significantly earlier than TA and PL (p < 0.01) without significant differences between the muscle activation onsets of men and women (p = 0.7). The results reflect that activation strategies of the ankle encompassing muscles differ between genders. In provoked stumbling, higher PL EMG activity in women compared to men is present. Future studies should aim to elucidate if this specific behavior has any relationship with ankle injury occurrence between genders.
KW  - Lower extremity
KW  - EMG
KW  - Perturbation
KW  - Split-belt treadmill
KW  - Ankle
Y1  - 2018
U6  - https://doi.org/10.1016/j.gaitpost.2018.01.023
SN  - 0966-6362
SN  - 1879-2219
VL  - 61
SP  - 226
EP  - 231
PB  - Elsevier
CY  - Clare
ER  - 
TY  - JOUR
A1  - Quarmby, Andrew James
A1  - Khajooei, Mina
A1  - Engel, Tilman
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - The feasibility of a split-belt instrumented treadmill running protocol with perturbations
JF  - Journal of biomechanics
N2  - Unexpected perturbations during locomotion can occur during daily life or sports performance. Adequate compensation for such perturbations is crucial in maintaining effective postural control. Studies utilising instrumented treadmills have previously validated perturbed walking protocols, however responses to perturbed running protocols remain less investigated. Therefore, the purpose of this study was to investigate the feasibility of a new instrumented treadmill-perturbed running protocol. <br /> Fifteen participants (age = 2 8 +/- 3 years; height = 172 +/- 9 cm; weight = 69 +/- 10 kg; 60% female) completed an 8-minute running protocol at baseline velocity of 2.5 m/s (9 km/h), whilst 15 one-sided belt perturbations were applied (pre-set perturbation characteristics: 150 ms delay (post-heel contact); 2.0 m/s amplitude; 100 ms duration). Perturbation characteristics and EMG responses were recorded. Bland-Altman analysis (BLA) was employed (bias +/- limits of agreement (LOA; bias +/- 1.96*SD)) and intra-individual variability of repeated perturbations was assessed via Coefficients of Variation (CV) (mean +/- SD). <br /> On average, 9.4 +/- 2.2 of 15 intended perturbations were successful. Perturbation delay was 143 +/- 10 ms, amplitude was 1.7 +/- 0.2 m/s and duration was 69 +/- 10 ms. BLA showed -7 +/- 13 ms for delay, -0.3 +/- 0.1 m/s for amplitude and -30 +/- 10 ms for duration. CV showed variability of 19 +/- 4.5% for delay, 58 +/- 12% for amplitude and 30 +/- 7% for duration. EMG RMS amplitudes of the legs and trunk ranged from 113 +/- 25% to 332 +/- 305% when compared to unperturbed gait. This study showed that the application of sudden perturbations during running can be achieved, though with increased variability across individuals. The perturbations with the above characteristics appear to have elicited a neuromuscular response during running.
KW  - Lower-extremity perturbations
KW  - Split-belt treadmill
KW  - Running
KW  - Stumbling
KW  - EMC
Y1  - 2020
U6  - https://doi.org/10.1016/j.jbiomech.2019.109493
SN  - 0021-9290
SN  - 1873-2380
VL  - 98
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Lin, Chiao-I
A1  - Khajooei, Mina
A1  - Engel, Tilman
A1  - Nair, Alexandra
A1  - Heikkila, Mika
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - The effect of chronic ankle instability on muscle activations in lower extremities
JF  - PLOS ONE / Public Library of Science
N2  - Background/Purpose

Muscular reflex responses of the lower extremities to sudden gait disturbances are related to postural stability and injury risk. Chronic ankle instability (CAI) has shown to affect activities related to the distal leg muscles while walking. Its effects on proximal muscle activities of the leg, both for the injured- (IN) and uninjured-side (NON), remain unclear. Therefore, the aim was to compare the difference of the motor control strategy in ipsilateral and contralateral proximal joints while unperturbed walking and perturbed walking between individuals with CAI and matched controls.
Materials and methods

In a cross-sectional study, 13 participants with unilateral CAI and 13 controls (CON) walked on a split-belt treadmill with and without random left- and right-sided perturbations. EMG amplitudes of muscles at lower extremities were analyzed 200 ms after perturbations, 200 ms before, and 100 ms after (Post100) heel contact while walking. Onset latencies were analyzed at heel contacts and after perturbations. Statistical significance was set at alpha≤0.05 and 95% confidence intervals were applied to determine group differences. Cohen’s d effect sizes were calculated to evaluate the extent of differences.
Results

Participants with CAI showed increased EMG amplitudes for NON-rectus abdominus at Post100 and shorter latencies for IN-gluteus maximus after heel contact compared to CON (p<0.05). Overall, leg muscles (rectus femoris, biceps femoris, and gluteus medius) activated earlier and less bilaterally (d = 0.30–0.88) and trunk muscles (bilateral rectus abdominus and NON-erector spinae) activated earlier and more for the CAI group than CON group (d = 0.33–1.09).
Conclusion

Unilateral CAI alters the pattern of the motor control strategy around proximal joints bilaterally. Neuromuscular training for the muscles, which alters motor control strategy because of CAI, could be taken into consideration when planning rehabilitation for CAI.
KW  - Ankles
KW  - Walking
KW  - Electromyography
KW  - Hip
KW  - Skeletal joints
KW  - Knees
KW  - Legs
KW  - Musculoskeletal injury
Y1  - 2020
U6  - https://doi.org/10.1371/journal.pone.0247581
SN  - 1932-6203
VL  - 16
IS  - 2
PB  - PLOS
CY  - San Francisco
ER  - 
TY  - CHAP
A1  - Engel, Tilman
A1  - Müller, Juliane
A1  - Müller, Steffen
A1  - Reschke, Antje
A1  - Kopinski, Stephan
A1  - Mayer, Frank
T1  - Validity and reliability of a new customised split-belt treadmill provoking unexpected walking perturbations
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2013
SN  - 0195-9131
SN  - 1530-0315
VL  - 45
IS  - 5
SP  - 462
EP  - 462
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - CHAP
A1  - Wochatz, Monique
A1  - Kopinski, Stephan
A1  - Engel, Tilman
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Flexion-extension ratio of trunk peak torque measures and antagonistic activity in males and females
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2014
SN  - 0195-9131
SN  - 1530-0315
VL  - 46
IS  - 5
SP  - 148
EP  - 148
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - CHAP
A1  - Kopinski, Stephan
A1  - Engel, Tilman
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Torque-EMG relationship of lower back muscles - a pilot study
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2013
SN  - 0195-9131
SN  - 1530-0315
VL  - 45
IS  - 5
SP  - 7
EP  - 8
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Mueller, Juliane
A1  - Engel, Tilman
A1  - Mueller, Steffen
A1  - Kopinski, Stephan
A1  - Baur, Heiner
A1  - Mayer, Frank
T1  - Neuromuscular response of the trunk to sudden gait disturbances: Forward vs. backward perturbation
JF  - Journal of electromyography and kinesiology
N2  - The study aimed to analyse neuromuscular activity of the trunk comparing four different perturbations during gait. Thirteen subjects (28 +/- 3 yrs) walked (1 m/s) on a split-belt treadmill, while 4 (belt) perturbations (F1, F2, B1, B2) were randomly applied. Perturbations differed, related to treadmill belt translation, in direction (forward (F)/backward (B)) and amplitude (20 m/s(2) (1)/40 m/s(2) (2)). Trunk muscle activity was assessed with a 12-lead-EMG. EMG-RMS [%] (0-200 ms after perturbation; normalized to RMS of normal gait) was analyzed for muscles and four trunk areas (ventral left/right; dorsal left/right). Ratio of ventral: dorsal muscles were calculated. Muscle onset [ms] was determined. Data analysis was conducted descriptively, followed by ANOVA (post hoc Tukey-Kramer (alpha = 0.05)). All perturbations lead to an increase in EMG-RMS (428 +/- 289%). F1 showed the lowest and F2 the highest increase for the flexors. B2 showed the highest increase for the extensors. Significant differences between perturbations could be observed for 6 muscles, as well as the 4 trunk areas. Ratio analysis revealed no significant differences (range 1.25 (B1) to 1.71 (F2) between stimuli. Muscle response time (ventral: 87.0 +/- 21.7 ms; dorsal: 88.4 +/- 17.0 ms) between stimuli was only significant (p = 0.005) for the dorsal muscles. Magnitude significantly influences neuromuscular trunk response patterns in healthy adults. Regardless of direction ventral muscles always revealed higher relative increase of activity while compensating the walking perturbations. (C) 2016 Elsevier Ltd. All rights reserved.
KW  - Stumbling
KW  - Gait perturbation
KW  - EMG
KW  - Core
KW  - MiSpEx*
Y1  - 2016
U6  - https://doi.org/10.1016/j.jelekin.2016.07.005
SN  - 1050-6411
SN  - 1873-5711
VL  - 30
SP  - 168
EP  - 176
PB  - Elsevier
CY  - Oxford
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, 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  - 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  - 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  - Risch, Lucie
A1  - Stoll, Josefine
A1  - Schomöller, Anne
A1  - Engel, Tilman
A1  - Mayer, Frank
A1  - Cassel, Michael
T1  - Intraindividual Doppler Flow Response to Exercise Differs Between Symptomatic and Asymptomatic Achilles Tendons
JF  - Frontiers in physiology
N2  - Objective: This study investigated intraindividual differences of intratendinous blood flow (IBF) in response to running exercise in participants with Achilles tendinopathy.

Design: This is a cross-sectional study.

Setting: The study was conducted at the University Outpatient Clinic.

Participants: Sonographic detectable intratendinous blood flow was examined in symptomatic and contralateral asymptomatic Achilles tendons of 19 participants (42 ± 13 years, 178 ± 10 cm, 76 ± 12 kg, VISA-A 75 ± 16) with clinically diagnosed unilateral Achilles tendinopathy and sonographic evident tendinosis.

Intervention: IBF was assessed using Doppler ultrasound “Advanced Dynamic Flow” before (Upre) and 5, 30, 60, and 120 min (U5–U120) after a standardized submaximal constant load run.

Main Outcome Measure: IBF was quantified by counting the number (n) of vessels in each tendon.

Results: At Upre, IBF was higher in symptomatic compared with asymptomatic tendons [mean 6.3 (95% CI: 2.8–9.9) and 1.7 (0.4–2.9), p < 0.01]. Overall, 63% of symptomatic and 47% of asymptomatic Achilles tendons responded to exercise, whereas 16 and 11% showed persisting IBF and 21 and 42% remained avascular throughout the investigation. At U5, IBF increased in both symptomatic and asymptomatic tendons [difference to baseline: 2.4 (0.3–4.5) and 0.9 (0.5–1.4), p = 0.05]. At U30 to U120, IBF was still increased in symptomatic but not in asymptomatic tendons [mean difference to baseline: 1.9 (0.8–2.9) and 0.1 (-0.9 to 1.2), p < 0.01].

Conclusion: Irrespective of pathology, 47–63% of Achilles tendons responded to exercise with an immediate acute physiological IBF increase by an average of one to two vessels (“responders”). A higher amount of baseline IBF (approximately five vessels) and a prolonged exercise-induced IBF response found in symptomatic ATs indicate a pain-associated altered intratendinous “neovascularization.”
KW  - achilles tendinopathy
KW  - tendinosis
KW  - neovascularization
KW  - ultrasound
KW  - advanced dynamic flow
KW  - sonography
Y1  - 2021
U6  - https://doi.org/10.3389/fphys.2021.617497
SN  - 1664-042X
VL  - 12
SP  - 1
EP  - 8
PB  - Frontiers Research Foundation
CY  - Lausanne, Schweiz
ER  - 
TY  - CHAP
A1  - Engel, Tilman
A1  - Kopinski, Stephan
A1  - Carlsohn, Anja
A1  - Cassel, Michael
A1  - Mayer, Frank
T1  - Correlation of sonographic subcutaneous adipose tissue measurements with air displacement plethysmography and calipermetry
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2014
SN  - 0195-9131
SN  - 1530-0315
VL  - 46
IS  - 5
SP  - 539
EP  - 539
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - CHAP
A1  - Kopinski, Stephan
A1  - Engel, Tilman
A1  - Cassel, Michael
A1  - Carlsohn, Anja
A1  - Mayer, Frank
T1  - Reliability of ultrasound measurements for subcutaneous adipose tissue in elite canoe athletes
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2014
SN  - 0195-9131
SN  - 1530-0315
VL  - 46
IS  - 5
SP  - 539
EP  - 539
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Kopinski, Stephan
A1  - Engel, Tilman
A1  - Cassel, Michael
A1  - Fröhlich, Katja
A1  - Mayer, Frank
A1  - Carlsohn, Anja
T1  - Ultrasound Applied to Subcutaneous Fat Tissue Measurements in International Elite Canoeists
JF  - International journal of sports medicine
N2  - Subcutaneous adipose tissue (SAT) measurements with ultrasound have recently been introduced to assess body fat in elite athletes. However, appropriate protocols and data on various groups of athletes are missing. We investigated intra-rater reliability of SAT measurements using ultrasound in elite canoe athletes. 25 international level canoeists (18 male, 7 female; 23 +/- 4 years; 81 +/- 11 kg; 1.83 +/- 0.09 m; 20 +/- 3 training h/wk) were measured on 2 consecutive days. SAT was assessed with B-mode ultrasound at 8 sites (ISAK): triceps, subscapular, biceps, iliac crest, supraspinal, abdominal, front thigh, medial calf, and quantified using image analysis software. Data was analyzed descriptively (mean +/- SD, [range]). Coefficient of variation (CV %), intraclass correlation coefficient (ICC, 2.1) and absolute (LoA) and ratio limits of agreement (RLoA) were calculated for day-to-day reliability. Mean sum of SAT thickness was 30.0 +/- 19.4 mm [8.0, 80.1 mm], with 3.9 +/- 1.8 mm [1.2 mm subscapular, 8.0 mm abdominal] for individual sites. CV for the sum of sites was 4.7 %, ICC 0.99, LoA 1.7 +/- 3.6 mm, RLoA 0.940 (*/divided by 1.155). Measuring SAT with ultrasound has proved to have excellent day-to-day reliability in elite canoe athletes. Recommendations for standardization of the method will further increase accuracy and reproducibility.
KW  - subcutaneous adipose tissue
KW  - skinfold thickness
KW  - elite athletes
KW  - body composition
KW  - ultrasonography
Y1  - 2015
U6  - https://doi.org/10.1055/s-0035-1555857
SN  - 0172-4622
SN  - 1439-3964
VL  - 36
IS  - 14
SP  - 1134
EP  - 1141
PB  - Thieme
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Mueller, Steffen
A1  - Engel, Tilman
A1  - Müller, Juliane
A1  - Stoll, Josefine
A1  - Baur, Heiner
A1  - Mayer, Frank
T1  - Sensorimotor exercises and enhanced trunk function
BT  - a randomized controlled trial
JF  - International journal of sports medicine
N2  - The aim of this study was to investigate the effect of a 6-week sensorimotor or resistance training on maximum trunk strength and response to sudden, high-intensity loading in athletes. Interventions showed no significant difference for maximum strength in concentric and eccentric testing (p>0.05). For perturbation compensation, higher peak torque response following SMT (Extension: +24Nm 95%CI +/- 19Nm; Rotation: + 19Nm 95%CI +/- 13Nm) and RT (Extension: +35Nm 95%CI +/- 16Nm; Rotation: +5Nm 95%CI +/- 4Nm) compared to CG (Extension: -4Nm 95%CI +/- 16Nm; Rotation: -2Nm 95%CI +/- 4Nm) was present (p<0.05).
KW  - core
KW  - training intervention
KW  - prevention
KW  - perturbation
KW  - MiSpEx*
Y1  - 2018
U6  - https://doi.org/10.1055/a-0592-7286
SN  - 0172-4622
SN  - 1439-3964
VL  - 39
IS  - 7
SP  - 555
EP  - 563
PB  - Thieme
CY  - Stuttgart
ER  - 
TY  - GEN
A1  - Schraplau, Anne
A1  - Sonnenburg, Dominik
A1  - Wochatz, Monique
A1  - Engel, Tilman
A1  - Schomöller, Anne
A1  - Risch, Lucie
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - Characterization of muscle damage and inflammation following repeated maximal eccentric loading of the trunk
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
N2  - Eccentric exercises (ECC) induce reversible muscle damage, delayed-onset muscle soreness and an inflammatory reaction that is often followed by a systemic anti-inflammatory response. Thus, ECC might be beneficial for treatment of metabolic disorders which are frequently accompanied by a low-grade systemic inflammation. However, extent and time course of a systemic immune response after repeated ECC bouts are poorly characterized.
PURPOSE: To analyze the (anti-)inflammatory response after repeated ECC loading of the trunk.
METHODS: Ten healthy participants (33 ± 6 y; 173 ± 14 cm; 74 ± 16 kg) performed three isokinetic strength measurements of the trunk (concentric (CON), ECC1, ECC2, each 2 wks apart; flexion/extension, velocity 60°/s, 120s MVC). Pre- and 4, 24, 48, 72, 168h post-exercise, muscle soreness (numeric rating scale, NRS) was assessed and blood samples were taken and analyzed [Creatine kinase (CK), C-reactive protein (CRP), Interleukin-6 (IL-6), IL-10, Tumor necrosis factor-α (TNF-α)]. Statistics were done by Friedman‘s test with Dunn‘s post hoc test (α=.05).
RESULTS: Mean peak torque was higher during ECC1 (319 ± 142 Nm) than during CON (268 ± 108 Nm; p<.05) and not different between ECC1 and ECC2 (297 ± 126 Nm; p>.05). Markers of muscle damage (peaks post-ECC1: NRS 48h, 4.4±2.9; CK 72h, 14407 ± 19991 U/l) were higher after ECC1 than after CON and ECC2 (p<.05). The responses over 72h (stated as Area under the Curve, AUC) were abolished after ECC2 compared to ECC1 (p<.05) indicating the presence of the repeated bout effect. CRP levels were not changed. IL-6 levels increased 2-fold post-ECC1 (pre: 0.5 ± 0.4 vs. 72h: 1.0 ± 0.8 pg/ml). The IL-6 response was enhanced after ECC1 (AUC 61 ± 37 pg/ml*72h) compared to CON (AUC 33 ± 31 pg/ml*72h; p<.05). After ECC2, the IL-6 response (AUC 43 ± 25 pg/ml*72h) remained lower than post-ECC1, but the difference was not statistically significant. Serum levels of TNF-α and of the anti-inflammatory cytokine IL-10 were below detection limits. Overall, markers of muscle damage and immune response showed high inter-individual variability.
CONCLUSION: Despite maximal ECC loading of a large muscle group, no anti-inflammatory and just weak inflammatory responses were detected in healthy adults. Whether ECC elicits a different reaction in inflammatory clinical conditions is unclear.
Y1  - 2020
U6  - https://doi.org/10.1249/01.mss.0000679532.65880.af
SN  - 0195-9131
SN  - 1530-0315
VL  - 52
IS  - 7S
SP  - 497
EP  - 497
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Engel, Tilman
A1  - Schraplau, Anne
A1  - Wochatz, Monique
A1  - Kopinski, Stephan
A1  - Sonnenburg, Dominik
A1  - Schomöller, Anne
A1  - Risch, Lucie
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - Feasability of An Eccentric Isokinetic Protocol to Induce Trunk Muscle Damage: A Pilot Study
JF  - Sports Medicine International Open
N2  - Eccentric exercise is discussed as a treatment option for clinical populations, but specific responses in terms of muscle damage and systemic inflammation after repeated loading of large muscle groups have not been conclusively characterized. Therefore, this study tested the feasibility of an isokinetic protocol for repeated maximum eccentric loading of the trunk muscles. Nine asymptomatic participants (5 f/4 m; 34±6 yrs; 175±13 cm; 76±17 kg) performed three isokinetic 2-minute all-out trunk strength tests (1x concentric (CON), 2x eccentric (ECC1, ECC2), 2 weeks apart; flexion/extension, 60°/s, ROM 55°). Outcomes were peak torque, torque decline, total work, and indicators of muscle damage and inflammation (over 168 h). Statistics were done using the Friedman test (Dunn’s post-test). For ECC1 and ECC2, peak torque and total work were increased and torque decline reduced compared to CON. Repeated ECC bouts yielded unaltered torque and work outcomes. Muscle damage markers were highest after ECC1 (soreness 48 h, creatine kinase 72 h; p<0.05). Their overall responses (area under the curve) were abolished post-ECC2 compared to post-ECC1 (p<0.05). Interleukin-6 was higher post-ECC1 than CON, and attenuated post-ECC2 (p>0.05). Interleukin-10 and tumor necrosis factor-α were not detectable. All markers showed high inter-individual variability. The protocol was feasible to induce muscle damage indicators after exercising a large muscle group, but the pilot results indicated only weak systemic inflammatory responses in asymptomatic adults.
KW  - exercise
KW  - eccentric
KW  - muscle fatigue
KW  - trunk muscles
KW  - isokinetics
KW  - repeated bout effect
KW  - inflammation
KW  - exercise induced muscle damage
KW  - interleukin-6
KW  - internleukin-10
KW  - tumor necrosis factor-α
Y1  - 2021
U6  - https://doi.org/10.1055/a-1757-6724
SN  - 2367-1890
VL  - 6
SP  - E9
EP  - E17
PB  - Thieme
CY  - Stuttgart
ET  - 1
ER  - 
TY  - GEN
A1  - Schomöller, Anne
A1  - Risch, Lucie
A1  - Kaplick, Hannes
A1  - Schraplau, Anne
A1  - Wochatz, Monique
A1  - Engel, Tilman
A1  - Sonnenburg, Dominik
A1  - Mayer, Frank
T1  - Changes in paraspinal muscle T2 times and creatine kinase after a bout of eccentric exercise
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
N2  - Eccentric (ECC) exercises might cause muscle damage, characterized by delayed-onset muscle soreness, elevated creatine kinase (CK) levels and local muscle oedema, shown by elevated T2 times in magnet resonance imaging (MRI) scans. Previous research suggests a high inter-individual difference regarding these systemic and local responses to eccentric workload. PURPOSE: To analyze ECC exercise-induced muscle damage in lumbar paraspinal muscles assessed via MRI. METHODS: Ten participants (3f/7m; 33±6y; 174±8cm; 71±12kg) were included in the study. Quantitative paraspinal muscle constitution of M. erector spinae and M. multifidius were assessed in supine position before and 72h after an intense eccentric trunk exercise bout in a mobile 1.5 tesla MRI device. MRI scans were recorded on spinal level L3 (T2-weighted TSE echo sequences, 11 slices, 2mm slice thickness, 3mm gap, echo times: 20, 40, 60, 80, 100ms, TR time: 2500ms). Muscle T2 times were calculated for manually traced regions of interest of the respective muscles with an imaging software. The exercise protocol was performed in an isokinetic device and consisted of 120sec alternating ECC trunk flexion-extension with maximal effort. Venous blood samples were taken before and 72h after the ECC exercise. Descriptive statistics (mean±SD) and t-testing for pre-post ECC exercises were performed. RESULTS: T2 times increased from pre- to post-ECC MRI measurements from 55±3ms to 79±28ms in M. erector spinae and from 62±5ms to 78±24ms in M. multifidius (p<0.001). CK increased from 126±97 U/L to 1447±20579 U/L. High SDs of T2 time and CK in post-ECC measures could be due to inter-individual reactions to ECC exercises. 3 participants showed high local and systemic reactions (HR) with T2 time increases of 120±24% (M. erector spinae) and 73±50% (M. multifidius). In comparison, the remaining 7 participants showed increases of 11±12% (M. erector spinae) and 7±9% (M. multifidius) in T2 time. Mean CK increased 9.5-fold in the 3 HR subjects compared with the remaining 7 subjects. CONCLUSIONS: The 120sec maximal ECC trunk flexion-extension protocol induced high amounts of muscle damage in 3 participants. Moderate to low responses were found in the remaining 7 subjects, assuming that inter-individual predictors play a role regarding physiological responses to ECC workload.
Y1  - 2020
U6  - https://doi.org/10.1249/01.mss.0000685648.68626.f1
SN  - 0195-9131
SN  - 1530-0315
SN  - 0025-7990
VL  - 52
IS  - 17
SP  - 929
EP  - 929
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Schomöller, Anne
A1  - Risch, Lucie
A1  - Kaplick, Hannes
A1  - Wochatz, Monique
A1  - Engel, Tilman
A1  - Schraplau, Anne
A1  - Sonnenburg, Dominik
A1  - Huppertz, Alexander
A1  - Mayer, Frank
T1  - Inter-rater and inter-session reliability of lumbar paraspinal muscle composition in a mobile MRI device
JF  - BJR : an international journal of radiology, radiation oncology and all related sciences / British Institute of Radiology
N2  - Objective: To assess the reliability of measurements of paraspinal muscle transverse relaxation times (T2 times) between two observers and within one observer on different time points. <br /> Methods: 14 participants (9f/5m, 33 +/- 5 years, 176 +/- 10 cm, 73 +/- 12 kg) underwent 2 consecutive MRI scans (M1,M2) on the same day, followed by 1 MRI scan 13-14 days later (M3) in a mobile 1.5 Tesla MRI. T2 times were calculated in T-2 weighted turbo spin- echo-sequences at the spinal level of the third lumbar vertebrae (11 slices, 2 mm slice thickness, 1 mm interslice gap, echo times: 20, 40, 60, 80, 100 ms) for M. erector spinae (ES) and M. multifidius (MF). The following reliability parameter were calculated for the agreement of T2 times between two different investigators (OBS1 & OBS2) on the same MRI (inter rater reliability, IR) and by one investigator between different MRI of the same participant (intersession variability, IS): Test-Retest Variability (TRV, Differences/Mean*100); Coefficient of Variation (CV, Standard deviation/Mean*100); Bland-Altman Analysis (systematic bias = Mean of the Differences; Upper/Lower Limits of Agreement = Bias+/-1.96*SD); Intraclass Correlation Coefficient 3.1 (ICC) with absolute agreement, as well as its 95% confidence interval. <br /> Results: Mean TRV for IR was 2.6% for ES and 4.2% for MF. Mean TRV for IS was 3.5% (ES) and 5.1% (MF). Mean CV for IR was 1.9 (ES) and 3.0 (MF). Mean CV for IS was 2.5% (ES) and 3.6% (MF). A systematic bias of 1.3 ms (ES) and 2.1 ms (MF) were detected for IR and a systematic bias of 0.4 ms (ES) and 0.07 ms (MF) for IS. ICC for IR was 0.94 (ES) and 0.87 (MF). ICC for IS was 0.88 (ES) and 0.82 (MF). <br /> Conclusion: Reliable assessment of paraspinal muscle T2 time justifies its use for scientific purposes. The applied technique could be recommended to use for future studies that aim to assess changes of T2 times, e.g. after an intense bout of eccentric exercises.
Y1  - 2021
U6  - https://doi.org/10.1259/bjr.20210141
SN  - 0007-1285
SN  - 1748-880X
VL  - 94
IS  - 1127
PB  - Wiley
CY  - Bognor Regis
ER  - 
TY  - JOUR
A1  - Rowley, K. Michael
A1  - Engel, Tilman
A1  - Kulig, Kornelia
T1  - Trunk and hip muscle activity during the Balance-Dexterity task in persons with and without recurrent low back pain
JF  - Journal of electromyography and kinesiology
N2  - Coordination of the trunk and hips is crucial for successful dynamic balance in many activities of daily living. Persons with recurrent low back pain (rLBP), both while symptomatic and during periods of symptom remission, exhibit dysfunctional muscle activation patterns and coordination of these joints. In a novel dynamic balance task where persons in remission from rLBP exhibit dissociated trunk motion, it is unknown how trunk and hip musculature are coordinated. Activation of hip and trunk muscles were acquired from nineteen persons with and without rLBP during the Balance-Dexterity Task, which involves balancing on one limb while compressing an unstable spring with the other. There were no between-group differences in activation amplitude for any muscle groups tested. In back-healthy control participants, hip and trunk muscle activation amplitudes increased proportionally in response to the added instability of the spring (R = 0.837, p < 0.001). Increases in muscle activation amplitudes in the group in remission from rLBP were not proportional (R = 0.113, p = 0.655). Instead, hip muscle activation in this group was associated with task performance, i.e. dexterous control of the spring (R = 0.676, p = 0.002). These findings highlight atypical coordination of hip and trunk musculature potentially related to task demands in persons with rLBP even during remission from pain.
KW  - balance
KW  - low back pain
KW  - trunk and hip coordination
KW  - lumbopelvic
Y1  - 2020
U6  - https://doi.org/10.1016/j.jelekin.2019.102378
SN  - 1050-6411
SN  - 1873-5711
VL  - 50
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Quarmby, Andrew
A1  - Mönnig, Jamal
A1  - Mugele, Hendrik
A1  - Henschke, Jakob
A1  - Kim, MyoungHwee
A1  - Cassel, Michael
A1  - Engel, Tilman
T1  - Biomechanics and lower limb function are altered in athletes and runners with achilles tendinopathy compared with healthy controls: A systematic review
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of “medial collapse”. Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 830 
KW  - achilles tendinopathy
KW  - biomechanics
KW  - neuromuscular
KW  - kinetics
KW  - electromyography
KW  - athletes
KW  - runners
KW  - kinematics
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-587603
SN  - 1866-8364
IS  - 830
ER  - 
TY  - JOUR
A1  - Quarmby, Andrew
A1  - Mönnig, Jamal
A1  - Mugele, Hendrik
A1  - Henschke, Jakob
A1  - Kim, MyoungHwee
A1  - Cassel, Michael
A1  - Engel, Tilman
T1  - Biomechanics and lower limb function are altered in athletes and runners with achilles tendinopathy compared with healthy controls: A systematic review
JF  - Frontiers in Sports and Active Living
N2  - Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of “medial collapse”. Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn.
KW  - achilles tendinopathy
KW  - biomechanics
KW  - neuromuscular
KW  - kinetics
KW  - electromyography
KW  - athletes
KW  - runners
KW  - kinematics
Y1  - 2023
U6  - https://doi.org/10.3389/fspor.2022.1012471
SN  - 2624-9367
PB  - Frontiers
CY  - Lausanne, Schweiz
ER  - 
TY  - JOUR
A1  - Henschke, Jakob
A1  - Zecher, Mahli Megan
A1  - Mayer, Frank
A1  - Engel, Tilman
T1  - Contralateral repeated bout effect following preconditioning exercises
BT  - a systematic review
JF  - Sport sciences for health
N2  - Background Recent studies indicate the existence of a repeated bout effect on the contralateral untrained limb following eccentric and isometric contractions. Aims This review aims to summarize the evidence for magnitude, duration and differences of this effect following isometric and eccentric preconditioning exercises. Methods Medline, Cochrane, and Web of science were searched from January 1971 until September 2020. Randomized controlled trials, case-control studies and cross-sectional studies were identified by combining keywords and synonyms (e.g., "contralateral", "exercise", "preconditioning", "protective effect"). At least two of the following outcome parameters were mandatory for study inclusion: strength, muscle soreness, muscle swelling, limb circumference, inflammatory blood markers or protective index (relative change of aforementioned measures). Results After identifying 1979 articles, 13 studies were included. Most investigations examined elbow flexors and utilized eccentric isokinetic protocols to induce the contralateral repeated bout effect. The magnitude of protection was observed in four studies, smaller values of the contralateral when compared to the ipsilateral repeated bout effect were noted in three studies. The potential mechanism is thought to be of neural central nature since no differences in peripheral muscle activity were observed. Time course was examined in three investigations. One study showed a smaller protective effect following isometric preconditioning when compared to eccentric preconditioning exercises. Conclusions The contralateral repeated bout effect demonstrates a smaller magnitude and lasts shorter than the ipsilateral repeated bout effect. Future research should incorporate long-term controlled trials including larger populations to identify central mechanisms. This knowledge should be used in clinical practice to prepare immobilized limbs prospectively for an incremental load.
KW  - musculoskeletal physiological phenomena
KW  - muscle damage
KW  - adaptation
KW  - Crossover
KW  - muscle soreness
KW  - isometric contraction
Y1  - 2021
U6  - https://doi.org/10.1007/s11332-021-00804-0
SN  - 1824-7490
SN  - 1825-1234
VL  - 18
IS  - 1
SP  - 1
EP  - 10
PB  - Soringer Italia
CY  - Milan
ER  - 
TY  - CHAP
A1  - Reschke, Antje
A1  - Müller, Juliane
A1  - Müller, Steffen
A1  - Engel, Tilman
A1  - Mayer, Frank
T1  - Three-dimensional spine kinematics during perturbed treadmill walking - a pilot study
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2013
SN  - 0195-9131
SN  - 1530-0315
VL  - 45
IS  - 5
SP  - 172
EP  - 172
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - CHAP
A1  - Torlak, Firdevs
A1  - Torlak, Firdevs
A1  - Appiah-Dwomoh, Edem Korkor
A1  - Engel, Tilman
A1  - Stoll, Josefine
A1  - Müller, Juliane
A1  - Mayer, Frank
T1  - Gender differences in lower leg muscular activity during provoked stumbling - a pilot study
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2014
SN  - 0195-9131
SN  - 1530-0315
VL  - 46
IS  - 5
SP  - 728
EP  - 728
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - CHAP
A1  - Appiah-Dwomoh, Edem Korkor
A1  - Torlak, Firdevs
A1  - Engel, Tilman
A1  - Stoll, Josefine
A1  - Müller, Juliane
A1  - Mayer, Frank
T1  - Does perturbed treadmill walking lead to emg-changes of the lower extremity?
T2  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
Y1  - 2014
SN  - 0195-9131
SN  - 1530-0315
VL  - 46
IS  - 5
SP  - 827
EP  - 827
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Müller, Juliane
A1  - Müller, Steffen
A1  - Engel, Tilman
A1  - Reschke, Antje
A1  - Baur, Heiner
A1  - Mayer, Frank
T1  - Stumbling reactions during perturbed walking: Neuromuscular reflex activity and 3-D kinematics of the trunk - A pilot study
JF  - Journal of biomechanics
N2  - 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.
KW  - Trunk kinematics
KW  - Treadmill walking
KW  - Gait perturbation
KW  - EMG
Y1  - 2016
U6  - https://doi.org/10.1016/j.jbiomech.2015.09.041
SN  - 0021-9290
SN  - 1873-2380
VL  - 49
SP  - 933
EP  - 938
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - THES
A1  - Engel, Tilman
T1  - Motor control strategies in response to unexpected disturbances of dynamic postural control in people with and without low back pain
T1  - Strategien der Bewegungskontrolle nach unerwarteten Störungen der dynamischen posturalen Kontrolle in Personen mit und ohne Rückenschmerzen
N2  - Background: Low back pain (LBP) is one of the world wide leading causes of limited activity and disability. Impaired motor control has been found to be one of the possible factors related to the development or persistence of LBP. In particularly, motor control strategies seemed to be altered in situations requiring reactive responses of the trunk counteracting sudden external forces. However, muscular responses were mostly assessed in (quasi) static testing situations under simplified laboratory conditions. Comprehensive investigations in motor control strategies during dynamic everyday situations are lacking. The present research project aimed to investigate muscular compensation strategies following unexpected gait perturbations in people with and without LBP. A novel treadmill stumbling protocol was tested for its validity and reliability to provoke muscular reflex responses at the trunk and the lower extremities (study 1). Thereafter, motor control strategies in response to sudden perturbations were compared between people with LBP and asymptomatic controls (CTRL) (study 2). In accordance with more recent concepts of motor adaptation to pain, it was hypothesized that pain may have profound consequences on motor control strategies in LBP. Therefore, it was investigated whether differences in compensation strategies were either consisting of changes local to the painful area at the trunk, or also being present in remote areas such as at the lower extremities.
Methods: All investigations were performed on a custom build split-belt treadmill simulating trip-like events by unexpected rapid deceleration impulses (amplitude: 2 m/s; duration: 100 ms; 200 ms after heel contact) at 1m/s baseline velocity. A total number of 5 (study 1) and 15 (study 2) right sided perturbations were applied during walking trials. Muscular activities were assessed by surface electromyography (EMG), recorded at 12 trunk muscles and 10 (study 1) respectively 5 (study 2) leg muscles. EMG latencies of muscle onset [ms] were retrieved by a semi-automatic detection method. EMG amplitudes (root mean square (RMS)) were assessed within 200 ms post perturbation, normalized to full strides prior to any perturbation [RMS%]. Latency and amplitude investigations were performed for each muscle individually, as well as for pooled data of muscles grouped by location. Characteristic pain intensity scores (CPIS; 0-100 points, von Korff) based on mean intensity ratings reported for current, worst and average pain over the last three months were used to allocate participants into LBP (≥30 points) or CTRL (≤10 points). Test-retest reproducibility between measurements was determined by a compilation of measures of reliability. Differences in muscular activities between LBP and CTRL were analysed descriptively for individual muscles; differences based on grouped muscles were statistically tested by using a multivariate analysis of variance (MANOVA, α =0.05).
Results: Thirteen individuals were included into the analysis of study 1. EMG latencies revealed reflex muscle activities following the perturbation (mean: 89 ms). Respective EMG amplitudes were on average 5-fold of those assessed in unperturbed strides, though being characterized by a high inter-subject variability. Test-retest reliability of muscle latencies showed a high reproducibility, both for muscles at the trunk and legs. In contrast, reproducibility of amplitudes was only weak to moderate for individual muscles, but increased when being assessed as a location specific outcome summary of grouped muscles. Seventy-six individuals were eligible for data analysis in study 2. Group allocation according to CPIS resulted in n=25 for LBP and n=29 for CTRL. Descriptive analysis of activity onsets revealed longer delays for all muscles within LBP compared to CTRL (trunk muscles:  mean 10 ms; leg muscles: mean 3 ms). Onset latencies of grouped muscles revealed statistically significant differences between LBP and CTRL for right (p=0.009) and left (p=0.007) abdominal muscle groups. EMG amplitude analysis showed a high variability in activation levels between individuals, independent of group assignment or location. Statistical testing of grouped muscles indicated no significant difference in amplitudes between LBP and CTRL. 
Discussion: The present research project could show that perturbed treadmill walking is suitable to provoke comprehensive reflex responses at the trunk and lower extremities, both in terms of sudden onsets and amplitudes of reflex activity. Moreover, it could demonstrate that sudden loadings under dynamic conditions provoke an altered reflex timing of muscles surrounding the trunk in people with LBP compared to CTRL. In line with previous investigations, compensation strategies seemed to be deployed in a task specific manner, with differences between LBP and CTRL being evident predominately at ventral sides. No muscular alterations exceeding the trunk could be found when being assessed under the automated task of locomotion. While rehabilitation programs tailored towards LBP are still under debate, it is tempting to urge the implementation of dynamic sudden loading incidents of the trunk to enhance motor control and thereby to improve spinal protection. Moreover, in respect to the consistently observed task specificity of muscular compensation strategies, such a rehabilitation program should be rich in variety.
N2  - Hintergrund: Unterer Rückenschmerz (LBP) stellt eine der weltweit führenden Ursachen für eine eingeschränkte körperliche Funktion und Belastbarkeit dar. Defizite in der neuromuskulären Ansteuerung gelten als einer der möglichen Faktoren im Zusammenhang mit der Entstehung und Persistenz von LBP. Insbesondere in Situationen, die eine aktive Kompensation von plötzlich auftretenden Lasten am Rumpf beinhalten, konnten veränderte Strategien in der muskulären Antwort bei LBP aufgezeigt werden. Allerdings basierten solche Untersuchungen meistens auf (quasi) statischen Testsituationen unter vereinfachten Laborbedingungen. Ob die beobachteten muskulären Reaktionen isolierter Rumpfbelastungen repräsentativ sind für eine neuromuskuläre Ansteuerung unter dynamischen Alltagsbedingungen ist bisher nicht geklärt. Ziel der vorliegenden Arbeit war es, muskuläre Kompensationsstrategien in Folge unerwarteter Gangperturbationen bei Personen mit und ohne LBP zu untersuchen. Um muskuläre Reflexantworten am Rumpf und an den unteren Extremitäten zu provozieren wurde ein neu entwickeltes Laufband-Stolperprotokoll auf Validität und Reliabilität getestet (Studie 1). Aufbauend erfolgte der Vergleich neuromuskulärer Antworten in Reaktion auf plötzlich applizierte Gangperturbationen zwischen Personen mit LBP und asymptomatischen Kontrollpersonen (CTRL) (Studie 2). In Übereinstimmung mit aktuellen Modellen zur motorischen Anpassung bei Schmerzen wurde untersucht, ob Unterschiede in den beobachteten Kompensationsstrategien auf lokale Veränderungen am Rumpf reduziert sind, oder ebenfalls in rumpffernen Körperregionen auftreten. Methoden: Alle Untersuchungen wurden mit einem Spezial-Laufband durchgeführt, welches mittels unerwarteter schneller Abbremsimpulse (Amplitude: 2 m/s, Dauer: 100 ms, 200 ms nach Fersenkontakt) die Simulation von Stolperereignissen während der Gangbewegung (1 m/s) erlaubt. Eine Anzahl von 5 (Studie 1) bzw. 15 (Studie 2) rechtsseitigen Perturbationen wurde im Verlaufs des Stolperprotokolls appliziert. Muskuläre Aktivitäten wurden mittels Elektromyographie (EMG) von 12 Rumpf- sowie 10 (Studie 1) bzw. 5 (Studie 2) Beinmuskeln aufgezeichnet. EMG-Latenzen wurden mittels eines halb-automatischen Detektions-Verfahrens ermittelt. Die Berechnung der EMG Amplituden (RMS) erfolgte für den Zeitraum von 200 ms nach Perturbation, normiert auf den gesamten Schrittzyklus des unperturbierten Ganges [%]. Latenz- und Amplituden-Messgrößen wurden für jeden Muskel individuell und für gepoolte Daten (gruppiert nach Lokalisation) berechnet. Charakteristische Schmerzintensitätswerte (CPIS, 0-100 Punkte, von Korff), basierend auf gemittelten Angaben zu akuten, sowie höchsten und durchschnittlichen Schmerzen der letzten drei Monate wurden zur Einteilung in LBP (≥30 Punkte) und CTRL (≤ 10 Punkte) verwendet. Zur Beurteilung der Test-retest Reliabilität wurden verschiedene Reliabilitätsparameter herangezogen. Unterschiede in den Muskelaktivitäten zwischen LBP und CTRL wurden für individuelle Muskeln deskriptiv analysiert. Gepoolte Daten gruppierter Muskeln wurden mittels multivariater Varianzanalyse (MANOVA; α = 0,05) statistisch getestet. Ergebnisse: Ergebnisse von 13 Probanden wurden für die Analyse von Studie 1 herangezogen. EMG-Latenzen zeigten Muskelaktivitäten repräsentativ für Reflexantworten im Nachgang applizierter Gangperturbationen, sowohl an Rumpf- als auch an Beinmuskulatur (Mittelwert: 89 ms, Range: 75 bis 117 ms). EMG-Amplituden erreichten im Durchschnitt ein 5-fach erhöhtes Aktivitätsniveau innerhalb des 200 ms Zeitfensters nach Perturbation (Range: 106 bis 909 RMS%), jedoch gezeichnet von einer hohen interindividuellen Variabilität zwischen den Probanden. Eine hohe Reproduzierbarkeit für EMG-Latenzen konnte anhand der Reliabilitätsparameter aufgezeigt werden. EMG-Amplituden dagegen erwiesen sich als nur geringfügig reliabel bei der Betrachtung individueller Muskeln. Für die Datenanalyse in Studie 2 waren 76 Probanden geeignet. Die Gruppenzuteilung nach CPIS ergab n = 25 für LBP und n = 29 für CTRL. EMG-Latenzen zeigten eine erhöhte Aktivitätsverzögerung aller Muskeln für LBP im Vergleich zu CTRL (Rumpf: Mittelwert 10 ms; Bein: Mittelwert 3 ms). EMG-Latenzen gruppierter Muskeln zeigten statistisch signifikante Unterschiede zwischen LBP und CTRL für rechtsseitige (p=0,009) und linksseitige (p=0,007) abdominale Muskelgruppen. EMG-Amplituden waren geprägt von einer hohen interindividuellen Variabilität, unabhängig von Gruppenzuordnung oder Lokalisation. Diskussion: Das vorliegende Forschungsprojekt konnte belegen, dass Gangperturbationen dafür geeignet sind, umfassende Reflexantworten am Rumpf und den unteren Extremitäten zu provozieren. Darüber hinaus konnte gezeigt werden, dass unerwartete Gangperturbationen zu einer zeitlich verzögerten Reflexantwort der rumpfumgreifenden Muskulatur bei Personen mit LBP im Vergleich zur Kontrollgruppe führen. In Übereinstimmung mit den Ergebnissen vorheriger Untersuchungen erscheinen dabei die gewählten Kompensationsstrategien aufgabenspezifisch angepasst zu sein. Veränderte muskuläre Reaktionsmuster abseits des Rumpfes konnten trotz Einbezug weiterer Lokalisationen nicht gefunden werden. Gegenüber isolierten Rumpfbelastungen erlaubt der Einsatz indirekter Perturbationsbelastungen während des Ganges alltagsrelevante situationsspezifische Defizite neuromuskulärer Kontrolle gezielt zu untersuchen. Bei der Erstellung neuer Theapiekonzepte zur Steigerung der neuromuskulären Kontrolle sollte in diesem Zusammenhang die Einbindung alltagsähnlicher indirekter Belastungsformen des Rumpfes diskutiert werden.
KW  - low back pain
KW  - trunk
KW  - perturbation
KW  - EMG
KW  - reflex
KW  - stumbling
KW  - Rückenschmerz
KW  - Rumpf
KW  - Perturbationen
KW  - Gang
KW  - Stolpern
KW  - Reflexaktivität
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400742
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  - 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
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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 317 
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394931
ER  - 
TY  - GEN
A1  - Lin, Chiao-I
A1  - Khajooei, Mina
A1  - Engel, Tilman
A1  - Nair, Alexandra
A1  - Heikkila, Mika
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - The effect of chronic ankle instability on muscle activations in lower extremities
T2  - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Background/Purpose

Muscular reflex responses of the lower extremities to sudden gait disturbances are related to postural stability and injury risk. Chronic ankle instability (CAI) has shown to affect activities related to the distal leg muscles while walking. Its effects on proximal muscle activities of the leg, both for the injured- (IN) and uninjured-side (NON), remain unclear. Therefore, the aim was to compare the difference of the motor control strategy in ipsilateral and contralateral proximal joints while unperturbed walking and perturbed walking between individuals with CAI and matched controls.
Materials and methods

In a cross-sectional study, 13 participants with unilateral CAI and 13 controls (CON) walked on a split-belt treadmill with and without random left- and right-sided perturbations. EMG amplitudes of muscles at lower extremities were analyzed 200 ms after perturbations, 200 ms before, and 100 ms after (Post100) heel contact while walking. Onset latencies were analyzed at heel contacts and after perturbations. Statistical significance was set at alpha≤0.05 and 95% confidence intervals were applied to determine group differences. Cohen’s d effect sizes were calculated to evaluate the extent of differences.
Results

Participants with CAI showed increased EMG amplitudes for NON-rectus abdominus at Post100 and shorter latencies for IN-gluteus maximus after heel contact compared to CON (p<0.05). Overall, leg muscles (rectus femoris, biceps femoris, and gluteus medius) activated earlier and less bilaterally (d = 0.30–0.88) and trunk muscles (bilateral rectus abdominus and NON-erector spinae) activated earlier and more for the CAI group than CON group (d = 0.33–1.09).
Conclusion

Unilateral CAI alters the pattern of the motor control strategy around proximal joints bilaterally. Neuromuscular training for the muscles, which alters motor control strategy because of CAI, could be taken into consideration when planning rehabilitation for CAI.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 712 
KW  - Electromyography
KW  - Hip
KW  - Skeletal joints
KW  - Knees
KW  - Legs
KW  - Musculoskeletal injury
KW  - Walking
KW  - Ankles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515632
SN  - 1866-8364
ER  - 
TY  - GEN
A1  - Wochatz, Monique
A1  - Schraplau, Anne
A1  - Engel, Tilman
A1  - Zecher, Mahli Megan
A1  - Sharon, Hadar
A1  - Alt, Yasmin
A1  - Mayer, Frank
A1  - Kalron, Alon
T1  - Application of eccentric training in various clinical populations
BT  - Protocol for a multi-centered pilot and feasibility study in people with low back pain and people with multiple sclerosis
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Physical activity and exercise are effective approaches in prevention and therapy of multiple diseases. Although the specific characteristics of lengthening contractions have the potential to be beneficial in many clinical conditions, eccentric training is not commonly used in clinical populations with metabolic, orthopaedic, or neurologic conditions. The purpose of this pilot study is to investigate the feasibility, functional benefits, and systemic responses of an eccentric exercise program focused on the trunk and lower extremities in people with low back pain (LBP) and multiple sclerosis (MS). A six-week eccentric training program with three weekly sessions is performed by people with LBP and MS. The program consists of ten exercises addressing strength of the trunk and lower extremities. The study follows a four-group design (N = 12 per group) in two study centers (Israel and Germany): three groups perform the eccentric training program: A) control group (healthy, asymptomatic); B) people with LBP; C) people with MS; group D (people with MS) receives standard care physiotherapy. Baseline measurements are conducted before first training, post-measurement takes place after the last session both comprise blood sampling, self-reported questionnaires, mobility, balance, and strength testing. The feasibility of the eccentric training program will be evaluated using quantitative and qualitative measures related to the study process, compliance and adherence, safety, and overall program assessment. For preliminary assessment of potential intervention effects, surrogate parameters related to mobility, postural control, muscle strength and systemic effects are assessed. The presented study will add knowledge regarding safety, feasibility, and initial effects of eccentric training in people with orthopaedic and neurological conditions. The simple exercises, that are easily modifiable in complexity and intensity, are likely beneficial to other populations. Thus, multiple applications and implementation pathways for the herein presented training program are conceivable.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 833 
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-588493
SN  - 1866-8364
IS  - 833
ER  - 
TY  - JOUR
A1  - Wochatz, Monique
A1  - Schraplau, Anne
A1  - Engel, Tilman
A1  - Zecher, Mahli Megan
A1  - Sharon, Hadar
A1  - Alt, Yasmin
A1  - Mayer, Frank
A1  - Kalron, Alon
T1  - Application of eccentric training in various clinical populations
BT  - Protocol for a multi-centered pilot and feasibility study in people with low back pain and people with multiple sclerosis
JF  - PLoS ONE
N2  - Physical activity and exercise are effective approaches in prevention and therapy of multiple diseases. Although the specific characteristics of lengthening contractions have the potential to be beneficial in many clinical conditions, eccentric training is not commonly used in clinical populations with metabolic, orthopaedic, or neurologic conditions. The purpose of this pilot study is to investigate the feasibility, functional benefits, and systemic responses of an eccentric exercise program focused on the trunk and lower extremities in people with low back pain (LBP) and multiple sclerosis (MS). A six-week eccentric training program with three weekly sessions is performed by people with LBP and MS. The program consists of ten exercises addressing strength of the trunk and lower extremities. The study follows a four-group design (N = 12 per group) in two study centers (Israel and Germany): three groups perform the eccentric training program: A) control group (healthy, asymptomatic); B) people with LBP; C) people with MS; group D (people with MS) receives standard care physiotherapy. Baseline measurements are conducted before first training, post-measurement takes place after the last session both comprise blood sampling, self-reported questionnaires, mobility, balance, and strength testing. The feasibility of the eccentric training program will be evaluated using quantitative and qualitative measures related to the study process, compliance and adherence, safety, and overall program assessment. For preliminary assessment of potential intervention effects, surrogate parameters related to mobility, postural control, muscle strength and systemic effects are assessed. The presented study will add knowledge regarding safety, feasibility, and initial effects of eccentric training in people with orthopaedic and neurological conditions. The simple exercises, that are easily modifiable in complexity and intensity, are likely beneficial to other populations. Thus, multiple applications and implementation pathways for the herein presented training program are conceivable.
Y1  - 2022
U6  - https://doi.org/10.1371/journal.pone.0270875
SN  - 1932-6203
VL  - 17
IS  - 12
PB  - Public Library of Science
CY  - San Francisco, California, USA
ER  - 
TY  - GEN
A1  - Engel, Tilman
A1  - Schraplau, Anne
A1  - Wochatz, Monique
A1  - Kopinski, Stephan
A1  - Sonnenburg, Dominik
A1  - Schomöller, Anne
A1  - Risch, Lucie
A1  - Kaplick, Hannes
A1  - Mayer, Frank
T1  - Feasability of An Eccentric Isokinetic Protocol to Induce Trunk Muscle Damage: A Pilot Study
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Eccentric exercise is discussed as a treatment option for clinical populations, but specific responses in terms of muscle damage and systemic inflammation after repeated loading of large muscle groups have not been conclusively characterized. Therefore, this study tested the feasibility of an isokinetic protocol for repeated maximum eccentric loading of the trunk muscles. Nine asymptomatic participants (5 f/4 m; 34±6 yrs; 175±13 cm; 76±17 kg) performed three isokinetic 2-minute all-out trunk strength tests (1x concentric (CON), 2x eccentric (ECC1, ECC2), 2 weeks apart; flexion/extension, 60°/s, ROM 55°). Outcomes were peak torque, torque decline, total work, and indicators of muscle damage and inflammation (over 168 h). Statistics were done using the Friedman test (Dunn’s post-test). For ECC1 and ECC2, peak torque and total work were increased and torque decline reduced compared to CON. Repeated ECC bouts yielded unaltered torque and work outcomes. Muscle damage markers were highest after ECC1 (soreness 48 h, creatine kinase 72 h; p<0.05). Their overall responses (area under the curve) were abolished post-ECC2 compared to post-ECC1 (p<0.05). Interleukin-6 was higher post-ECC1 than CON, and attenuated post-ECC2 (p>0.05). Interleukin-10 and tumor necrosis factor-α were not detectable. All markers showed high inter-individual variability. The protocol was feasible to induce muscle damage indicators after exercising a large muscle group, but the pilot results indicated only weak systemic inflammatory responses in asymptomatic adults.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 773 
KW  - exercise
KW  - eccentric
KW  - muscle fatigue
KW  - trunk muscles
KW  - isokinetics
KW  - repeated bout effect
KW  - inflammation
KW  - exercise induced muscle damage
KW  - interleukin-6
KW  - internleukin-10
KW  - tumor necrosis factor-α
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-557409
SN  - 1866-8364
SP  - E9
EP  - E17
PB  - Universitätsverlag Potsdam
CY  - Potsdam
ER  - 
TY  - GEN
A1  - Risch, Lucie
A1  - Stoll, Josefine
A1  - Schomöller, Anne
A1  - Engel, Tilman
A1  - Mayer, Frank
A1  - Cassel, Michael
T1  - Intraindividual Doppler Flow Response to Exercise Differs Between Symptomatic and Asymptomatic Achilles Tendons
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Objective: This study investigated intraindividual differences of intratendinous blood flow (IBF) in response to running exercise in participants with Achilles tendinopathy.

Design: This is a cross-sectional study.

Setting: The study was conducted at the University Outpatient Clinic.

Participants: Sonographic detectable intratendinous blood flow was examined in symptomatic and contralateral asymptomatic Achilles tendons of 19 participants (42 ± 13 years, 178 ± 10 cm, 76 ± 12 kg, VISA-A 75 ± 16) with clinically diagnosed unilateral Achilles tendinopathy and sonographic evident tendinosis.

Intervention: IBF was assessed using Doppler ultrasound “Advanced Dynamic Flow” before (Upre) and 5, 30, 60, and 120 min (U5–U120) after a standardized submaximal constant load run.

Main Outcome Measure: IBF was quantified by counting the number (n) of vessels in each tendon.

Results: At Upre, IBF was higher in symptomatic compared with asymptomatic tendons [mean 6.3 (95% CI: 2.8–9.9) and 1.7 (0.4–2.9), p < 0.01]. Overall, 63% of symptomatic and 47% of asymptomatic Achilles tendons responded to exercise, whereas 16 and 11% showed persisting IBF and 21 and 42% remained avascular throughout the investigation. At U5, IBF increased in both symptomatic and asymptomatic tendons [difference to baseline: 2.4 (0.3–4.5) and 0.9 (0.5–1.4), p = 0.05]. At U30 to U120, IBF was still increased in symptomatic but not in asymptomatic tendons [mean difference to baseline: 1.9 (0.8–2.9) and 0.1 (-0.9 to 1.2), p < 0.01].

Conclusion: Irrespective of pathology, 47–63% of Achilles tendons responded to exercise with an immediate acute physiological IBF increase by an average of one to two vessels (“responders”). A higher amount of baseline IBF (approximately five vessels) and a prolonged exercise-induced IBF response found in symptomatic ATs indicate a pain-associated altered intratendinous “neovascularization.”
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 746 
KW  - achilles tendinopathy
KW  - tendinosis
KW  - neovascularization
KW  - ultrasound
KW  - advanced dynamic flow
KW  - sonography
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-542865
SN  - 1866-8364
SP  - 1
EP  - 8
PB  - Universitätsverlag Potsdam
CY  - Potsdam
ER  - 
TY  - GEN
A1  - Kuschel, Luciano Bruno
A1  - Sonnenburg, Dominik
A1  - Engel, Tilman
T1  - Factors of muscle quality and determinants of muscle strength
BT  - a systematic literature review
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak–moderate negative (range r: [−0.26]–[−0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak–moderate positive correlation (range r: 0.177–0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [−0.446]–[−0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28–0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 838 
KW  - muscle quality
KW  - muscle strength
KW  - phase angle
KW  - echo intensity
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-589104
SN  - 1866-8364
IS  - 838
ER  - 
TY  - JOUR
A1  - Kuschel, Luciano Bruno
A1  - Sonnenburg, Dominik
A1  - Engel, Tilman
T1  - Factors of muscle quality and determinants of muscle strength
BT  - a systematic literature review
JF  - Healthcare
N2  - Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak–moderate negative (range r: [−0.26]–[−0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak–moderate positive correlation (range r: 0.177–0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [−0.446]–[−0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28–0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.
KW  - muscle quality
KW  - muscle strength
KW  - phase angle
KW  - echo intensity
Y1  - 2022
U6  - https://doi.org/10.3390/healthcare10101937
SN  - 2227-9032
VL  - 10
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
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
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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 355 
KW  - Achilles and patellar tendon
KW  - non-athletes
KW  - sonography
KW  - training adaptation
KW  - young athletes
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-403823
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  - 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  - Baritello, Omar
A1  - Khajooei, Mina
A1  - Engel, Tilman
A1  - Kopinski, Stephan
A1  - Quarmby, Andrew James
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass
JF  - BMC sports science, medicine and rehabilitation
N2  - 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.
KW  - EMG
KW  - instability
KW  - overhead athlete
KW  - unstable resistance training
KW  - water
KW  - pipe
KW  - rotator cuff
Y1  - 2020
U6  - https://doi.org/10.1186/s13102-020-00168-x
SN  - 2052-1847
VL  - 12
IS  - 1
PB  - BioMed Central
CY  - London
ER  - 
TY  - JOUR
A1  - Wochatz, Monique
A1  - Rabe, Sophie
A1  - Engel, Tilman
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Scapular kinematics during unloaded and maximal loaded isokinetic concentric and eccentric shoulder flexion and extension movements
JF  - Journal of electromyography & kinesiology : official journal of the International Society of Electrophysiology and Kinesiology
N2  - 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.
KW  - Isokinetics
KW  - Motion analysis
KW  - Scapular dyskinesis
KW  - Scapulohumeral rhythm
KW  - Scapulothoracic
Y1  - 2020
U6  - https://doi.org/10.1016/j.jelekin.2021.102517
SN  - 1050-6411
SN  - 1873-5711
VL  - 57
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Lin, Chiao-I
A1  - Khajooei, Mina
A1  - Nair, Alexandra
A1  - Heikkila, Mika
A1  - Kaplick, Hannes
A1  - Tilman, Engel
A1  - Mayer, Frank
T1  - Activities of hip muscles in response to perturbed walking in individual with chronic ankle instability
T2  - Medicine and science in sports and exercise : MSSE
N2  - Chronic ankle instability (CAI) is not only an ankle issue, but also affects sensorimotor system. People with CAI show altered muscle activation in proximal joints such as hip and knee. However, evidence is limited as controversial results have been presented regarding changes in activation of hip muscles in CAI population. PURPOSE: To investigate the effect of CAI on activity of hip muscles during normal walking and walking with perturbations. METHODS: 8 subjects with CAI (23 ± 2 years, 171 ± 7 cm and 65 ± 4 kg) and 8 controls (CON) matched by age, height, weight and dominant leg (25 ± 3 years, 172 ± 7 cm and 65 ± 6 kg) walked shoed on a split-belt treadmill (1 m/s). Subjects performed 5 minutes of baseline walking and 6 minutes walking with 10 perturbations (at 200 ms after heel contact with 42 m/s2 deceleration impulse) on each side. Electromyography signals from gluteus medius (Gmed) and gluteus maximus (Gmax) were recorded while walking. Muscle amplitudes (Root Mean Square normalized to maximum voluntary isometric contraction) were calculated at 200 ms before heel contact (Pre200), 100 ms after heel contact (Post100) during normal walking and 200 ms after perturbations (Pert200). Differences between groups were examined using Mann Whitney U test and Bonferroni correction to account for multiple testing (adjust α level p≤ 0.0125). RESULT: In Gmed, CAI group showed lower muscle amplitude than CON group after heel contact (Post100: 18±7 % and 47±21 %, p< .01) and after walking perturbations ( 31±13 % and 62±26 %, p< .01), but not before heel contact (Pre200: 5±2 % and 11±10 %, p= 0.195). In Gmax, no difference was found between CAI and CON groups in all three time points (Pre200: 12±5 % and 17±12 %, p= 0.574; Post100: 41±21 % and 41±13 %, p= 1.00; Pert200: 79±46 % and 62±35 %, p= 0.505). CONCLUSION: People with CAI activated Gmed less than healthy control in feedback mechanism (after heel contact and walking with perturbations), but not in feedforward mechanism (before heel contact). Less activation on Gmed may affect the balance in frontal plane and increase the risk of recurrent ankle sprain, giving way or feeling ankle instability in patients with CAI during walking. Future studies should investigate the effect of Gmed strengthening or neuromuscular training on CAI rehabilitation.
Y1  - 2020
U6  - https://doi.org/10.1249/01.mss.0000671060.98581.0b
SN  - 0195-9131
SN  - 1530-0315
VL  - 52
IS  - 17
SP  - 94
EP  - 94
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  - 
TY  - GEN
A1  - Nair, Alexandra
A1  - Lin, Chiao-I
A1  - Khajooei, Mina
A1  - Heikkila, Mika
A1  - Engel, Tilman
A1  - Mayer, Frank
T1  - Side comparison of knee muscle activities in response to perturbed walking of unilateral ankle instability
T2  - Medicine and science in sports and exercise : MSSE
N2  - Acute ankle sprain leads in 40% of all cases to chronic ankle instability (CAI). CAI is related to a variety of motor adaptations at the lower extremities. Previous investigations identified increased muscle activities while landing in CAI compared to healthy control participants. However, it remains unclear whether muscular alterations at the knee muscles are limited to the involved (unstable) ankle or are also present at the uninvolved leg. The latter might potentially indicate a risk of ankle sprain or future injury on the uninvolved leg. Purpose: To assess if there is a difference of knee muscle activities between the involved and uninvolved leg in participants with CAI during perturbed walking. Method: 10 participants (6 females; 4 males; 26±4 years; 169±9 cm; 65±7 kg) with unilateral CAI walked on a split-belt treadmill (1m/s) for 5 minutes of baseline walking and 6 minutes of perturbed walking (left and right side, each 10 perturbations). Electromyography (EMG) measurements were performed at biceps femoris (BF) and rectus femoris (RF). EMG amplitude (RMS; normalized to MVIC) were analyzed for 200ms pre-heel contact (Pre200), 100ms post heel contact (Post100) and 200ms after perturbation (Pert200). Data was analyzed by paired t-test/Wilcoxon test based on presence or absence of normal distribution (Bonferroni adjusted α level p≤ 0.0125). Results: No statistical difference was found between involved and uninvolved leg for RF (Pre200: 4±2% and 11± 22%, respectively, p= 0.878; Post100: 10± 5 and 18±31%, p=0.959; Pert200: 6±3% and 13±24%, p=0.721) as well as for BF (Pre200: 12±7% and 11±6, p=0.576; Post100: 10±7% and 9±7%, p=0.732; Pert200: 7±4 and 7±7%, p=0.386). Discussion: No side differences in muscle activity could be revealed for assessed feedforward and feedback responses (perturbed and unperturbed) in unilateral CAI. Reduced inter-individual variability of muscular activities at the involved leg might indicate a rather stereotypical response pattern. It remains to be investigated, whether muscular control at the knee is not affected by CAI, or whether both sides adapted in a similar style to the chronic condition at the ankle.
Y1  - 2020
U6  - https://doi.org/10.1249/01.mss.0000671088.10003.6b
SN  - 0195-9131
SN  - 1530-0315
VL  - 52
IS  - 17
SP  - 97
EP  - 97
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
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  - GEN
A1  - Henschke, Jakob
A1  - Kaplick, Hannes
A1  - Wochatz, Monique
A1  - Engel, Tilman
T1  - Assessing the validity of inertial measurement units for shoulder kinematics using a commercial sensor-software system
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - Background and Aims Wearable inertial sensors may offer additional kinematic parameters of the shoulder compared to traditional instruments such as goniometers when elaborate and time-consuming data processing procedures are undertaken. However, in clinical practice simple-real time motion analysis is required to improve clinical reasoning. Therefore, the aim was to assess the criterion validity between a portable "off-the-shelf" sensor-software system (IMU) and optical motion (Mocap) for measuring kinematic parameters during active shoulder movements. Methods 24 healthy participants (9 female, 15 male, age 29 +/- 4 years, height 177 +/- 11 cm, weight 73 +/- 14 kg) were included. Range of motion (ROM), total range of motion (TROM), peak and mean angular velocity of both systems were assessed during simple (abduction/adduction, horizontal flexion/horizontal extension, vertical flexion/extension, and external/internal rotation) and complex shoulder movements. Criterion validity was determined using intraclass-correlation coefficients (ICC), root mean square error (RMSE) and Bland and Altmann analysis (bias; upper and lower limits of agreement). Results ROM and TROM analysis revealed inconsistent validity during simple (ICC: 0.040-0.733, RMSE: 9.7 degrees-20.3 degrees, bias: 1.2 degrees-50.7 degrees) and insufficient agreement during complex shoulder movements (ICC: 0.104-0.453, RMSE: 10.1 degrees-23.3 degrees, bias: 1.0 degrees-55.9 degrees). Peak angular velocity (ICC: 0.202-0.865, RMSE: 14.6 degrees/s-26.7 degrees/s, bias: 10.2 degrees/s-29.9 degrees/s) and mean angular velocity (ICC: 0.019-0.786, RMSE:6.1 degrees/s-34.2 degrees/s, bias: 1.6 degrees/s-27.8 degrees/s) were inconsistent. Conclusions The "off-the-shelf" sensor-software system showed overall insufficient agreement with the gold standard. Further development of commercial IMU-software-solutions may increase measurement accuracy and permit their integration into everyday clinical practice.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 809 
KW  - diagnostic techniques and procedures
KW  - kinematics
KW  - shoulder joint
KW  - validation study
KW  - wearable devices
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-578278
SN  - 1866-8364
SP  - 1
EP  - 11
PB  - Universitätsverlag Potsdam
CY  - Potsdam
ER  - 
TY  - GEN
A1  - Baritello, Omar
A1  - Khajooei, Mina
A1  - Engel, Tilman
A1  - Kopinski, Stephan
A1  - Quarmby, Andrew
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Neuromuscular shoulder activity during exercises with different combinations of stable and unstable weight mass
T2  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe
N2  - 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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 867 
KW  - EMG
KW  - instability
KW  - overhead athlete
KW  - unstable resistance training
KW  - water pipe
KW  - rotator cuff
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-509366
SN  - 1866-8364
IS  - 1
ER  -