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 - 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 - 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 - 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 - 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.
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.
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).
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 - 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 - 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 - 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 - 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 - 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 - 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 -