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  - 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  -