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  - Müller, Juliane
A1  - Hadzic, Miralem
A1  - Mugele, Hendrik
A1  - Stoll, Josefine
A1  - Müller, Steffen
A1  - Mayer, Frank
T1  - Effect of high-intensity perturbations during core-specific sensorimotor exercises on trunk muscle activation
JF  - Journal of biomechanics
N2  - Core-specific sensorimotor exercises are proven to enhance neuromuscular activity of the trunk. However, the influence of high-intensity perturbations on training efficiency is unclear within this context. Sixteen participants (29 +/- 2 yrs; 175 +/- 8 cm; 69 +/- 13 kg) were prepared with a 12-lead bilateral trunk EMG. Warm-up on a dynamometer was followed by maximum voluntary isometric trunk (flex/ext) contraction (MVC). Next, participants performed four conditions for a one-legged stance with hip abduction on a stable surface (HA) repeated randomly on an unstable surface (HAP), on a stable surface with perturbation (HA + P), and on an unstable surface with perturbation (HAP + P). Afterwards, bird dog (BD) was performed under the same conditions (BD, BDP, BD + P, BDP + P). A foam pad under the foot (HA) or the knee (BD) was used as an unstable surface. Exercises were conducted on a moveable platform. Perturbations (ACC 50 m/sec(2);100 ms duration;10rep.) were randomly applied in the anterior-posterior direction. The root mean square (RMS) normalized to MVC (%) was calculated (whole movement cycle). Muscles were grouped into ventral right and left (VR;VL), and dorsal right and left (DR;DL). Ventral Dorsal and right-left ratios were calculated (two way repeated-measures ANOVA;alpha = 0,05). Amplitudes of all muscle groups in bird dog were higher compared to hip abduction (p <= 0.0001; Range: BD: 14 +/- 3% (BD;VR) to 53 +/- 4%; HA: 7 +/- 2% (HA;DR) to 16 +/- 4% (HA;DR)). EMG-RMS showed significant differences (p < 0.001) between conditions and muscle groups per exercise. Interaction effects were only significant for HA (p = 0.02). No significant differences were present in EMG ratios (p > 0.05). Additional high-intensity perturbations during core-specific sensorimotor exercises lead to increased neuromuscular activity and therefore higher exercise intensities. However, the beneficial effects on trunk function remain unclear. Nevertheless, BD is more suitable to address trunk muscles.
KW  - Split-belt treadmill
KW  - EMG
KW  - Core stability
KW  - MiSpEx
Y1  - 2017
U6  - https://doi.org/10.1016/j.jbiomech.2017.12.013
SN  - 0021-9290
SN  - 1873-2380
VL  - 70
SP  - 212
EP  - 218
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Lesinski, Melanie
A1  - Prieske, Olaf
A1  - Beurskens, Rainer
A1  - Behm, David George
A1  - Granacher, Urs
T1  - Effects of drop height and surface instability on neuromuscular activation during drop jumps
JF  - Scandinavian journal of medicine & science in sports
N2  - The purpose of this study was to examine whether drop height-induced changes in leg muscle activity during drop jumps (DJ) are additionally modulated by surface condition. Twenty-four healthy participants (23.7 +/- 1.8years) performed DJs on a force plate on stable, unstable, and highly unstable surfaces using different drop heights (i.e., 20cm, 40cm, 60cm). Electromyographic (EMG) activity of soleus (SOL), gastrocnemius (GM), tibialis anterior (TA) muscles and coactivation of TA/SOL and TA/GM were analyzed for time intervals 100ms prior to ground contact (preactivation) and 30-60ms after ground contact [short latency response (SLR)]. Increasing drop heights resulted in progressively increased SOL and GM activity during preactivation and SLR (P<0.01; 1.01 d 5.34) while TA/SOL coactivation decreased (P<0.05; 0.51 d 3.01). Increasing surface instability produced decreased activities during preactivation (GM) and SLR (GM, SOL) (P<0.05; 1.36 d 4.30). Coactivation increased during SLR (P<0.05; 1.50 d 2.58). A significant drop heightxsurface interaction was observed for SOL during SLR. Lower SOL activity was found on unstable compared to stable surfaces for drop heights 40cm (P<0.05; 1.25 d 2.12). Findings revealed that instability-related changes in activity of selected leg muscles are minimally affected by drop height.
KW  - Stretch-shortening cycle
KW  - EMG
KW  - preactivation
KW  - short latency response
Y1  - 2017
U6  - https://doi.org/10.1111/sms.12732
SN  - 0905-7188
SN  - 1600-0838
VL  - 27
SP  - 1090
EP  - 1098
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Beijersbergen, Chantal M. I.
A1  - Granacher, Urs
A1  - Gäbler, Martijn
A1  - Devita, Paul
A1  - Hortobagyi, Tibor
T1  - Power Training-induced Increases in Muscle Activation during Gait in Old Adults
JF  - Medicine and science in sports and exercise : official journal of the American College of Sports Medicine
N2  - Introduction/Purpose: Aging modifies neuromuscular activation of agonist and antagonist muscles during walking. Power training can evoke adaptations in neuromuscular activation that underlie gains in muscle strength and power but it is unknown if these adaptations transfer to dynamic tasks such as walking. We examined the effects of lower-extremity power training on neuromuscular activation during level gait in old adults. Methods: Twelve community-dwelling old adults (age >= 65 yr) completed a 10-wk lower-extremity power training program and 13 old adults completed a 10-wk control period. Before and after the interventions, we measured maximal isometric muscle strength and electromyographic (EMG) activation of the right knee flexor, knee extensor, and plantarflexor muscles on a dynamometer and we measured EMG amplitudes, activation onsets and offsets, and activation duration of the knee flexors, knee extensors, and plantarflexors during gait at habitual, fast, and standardized (1.25 +/- 0.6 m.s(-1)) speeds. Results: Power training-induced increases in EMG amplitude (similar to 41%; 0.47 <= d <= 1.47; P <= 0.05) explained 33% (P = 0.049) of increases in isometric muscle strength (similar to 43%; 0.34 <= d <= 0.80; P <= 0.05). Power training-induced gains in plantarflexor activation during push-off (+11%; d = 0.38; P = 0.045) explained 57% (P = 0.004) of the gains in fast gait velocity (+4%; d = 0.31; P = 0.059). Furthermore, power training increased knee extensor activation (similar to 18%; 0.26 <= d <= 0.29; P <= 0.05) and knee extensor coactivation during the main knee flexor burst (similar to 24%, 0.26 <= d <= 0.44; P <= 0.05) at habitual and fast speed but these adaptations did not correlate with changes in gait velocity. Conclusions: Power training increased neuromuscular activation during isometric contractions and level gait in old adults. The power training-induced neuromuscular adaptations were associated with increases in isometric muscle strength and partly with increases in fast gait velocity.
KW  - WALKING
KW  - MUSCLE
KW  - EXERCISE
KW  - EMG
Y1  - 2017
U6  - https://doi.org/10.1249/MSS.0000000000001345
SN  - 0195-9131
SN  - 1530-0315
VL  - 49
SP  - 2198
EP  - 2205
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  -