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  - Lesinski, Melanie
A1  - Prieske, Olaf
A1  - Borde, Ron
A1  - Beurskens, Rainer
A1  - Granacher, Urs
T1  - Effects of Different Footwear Properties and Surface Instability on Neuromuscular Activity and Kinematics During Jumping
JF  - Journal of strength and conditioning research : the research journal of the NSCA
N2  - The purpose of this study was to examine sex-specific effects of different footwear properties vs. barefoot condition during the performance of drop jumps (DJs) on stable and unstable surfaces on measures of jump performance, electromyographic (EMG) activity, and knee joint kinematics. Drop jump performance, EMG activity of lower-extremity muscles, as well as sagittal and frontal knee joint kinematics were tested in 28 healthy male (n = 14) and female (n = 14) physically active sports science students (23 6 2 years) during the performance of DJs on stable and unstable surfaces using different footwear properties (elastic vs. minimal shoes) vs. barefoot condition. Analysis revealed a significantly lower jump height and performance index (Delta 7-12%; p < 0.001; 2.22 <= d = 2.90) during DJs on unstable compared with stable surfaces. This was accompanied by lower thigh/shank muscle activities (Delta 11-28%; p < 0.05; 0.99 <= d = 2.16) and knee flexion angles (Delta 5-8%; p < 0.05; 1.02 <= d = 2.09). Furthermore, knee valgus angles during DJs were significantly lower when wearing shoes compared with barefoot condition (Delta 22-32%; p < 0.01; 1.38 <= d = 3.31). Sex-specific analyses indicated higher knee flexion angles in females compared with males during DJs, irrespective of the examined surface and footwear conditions (Delta 29%; p < 0.05; d = 0.92). Finally, hardly any significant footwear-surface interactions were detected. Our findings revealed that surface instability had an impact on DJ performance, thigh/shank muscle activity, and knee joint kinematics. In addition, the single factors "footwear" and "sex" modulated knee joint kinematics during DJs. However, hardly any significant interaction effects were found. Thus, additional footwear-related effects can be neglected when performing DJs during training on different surfaces.
KW  - shoe
KW  - drop jump
KW  - EMG
KW  - knee
KW  - biomechanics
Y1  - 2018
U6  - https://doi.org/10.1519/JSC.0000000000002556
SN  - 1064-8011
SN  - 1533-4287
VL  - 32
IS  - 11
SP  - 3246
EP  - 3257
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  -