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 Jump Performance and Knee Kinematics
JF  - International journal of sports medicine
N2  - The purpose of this study was to examine the combined effects of drop-height and surface condition on drop jump (DJ) performance and knee joint kinematics. DJ performance, sagittal and frontal plane knee joint kinematics were measured in jump experienced young male and female adults during DJs on stable, unstable and highly unstable surfaces using different drop-heights (20, 40, 60 cm). Findings revealed impaired DJ performance (Δ5–16%; p<0.05; 1.43≤d≤2.82), reduced knee valgus motion (Δ33–52%; p<0.001; 2.70≤d≤3.59), and larger maximum knee flexion angles (Δ13–19%; p<0.01; 1.74≤d≤1.75) when using higher (60 cm) compared to lower drop-heights (≤40 cm). Further, lower knee flexion angles and velocity were found (Δ8-16%; p<0.01; 1.49≤d≤2.38) with increasing surface instability. When performing DJs from high (60 cm) compared to moderate drop-heights (40 cm) on highly unstable surfaces, higher knee flexion velocity and maximum knee valgus angles were found (Δ15–19%; p<0.01; 1.50≤d≤1.53). No significant main and/or interaction effects were observed for the factor sex. In conclusion, knee motion strategies were modified by the factors ‘drop-height’ and/or ‘surface instability’. The combination of high drop-heights (>40 cm) together with highly unstable surfaces should be used cautiously during plyometrics because this may increase the risk of injury due to higher knee valgus stress.
KW  - drop jump
KW  - knee flexion angle
KW  - knee valgus angle
KW  - knee valgus motion
Y1  - 2017
U6  - https://doi.org/10.1055/s-0043-117610
SN  - 0172-4622
SN  - 1439-3964
VL  - 39
IS  - 1
SP  - 50
EP  - 57
PB  - Thieme
CY  - Stuttgart
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  -