TY  - JOUR
A1  - Prieske, Olaf
A1  - Demps, Marie
A1  - Lesinski, Melanie
A1  - Granacher, Urs
T1  - Combined Effects of Fatigue and Surface Instability on Jump Biomechanics in Elite Athletes
JF  - International journal of sports medicine
N2  - The present study aimed to examine the effects of fatigue and surface instability on kinetic and kinematic jump performance measures. Ten female and 10 male elite volleyball players (18 +/- 2 years) performed repetitive vertical double-leg box jumps until failure. Pre and post fatigue, jump height/performance index, ground reaction force and knee flexion/valgus angles were assessed during drop and countermovement jumps on stable and unstable surfaces. Fatigue, surface condition, and sex resulted in significantly lower drop jump performance and ground reaction force (p0.031, 1.1d3.5). Additionally, drop jump knee flexion angles were significantly lower following fatigue (p=0.006, d=1.5). A significant fatiguexsurfacexsex interaction (p=0.020, d=1.2) revealed fatigue-related decrements in drop jump peak knee flexion angles under unstable conditions and in men only. Knee valgus angles were higher on unstable compared to stable surfaces during drop jumps and in females compared to males during drop and countermovement jumps (p0.054, 1.0d1.1). Significant surfacexsex interactions during countermovement jumps (p=0.002, d=1.9) indicated that knee valgus angles at onset of ground contact were significantly lower on unstable compared to stable surfaces in males but higher in females. Our findings revealed that fatigue and surface instability resulted in sex-specific knee motion strategies during jumping in elite volleyball players.
KW  - stretch-shortening cycle
KW  - knee joint angle
KW  - exhaustion
KW  - injury risk
KW  - gender
Y1  - 2017
U6  - https://doi.org/10.1055/s-0043-111894
SN  - 0172-4622
SN  - 1439-3964
VL  - 38
SP  - 781
EP  - 790
PB  - Thieme
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Prieske, Olaf
A1  - Mühlbauer, Thomas
A1  - Krüger, Tom
A1  - Kibele, A.
A1  - Behm, David George
A1  - Granacher, Urs
T1  - Sex-Specific effects of surface instability on drop jump and landing biomechanics
JF  - International journal of sports medicine
N2  - This study investigated sex-specific effects of surface instability on kinetics and lower extremity kinematics during drop jumping and landing. Ground reaction forces as well as knee valgus and flexion angles were tested in 14 males (age: 23 +/- 2 years) and 14 females (age: 24 +/- 3 years) when jumping and landing on stable and unstable surfaces. Jump height was found to be significantly lower (9 %, p < 0.001) when drop jumps were performed on unstable vs. stable surface. Significantly higher peak ground reaction forces were observed when jumping was performed on unstable vs. stable surfaces (5 %, p = 0.022). Regarding frontal plane kinematics during jumping and landing, knee valgus angles were higher on unstable compared to stable surfaces (1932 %, p < 0.05). Additionally, at the onset of ground contact during landings, females showed higher knee valgus angles than males (222 %, p = 0.027). Sagittal plane kinematics indicated significantly smaller knee flexion angles (6-35 %, p < 0.05) when jumping and landing on unstable vs. stable surfaces. During drop jumps and landings, women showed smaller knee flexion angles at ground contact compared to men (27-33 %, p < 0.05). These findings imply that knee motion strategies were modified by surface instability and sex during drop jumps and landings.
KW  - stretch-shortening cycle
KW  - ground reaction force
KW  - knee joint angle
KW  - injury risk
Y1  - 2015
U6  - https://doi.org/10.1055/s-0034-1384549
SN  - 0172-4622
SN  - 1439-3964
VL  - 36
IS  - 1
SP  - 75
EP  - 81
PB  - Thieme
CY  - Stuttgart
ER  -