TY  - JOUR
A1  - Howard, Joshua
A1  - Granacher, Urs
A1  - Behm, David George
T1  - Trunk extensor fatigue decreases jump height similarly under stable and unstable conditions with experienced jumpers
JF  - European journal of applied physiology
N2  - The purpose of this study was to investigate the effects of back extensor fatigue on performance measures and electromyographic (EMG) activity of leg and trunk muscles during jumping on stable and unstable surfaces.
 Before and after a modified Biering-Sorensen fatigue protocol for the back extensors, countermovement (CMJ) and lateral jumps (LJ) were performed on a force plate under stable and unstable (balance pad on the force plate) conditions. Performance measures for LJ (contact time) and CMJ height and leg and trunk muscles EMG activity were tested in 14 male experienced jumpers during 2 time intervals for CMJ (braking phase, push-off phase) and 5 intervals for LJ (-30 to 0, 0-30, 30-60, 60-90, and 90-120 ms) in non-fatigued and fatigued conditions.
 A significant main effect of test (fatigue) (p = 0.007, f = 0.57) was observed for CMJ height. EMG analysis showed a significant fatigue-induced decrease in biceps femoris and gastrocnemius activity with CMJ (p = 0.008, f = 0.58 andp = 0.04, f = 0.422, respectively). LJ contact time was not affected by fatigue or surface interaction. EMG activity was significantly lower in the tibialis anterior with LJ following fatigue (p = 0.05, f = 0.405). A test x surface (p = 0.04, f = 0.438) interaction revealed that the non-fatigued unstable CMJ gastrocnemius EMG activity was lower than the non-fatigued stable condition during the onset-of-force phase.
 The findings revealed that fatiguing the trunk negatively impacts CMJ height and muscle activity during the performance of CMJs. However, skilled jumpers are not additionally affected by a moderately unstable surface as compared to a stable surface.
KW  - Countermovement jump
KW  - Instability
KW  - Balance
KW  - Crossover fatigue
KW  - Lateral jumps
Y1  - 2015
U6  - https://doi.org/10.1007/s00421-014-3011-x
SN  - 1439-6319
SN  - 1439-6327
VL  - 115
IS  - 2
SP  - 285
EP  - 294
PB  - Springer
CY  - New York
ER  -