Effects of Different Levels of Fatigue on Vertical Jump Performance, Vertical Stiffness, and Intralimb Coordination

This study aimed to investigate the acute effects of different levels of muscular fatigue on vertical jump perfor- mance, vertical stiffness, and intralimb coordination. Seventeen physically active men performed two fatigue protocols (low volume and high volume) composed of continuous vertical jumps on separate weeks. Jump height, vertical stiffness, and intralimb coordination were measured during countermovement vertical jumps prior to and immediately following the fatigue protocols. The jumps were performed on a force plate and filmed with high-speed cameras. The continuous relative phase was calculated as a measure of intralimb coordination. Mixed-model ANOVA was used to compare the variables between conditions and times. The fatigue index was greater in the high-volume protocol (27±12%) than in the low-volume protocol (16±7%). Jump height decreased (p≤0.01) after the high-volume protocol. Vertical stiffness decreased (p=0.05), and the continuous relative phase of thigh-shank coupling in the ascent phase of countermovement jumps increased (p=0.04) after both proto- cols. In conclusion, jump performance was only affected by higher fatigue indexes, while vertical stiffness and intralimb coordination were affected similarly irrespective of the fatigue levels.