Variations on the vertical jump: individual adaptations to changing task demands

Here we explored the coordination of joint behaviors exhibited during the vertical jump and variations of that jump. By manipulating the take-off angle, we required an adjustment to changing task demands. It was hypothesized that kinematic features of the jump would change but that spatiotemporal relationships essential to propulsion would remain invariant across all conditions. To test this hypothesis, six adult male subjects performed jumps at six different take-off angles. An analysis of cinematographic data revealed that individual subjects changed the sequence and timing of lower-extremity joint reversals. In contrast, the covariation of joint behaviors during the propulsive phase and the timing of maximum intersegmental extension velocities were extremely stable within each individual across changes in task. We argue that the flexibility to alter sequence and timing is part of a strategy that permits adaptation to the context and facilitates a continued coordination among variables associated with propulsion.