Effects of varying levels of muscular fatigue on vertical jump performance

This study was conducted (a) to determine the effects of varying levels of muscular fatigue on vertical jump performance and (b) to see if the initial level of leg strength influenced this response. Twelve college men were tested for leg-press strength (1-RM) and for vertical jump. Subjects were separated into a high- or low-strength group (n = 6 per group) based on 1-RM leg press. Vertical jump was measured before and after fatigue was induced (by Lifting loads of 50, 70, or 90% I-RM until exhaustion). The effect was to produce strength decrements of 50, 30, and 10%, respectively. All fatigue values differed significantly (p < 0.02) from resting values. When comparing work and distance jumped, there were significant differences between 50% and 10% fatigue levels, as well as between 30% and 10% only on the work produced. No differences (p > 0.05) were found between groups under all conditions. Thus, increasing fatigue by reducing the strength capacity of the leg muscles leads to gradual decrements in vertical jump, but not in proportion to strength decrement. The decrease in vertical jump performance is independent of the initial strength level.