The ability to jump is an important characteristic in volleyball. The relationship between factors associated with vertical jump height and how they change as an athlete develops from generally untrained (incoming freshman) to trained as part of a periodized conditioning program is not well known.
PURPOSE: To analyze how the relationship of body composition, maximum strength, and strength characteristics with static weighted (20kg) and un-weighted vertical jumps changes as an athlete increases explosive strength (as measured by vertical jump height).
METHODS: Data from seventeen female NCAA DI volleyball players collected from 2007-2010 as part of an ongoing athlete monitoring program was analyzed. Body composition was measured via air displacement plethsmography. Maximum strength (isometric peak force - IPF) and strength characteristics (peak force [email protected] 50ms, 90ms, and 250ms; rate of force development, 0-200ms -RFD) were measured with isometric mid-thigh pulls on a force plate, and static jumps with 0 and 20kg. Jump height was determined through flight time using a force plate. Allometric scaling of the different force values (IPFa, [email protected], [email protected], [email protected]) was used to normalize differences in the body mass of the athletes (absolute force/ (body mass (kg0.67)). Correlations (Pearson) were used to determine the strength of relationships and paired t-tests were used to determine differences in explosive strength over time.
RESULTS: Over three years, there was a significant increase (p≤0.01) in un-weighted jump height (23.5±2.8 to 27.1±4.5), jump height with 20kg (15.7±2.8cm to 19.9±4.5cm, IPF (2584±425N to 2941±578N), and IPFa (152±21N /kg0.67 to 172±3021N /kg0.67). Correlations increased in magnitude between: un-weighted vertical jump height and IPF (-0.26 to 0.34), IPFa (-0.14 to 0.41), [email protected] (0.02 to 0.53), [email protected](0.11 to 0.54) and RFD (0.10 to 0.51); and vertical jump height with 20kg and IPF (0.05 to 0.48), IPFa (0.14 to 0.57). Correlations decreased in magnitude between both vertical jump conditions (0kg and 20kg) and % body fat (0kg: -0.73 to -0.61, 20kg -0.61 to -0.54).
CONCLUSIONS: As strength increases throughout the athletes' collegiate career their relationship to jumping ability becomes stronger. The relationship between % body fat and jump height decreases with no change in % body fat.