Effects of two different terrains on vertical jump performance

The purpose of this study was to evaluate through video-kinematic analysis vertical jump performance (VJP) on two types of surface; namely sand (compliant) and a hard surface (non-compliant). Forty-one physically active male subjects whose average age was 20.34 (± 2.95) years volunteered with written informed consent. Parameters measured included stature, mass, and percentage body fat. VJP was assessed by tracking the centre of mass via video-kinematic analysis on sand and a hard surface. The results indicated that the subjects had an average stature of 178.03 (± 7.75) cm, a mean mass of 79.56 (± 11.47) kg and body fat of 12.6 (± 1.2) %. The mean VJP achieved on sand was 49.0 (± 5.34 cm), compared to 55.11 (± 5.53) cm on a hard surface. Thus the mean VJP on sand was 11.03% lower than that achieved on a hard surface, which was significant (p0.05) between the decent distances of the centre of mass during the preparatory phase (squat) of the jump on sand (26.77 cm) compared to the same action on a hard surface (27.09 cm). As a consequence of these findings one may speculate that for any given jumping action that is performed on sand, an individual will suffer a significant loss in performance equaling approximately 10-12% when compared to the same action on a hard surface. In terms of the preparatory jump phase it was noted that there appears to be an optimal decent distance by the centre of mass (squat) relative to the individual irrespective of terrain on which the jump is performed. Key Words: . AJPHERD Vol.10(2) 2004: 133-14