Box jumps and depth jumps might elicit post activiation potentiation (PAP), which can improve vertical jump performance. The purpose of this study was to compare the potentiating effects of a depth jump vs. a box jump warm-up on vertical jump performance. Ten NCAA Division I female volleyball players participated in this study (age; 19.10 +/- 1.28 yrs, height; 177.33 +/- 8.13 cm, mass; 73.92 +/- 5.30 kg). Participants completed three testing sessions each separated by at least 48 hours. Investigators measured each subject's height, mass, and standing reach on Day one. On each day, subjects warmed up for five minutes on the cycle ergometer at a moderate self-selected pace with 0.5 kps of resistance. Subjects then performed three maximum countermovement jumps with arm-swing (vertical jumps), which served as a pre-test for that day. Subjects then performed one of three experimental conditions in random order: a control condition (no intervention), a box jump condition (ten jumps onto a box), and a depth jump condition (ten trials of stepping off a box with immediate maximal rebound). Individualized box height equaled the distance from the floor to the halfway point between the greater trochanter and the lateral femoral condyle. Upon completion of each condition, subjects rested for ten minutes. Subjects then performed three final vertical jumps (post-test). Dependent variables included vertical jump height (as measured by a Vertec and force plate) and ground reaction force. ANOVA revealed a significant (p < 0.05) interaction for condition by time on vertical jump height measured by the Vertec. Vertical jump height (as measured by the Vertec) significantly (p < 0.05) decreased for the control condition. No significant differences existed in vertical jump height for the box jump (pre = 43.94 +/- 5.28 cm; post = 44.70 +/- 6.45 cm) or depth jump conditions (pre = 44.70 +/- 7.11 cm; post = 45.08 +/- 6.70 cm). ANOVA revealed no significant difference from pre to post for vertical jump height and ground reaction force as measured by the force plate for any condition. The significant decrease in performance during the control trial suggests that 1) ten minutes of seated rest and/or 2) the performance of three preliminary jumps impaired subsequent jumping performance. The box and depth jumps tended to increase vertical jump height (as measured by the Vertec), suggesting these jumps at a greater intensity might elicit PAP. This might also indicate that ten minutes rest is too long for these types of jumps at this intensity. Ten box jumps or depth jumps at this intensity should not be used for female collegiate volleyball players as a warm-up since these exercises fail to elicit a PAP response in the vertical jump.
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