Resumen de Kinematic and Kinetic Variations Among Three Depth Jump Conditions in Male NCAA Division III Athletes
Joel P. Smith, Thomas W. Kernozek, Dennis E. Kline, Glenn A. Wright
Our purpose was to provide an in-depth investigation of 2 commonly used depth jump variants: depth jumping over a hurdle and depth jumping while touching as high as possible using an overhead goal. Fourteen male athletes performed a series of depth jumps from a 45-cm box. Three types of jumping conditions were used. One type of depth jump was a control jump (DJ45-C), performed for maximal height with no external apparatus used to influence the jump. Another type of depth jump was performed over a hurdle (DJ45-H), which was set at an individualized height for each athlete based on their leaping ability. The final type of depth jump was performed for maximal touch height on a Vertec measuring device (DJ45-T). Timing, kinematics, and kinetics of the 3 jumping conditions were compared. The hurdle depth jumping condition demonstrated lower ground contact times and significantly less (p < 0.05) flexion in the hips (41.22 ± 8.10 degrees) and knees (67.47 ± 8.36 degrees) when compared to control (49.26 ± 10.90 degrees of hip flexion and 73.85 ± 10.68 degrees of knee flexion) and target (50.51 ± 9.51 degrees of hip flexion and 75.01 ± 9.97 degrees of knee flexion) conditions. Jumping conditions that used goals (DJ45-H, DJ45-T) produced significantly higher (p < 0.05) vertical velocity of the sacrum at toe-off (3.57 ± .34 m/s and 3.46 ± .36 m/s, respectively) than the control condition (3.32 ± .34 m/s). The hurdle depth jump condition had higher ground reaction forces (875.36 ± 135.66 N) and higher dorsiflexion (566.02 ± 402.45 W) and plantar flexion power (768.84 ± 192.19 W) at the ankle than the Vertec (409.83 ± 387.23 W for dorsiflexion and 622.54 ± 188.95 W for plantar flexion) and control conditions (425.60 ± 380.01 W for dorsiflexion and 643.35 ± 166.70 W for plantar flexion). Few differences were found to exist between the Vertec and control conditions. Hurdle jumping in particular may be superior for the development of short ground contact time (<0.3 s) sport movements requiring brief but powerful lower-extremity power production.
