title: Kinematic and kinetic variations among three depth jump conditions in male NCAA division III athletes.
abstract: 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.
authors.affiliation: Strzelczyk Clinical Biomechanics Laboratory, Department of Health Professions, University of Wisconsin-La Crosse, Health Science Center, La Crosse, Wisconsin, USA.
authors.forename: Joel P
authors.initials: JP
authors.lastname: Smith
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Kernozek
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Kline
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Wright
mesh_terms: D000842:Ankle / Q000502:physiology; D056352:Athletes; D054874:Athletic Performance; D001696:Biomechanical Phenomena / Q000502:physiology; D006615:Hip / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D008297:Male; D009068:Movement / Q000502:physiology; D055815:Young Adult