title: Power-time, force-time, and velocity-time curve analysis during the jump squat: impact of load.
abstract: The purpose of this investigation was to examine the impact of load on the power-, force- and velocity-time curves during the jump squat. The analysis of these curves for the entire movement at a sampling frequency of 200-500 Hz averaged across 18 untrained male subjects is the most novel aspect of this study. Jump squat performance was assessed in a randomized fashion across five different external loads: 0, 20, 40, 60, and 80 kg (equivalent to 0 +/- 0, 18 +/- 4, 37 +/- 8, 55 +/- 12, 74 +/- 15% of 1RM, respectively). The 0-kg loading condition (i.e., body mass only) was the load that maximized peak power output, displaying a significantly (p <or=.05) greater value than the 40, 60, and 80 kg loads. The shape of the force-, power-, and velocity-time curves changed significantly as the load applied to the jump squat increased. There was a significantly greater rate of power development in the 0 kg load in comparison with all other loads examined. As the first comprehensive illustration of how the entire power-, force-, and velocity-time curves change across various loading conditions, this study provides extensive evidence that a load equaling an individuals body mass (i.e., external load = 0 kg) maximizes power output in untrained individuals during the jump squat.
authors.affiliation: School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, Western Australia.
authors.forename: Prue
authors.initials: P
authors.lastname: Cormie
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: McBride
authors.forename: Grant O
authors.initials: GO
authors.lastname: McCaulley
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D013997:Time Factors; D014891:Weight Lifting / Q000502:physiology*