Garrett M. Hester, Zachary K. Pope, John H. Sellers, Ryan M. Thiele & Jason M. DeFreitas

Oklahoma State University, Stillwater, Oklahoma

Post-activation potentiation (PAP) refers to the enhancement of muscular performance characteristics as a result of their contractile history. PAP may be elicited at an earlier time interval following ballistic exercise compared to heavy exercise. PURPOSE: The purpose of this study was to compare the temporal effects of a jump squat and back squat protocol on vertical jump performance. METHODS: Fourteen resistance-trained men (mean ± SD: age = 22 ± 2.1 yrs., body mass = 86.29 ± 9.95 kg, height = 175.39 ± 9.34 cm, back squat 1-RM = 173.05 ± 24.61 kg) with an average relative full squat of 2.02 ± 0.28 times their body mass participated in this study. In randomized, counter-balanced order subjects performed two countermovement vertical jumps (CMVJs) before and 1 min, 3 min, 5 min, and 10 min after either performing 10 rapid jump squats or 5 heavy back squats. Each subject visited the laboratory on 3 occasions; one familiarization session which comprised 1-RM testing, followed by two testing sessions, separated by at least 72 hours. The back squat protocol (BS) consisted of one set of 5 parallel back squats at 80% 1-RM, whereas the jump squat protocol (JS) consisted of one set of 10 jump squats at 20% 1-RM. Peak jump height (in) using a jump mat, along with power output (W) and velocity (m/s) via a linear transducer were recorded for each time interval. RESULTS: There was no significant condition × time interaction for any of the dependent variables (p = 0.066-0.127). There was no main effect of time for any of the dependent variables for the JS (p = 0.159-0.283) or BS (p = 0.119-0.121), except for jump height which was significantly lower at 1 min post BS compared to baseline (p = 0.014). CONCLUSION: Neither the JS nor BS induced PAP during the CMVJ. The BS significantly impaired CMVJ height at 1 min post (-3.74%), while the JS tended to have an insignificant positive effect (0.13-0.65%) during early time intervals (i.e., 1-5 min). Future research should investigate the effectiveness of other ballistic exercises to produce PAP at early time intervals.

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