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Jessica A. Schnaiter, Ryan M. Thiele, Mitchel A. Magrini, Douglas B. Smith. Oklahoma State University, Stillwater, OK; e-mail: Jessica.schnaiter@okstate.edu

Previous researchers have examined the time-course effects of explosive resistance training protocols on maximal and rapid strength characteristics in anaerobically trained individuals. However, sport-related measures, such as the vertical jump (VJ), may be more practical and functionally-relevant in order to track performance recovery after an explosive exercise. PURPOSE: The purpose of this study was to investigate the effects of an explosive free-weight back squat protocol on maximal power (Pmax) in resistance-trained females using a commercially-designed linear transducer during VJs. METHODS: Thirteen resistance-trained (> 3 days . wk-1 of free-weight training 6.3 ± 3.4 years) college-aged females (mean ± SD: age = 21.6 ± 0.9 years, height = 165.6 ± 7.6 cm, weight = 72.0 ± 12.1 kg) volunteered to participate in this investigation. Participants visited the laboratory on two occasions separated by 7 ± 4 days. The first visit consisted of familiarization to testing procedures, and a one-repetition maximum (1-RM) of the free-weight back squat exercise was determined. The second visit consisted of two countermovement VJs (CMJ) before (Pre), immediately after (Post0), five (Post5), ten (Post10), fifteen (Post15), and twenty (Post20) minutes following the completion of the explosive back squat protocol (5 × 16 at 40% 1-RM). To determine Pmax, a linear transducer was attached to the posterior portion of a belt fastened around the participant’s waistline. Participants were asked to perform a rapid downward countermovement and then jump up as explosively as possibly for all CMJs, with feet shoulder width apart and hands positioned on the hips. A one-way repeated measures ANOVA was used to analyze Pmax at all time points. RESULTS: Pmax was significantly decreased at Post0 (P = 0.006) and Post15 (P = 0.009) compared to Pre. No significant differences (P = 0.061 - 0.071) were observed at all other time points (i.e., Post 5, Post 10, and Post 20) compared to Pre. CONCLUSION: These findings suggest Pmax may be significantly affected by explosive bouts of exercise for up to five minutes. The ability to produce maximal vertical power after an explosive squat protocol may be reduced for brief periods of time, with possible differential recovery up to 20 minutes. Although CMJs may be a functional measure for performance, inconsistent recovery patterns may be observed. The acute decrease in maximal power after explosive back squats may have important recovery implications for practitioners when developing and implementing resistance-training programs.

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