Skip Navigation LinksHome > April 2012 - Volume 26 - Issue 4 > The Acute Effects of Moderately Loaded Concentric-Only Quart...
Journal of Strength & Conditioning Research:
doi: 10.1519/JSC.0b013e318248d79c
Original Research

The Acute Effects of Moderately Loaded Concentric-Only Quarter Squats on Vertical Jump Performance

Crum, Aaron J.1; Kawamori, Naoki2; Stone, Michael H.3; Haff, G. Gregory4

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Abstract

Abstract: Crum, AJ, Kawamori, N, Stone, MH, and Haff, GG. The acute effects of moderately loaded concentric-only quarter squats on vertical jump performance. J Strength Cond Res 26(4): 914–925, 2012—Limited research exists examining the effect of moderately loaded conditioning activities that are employed as part of a strength-power potentiating complex (SPPC). Additionally, no studies to date have explored the effects of using a concentric-only quarter back squat protocol as part of an SPPC. Therefore, the purpose of this study was to examine the effects of a moderately loaded (50–65% of 1RM) concentric-only quarter back squat protocol on the occurrence of potentiation effects at various time points. Twenty men who could quarter back squat a minimum of 2.4 times their body mass (3.7 ± 0.7 kg·per body mass) participated in this investigation. All subjects participated in 3 conditions: control (CT), a 50% of 1RM trial (50POT), and a 65% of 1RM trial (65POT). One minute before each condition, a maximal countermovement vertical jump (CMJ) was performed. One minute later, the subject performed 1 of 3 conditions: CT condition, 50POT, or 65POT, followed by vertical jumps at 0.5, 3, 5, 10, and 15 minutes after conditioning activity. A force plate was used to quantify displacement, peak power output, peak force, and the rate of force development for each CMJ. There were no significant differences (p > 0.05) in any of the performance measures quantified during the CMJ trials when comparing the CT, 50POT, and 65POT treatment conditions. However, 48% of the subjects demonstrated some degree of potentiation at the 30 seconds after completing the 65POT trial, but this percent increase was not statistically significant. From a practical perspective, if the goal of the SPPC is to create a maximization of the potentiation effect, moderately loaded activities may not be the best alternative.

© 2012 National Strength and Conditioning Association

 

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