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ABSTRACT. Mangue, B.C., M. Takahashi, J.A. Mercer, W.R. Holcomb, J.W. McWhorter, and R. Sanchez. Investigation of vertical jump performance after completing heavy squat exercises. J. Strength Cond. Res. 20(3):597-600. 2006.-The purpose of this study was to determine whether vertical jump height was influenced by completing a half squat or quarter squat exercise prior to jumping. Ten male subjects experienced with the squat exercise performed 4 warm up squat sets followed by 1 repetition with the weight of 90% of 1 repetition maximum of the half squat or quarter squat. No difference in jump heights after any of the 3 conditions, including a control group (F = 3.096, p = 0.070), was found. Correlations between the relative strength ratio and the difference in averaged jump heights before and after the half and quarter squat conditions were also tested, and no correlation was found (r = -0.128, p = 0.724, and r = -0.189, p = 0.601, respectively). Although statistical significance at the 0.05 level was not observed for the comparison of jump heights between conditions, we did observe a trend (i.e., p = 0.07). Therefore, we examined the individual responses to the exercises and determined that 5 of the subjects did increase their vertical jumps after both squat exercises. It may be that the influence of prejump exercise on jump performance may be individualized. Nevertheless, the use of a strength ratio does not appear to predict who will benefit from posttetanic potentiation in this type of exercise situation.
KEY WORDS. half squat, quarter squat, posttetanic potentiation
INTRODUCTION
For competitive athletes, the warm up is about more than preventing injuries. It is also common to use a warm up session to enhance athletic performance. To gain a performance edge, some athletes may execute heavy-load exercise just before explosive activities, with the goal being to enhance the performance of the bench press or vertical jump (1, 7). It has been hypothesized that the use of specific heavy-load exercises will elicit a posttetanic potentiation (PTP) (1, 7).
Posttetanic potentiation is generally explained as the enhancement of power, force, or contractile response of a muscle resulting from prior highly intense muscle contractile activity. Physiologically, the PTP has been explained as an increase in blood flow and neural activity to...