THE EFFECT OF INITIAL KNEE ANGLE ON THE RELIABILITY OF VARIABLES DERIVED FROM A SQUAT JUMP

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THE EFFECT OF INITIAL KNEE ANGLE ON THE RELIABILITY OF VARIABLES DERIVED FROM A SQUAT JUMP

Journal Title: Medicina Sportiva - Year 2014, Vol 18, Issue 4

Abstract

Introduction: Despite wide use of the concentric only squat jump (SJ) as a performance test, the reliability of contributing kinetic variables of the performance has not been well established. Furthermore, it is common for researchers to assess the reliability of one variable to make inferences about the reliability of others. Making such assumptions may lead to inappropriate interpretation of findings.Objective: To determine the reliability across multiple variables (relative net impulse, flight time, peak velocity, peak force, peak power) at five different knee angles during performance of SJ.Methods: Ten recreationally trained subjects performed three body weight squat jumps from knee angles of 90°, 100°, 110°, 120°, 130°, and a self-selected knee angle on two occasions. A one-way ANOVA was used to determine the difference in reliability of variables within a single knee angle; and to compare the reliability of a variable across knee joint angles. Statistical significance was set at P ≤ 0.1 to reduce the likelihood of a type II error due to the small sample size involved.Results: There were no significant differences in the reliability between variables within a single knee angle. However, significant differences were observed for the variables relative net impulse (P = 0.002) and flight time (P = 0.010) between the different knee angles.Conclusions: Assessing the reliability of a single variable and making assumptions about the reliability of other variables appears to be appropriate when the variables are all interdependent.

Authors and Affiliations

Christos K. Argus, Lachlan J. Mitchell, Dale W. Chapman

Keywords

monitoring testing power velocity relative net impulse flight time

EP ID EP74243
DOI 10.5604/17342260.1127307
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