The development of an isokinetic squat device: reliability and relationship to functional performance

Abstract

This study was performed to determine the reliability and validity of a new isokinetic squat device in comparison to knee-extension tests performed using a Cybex. Athletic male subjects (n = 29) performed a series of isokinetic squat tests at 0.4 m.s-1, knee-extension tests at 1.05, 2.09 and 3.14 rad.s-1, and a 6-s stationary cycle test which was used as the measure of functional performance. The squat tests included a purely concentric squat without pre-load, a test with pre-load and a stretch-shorten cycle test. Two trials of each test were performed on one testing occasion. Intraclass correlation co-efficients (r = 0.89-0.96) and co-efficients of variation (3.1-8.7%) were determined between trials, and these indicated that all of the tests were highly reliable. The velocity characteristics of the newly developed system demonstrated that it was an effective isokinetic device, with the mean velocity of 0.41 m.s-1 varying within narrow limits, a relatively small velocity overshoot and an isokinetic portion of movement of approximately 80%. The squat tests demonstrated a higher relationship to cycling performance (r = 0.57-0.65) as compared to the knee-extension tests (r = 0.45-0.51). This difference was amplified when a more homogeneous group of subjects was examined. Further, the squat tests were superior to the knee-extension tests in discriminating between differing levels of cycling performance ability. These differences were believed to be due to the greater specificity of the squat movement, in comparison to the knee extension, to the performance of interest.

A new device for controlled eccentric overloading in training and rehabilitation

“…The results showed that the variation between the two test occasions was of a similar magnitude as reported earlier for reproducibility of concentric strength performance in squat (Munich et al 1997;Wilson et al 1997). Relevant reliability data for eccentric strength performance in squat are lacking.…”

Reliability of a Unilateral Horizontal Leg Power Test to Assess Stretch Load Tolerance

“…Such an approach is common in the literature (Thompson & Bemben, 1999;Walshe, Wilson, & Murphy, 1996;Wilson, Walshe, & Fisher, 1997). "Absolute" reliability refers to the degree, which repeated measures vary for individuals (Sale, 1991).…”

Lunge performance and its determinants

“…It would appear that the procedures and equipment used to measure the dependent and independent variables were stable between trials and similar to other research testing new devices and procedures. For example, testing the reliability of an isokinetic squat device, Wilson et al (1997) reported inter-trial ICCs of 0.89-0.96 and coefficients of variation of 3.1-8.7% for a concentric and stretch-shorten cycle (SSC) squat. Lower correlation's were noted by Rahmani et al (2000), who reported intraclass correlation coefficients of 0.57-0.91 for peak force, peak velocity and peak power during a half squat on an isoinertial squat rack instrumented with an optical encoder.…”