The ability to examine force curves from multiple-joint assessments combines many of the benefits of dynamic constant external resistance exercise and isokinetic dynamometry. The purpose of this investigation was to examine test-retest reliability statistics for peak and mean force using the Exerbotics eSQ during maximal concentric and eccentric squats. Seventeen resistance-trained men (mean ± SD age = 21 ± 2 years) visited the laboratory on two occasions. For each trial, the subjects performed two maximal concentric and eccentric squats, and the muscle actions with the highest force values were analyzed. There were no mean differences between the trials (P > .05), and the effect sizes were < 0.12. When the entire force curve was examined, the intraclass correlation coefficients (model 2,1) and standard errors of measurement, respectively, were concentric peak force = 0.743 (8.8%); concentric mean force = 0.804 (6.0%); eccentric peak force = 0.696 (10.6%); eccentric mean force = 0.736 (9.6%). These findings indicated moderate-to-high reliability for the peak and mean force values obtained from the Exerbotics eSQ during maximal squat testing. The analysis of force curves from multiple-joint testing provides researchers and practitioners with a reliable means of assessing performance, especially during concentric muscle actions.
Matt S. Stock and Micheal J. Luera are with the Human Performance Laboratory, Department of Health, Exercise, and Sport Sciences, Texas Tech University, Lubbock, TX. Address author correspondence to Matt S. Stock at email@example.com.