Lynch, Arthur, Davies, Robert W., Jakeman, Philip M., Locke, Tim, Allardyce, Joanna M., Carson, Brian P., Lynch, Arthur, Davies, Robert W., Jakeman, Philip M., Locke, Tim, Allardyce, Joanna M., and Carson, Brian P.
peer-reviewed, This study aimed to investigate the test-retest reliability of peak force in the isometric squat across the strength spectrum using coefficient of variation (CV) and intra-class correlation coefficient (ICC). On two separate days, 59 healthy men (mean (SD) age 23.0 (4.1) years; height 1.79 (0.7) m; body mass 84.0 (15.2) kg) performed three maximal effort isometric squats in two positions (at a 120◦ and a 90◦ knee angle). Acceptable reliability was observed at both the 120◦ (CV = 7.5 (6.7), ICC = 0.960 [0.933, 0.977]) and 90◦ positions (CV = 9.2 (8.8), ICC = 0.920 [0.865, 0.953]). There was no relationship between peak force in the isometric squat and the test-retest reliability at either the 120◦ (r = 0.052, p = 0.327) or 90◦ (r = 0.014, p = 0.613) positions. A subgroup of subjects (n = 17) also completed the isometric squat test at a 65◦ knee angle. Acceptable reliability was observed in this position (CV = 9.6 (9.3), ICC = 0.916 [0.766, 0.970]) and reliability was comparable to the 120◦ and 90◦ positions. Therefore, we deem isometric squat peak force output to be a valid and reliable measure across the strength spectrum and in different isometric squat position