Reliability and Divergent Validity of Novel Tools to Assess Occupationally Relevant Performance in Infantry Soldiers

Abstract Heilbronn, BE, Doma, K, Sinclair, WH, Drain, J, Connor, J, and Leicht, AS. Reliability and divergent validity of novel tools to assess occupationally relevant performance in infantry soldiers. J Strength Cond Res 39(6): e815–e823, 2025—The primary aim of this study was to determine the reliability and divergent validity of several weighted physical assessments for the Army, including the counter movement jump (CMJ), plyometric push-ups (PPU), an incremental fire and movement assessment (IMFA), and a repeated sprint ability (RSA) test. Male infantry soldiers (n = 30) completed the CMJ, PPU, IFMA, and RSA during both unweighted and weighted conditions with a 48-hour interval between sessions, and then repeated the tests during a weighted condition after a 7-day wash-out period. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) assessed between-session reliability. Divergent validity between weighted and unweighted conditions was determined using Pearson's correlation coefficient (r), with correlation effect size (ES) calculated between the r-values using a Fisher Z-transformation. Good test-retest reliability and divergent validity were demonstrated for most CMJ (ICC 0.50–0.99, CV% 1.18–7.73, ES 0.50–0.69), PPU (ICC 0.61–0.99, CV% 1.03–12.33, ES 0.31–0.68), RSA (ICC 0.50–0.94, CV% 1.34–8.41, ES 0.37–0.75), and IFMA (ICC 0.65–0.94, CV% 2.80–10.99, ES 0.32–0.39) measures. It was concluded that the weighted CMJ, PPU, IMFA, and RSA were reliable tests for Army-specific fitness to determine combat task readiness. Good divergent validity between weighted and unweighted conditions for most test measures supported practitioner's use of weighted assessments for Army-specific capability, while unweighted assessments were recommended for fitness optimization and monitoring training for Army personnel.