Which Strength Qualities Matter Most for Sprinting? Partitioning Unique and Shared Variance in a Multivariable Model.

Individual strength qualities have been associated with sprint performance, but previous researchers have not partitioned the unique and shared variance each contributes, nor included the full range of strength qualities in a single analysis. This study is the first to model all five strength qualities (heavy dynamic, fast dynamic, reactive, isometric, and explosive) concurrently against sprint performance. Multiple regression was used to quantify the unique and shared variance each quality contributes across multiple sprint distances. Eighty-four resistance-trained individuals (62 male, 22 female; 21.4 ± 3.4 years, 79.9 ± 12.1 kg), completed countermovement jumps, drop jumps, isometric squat, isometric mid-thigh pull, and a three-repetition maximum (3RM) back squat, alongside a 40-m sprint. Three multiple linear regression models were constructed to partition the unique and shared variance contributed by each strength quality to sprint performance across 5-40 m and maximal velocity, with sex included as a covariate. Combining countermovement jump height, 3RM back squat, and drop jump reactive strength index explained up to 75.2% of variance in sprint performance. The addition of isometric peak force or force at 100 milliseconds resulted in negligible increases in explained variance.