Repeated-measures associations between countermovement jump variables and driving performance in sub-elite male golfers

Background: Countermovement jump (CMJ) force–time variables are commonly used to monitor physical qualities linked to golf driving performance, but most evidence derives from single time-point, mean-based correlations. This study examined repeated-measures associations between CMJ variables and driving performance in sub-elite male golfers using Bayesian quantile regression. Methods: Twenty-eight male golfers (handicap 0.8 ± 1.9) completed two sessions, one week apart, of maximal CMJs and driver swings. Jump height, jump momentum and peak propulsive power were calculated from the CMJs, while clubhead speed (CHS), ball speed and smash factor were obtained from the driver swings. Results: Between-session absolute reliability was excellent for all variables (CV upper 95% credible interval [CrI] ≤ 3.8%), whereas relative reliability was excellent for CHS and all CMJ variables (ICC lower 95% CrI ≥ 0.96), moderate for ball speed (lower 95% CrI = 0.71) and poor for smash factor (lower 95% CrI = 0.00). All CMJ variables showed positive associations with CHS across percentiles in both sessions, with little evidence of session-related change for jump momentum or peak propulsive power. In contrast, the jump height–CHS association weakened in session two at the median and upper percentiles (from 1.3–1.4 to 1.0–1.2 mph per 0.05 m increase in jump height; 98–99% posterior probability of a decrease). Associations between CMJ variables and ball speed and smash factor were uncertain, with 95% CrI spanning zero in almost all cases. Conclusions: Repeated-measures designs may add value in applied golf settings. Jump momentum and peak propulsive power showed comparatively stable associations with CHS across sessions, although both scale with body mass, which may partly account for this stability. They may therefore be useful complementary monitoring variables, but their predictive value and responsiveness to training are yet to be established.