Introduction: This exploratory study examined how eccentric braking characteristics (braking rate of force development (RFD) and braking force impulse (FI) relate to push-off force distribution and jump height during bilateral and unilateral countermovement jumps (CMJ). Methods Data from 206 physically active individuals (basketball players and students) were retrospectively analyzed. Hierarchical multiple regression models predicted jump height, with sex and training status entered as covariates, followed by braking RFD and braking FI, and finally the early-to-late push-off FI ratio. Additional models examined whether braking variables predicted the FI ratio. Results In bilateral CMJ, braking variables and the FI ratio significantly improved model fit beyond sex and training status, with the FI ratio emerging as a strong independent predictor of jump height (lower early-to-late push-off FI ratio: β = −0.367, p < 0.001). Braking FI was positively associated with jump height (β = 0.165, p = 0.003), and braking RFD also showed a positive independent association in the final model (β = 0.197, p < 0.001). In unilateral CMJ, the FI ratio similarly predicted jump height (lower ratio: β = −0.311, p < 0.001), whereas braking RFD was not independently associated and braking FI showed a modest positive effect (β = 0.154, p = 0.009). Braking RFD positively predicted the FI ratio in both jump tasks, indicating an association with a more early-loaded push-off profile. Conclusion Jump height was consistently related to push-off force distribution, with relatively greater late-phase FI (i.e., a lower early-to-late ratio) associated with superior performance. Braking FI showed modest positive associations with jump height, whereas braking RFD primarily influenced push-off force distribution and displayed task-dependent relevance for performance.
Kozinc et al. (Wed,) studied this question.