Stronger Legs Means Higher Jumps? Exploring the Role of Maximal Isometric Strength on Vertical Jump Performance in Competitive Female Handball and Basketball Players

Abstract

Objective: The aim of this study was to (1) explore differences in countermovement jump (CMJ) force–time metrics between stronger and weaker female handball and basketball players, (2) examine relationships between isometric midthigh pull (IMTP) peak force and CMJ metrics, and (3) produce reference values for CMJ and IMTP metrics. Methods: A cross-sectional design was used with 125 competitive female players (74 handball and 51 basketball). Each player performed 2 trials of IMTP and 3 of CMJ using force plates. Based on IMTP relative net peak force, players were split into stronger (n = 62) and weaker (n = 63) groups using a median split analysis. Differences between groups were analyzed with independent t tests and Hedge g effect sizes, and Pearson correlations were calculated to assess associations between IMTP peak force and CMJ force–time metrics for stronger and weaker players separately. Results: Stronger players demonstrated large and moderate differences in jump height (0.30 [0.04] vs 0.26 [0.04] m; P < .001; effect size = 0.95, large) and modified reactive strength index (0.47 [0.09] vs 0.41 [0.08] a.u.; P < .001; effect size = 0.67, moderate), respectively. Moreover, moderate to strong correlations were found between IMTP peak force and CMJ propulsive net impulse and braking net impulse (r = .495–.647, P < .001). Conclusions: These results highlight the association between maximal isometric strength and vertical jump performance in handball and basketball players. Strength and conditioning coaches may design and implement training programs that focus on developing and preserving maximal strength throughout the season to potentially support jump performance.