(64) DETERMINE THE CORRELATION BETWEEN COUNTERMOVEMENT JUMP HEIGHT WITH ECCENTRIC PHASE DURATION AND MODIFIED REACTIVE STRENGTH INDEX IN YOUTH ATHLETES

Purpose: Determine the correlation between countermovement jump height with eccentric phase duration and modified reactive strength index (mRSI) in youth athletes. Methods: Forty youth athletes participated in the study. Athletes performed two CMJs on force platforms, with hands placed on the pelvis. Participants were instructed to jump vertically as high as possible. Between jumps, athletes rested for one to two minutes. Force plates captured vertical ground reaction forces during the CMJ, allowing for the calculation of jump metrics of interest. Measures of interest included jump height, eccentric phase duration, and mRSI. Averages were used for statistical analyses. Spearman’s rho correlations were used to determine the association between measures of interest. Results: The results indicate a positive correlation between jump height and the duration of the eccentric phase (r_s = 0.505, p = 0.06). In contrast, a strong positive correlation was observed between jump height and mRSI (r_s = 0.869, p < 0.001). Conclusions: The duration of the eccentric phase was associated with a higher jump height in youth athletes. There is a strong correlation between jump height and mRSI in youth athletes. Practical Applications: The strong relationship between jump height and mRSI underscores the critical role of reactive strength and the efficiency of the SSC in athletic performance. mRSI reflects an athlete’s ability to rapidly transition from eccentric to concentric muscle actions, which is essential for maximizing jump height and overall explosiveness. SSC enhances force production, energy storage, and neuromuscular coordination, all of which contribute to improved jump performance. To optimize these qualities, coaches should implement structured plyometric training alongside targeted strength development to enhance power output and neuromuscular efficiency. By focusing on both explosive strength and reactive ability, athletes can improve their ability to generate force quickly and efficiently, leading to greater jump heights and improved overall performance. Acknowledgements: None