Associations of Bilateral Deficit during Jumpingwith Physical Performance in Tennis Players
(Linjie Shu, Jiacheng Zhang, Tingting Chen, Hui Dong, Zhen Wang, Jiancai Chen, Min Hu, Jingwen Liao)

This study aimed to investigate the associations of bilateral deficit (BLD) during jumping with physical performance represented by linear sprints and changes of direction (CODs) in tennis players. Thirty-eight tennis players (10 females and 28 males) completed a test program that included three types of jumping tests to determine BLD, two types of linear sprint tests (10 m and 20 m) to assess sprint performance, and three types of COD tests (505COD, 5105COD, and T-test) to evaluate COD performance. The three types of jumping tests included countermovement jumps (CMJs), squat jumps (SJs), and horizontal countermovement jumps (HCMJs). The bilateral index (BI) in jump height (JH), flight time (FT), peak force (PF), peak power (PP), average power (AP), and the force impulse (FI) were then calculated to quantify BLD. Change of direction deficit (CODD) was calculated by subtracting linear sprint test time from COD test time. Results showed that the BI during the CMJ was positively correlated with the linear sprint index (1 correlation, r = 0.33, p = 0.045) and most COD indices (19 correlations, r = 0.32–0.40, p = 0.013–0.049). The BI during the SJ was positively correlated with linear sprint indices (2 correlations, r = 0.32–0.35, p = 0.033–0.049) and most COD indices (17 correlations, r = 0.32–0.44, p = 0.006–0.049). The BI during the HCMJ was positively correlated with COD indices (12 correlations, r = 0.32–0.41, p = 0.010–0.049). Conclusively, BLD during jumping is positively associated with linear sprint and COD performance in tennis players, indicating that lower limb BLD could serve as an index to optimize physical performance and training.