Determining jump and change of direction inter-limb asymmetries over pre-season in basketball players: An individualised approach.

Asymmetries are practical indicators of basketball players performance; however, longitudinal evidence remains limited. The aims of this study were to: (i) examine the variation of inter-limb asymmetry across three different time points during the pre-season in basketball players; and (ii) analyse the relationship between asymmetry, jump, linear sprint and change of direction (COD) performance over time. Forty-five male basketball players (age: 24.2 ± 5.21 years; height: 1.96 ± 0.12 m; body mass: 98.2 ± 15.3 kg) performed vertical and horizontal jump, linear speed and COD tests over the pre-season at T1 (August), T2 (September), and T3 (October). Asymmetry was quantified for unilateral drop jump (uDJ), reactive strength index (RSI), and 505-COD at different angles. Whereas the asymmetry significantly decreased from T1-T3 in uDJ and RSI (d≤-0.53,p ≤ 0.03), it increased in COD90° and COD180° (d ≥ 0.24,p ≤ 0.04). For the direction of asymmetry, levels of agreement between-time points ranged from poor to moderate for all tests (kappa=-0.02-0.60), with uDJ showing noticeably better results than other metrics (kappa ≥ 0.51). Despite the significant relationship between asymmetry and performance variables, this relationship was temporary and inconsistent during the pre-season. These findings confirm the substantial variability in the magnitude and direction of inter-limb asymmetry across tests over time, indicating that asymmetry is unlikely to have a real effect on athletes' performance.