Effect of Task Constraints During Drop Vertical Jump Test on Movement Variability in Anterior Cruciate Ligament Reconstructed Female Basketball Players: A Nonlinear Approach

The aim of this study was to analyze the impact of an Anterior Cruciate Ligament (ACL) injury on movement variability (MV) and biomechanical variables in female basketball players during a drop vertical jump (DVJ) task, both with and without a ball. Female basketball players (n = 15) participated in this study. The participants performed two jump in each of six conditions (total = 12 jumps) in randomizer order: (i) Bilateral No Ball (2NB)-two-leg jump without a ball; (ii) Bilateral Ball (2B)-two-leg jump with a ball; (iii) ACL No Ball (ACLNB)-injured-leg jump without a ball; (iv) ACL Ball (ACLB)-injured-leg jump with a ball; (v) No ACL No Ball (NOACLNB) -uninjured-leg jump without a ball; (vi) No ACL Ball (NOACLB)-uninjured-leg jump with a ball. DVJ performance parameters were assessed using an accelerometer placed on the lower back and a force platform. MV was quantified using the multiscale entropy (MSE) derived from the acceleration data. The Complexity Index (CI) was also calculated. The ACLB condition exhibited the highest sample entropy (SampEn) value across all scales, followed by the 2B and NOACLB conditions, whereas ACLNB showed the lowest values. The CI also indicated significant variability across conditions. For linear biomechanical variables, significant differences were only observed in contact time (CT) between NOACLB and NOACLNB. The inclusion of a task constraint did not result in differences between ACL and NOACL groups in linear jumping performance metrics. However, nonlinear MV analyses, using MSE and CI, revealed condition differences.