Chi-Hsien Chen

Background: This study aimed to compare the kinetic profiles of two different change of direction (COD) sprint tests and two single-leg lateral rebound jump tests in basketball players. Methods: Twenty-eight male basketball players performed tasks involving 180° (COD180) and 60° (COD60) changes of direction, alongside controlled (CLRJ) and maximal (MLRJ) lateral rebound jump tests. Measurements were taken for contact times (CTs), vertical and horizontal ground reaction forces (VGRF and HGRF), and impulses (VImp and HImp) during braking and propulsive phases, for both legs, using a force plate. Results: No significant differences emerged between legs. No significant differences in CTs emerged between COD180 and MLRJ, which were longer than COD60 and CLRJ. COD60 showed greater VGRFs during braking phase, and no significant differences in VGRFs to CLRJ during the propulsive phase. Furthermore, no differences emerged in VImp values during the braking phase and HImp values during the propulsive phase between MLRJ and COD180 and between CLRJ and COD60. Conclusions: Kinetic analyses of CT, GRF, and impulses suggest that the two lateral rebound jump tasks may reflect specific mechanical demands of CODs performed at different cutting angles. Therefore, CLRJ and MLRJ may represent useful exercises to target angle-specific COD capabilities.

Chen, C-H, Yeh, M-C, Liu, C, Tseng, Y-J, and Lu, S-T. Association of ankle joint moment and ankle joint velocity with 60° ipsilateral change-of-direction performance. J Strength Cond Res XX(X): 000–000, 2026—The rapid acceleration and deceleration associated with a change of direction (COD) is associated with high ankle loading, including high ankle moment and velocity, which have been linked to ankle sprain or chronic ankle instability. Although the correlations between ankle joint loading and contralateral COD (contra-COD) have been investigated, one study reported that ipsilateral COD (ipsi-COD) and contra-COD involve distinct, asymmetrical mechanisms. Therefore, the aim of this study is to evaluate the associations of ankle joint moment and ankle joint velocity with 60° ipsi-COD performance. Thirty-five male athletes of recreational team sports performed an ipsi-COD task with their nondominant leg. A three-dimensional motion-capture system and a force platform were used to collect biomechanical data. Ground contact time was negatively associated with plantarflexion moment ( r = −0.511) and inversion moment ( r = −0.424). By contrast, horizontal impulse was positively correlated with plantarflexion moment ( r = 0.407). No correlation was observed between ground contact time and ground reaction force. The moderate negative correlations of ground contact time with plantarflexion moment and inversion moment suggest that increasing ipsi-COD performance may result in high ankle moments and potentially excessive ankle loading. In addition, the absence of a correlation between ground contact time and GRF suggests that athletes consider focusing on converting their approaching velocity to the intended direction during ipsi-COD, as this study indicates that ground reaction force and impulse are not associated with ipsi-COD performance.

The aim of this study was to characterize the turning phase during a modified 505 test. Forty collegiate basketball students, divided into faster and slower performers and high-playing-level and low-playing-level groups, were evaluated for the force-time characteristics (braking and/or propulsive phase) of the penultimate foot contact (PFC), final foot contact (FFC), and first accelerating foot contact (AFC), and for completion time and approach velocity. Based on the composition of the AFC, trials were classified as braking/propulsive or only propulsive. Regression analysis for the prediction of completion time was performed. The AFC contributed to reacceleration through shorter contact times and step length, and lower braking force production (p < 0.05). Faster performers and the high-playing-level group demonstrated (p < 0.05): lower completion times, higher approach velocities, longer steps length in the PFC and FFC, greater braking forces and impulses in the PFC; greater braking and propulsive forces, braking impulses, lower contact times in the FFC; greater braking and propulsive horizontal forces, horizontal impulses, lower contact times and vertical impulses in the AFC. Kinetic variables from only the FFC and AFC and approach velocity predicted 75% (braking/propulsive trials) and 76.2% (only-propulsive trials) of completion times. The characterization of the turning phase demonstrated the specific contribution of each foot contact and the possible implications for training prescription.