The validity and reliability of the Optojump system were investigated for jumping height and flight time in vertical jump tests. Conversely, the purpose of the present study was to investigate the validity and reliability of the Optojump system for measuring contact time and lateral displacement in change of direction and lateral jump tests. Thirty basketball collegiate athletes were tested on two 10 m sprints with a 60° (COD60) or 180° (COD180) change of direction, lateral controlled (CLRJ) and maximal (MLRJ) rebound jump, and lateral countermovement (LCMJ) and squat (LSJ) jump with the concomitant use of two force plates and the Optojump system for the measurement of contact time in COD60, COD180, CLRJ, MLRJ, and lateral jumping distance in all the lateral jump tests. Almost perfect coefficients (r ≥ 0.95) emerged for contact time in COD60, COD180, CLRJ, MLRJ, although a systematic bias was found for COD60 (−0.01 s). Good-to-excellent reliability was found for almost all the measurements of contact time and lateral jumping distance for change of direction and lateral jump tests. Therefore, the use of Optojump system for testing change of direction and lateral jumping abilities should be executed with caution, avoiding misinterpretation of data.

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.

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.