Is There a Performance-Injury Conflict Between Maximum Horizontal Deceleration and Surrogates of Noncontact Anterior Cruciate Ligament Injury?

This study aimed to examine the biomechanical determinants of horizontal deceleration and their correlations with noncontact ACL injury surrogates (e.g., knee joint moments). Thirty-two male team-sport players (Age: 21.85 ± 0.33 years; Height: 1.80 ± 0.11 m; Mass: 71.28 ± 1.39 kg) performed horizontal deceleration following 15 m sprints. Lower limb kinetics and kinematics of the first braking step were collected using 3D motion and force plates, and deceleration was assessed using radar gun. The Pearson correlation was used to determine correlations between selected variables and p ≤ 0.05 was considered statistically significant. Greater peak and mean horizontal deceleration were significantly correlated (p ≤ 0.05) with greater mean horizontal braking GRF (r = 0.52 and 0.41) and greater mean horizontal braking GRF ratio (r = 0.43 and 0.48). Greater knee joint loading (knee flexion moment, knee abduction moment, and knee internal rotation moment) were significantly correlated (p ≤ 0.05) with greater peak and mean vertical braking GRF (r = 0.30-0.41) and greater peak resultant braking GRF (r = 0.33-0.48). There were nonsignificant correlations between mean and peak deceleration and knee joint loading variables (p > 0.05). Therefore, deceleration strategies that emphasize greater horizontal and posteriorly orientated forces during the first contact of deceleration appear effective for facilitating more effective deceleration, without concomitant increases in the loading of noncontact ACL injury surrogates.