Acute biomechanical responses to stroboscopic vision during change-of-direction tasks in elite rugby athletes.

INTRODUCTION: Stroboscopic vision (SV), characterized by intermittent visual occlusion, has been proposed as a novel perceptual stimulus to challenge sensorimotor integration in sport. This study aimed to investigate the acute effects of SV on lower-limb biomechanics during rugby-specific side-cutting manoeuvers. METHODS: Twenty-one elite male rugby athletes performed side-cutting tasks under full vision (FV) and SV conditions, both with and without ball-carrying, using a randomized crossover design. Three-dimensional kinematics and ground reaction forces (GRF) were recorded via an eight-camera motion capture system and a force platform. Paired-samples t-tests or Wilcoxon signed-rank tests were used according to the distribution of paired differences, and effect sizes were calculated as Cohen's d or r, respectively. Statistical significance was set at p< 0.05. RESULTS: Under SV, non-ball-carrying side-cutting showed significantly greater peak vertical GRF (p = 0.033, d = 0.614), more negative hip moment (p< 0.001, r = 0.808), greater knee moment (p = 0.006, r = 0.693), and greater peak knee joint power (p< 0.001, r = 0.869). During ball-carrying side-cutting, SV was associated with greater peak vertical GRF (p = 0.003, r = 0.726), more negative hip moment (p< 0.001, r = 0.876), greater knee moment (p = 0.006, d = 0.785), and greater peak knee joint power (p = 0.048, r = 0.527). No significant effects of SV were observed for ankle joint moments or power. CONCLUSION: Acute SV exposure was associated with altered lower-limb loading and joint mechanics during rugby-related side-cutting, with the most consistent changes observed in vertical GRF and hip and knee joint kinetics. Longitudinal studies incorporating neuromuscular, perceptual, and performance measures are needed to determine whether repeated SV exposure produces transferable training adaptations relevant to rugby performance.