Dissociation Between Subjective Fatigue and Objective Performance During Repeated Tackling in Amateur Rugby Players

Rugby involves frequent, high-intensity collisions. While cumulative fatigue is known to impair performance, recent evidence suggests a dissociation between subjective fatigue and objective performance. Understanding this gap is critical for optimizing training and reducing injury risk in collision sports.

Twenty-nine amateur male rugby players each performed 30 maximal-effort tackles against a stationary tackle dummy. The kinetics and kinematics tackle motion was captured using a 3D motion analysis system (Vicon Motion Systems Ltd, UK) including 10 motion capture cameras. The subjective fatigue, encompassing physical, mental, and motivation aspects, was assessed using visual analog scales at four distinct time points (Pre, Post1, Post2, and Post3). The objective performance was evaluated through countermovement jump (CMJ) height and tackle variables (velocity, momentum, and kinetic energy) extracted from the tackle motion. The analyses included repeated-measures ANOVA, Friedman tests, linear mixed models, and Spearman's correlations.

Physical and mental fatigue increased significantly over time (p < 0.05), particularly after the 20th tackle. However, despite a slight improvement in CMJ performance, no statistically significant changes were detected in kinetics and kinematics parameters. A moderate positive association was revealed between CMJ height and tackle velocity, as determined by correlational analysis. However, no significant relationship was found between subjective fatigue and CMJ height.

Repeated tackling led to substantial subjective fatigue without corresponding declines in objective performance. This dissociation suggests that athletes may experience fatigue without associated actual performance impairment. Perceived fatigue increased markedly after around 20 tackles. However, performance decline may occur only beyond this threshold, which was not reached in the present protocol. These results highlight the need to integrate subjective and objective assessments when monitoring athletes to optimize training and reduce injury risk.