The impact of mental fatigue on repeated sprint and change-of-direction performance in soccer

Purpose Elucidating the impact of mental fatigue (MF) on physical performance in soccer is essential for optimizing athlete assessment, training, and competition strategies. However, the relationship between MF and both repeated sprint (RSA) and repeated change-of-direction performance (RCOD) remains unclear. Therefore, the aim of this study was to investigate the effects of MF on RSA and RCOD performance in soccer players. Methods In a randomized, counterbalanced crossover design, 18 male amateur soccer players completed two experimental sessions, separated by a minimum 48 h washout period: (1) a 45-min Stroop task to induce mental fatigue (MF condition), and (2) watching a 45-min emotionally neutral video as control (CON condition). Following each treatment, participants performed a RSA test and a RCOD test. Measured variables included: Visual Analogue Scale for mental fatigue (VAS-MF), Brunel Mood Scale for fatigue (BRUMS-F), and vigor (BRUMS-V) (assessed pre- and post-treatment); average heart rate (HR ave ) during the treatment, RSA and ROCD test; Visual Analogue Scale for mental effort (VAS-ME) (assessed post-treatment); and blood lactate (BLA) along with ratings of perceived exertion (RPE) following each performance test. Results Pre-treatment VAS-MF and BRUMS-F, HR ave during the treatment did not differ significantly between conditions ( p = 0.155, 0.429 and 0.262, respectively), post-treatment, the MF condition resulted in significantly higher VAS-MF, VAS-ME and BRUMS-F than control condition ( p = 0.002, 0.001 and 0.05, respectively). The RSA performance p = 0.885, 0.714 and 0.483 for total time (TT), best time (BT) and fatigue index (FI) and BLA, RPE during two tests were not significantly affected by MF, however the RCOD performance was significantly reduced in the condition of MF ( p = 0.006 and 0.007 for TT and BT). Conclusion MF did not impair RSA performance but significantly reduced RCOD performance in soccer.