Recovery Patterns of Low-frequency Fatigue in Elite Youth Soccer Players after Official Matches

This study aimed to analyze the associations between recovery of low-frequency fatigue, jump height, and perceptual responses following official soccer matches. Forty-two male youth elite soccer players (age: 17.13±0.70 years; height: 179.17±5.94 cm; weight: 69.74±4.91 kg) participated in this study. Low-frequency fatigue, countermovement jump, perceived fatigue, muscle soreness, and perceived recovery were assessed at - 2 h, +30 min, +24 h and +48 h relative to the match. Linear mixed models analysis showed that low-frequency fatigue was reduced at the match-end (ES=- 0.679 [95% CI =- 1.01; - 0.34]; p<0.001) but returned to baseline after 24 h (ES=0.149 [95% CI = - 0.26; 0.56]; p=1.00). Perceptual responses were impaired for up to 48 hours following the match (ES=- 0.868-1.174; p<0.001). Countermovement jump did not differ between any time point (ES=- 0.204-0.216; p>0.05). Additionally, the within-subject correlation analysis showed that low-frequency fatigue pre- to post-match changes presented moderate to large associations with perceived fatigue (rm[57]=- 0.43; p<0.001), muscle soreness (rm[57]=- 0.52; p<0.001), and perceived recovery (rm[57]=0.38; p=0.003). The assessment of low-frequency fatigue could serve as an additional objective measurement for monitoring post-match fatigue, as findings suggest that young elite soccer players experience transient reductions following match-play, which are strongly correlated with subjective markers of recovery.