Monitoring Fatigue During the In-Season Competitive Phase in Elite Soccer Players

Thorpe RT, Strudwick AJ, Buchheit M, Atkinson G, Drust B, Gregson W

Objective: The purpose of this study was to investigate the relationship between daily training load and various potential measures of fatigue in elite soccer players during an in-season competitive phase spanning 17 days.

Methodology: The study analyzed total high-intensity running distance (THIR), perceived ratings of wellness (including fatigue, muscle soreness, and sleep quality), counter-movement jump height (CMJ), post-exercise heart rate recovery (HRR), and heart rate variability (Ln rMSSD) over the 17-day competitive period. General linear models were employed to assess the influence of daily fluctuations in THIR distance on the potential fatigue variables.

Key Findings: The study found significant correlations between fluctuations in THIR distance and perceived ratings of fatigue (r=-0.51; large; P<0.001), as well as heart rate variability (Ln rMSSD) (r=-0.24; small; P=0.04), and CMJ (r=0.23; small; P=0.04). However, correlations between THIR distance and variability in muscle soreness, sleep quality, and HRR were negligible and not statistically significant. Implications: The findings suggest that perceived ratings of fatigue and heart rate variability are sensitive to daily fluctuations in THIR distance among elite soccer players. These markers may serve as simple, non-invasive assessments of fatigue status during short in-season competitive phases. Understanding these relationships can help coaches and sports scientists better manage training loads and optimize player performance and recovery during intense competitive periods.

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