The tracking of internal and external training loads with next-day player-reported fatigue at different times of the season in elite soccer players

The aim was to assess factor structure of player-reported fatigue and quantify within-subjects association between changes in training load measures next day at different time points an elite football season. Using longitudinal research design, twenty-four professional footballers, mean (SD) age 25.7 (3.4) years, were monitored during their competitive season, including pre-season. Player-reported data session ratings perceived exertion (session-RPE) collected via a mobile application. Player’s Heart rate (HR) global positioning system (GPS) daily for each player field sessions. Principal component analysis (PCA) indicated three components with Eigenvalues above 1.0; “soreness”, “mood, “hydration”. Within-player correlations values trivial moderate (r ≈ −0.42 −0.04). In-season we observed large Total Distance (TD) PlayerLoad Soreness = −0.55, 95% CI: −0.62 −0.46; r −.054, −0.46), but pre-season, small −0.15, −0.28 −0.01; −0.13, −0.26 0.01). HR TRIMP, TD session-RPE showed −0.41 −0.08) “mood”. Our in-house questionnaire sensitive the multi-dimensional nature fatigue, identifying physiological (soreness), psychological (mood stress) nutritional (hydration nutrition) components. We found in-season be greater than previously reported literature, specifically “soreness”. Nevertheless, items our scale pre-season small.