The association between training load indices and upper respiratory tract infections (URTIs) in elite soccer players

This study aimed to investigate the association between training load indices and Upper Respiratory Tract Infection (URTI) across different lag periods in elite soccer players. Internal was collected from 15 players over one full season (40 weeks). Acute, chronic, Acute:Chronic Workload Ratio (ACWR), Exponentially Weighted Moving Averages (EWMA) ACWR, 2, 3 4-week cumulative load, strain monotony were calculated on a rolling weekly basis. Players completed daily illness log, documenting any signs symptoms, help determine an URTI. Multilevel logistic regression used analyze associations URTIs (1 7-days). The results found significant 2-week increased likelihood of player contracting URTI days later (Odds Ratio, 95% Confidence Interval: OR = 2.07, CI 0.026-1.431). Additionally, 3-week players’ risk 4 (OR 1.66, 0.013–1.006). These indicate that accumulated high (2- 3-week) associated with URTI, which may lead performance decrements, missed sessions or even competitions.