Monitoring internal training load and mucosal immune responses in futsal athletes

The purpose of this study was to examine the changes in salivary immunoglobulin A (SIgA), cortisol, and upper respiratory tract infection (URTI) and their relationships with training loads (TLs) during a 4-week period of intensive training during the competitive season in elite Brazilian futsal players. Twelve athletes (age: 19 ± 1 years; height: 180 ± 4 cm; and body mass: 73 ± 7 kg) participated in the study. The training program included tactical, technical, specific conditioning and strength training, and competition matches. Training load was quantified using the session rating of perceived exertion. Salivary immunoglobulin A, salivary cortisol and symptoms of URTIs were assessed weekly. A significant decrease in weekly TL was observed for week 4 (tapering) compared with that of other weeks (p < 0.05). No significant differences were observed for cortisol and SIgA during the study (p > 0.05). There was a significant decrease in URTI symptom severity during week 4 as compared with that of weeks 1 and 2 (p < 0.05), with a significant correlation between weekly TL and URTI severity and weekly TL during week 4 (rs = 0.75; p < 0.05). The present findings suggest that futsal athletes are more susceptible to high URTI symptom severity in the periods of higher training. Therefore, the reduction in TLs before competitions is an appropriate strategy to minimize URTI symptoms ensuring the athlete's ability to train and compete.