Sleep, Musculoskeletal Injuries, and Hormonal Status in Different Training Stages in Adolescent Athletes.

This study aimed to compare sleep, musculoskeletal injuries, and testosterone and cortisol levels in different training stages in adolescent athletes, and to investigate the association between these variables.  The study has a prospective cohort design, and the sample consisted of 19 adolescent track and field athletes. They were followed for six months, with evaluations done at three different training phases: preparatory, competitive, and post-competitive. In each phase, we evaluated their sleep through actigraphy for 10 days and testosterone and cortisol levels through saliva samples. The incidence of injuries was obtained through the physical therapy department.  In the post-competitive phase, the athletes presented a longer total sleep time (TST) than the competitive phase. Moreover, a shorter wakefulness after sleep onset was observed in the post-competitive and competitive phases compared with the preparatory phase. Furthermore, cortisol levels were higher in the preparatory phase than in the post-competition phase. On the other hand, no differences were observed in the incidence of injuries and testosterone, nor was there a correlation between the variables.  Adolescent track and field athletes had a higher TST in the post-competitive phase and more fragmented sleep in the pre-competitive and competitive phases. On the other hand, higher cortisol was observed in the preparatory phase, however, there were no correlations between sleep, hormones, and the incidence of injuries.