Introduction: Circadian rhythms can impact athletes' sports performance, where the plateau occurs between 15 and 21 hours. Swimming is a peculiar case, as athletes perform training and final sessions in competitions at different times, as in the Rio2016 Olympic Games for example, where the semifinal and final competitions took place from ten o'clock at night. Objectives: (1) to present the protocol of an intervention performed with elite athletes of the Brazilian swimming team during the 2016 Olympic Games in Rio; (2) to find out whether the time at which the competitions were held affected the swimming performances of these athletes during the competition. Materials and Methods: Fourteen athletes of the Brazilian swimming team (males: n= 10; 71% and females: n= 4; 29%) participated in the study. They were followed up during two preparation periods (baseline and intervention) for the 2016 Olympic Games in Rio during June and July 2016. During the competition, we recorded the Reaction Time (RT) and Competition Time (CT) of each athlete in different modalities. The intervention strategies used were light therapy and sleep hygiene. The values of RT at the starting block and CT were registered and conferred with the official results. Results: The athletes showed a decrease in the total time awake (Δ = −13%; Effect size [ES] = 1.0) and sleep latency (Δ = −33%; ES = 0.7), and an increase in total sleep time (Δ = 13%; ES = 1.1; p = 0.04) between the baseline and the period of the intervention, pre-competition. We identified an improvement in the RT (Δ = −2.2% to −1.0%; ES = 0.2 to 0.5) during the competition only for the athletes who participated in the competition finals. Conclusion: We conclude that the intervention carried out was effective in mitigating any negative influence of competition time on the RT and CT of elite athletes of the Brazilian swimming team. Level of evidence II; Prospective comparative study.

Objectives: Sleep is essential for musculoskeletal and cognitive recovery. Adolescent athletes tend to sleep poorly compared to adults and it may predispose them to sports injuries. Our aims are to estimate whether the quantity/quality of sleep are associated with sports injuries in adolescent athletes and to compare the quantity/quality of sleep between the training and competition seasons, and the school vacation period. Material and Methods: It was a cohort study with 19 track and field athletes of both sexes, aged between 12 and 21 years. We evaluated their sleep-wake habit through actigraphy during three phases: 1 -mid-season, 2 -competition, and 3 -school vacation. The previous six months injury history and the occurrence of injuries in a six-month follow-up were recorded. Logistic regression and variance analysis were performed. The significance level used was 0.05. Results: Wake after sleep onset (WASO) predicted previous injuries (OR=1.144) and time awake (TA) predicted injury occurrence (OR=0.974). TA decreased from phase 2 to phase 3 (p=0.004), total sleep time (TST) increased from phase 2 to phase 3 (p=0.012), and WASO decreased between phases 1 and 2 (p=0.001) and between phases 1 and 3 (p=0.025). Conclusion: Our study demonstrated that the quantity and quality of sleep were associated with musculoskeletal injuries in adolescent track and field athletes. Previous injuries were predicted by WASO and the occurrence of injuries was predicted by TA. Furthermore, during the vacation period they had lower TA and WASO, and higher TST than on school days.

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Introduction: Muscle injuries are the most frequent cause of physical disability in sports, representing a large percentage of all sports injuries. In high-performance sports in particular, there is great interest in optimizing the process of diagnosis and rehabilitation of muscle injuries in order to reduce the amount of time taken off by athletes due to their injuries. Infrared thermography, or cutaneous thermometry, is a technique used for complementary investigation of pain. It provides thermal imaging with an infrared camera, to measure the surface temperature of the body. Objective: To conduct a systematic review of the use of thermography as a functional evaluation for the identification and prevention of muscle injuries, and of the control variables used in its applicability. Methods: A systematic review was conducted in the MEDLINE, ResearchGate and Scielo databases, using the search terms: “thermography”, “muscle injury”, “rehabilitation” and “diagnosis”, searching on articles published from 2000 to 2017, in Portuguese, English and Spanish. The eligibility criteria for the studies was the use of thermography as an outcome, and the reporting of standards for evaluating skin temperature variation in athletes. Results: Following the systematic review, 94 studies were retrieved. Of these, only 12 met the criteria for inclusion in the study. Conclusion: Thermography is a suitable tool for the evaluation and prevention of muscle injuries in athletes, and care should be taken with the control variables during its use. The most efficient variables for capturing the thermographic image appear to be an environment with a temperature of between 18 and 25°C, for 15 minutes for acclimatization, and with the individual placed in a pre-determined position, depending on the body segment being evaluated, without contact with another object. Level of evidence I; Systematic review.