Pacing strategy and heart rate on the influence of circadian rhythms

Circadian rhythms (CR) control several important human physiological activities such as the sleep-wake cycle, heart rate (HR), body temperature, and hormone secretion. Although CR can directly influence athletes' physical performance, no other study has indicated the influence of this biological control on HR and pacing in 3000 m and 5000 m races. Eight physically active adults (average age 26.62 ± 7.79 yrs) participated in this study. The races were held in a 400 m track in the morning, afternoon, and evening. In order to evaluate pacing strategy, time and HR were registered in each lap. The data were analyzed using descriptive statistics, Shapiro-Wilk W-test, Two-Way ANOVA with Tuckey's Post-Hoc test. Correlation coefficient between HR and the time of each lap was determined according to the Pearson correlation test (P