The Effect of Acute Training and Circadian Rhythm on Blood Hemostasis in Female Athletes

Background: Circadian rhythm and physical activity are factors that influence the homeostasis of blood. This study aimed to investigate the effect of exhaustive exercise in the morning and evening on the blood hemostasis in female athletes. Methods: In the present quasi-experimental study, 30 female athletes aged 18-25 were selected by convenience sampling method and randomly divided into two groups (morning and afternoon exercises). The standard Bruce protocol test was used. In the present study, platelets, fibrinogen, and thromboplastin time were measured as indicators of blood coagulation before and after testing. Paired t-test and covariance analysis were used to analyze the measured indices and P ≤ 0.05 was considered significant. Results: An acute exhausting aerobic training session in both groups significantly increased platelet and fibrinogen levels, but a significant decrease was observed in thromboplastin time. Considering the training time, significant difference was observed in the blood thromboplastin time in the morning in comparison with the afternoon. Conclusion: According to the results of this study, the circadian rhythm and acute exhausting aerobic training are effective factors on the blood coagulation and a training session in the morning compared with the evening training has a greater effect on the blood coagulation.