Document Type : Research Paper
Department of Sport Sciences, School of Education and Psychology, Shiraz University, Iran.
Energy Balance & Body Composition Laboratory, Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA.
Introduction: Nutrition programs can effectively influence physiological systems both at rest and in response to exercise. In the present study, the effect of time-restricted eating (TRE) on two steroid hormones, namely testosterone and cortisol and the ratio of testosterone to cortisol, at rest and in response to a session of exhaustive endurance exercise was investigated. Methods: Participants of this study were 8 active boys (age: 22.63±3.50 years, body mass index: 23.46±5.61kg/m2) who participated in the study voluntarily. Subjects performed TRE for two weeks. That is, they abstained from eating and drinking (except water) from 8 am to 4 pm, and continued their usual diet for the rest of the day. Before and after the two weeks of diet, they participated in the Yo-Yo exercise test. In both stages, blood samples were taken before the breakfast, and immediately after eating breakfast and the yo-yo test to measure the concentration of testosterone and cortisol. Paired t-tests were used to analyze the findings. Results: Findings indicated that TRE increased fasting testosterone levels. Testosterone decreased after exercise following two weeks of TRE. Cortisol and the ratio of testosterone to cortisol at rest and in response to exercise after TRE were not significantly different compared to before TRE. Conclusion: It can be concluded that TRE improved fasting testosterone as an anabolic index but reduced its response to exercise.