Document Type : Original Article
Authors
1 Department of Sport Sciences, Faculty of Educational Sciences and Psychology, Payame Noor University, Tehran, Iran.
2 Department of Sport Sciences, Faculty of Literature and Humanities, Ilam University, Ilam, Iran.
Abstract
Background and Aim: Beyond the quantity, duration, and type of exercise, the timing of physical activity also plays a significant role in modulating physiological adaptations. The present study aimed to examine the effects of endurance training conducted in the morning and night on bone metabolism markers in middle-aged women. Methods: Thirty-six female participants, aged 40 to 50 years, were purposively selected and randomly assigned to one of three groups: morning training, night training, and control. The training groups performed aerobic training for 8 weeks, with three sessions per week, each lasting 60 minutes at an intensity of 55–70% of heart rate reserve. To evaluate biochemical markers, blood samples were collected from the brachial vein under fasting conditions 48 hours prior to the initiation of the training program and 48 hours following the final training session. Following serum separation, the samples were transported to a biochemistry laboratory for analysis. Serum concentrations of alkaline phosphatase, vitamin D, parathyroid hormone, and calcitonin were quantified. The data were analyzed using paired t-tests and analysis of covariance (ANCOVA) at a significance level of p≤0.05. Results: The findings revealed a significant increase in serum alkaline phosphatase levels in the night training group compared to the control group (p = 0.003). However, no significant differences were observed between the training groups and control in serum levels of vitamin D (p=0.413), parathyroid hormone (p=0.495), or calcitonin (p=0.721). Furthermore, there were no significant differences in biochemical serum markers among the training intervention groups (p ≥ 0.05). Conclusion: In summary, the timing of aerobic training does not appear to have a significant effect on bone metabolism-related markers such as vitamin D, parathyroid hormone, or calcitonin. However, it exerts a particularly beneficial effect on bone-specific alkaline phosphatase.
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