The effect of melatonin on aerobic capacity and time of exhaustion during a sub-maximum activity in girl students of physical education

Background: Preservation and storage of muscle glycogen is the most important factor limiting the success of individuals in performing the following activities. It has been shown that melatonin supplementation before exercise can maintain glycogen stores. This study aimed to investigate the effect of melatonin consumption (6 mg) on the time of exhaustion during a submaximal-activity and also the maximum oxygen consumption during an increasing activity in physical education girl students of Shahid Chamran University of Ahvaz. Materials and Methods: In this clinical trial study, 13 girls with the mean age of 21.5±1.29 years, the mean weight of 58.36±2.69 kg and vo2max 39.08±4.17 mg/kg/min were participated and received melatonin (6 mg) and placebo (starch capsules) in two complementary steps. Supplements were administered acutely 30 minutes before the exercise. Each test was repeated in placebo and supplement conditions. To ensure the elimination of exercise and supplement impact, the interval of 5 to 7 days was considered between the two tests. The sub-maximal and progressive protocols respectively included running below the maximum intensity (70% of the heart rate reserve) to exhaustion and the Bruce's test on the treadmill. Results: The results showed that consumption of 6 mg melatonin significantly increased the time to reach exhaustion (P=0.01) and the maximum oxygen consumption (P=0.002). Conclusion: It appears that trained girls can use 6 mg of melatonin supplement 30 minutes before starting the exercise to improve endurance performance and aerobic capacity