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Background and Objective: Rapid and adequate rehydration is important for many athletes, especially those taking multiple sessions of exercise each day, or those involved in weight category sports. The macronutrient and electrolyte concentration of the fluid ingested following exercise can affect the amount retained within the body can influence hydration status. This study was done to compare the effect of milk consumption on healthy young men rehydration and endurance performance after dehydration due to intermittent exercise in warm environmental condition. Methods: In this quasi-experimental study, the labroratory protocol was carried out by ten young healthy men in three sessions within one week intervals. Participants were on drinking regiment including water, low-fat milk, and powerade. Urine samples were collected pre-exercise, post-exercise, post-drinking and 1, 2 and 3 hours over recovery. Exercise capacity test commenced within 10 min after 3h recovery. This was undertaken in warm environmental condition at a power output corresponding to 70% VO2 max. Exercise continued until voluntary exhaustion. Heart rate and RPE were recorded at 5 min intervals throughout exercise. Results: Pre-exercise urine specific gravity value was not different between the milk and the, powerade and the water groups. Total urine output was significantly reduced in the milk group in compared to powerade and the water consumption (P<0.05). At the end of the study, net fluid balance was significantly positive in milk group compared to powerade and water groups (P<0.05). Time of exhaustion on the exercise capacity test (70% VO2 max) was significantly more in milk in comparision with powerade group (P<0.05). Conclusion: Low-fat milk is more effective at rehydrating compared to water and exercise capacity in intermittent activity of heat in healthy young men.

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Background and Objective: Differentiation of white adipose tissue into brown through hormonal and non-hormonal factors, causes weight loss and weakens in obese and overweight people. This study was performed to determine the effect of 12 weeks of interval exercise with different intensities on serum levels of fibroblast growth factor 21 and myostatin in obese and overweight males.
Methods: This clinical trial study was done on 47 obese and overweight males (20.5±0.73 years old). Subjects were randomly divided into four groups: control, interval exercise with low intensity, moderate intensity and high intensity. The exercise program consisted of 12weeks of interval exercise with light, medium and heavy intensity respectively with 58-63, 73-78 and 88-93 percent of Reserve heart rate for 25 to 63 minutes and three sessions per week. Serum indices of fibroblast growth factor 21 and myostatin were measured using fasting blood sample 48 hours before and after exercise program using ELISA method.
Results: Performing 12 weeks of interval training with different intensities was not contribute to significant changes in the serum levels of fibroblast growth factor 21 and myostatin. Implementation of interval exercise at moderate and high intensities was associated with reduction of body fat percentage and increasing in maximal oxygen consumption (VO₂max) in overweight and obese men (P<0.05).
Conclusion: Performing 12 weeks of low, medium and high intensity interval training without changing the serum level of fibroblast growth factor 21 and myostatin has a beneficial effect on improving body composition and increasing VO₂max in obese and overweight young males.