The effects of acute and regular exercise on calcium, phosphorus and trace elements in young amateur boxers.

BACKGROUND: The aim of this study was to assess the acute and chronic effects of vigorous physical activity, with and without zinc supplementation, on distribution of elements in young amateur boxers. METHODS: The 8 week intervention trial experiment was designed with 32 healthy adolescent males in three parts: part 1, a 1 hour boxing training program; part 2, 4 weeks of regular boxing training without any supplementation; part 3, 4 weeks of regular boxing training with supplementation of pills containing 50 mg oral zinc. Plasma calcium, phosphorus, zinc, iron, copper, and magnesium levels of all participants were measured before and after each part of the study. RESULTS: After acute exercise serum calcium, zinc, copper levels decreased (p < 0.001; 0.001 and 0.017, respectively) and phosphorus increased (p < 0.001); iron and magnesium levels did not differ (p > 0.05). However, after 4 weeks of regular boxing training there was a decrease in zinc (93.92 +/- 9.03 microg/dL vs. 85.86 +/- 10.32 microg/dL, p < 0.001) and an increase in calcium concentrations (9.62 +/- 0.34 microg/dL vs. 9.90 +/- 0.26 microg/dL, p < 0.001). Zinc supplementation increased plasma calcium, phosphorus, and iron and decreased copper and magnesium (p < 0.001). CONCLUSIONS: The body element distribution of children in pubertal age changes with physical activities. Zinc supplementation can negatively affect their magnesium and copper concentrations.

Adrenocorticotropic hormone and cortisol levels in athletes and sedentary subjects at rest and exhaustion: effects of magnesium supplementation.

The effects of a 1-month exercise program and magnesium supplementation on the adrenocorticotropic hormone and cortisol levels were studied in young tae-kwon-do and sedentary subjects both at rest and exhaustion. The hormone levels were compared before and after supplementation with 10 mg of magnesium (as magnesium sulfate) per kilogram of body weight. Both exercise and magnesium supplements caused significant increases of the adrenocorticotropic hormone (p < 0.05). The cortisol levels were increased in training subjects receiving supplements (p < 0.05) but not so in subjects that either trained or received magnesium supplements in an independent manner. The cortisol levels measured in resting individuals were higher in the supplemented and non-supplemented athletes than those in sedentary subjects (p < 0.05). The results of this study show that exercise and/or magnesium supplementation causes a rise of the adrenocorticotropic hormone, whereas cortisol is increased only as a result of combined exhaustion and magnesium supplements.

The effect of magnesium supplementation on glucose and insulin levels of tae-kwan-do sportsmen and sedentary subjects.

This study was performed to determine how the magnesium supplementation for a 4-week period affects the glucose and insulin levels at rest and at exhaustion in sportsmen. This is a 4 week study performed on 30 healthy male subjects varying between 18-22 ages. Subjects were separated into 3 groups. 1st group; group supplemented with magnesium, 2nd group; Magnesium supplementations exercise group, 3rd group; training group. Glucose and insulin parameters of the groups were measured 4 times; at rest and exhaustion in the beginning of the research and at rest and exhaustion after the end of 4 weeks application period. Glucose levels in exhaustion measurements both before and after the supplementation significantly increased compared to resting levels (p<0.05). Significant difference was determined in the glucose values of 1st and 2nd groups supplemented with magnesium in comparison to their first measurements (p<0.05). Insulin values a decrease in all of the 3 groups occurred with exercise both before and after the supplementation (p<0.05). Magnesium supplementation has an important effect on glucose levels whereas it has no effect on insulin levels.

Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion.

This study was performed to assess how 4 weeks of magnesium supplementation and exercise affect the free and total plasma testosterone levels of sportsmen practicing tae kwon do and sedentary controls at rest and after exhaustion. The testosterone levels were determined at four different periods: resting before supplementation, exhaustion before supplementation, resting after supplementation, and exhaustion after supplementation in three study groups, which are as follows: Group 1-sedentary controls supplemented with 10 mg magnesium per kilogram body weight. Group 2-tae kwon do athletes practicing 90-120 min/day supplemented with 10 mg magnesium per kilogram body weight. Group 3-tae kwon do athletes practicing 90-120 min/day receiving no magnesium supplements. The free plasma testosterone levels increased at exhaustion before and after supplementation compared to resting levels. Exercise also increased testosterone levels relative to sedentary subjects. Similar increases were observed for total testosterone. Our results show that supplementation with magnesium increases free and total testosterone values in sedentary and in athletes. The increases are higher in those who exercise than in sedentary individuals.