Effects of aerobic exercise and training on the trace minerals chromium, zinc and copper.

Aerobic exercise and training lead to numerous changes and/or adaptations in the normal physiological functioning of the body. The trace minerals chromium, zinc, and copper are directly involved in maintaining and regulating many of these physiological processes, especially those involved in normal carbohydrate, fat and protein metabolism and the ultimate formation of usable energy. Therefore, it is important to establish whether exercise and training alter the functions of these trace elements, and to determine the overall effects of exercise on nutritional status and physical performance. Exercise results in a marked mobilisation of chromium into circulation, while zinc and copper levels have been shown to either remain stable or increase. Exercise also results in large increases in excretion of chromium, zinc and copper. Urinary chromium excretion has been shown to increase on an exercise day compared with a rest day, while increased zinc losses occur in urine and sweat and increased copper losses occur in urine, and faeces. When exercise-enhanced trace mineral losses are coupled with dietary intakes below the recommended levels, which are commonplace for both sedentary and exercising individuals, the nutritional status and overall health of exercising individuals may be suboptimal. Individuals who train intensively may be at special risk due to repeated increased losses. Trained athletes have lower resting urinary chromium losses, larger increases in urinary chromium losses due to exercise, lower resting serum zinc levels, and possible alterations in copper nutriture compared with sedentary controls. These changes suggest an altered metabolism and/or nutritional status of the trace minerals chromium, zinc, and copper in trained individuals and those who exercise strenuously.