The significance of physical activity for fitness is that it may change risk factors for chronic disease and improve functional and psychological status. Rational nutrition and scientific training are prerequisites for safe and useful exercise. Even mild iron deficiency anaemia can affect physical capacity. Intensive exercise has been found to increase serum and erythrocyte lipid peroxide levels. Zinc deficiency not only leads to an increase in free radical generation and lipid peroxidation and a depression of SOD activity, but also is harmful to immune function.
Exercise can exacerbate the damage induced by iron deficiency or zinc deficiency.
Long term diet restriction by gymnasts to control weight showed detrimental effects including growth retardation, menstrual disturbances, malnutrition, mental stress and muscle weakness. Comprehensive nutrition promotes growth rate and corrects malnutrition without a body fat increase in athletes. Exercise benefits the growth and development of bone and muscle and enhances muscle strength. The prevention of obesity is particularly important during periods of rapid growth. The establishment of an exercise life style during childhood will favour the best health.