Exercise, aging, and nutrition.

Age-associated declines in resting energy expenditure and the thermogenesis of activity result in lower energy requirements in older adults. Regular aerobic exercise programs and strength or resistive training may increase the daily energy expenditure and/or may preserve or increase the lean body mass, which decreases with increasing age. Regular strength training exercise programs may improve bone mineral density and ambulation in older adults. Nutritional assessments suggest that older adults' protein intake should be at least 1 g per kilogram of body weight, and that calcium intake should be between 1,200 and 1,500 mg/day. Regular strenuous physical activity may require subtle changes in vitamin and mineral intake to compensate for loss of minerals in sweat and for exercise-induced increases in metabolism. Older adults may have a decreased thirst response to fluid deprivation. Fluid intake must be closely monitored with exercise activity to prevent dehydration.