Combined Exercise and Dietary Intervention to Optimize Body Composition in Aging

Concomitant losses of skeletal muscle and bone mass along with gradual accretion of adipose tissue typify usual human aging. Recent investigations have attempted to modify these processes with various combinations of dietary and exercise intervention in older adults. Complete nutritional supplements given with weight-lifting exercise have been shown to augment muscle and fat gains in healthy older men, but have merely suppressed habitual dietary intake when administered to frail sedentary elders, and have not altered body composition responses to strength training in this population. Protein supplementation at twice the RDA does not improve skeletal muscle function or increase muscle mass in healthy elderly weight lifters compared to those on a normal diet. Calcium supplementation during one year of aerobic training has an independent beneficial effect on cortical bone density at the femoral neck in postmenopausal women, whereas the exercise is associated with trabecular bone increases in the lumbar vertebrae. Hypocaloric dieting, with or without aerobic exercise, results in losses of weight, fat and lean mass in obese elderly men and women. By contrast, resistance training during hypocaloric dieting augments lean mass while further reducing fat mass. Low protein, isoenergetic diets result in muscle atrophy in older women. Current studies will determine the ability of resistance training to offset these catabolic effects on skeletal muscles of a low-protein (0.6 g/kg/day) diet prescribed for elderly with chronic renal failure. More long-term studies of efficacy and feasibility of diet and exercise combinations are needed in the aged to optimize the potential for healthful shifts in body composition.