Jean Mayer USDA Human Nutrition Research Center, Tufts University, Exercise and Nutrition Laboratory, 711 Washington Street, Boston, Massachusetts 02111, USA
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.
