AGING - EFFECTS ON OXIDATIVE FUNCTION OF SKELETAL-MUSCLE IN-VIVO

P-31 magnetic resonance spectroscopy studies were carried out on calf muscle of 144 normal male and female subjects age 20-83 years in order to investigate age-related changes in muscle metabolism. Compared to the young adults (20-29 years), oxidative capacity was higher in the c hildren (6-12 years) and was significantly decreased in the elderly (7 0-83 years). In the adults, the intracellular pH change during exercis e diminished with increasing age, resulting in higher calculated free [ADP] and possibly serving as an adaptive mechanism to stimulate mitoc hondrial ATP production. Children also had higher pH and [ADP] in exer cise, but unlike results from the elderly, this was associated with hi gher oxidative capacity and more rapid metabolic recovery from exercis e.