Ageing: Effects on oxidative function of skeletal muscle in vivo

31P 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 children (6–12 years) and was significantly decreased in the elderly (70–83 years). In the adults, the intracellular pH change during exercise diminished with increasing age, resulting in higher calculated free [ADP] and possibly serving as an adaptive mechanism to stimulate mitochondrial ATP production. Children also had higher pH and [ADP] in exercise, but unlike results from the elderly, this was associated with higher oxidative capacity and more rapid metabolic recovery from exercise. (Mol Cell Biochem 174: 321–324, 1997)