ENDURANCE EXERCISE TRAINING DECREASES CAPILLARY BASEMENT-MEMBRANE WIDTH IN OLDER NONDIABETIC AND DIABETIC ADULTS

The objectives of these studies were to 1) evaluate the relationships among age, glucose intolerance, and skeletal muscle capillary basement membrane (CBM) width (CBMW) and 2) determine the effects of exercise training on CBMW by comparing values of young (28 +/- 4 yr) and older (63 +/- 7 yr) athletes with those of age-matched sedentary control sub jects and by measuring CBMW in older men and women before and after a 9-mo endurance-exercise training program. CBMW was measured in tissue samples obtained from the gastrocnemius muscle. CBMW in sedentary 64 /- 3-yr-old subjects was 25% thicker than in sedentary 24 +/- 3-yr-old subjects. CBMW was similar in young and older athletes and was thinne r than the CBMW of age-matched sedentary control subjects. There were no differences in CBMW among older sedentary individuals with normal o r impaired glucose tolerance or mild noninsulin-dependent diabetes mel litus. Nine months of endurance exercise training reduced CBMW in olde r men and women by 30-40%, to widths that were not different from thos e of the young subjects; this response was independent of glucose tole rance status. These findings suggest that habitual exercise prevents t he thickening of the skeletal muscle CBM that is characteristic of adv ancing age. Moreover, the thickening of the CBM appears to be readily reversed as a result of exercise training, even in older individuals.