Glucose tolerance in young and older athletes and sedentary men

Groups of endurance-trained masters athletes (60 ± 2 yr), older untrained men (62 ± 1 yr), lean older untrained men (61 ± 2 yr), endurance-trained young athletes (26 ± 1 yr), and young untrained men (28 ± 1 yr) were studied to obtain information on the separate effects of age, physical activity, and body fatness on glucose tolerance and insulin sensitivity. Each subject underwent an oral 100-g glucose tolerance test. Skinfold thickness was determined at six sites. The trained groups had a higher maximum O₂ uptake capacity and lower sum of skinfolds than their sedentary peers. The lean older untrained group had a sum of skinfolds simlar to that of the young untrained group. The masters athletes, young athletes, and young untrained men exhibited similar glucose tolerance, whereas the two older untrained groups had an almost 2-fold greater total area under the glucose curve (P < 0.05). The masters and young athletes had significantly blunted plasma insulin responses compared with the other three groups (P < 0.05). The young and the lean older untrained groups had similar plasma insulin responses with significantly lower insulin levels than the older untrained group (P < 0.05). These results provide evidence that regularly performed vigorous exercise can, in some individuals, prevent the deterioration of glucose tolerance and insulin sensitivity with age.