AEROBIC ENDURANCE EXERCISE OR CIRCUIT-TYPE RESISTANCE TRAINING FOR INDIVIDUALS WITH IMPAIRED GLUCOSE-TOLERANCE

The role of physical activity in the prevention of non-insulin-depende nt diabetes mellitus (NIDDM) is of utmost importance. The aim of the p resent study was to evaluate the metabolic effects of aerobic enduranc e exercise and circuit-type resistance training in subjects with impai red glucose tolerance (IGT). Twenty-two individuals participated in th e study. Fourteen subjects were enrolled in the aerobic endurance exer cise part of the study; seven exercised regularly for six months, whil e seven served as controls. Maximal aerobic capacity ((V) over dot O(2 )max) was measured and insulin sensitivity and insulin secretion were assessed by a frequently sampled intravenous glucose tolerance test (F SIVGTT). Eight subjects participated in a circuit-type resistance trai ning program for three months. Insulin sensitivity and substrate oxida tion were then assessed using the euglycemic insulin clamp technique c ombined with indirect calorimetry. The aerobic endurance exercise prog ram caused an increase in (V) over dot O(2)max (21.6 +/- 1.9 to 25.4 /- 2.4 ml/kg.min; p < 0.05) and HDL-cholesterol (1.14 +/- 0.06 to 1.23 +/- 0.08 mmol/l; p < 0.05), but no change in insulin sensitivity nor insulin secretion occurred. However, comparing the changes between the intervention and control group, the differences disappeared. Circuit- type resistance training increased insulin sensitivity (glucose dispos al) by 23% (p < 0.05), primarily due to a 27% increase in non-oxidativ e glucose metabolism. Both circuit-type resistance training and aerobi c endurance exercise seem to have beneficial effects in subjects with impaired glucose tolerance. However, by improving insulin sensitivity, circuit-type resistance training may postpone the manifestations of N IDDM in these high-risk individuals and should therefore be included i n an exercise program for IGT subjects.