Effects of exercise training on oxygen uptake kinetic responses in women with type 2 diabetes.

Abstract

OBJECTIVE: Women with uncomplicated type 2 diabetes have both a decreased maximal oxygen consumption (VO2max) and slowed oxygen uptake (VO2) kinetics at the onset of exercise compared with nondiabetic women. These abnormalities are seen not only at maximal workloads, but also at the onset of low-level exercise. To evaluate the hypothesis that VO2max and VO2 kinetics would improve with exercise training in untrained people with type 2 diabetes, we measured these parameters in premenopausal sedentary women before and after 3 months of supervised exercise training. RESEARCH DESIGN AND METHODS: A total of 8 women with type 2 diabetes, 9 overweight nondiabetic women, and 10 lean nondiabetic women were studied. At baseline and after 3 months of exercise training, subjects underwent bicycle ergometer testing to obtain VO2max and VO2 kinetics data. RESULTS: On entry, women with type 2 diabetes had the lowest VO2max and slowest VO2 kinetics of the three groups. After exercise training, the women with type 2 diabetes improved their VO2max more than the lean and overweight control women: 28 vs. 5 and 8%, respectively (P < 0.05 for the diabetic group vs. both control groups). In the group with diabetes, VO2 kinetics improved by 39 and 22% at 20 and 30 W, respectively. For the control subjects, VO2 kinetics did not improve at any workload in either group. CONCLUSIONS: Despite beginning with the lowest VO2max and slowest VO2 kinetics, subjects with type 2 diabetes benefited more from an exercise training program than did control subjects. These findings suggest that in addition to its known metabolic effects, exercise training in individuals with type 2 diabetes may be an effective therapy to improve the cardiovascular response to exercise and to overcome low-level exercise impairment as reflected by improved VO2max and VO2 kinetics. If the ability to make circulatory adjustments at the beginning of exercise at low workloads is improved by an exercise training program, as suggested by the VO2 kinetics data, the clinical significance of exercise for people with type 2 diabetes is clear.