Impact of exercise intensity and duration on insulin sensitivity in women with T2D

Clinical guidelines seldom provide in depth information about the most suitable type and intensity of exercise to obtain optimal benefit in different subgroups of T2D individuals. The aim of this study was to examine the effect of group exercise training on exercise capacity, insulin sensitivity and HbA1c in women with diabetes.

Twenty-two women with T2D participated in a supervised group exercise program for six months. The program combined endurance and resistance exercise. The duration and intensity of exercise for each subject was recorded. The volume of exercise was calculated as the product of exercise duration and intensity. Exercise capacity, insulin sensitivity and HbA1c were measured at baseline and after six months of training. The subjects were dichotomized with respect to training volume in a high training volume group and a low training volume group.

Exercise capacity did not change significantly during the training period. Insulin sensitivity increased significantly and HbA1c decreased significantly from baseline in the high volume group but not in the low volume group. The increase in insulin sensitivity was explained with the intensity of exercise by 30%. The reduction in HbA1c was explained with exercise by 25%.

Improvement in insulin sensitivity after six months combined supervised group training in female diabetic subjects is related to exercise intensity, whereas the reduction in HbA1c is related mainly to training volume. Metabolic effects of training may be seen in the absence of improved exercise capacity.