The volume and order of starting exercise modulates the glucose-lowering effect of a single session of combined exercise in middle-aged and older adults with type 2 diabetes.

Abstract

Problem Statement: Although combined exercise (CE) is frequently prescribed for glycemic control of Type 2 Diabetes Mellitus (T2DM) subjects, beginning CE session with aerobic or resistance exercises can lead to distinct responses in capillary glucose, especially when training prescriptions differ in intensity and volume. Approach: This study aimed to evaluate the effect of exercise intensity, volume, and order within combined exercise sessions on glycemic response. Purpose: Forty T2DM subjects participated in this study. The subjects were divided into three different protocols: standard (S-P, n = 13), high intensity (HI-P, n = 16), and high volume (HV-P, n = 11) in two counter-balanced orders each [i.e., resistance exercise followed by aerobic exercise (R-A) or vice versa (A-R)]. The capillary glucose was evaluated before and after each CE session. Results: All protocols of combined exercise reduced glucose concentrations (p < .001). HV-P induced a glycemic reduction that was 2-fold higher than that observed in HI-P (34% vs. 18%; p < .05). Both exercise orders within combined exercise session reduced glucose concentrations (S-P: 25%, 28%; HI-P: 17%, 19%, and HV-P: 31%, 36% for A-R and R-A, respectively); however, R-A induced slightly larger (Cohen’s d was 13-33%

higher in R-A compared to A-R), but clinically relevant, reductions in all combined exercise protocols. Pre- exercise glucose concentrations were correlated to exercise-induced glucose reduction only in the A-R order (r =

65 to .79, p < .05). Conclusion: All combined exercise protocols were effective in decreasing glucose concentrations. Nonetheless, a higher magnitude of glucose-lowering effect occurred when a higher exercise volume was performed and when performing resistance instead of aerobic exercise in the first place.