Effects of Exercise Intensity on Acute Glucose Responses Following Combined Arm and Leg Cycling

INTRODUCTION: Prolonged and chronic sedentary behavior (SB) contributes to negative metabolic health. As SB time continues to increase, there is an increasing trend towards performing short bouts of exercise over the course of the day to break up the SB. Recent research into the metabolic benefits of short exercise bouts have focused on exercise done at a self-selected pace. Although exercise at a self-selected pace has been shown to improve glucose metabolism, these studies have not looked at the relationship between the intensity of these bouts and the improvements in glucose metabolism. PURPOSE: The purpose of this study was to examine the relationship between exercise intensity during a short bout of combined arm and leg cycling (CALC) at a self-selected pace and the acute effects on glucose metabolism. We hypothesized that as exercise intensity increased there would be a greater decrease in the 60-min total (tAUC) and incremental area under the curve (iAUC) compared to control. METHODS: Participants completed a VO2max test at baseline and three randomized experimental trials. Two of the experimental trials consisted of a 1-min (1 M) or 5-min (5 M) bout of CALC at a self-selected pace. The third trial was a non-exercise control (CON) trial. Exercise intensity was measured via indirect calorimetry. Immediately following both exercise trials and during the CON trial, participants completed a 60-min oral glucose tolerance test. A simple linear regression was used to look at the relationship between the change in iAUC and tAUC and exercise intensity following the exercise bouts. RESULTS: Average exercise intensity during the 1 M and 5 M bouts was 45.5 ± 15.0% and 54.0 ± 15.2 % of VO2max respectively. The average decrease in iAUC and tAUC for the 1 M bout was 40.0 ± 139.0 mg/dl/hr and 37.0 ± 125.3 mg/dl/hr respectively. The average decrease in iAUC and tAUC for the 5 M bout was 39.9 ± 122.5 mg/dl/hr and 71.6 ± 104.7 mg/dl/hr respectively. The results of the linear regression show that exercise intensity did not predict the change in iAUC or tAUC during either the 1 M or 5 M exercise trial. CONCLUSION: These results suggest that there is no relationship between exercise intensity and the change in iAUC and tAUC following a short bout of CALC. Short bouts of CALC done at a self-selected pace may have the potential to improve glucose metabolism.