The Glycemia-increasing Effect of a 30-second Sprint is Attenuated Following 60 Minutes of Moderate-Intensity Exercise

Abstract

The glycemia-increasing effect of a short sprint has been proposed as a potential clinical tool to prevent exercise-mediated hypoglycemia in type 1 diabetes. However, prior moderate-intensity exercise may blunt the counterregulatory responses to further exercise. The purpose of this study was to investigate whether prior moderate-intensity exercise attenuates the counterregulatory response and associated glycemia-increasing effect of a 30-second sprint. Eight healthy males (age 21.8 ± 1.8 years; BMI 23.9 ± 2.2 kg•m-2; VO2peak 48.6 ± 6.6 ml•kg-1•min-1) completed two trials during which they either rested for 60 minutes (CON) or performed 60 minutes of moderate-intensity cycling at ∼65% VO2peak (EX). Following EX or CON, each participant rested for 3 hours and 15 minutes before performing a 30-second maximal cycling sprint and recovering in the laboratory for one hour. Blood glucose increased significantly and similarly in response to the sprint in both trials, peaking at 10 minutes of recovery. Blood glucose then declined at a faster rate in EX compared with CON, resulting in lower blood glucose at 45 minutes of recovery (p=0.024). The faster fall in blood glucose in EX was associated with a more consistent rise in glucose rate of disappearance (Rd) above the rate of appearance (Ra) during recovery. This might be explained, at least in part, by the lesser post-exercise rise in growth hormone levels in EX (p<0.05). These results suggest that prior moderate-intensity exercise does not affect the magnitude of the glycemia-increasing response of a 30-second sprint; however, the subsequent decline in blood glucose is more rapid.