Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes

Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes. Am J Physiol Endocrinol Metab 292: E865-E870, 2007; doi: 10.1152/ajpendo.00533.2006.- Previously, the decline in glycemia in individuals with type 1 diabetes has been shown to be less with intermittent high-intensity exercise (IHE) compared with continuous moderate-intensity exercise (MOD) despite the performance of a greater amount of total work. The purpose of the present study was to determine whether this lesser decline in glycemia can be attributed to a greater increment in endogenous glucose production (R-a) or attenuated glucose utilization (R-d). Nine individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed under conditions of a euglycemic clamp in combination with the infusion of [6,6-H-2] glucose. MOD consisted of continuous cycling at 40% VO2 peak, whereas IHE involved a combination of continuous exercise at 40% VO2 peak interspersed with additional 4-s maximal sprint efforts performed every 2 min to simulate the activity patterns of intermittent sports. During IHE, glucose R-a increased earlier and to a greater extent compared with MOD. Similarly, glucose R-d increased sooner during IHE, but the increase by the end of exercise was comparable with that elicited by MOD. During early recovery from IHE, R-d rapidly declined, whereas it remained elevated after MOD, a finding consistent with a lower glucose infusion rate during early recovery from IHE compared with MOD (P < 0.05). The results suggest that the lesser decline in glycemia with IHE may be attributed to a greater increment in R-a during exercise and attenuated R-d during exercise and early recovery.