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Am J Physiol Endocrinol Metab 292: E865-E870, 2007; doi:10.1152/ajpendo.00533.2006
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Effect of intermittent high-intensity compared with continuous moderate exercise on glucose production and utilization in individuals with type 1 diabetes

¹School of Human Movement and Exercise Science, University of Western Australia, Crawley; ²Department of Endocrinology and Diabetes, Princess Margaret Hospital, Subiaco; ³Centre for Child Health Research, The University of Western Australia, Telethon Institute of Child Health Research, Perth, Western Australia; and ⁴Bioanalytical Mass Spectrometry Facility, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia

Submitted 29 September 2006 ; accepted in final form 10 November 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 [6,6-²H]glucose. MOD consisted of continuous cycling at 40% O_{2 peak}, whereas IHE involved a combination of continuous exercise at 40% O_{2 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.

glycemia; hypoglycemia; physical activity