Improved end-stage high intensity performance but similar glycaemic responses after waxy barley starch ingestion compared to dextrose in type 1 diabetes.

Pre-exercise carbohydrate (CHO) ingestion is an effective strategy for reducing the occurrence of hypoglycaemia during or after exercise in individuals with type 1 diabetes (T1DM). The metabolic effects of ingestion of different CHOs for glycaemic or performance gains have been under-researched. This study compared metabolic responses and fuel use during sub-maximal and high-intensity performance running following preexercise ingestion of waxy barley starch (WBS) or dextrose (DEX) in T1DM.Seven participants attended the laboratory on two separate occasions following preliminary testing. On each visit participants consumed either 0.6 g.kg-1 body mass of DEX or WBS 2-h before a 26-min discontinuous incremental treadmill protocol (4-min running: 1.5-min rest) finishing at 80±4% O2peak followed by a 10-min performance run on a nonmotorised treadmill. Capillary blood samples were taken at rest, during and following exercise and analysed for glucose (BG) and acid-base variables. Data (mean±SEM) were analysed using repeated measures ANOVA (P<0.05).BG reached similar peak values one hour after CHO ingestion and immediate presub- maximal exercise BG were comparable. Resting CHO oxidation was elevated and lipid oxidation lower under WBS (P<0.05). There were no metabolic or cardio-respiratory differences during the sub-maximal exercise (P>0.05). In the final quartile of the performance run, a greater distance was completed under WBS (WBS 323±21 vs. DEX 301±20 m, P=0.02).Consumption of WBS demonstrated similar hyperglycaemic responses to dextrose ingestion but a greater rate of CHO use at rest. Interestingly, T1DM individuals displayed an improved performance at the latter stages of a high-intensity run test.

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