Hyperinsulinaemia and hyperglycaemia promote glucose utilization and storage during low- and high-intensity exercise

Mohebbi, Hamid and Campbell, Iain and Keegan, Marie and Malone, James J. and Hulton, Andrew and MacLaren, Don (2019) Hyperinsulinaemia and hyperglycaemia promote glucose utilization and storage during low- and high-intensity exercise. European Journal of Applied Physiology. ISSN 1439-6319

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Abstract

Purpose
The effect of hyperglycaemia with and without additional insulin was explored at a low and high intensity of exercise (40% vs 70% VO2peak) on glucose utilization (GUR), carbohydrate oxidation, non-oxidative glucose disposal (NOGD), and muscle glycogen.

Methods
Eight healthy trained males were exercised for 120 min in four trials, twice at 40% VO2peak and twice at 70% VO2peak, while glucose was infused intravenously (40%G; 70%G) at rates to “clamp” blood glucose at 10 mM. On one occasion at each exercise intensity, insulin was also infused at 40 mU/m2/per min (i.e. 40%GI and 70%GI). The glucose and insulin infusion began 30 min prior to exercise and throughout exercise. A muscle biopsy was taken at the end of exercise for glycogen analysis.

Results
Hyperglycaemia significantly elevated plasma insulin concentration (p < 0.001), although no difference was observed between the exercise intensities. Insulin infusion during both mild and severe exercise resulted in increased insulin concentrations (p < 0.01) and GUR (p < 0.01) compared with glucose (40%GI by 25.2%; 70%GI by 26.2%), but failed to significantly affect carbohydrate, fat and protein oxidation. NOGD was significantly higher for GI trials at both intensities (p < 0.05) with storage occurring during both lower intensities (62.7 ± 19.6 g 40%GI; 127 ± 20.7 g 40%GI) and 70%GI (29.0 ± 20.0 g). Muscle glycogen concentrations were significantly depleted from rest (p < 0.01) after all four trials.

Conclusion
Hyperinsulinaemia in the presence of hyperglycaemia during both low- and high-intensity exercise promotes GUR and NOGD, but does not significantly affect substrate oxidation.

Item Type:	Article
Additional Information and Comments:	This is the author's version of an article that was accepted for publication in the European Journal of Applied Physiology. The final publication is available at https://link.springer.com/article/10.1007/s00421-019-04257-9
Keywords:	Glucose Insulin Severity of exercise Glucose utilization Carbohydrate oxidation Non-oxidative glucose disposal Muscle glycogen
Faculty / Department:	Faculty of Human and Digital Sciences > School of Health and Sport Sciences
Depositing User:	James Malone
Date Deposited:	22 Nov 2019 14:30
Last Modified:	22 Nov 2019 14:30
URI:	https://hira.hope.ac.uk/id/eprint/2970

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