The effect of carbohydrate ingestion type and timing on substrate utilization during low intensity shivering

Abstract

During cold exposure, carbohydrates (CHO) play a substantial role in providing substrate for shivering muscles. To date, little is known about the effects of CHO ingestion on substrate utilization in the cold. The purpose of this study was to determine the rate of exogenous glucose oxidation (RGox-exo) and quantify the rate of substrate utilization during low-intensity shivering when: (1) glucose is given from the onset (GO) or after 60 min (G60) or (2) ingesting glucose alone or in equal parts with fructose (GF60). Results showed that although CHO and lipid oxidation and their relative contribution to heat production increased during cold exposure when ingesting a CHO beverage, the timing and type of CHO ingested had no effect on overall substrate utilization. However, RGox-exo during cold exposure was significantly greater in the GO and GF60 condition relative to G60 (p<0.05) but no significant difference was found between the GO and GF60.