The Effects of Pre-Exercise Glycemic Index Food on Running Capacity

Abstract

This study examined the effects of pre-exercise food on different glycemic indexes (GI) on exercise metabolism and endurance running capacity. 9 subjects performed 3 exercise trials on different days 15 min after ingesting: lentils, (LGI), potatoes, (HGI), and placebo. Each subject ingested an equal amount of each food (1 g/kg body mass) and ran on a level treadmill for 5 min at 60%, 45 min at 70% and then at 80% of VO_2max until exhaustion. Serum glucose concentrations were higher (P<0.01) 15 min after the HGI trial compared to the LGI and placebo trials. In addition, serum glucose levels were higher (P<0.05) during the LGI trial at the time of exhaustion compared to the HGI and placebo trials. Plasma insulin levels, 15 min after ingestion, were higher (P<0.001) in the HGI trial as compared to the LGI and placebo trials. Exercise time was longer during the LGI trial (P<0.05) compared to the placebo, but the time to exhaustion in the HGI condition did not differ from the placebo (LGI: 90.0±7.9; HGI: 81.8±5; placebo: 73.0±6.4 min). These results suggest that lentils, the LGI food, ingested 15 min before prolonged exercise maintained euglycemia during exercise and enhanced endurance running capacity.

Key words

glucose - insulin - metabolism - exhaustion

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