Effects of Different Carbohydrate Supplementation on Marathon for Amateur Runners: A Controlled Trial

Objective This study examined the relationship between glycemic changes and marathon performance in amateur runners using Continuous Glucose Monitoring (CGM). It also assessed the impact of different carbohydrate intake strategies on performance. METHODS Continuous glucose monitoring was used to continuously monitor the blood glucose levels of 18 elite amateur runners and 12 sub-elite amateur runners participating in one race. The race performance data were obtained from a sports watch. At the same time, the runners were randomly grouped into 10 in the elite high-carb group, 8 in the elite normal-carb group, 6 in the sub-elite high-carb group, and 6 in the sub-elite normal-carb group. The recharge standard for the high-carb group is 80g/h, and the normal-carb group's is 50g/h. RESULTS Results showed that high-carb intake significantly improved finishing times. While various supplementation methods did not affect segmental speed and blood glucose variations, elite runners maintained a consistent speed, unlike sub-elite runners who saw a decrease in the final 10KM. Conclusion In the marathon, both supplementation schedules ensured energy availability and avoided hypoglycemia; there was no difference in segmental performance between runners in the regular and high Carbohydrate groups, but high Carbohydrate supplementation may have been beneficial to final performance; the higher the level of the runner, the more consistent the speed maintenance, and in the marathon, the more stable the blood glucose in the second half of the race may be beneficial in avoiding the exercise performance Decline.