Glycemic Index Does Not Affect Muscles During Exercises

Carbohydrates are the main fuels during exercise at intensities above 65 percent of maximum effort. Carbs are important fuels during intense exercise because they provide more energy per unit of time than fats. While people have plenty of fat to fuel exercise, car­bohydrate stores

are limited to approxi­mately 400 grams distributed in the liver and skeletal muscles. Post-exercise meals are critical for restoring depleted glycogen stores, but should these meals be high or low in simple sugars?

British researchers found that the glycemic index of a meal consumed between two intense bouts of endurance exercise (90 minutes at 70 percent of maximum effort, on two con­secutive days) had no effect on the depletion rate of muscle or liver glyco­gen. Glycemic index is a measure of how fast foods increase blood sugar. High-glycemic index meals are high in simple sugars, while low-glycemic index meals contain more complex car­bohydrates and fats. During the second exercise session, intramuscular fat use during exercise was higher following the high-glycemic index meal. This was an interesting and sophisticated study, but we need more research on the influ­ence of diet during repeated days of intense exercise.