When athletes consume carbohydrates before running for a long time, higher rates of carbohydrate use and insulin release are linked to less decline in the brain's ability to fully activate muscles during the run.

Eating a meal with 1.5 grams of carbohydrate per kilogram of body weight before running for 90 minutes helps maintain muscle strength and nervous system drive during the run better than eating a meal with 0.8 grams per kilogram, and leads to higher use of carbohydrates for energy and a stronger insulin response.

When you exercise for a long time (over 2-3 hours), it's actually having low blood sugar that makes you feel tired and stop exercising—not your muscles running out of stored energy.

Eating high glycemic index carbohydrates before running may help maintain muscle strength, neural activation, and tryptophan levels during prolonged exercise, and lead to higher rates of carbohydrate burning and insulin release compared to low glycemic index carbohydrates.

If you eat before working out, your blood sugar and insulin levels spike more during exercise than if you work out on an empty stomach.

After eating, when adults go for a moderate workout, their bodies burn more carbs over the next 24 hours but don’t burn any more fat — meaning meals push the body to use carbs for energy instead of fat, even with exercise.