Glucose and fructose are both rapidly digesting carbohydrates used by endurance athletes to refuel during extended duration training and competition. Does it make a difference which one you choose? If maintaining hydration is a consideration, the answer is yes according to a study published in the journal Medicine and Science in Sports and Exercise.

Researchers had 10 healthy young subjects consume a little more than 10 ounces of water or a solution containing 75 grams of glucose or fructose after sitting in 82 degree heat and before dangling their legs in 107 degree water. During these events, insulin levels rose to a greater degree with glucose compared to fructose, but sweat rate was significantly higher with fructose. Glucose intake produced a sweat rate similar to water.

True Strength Moment: Whether exercise produces the same results is unknown, but because fluid loss amounting to just 2% of your body weight can impair athletic performance, this study might offer a potential competitive edge to cyclists, marathoners and other endurance athletes. Test a switch in carbs while training to see if it elevates your game.