The Role of Sugar and Caffeine During Competition

Tour of California 2008
Once again, Dr. Gabe Mirkin gives us valuable evidence-based recommendations for nutrition and competition. Here's his blog reposted with permission.

Sugar and Caffeine for Competition

By Dr. Gabe Mirkin

The limiting factor to how fast you can move during a race is the amount of oxygen that you can take in and use. Since sugar requires less oxygen than fat to power your muscles, you want to get as much sugar into your muscles as quickly as possible. Anything that increases the amount of sugar that can be absorbed from your intestines into your bloodstream will help you ride or run faster and longer. Sugar is carried across your intestinal tract into your bloodstream by special protein transporter molecules. Glucose has its own specific transporter protein and so does another sugar, fructose. So your muscles use 165 percent as much sugar when you take in glucose and fructose, compared to taking in only glucose. To put it another way, when you take in drinks that contain only glucose, your muscles can absorb and use only one gram sugar per minute, compared to 1.75 grams per minute when you take a drink that contains both glucose and fructose (Current Opinion in Clinical Nutrition and Metabolic Care, July 2010). Furthermore, adding caffeine to a drink can increase absorption of sugar into the bloodstream by as much as 26 percent (Journal of Applied Physiology, June 2006). The most effective drinks for endurance competition therefore may be those that contain glucose, fructose and caffeine, such as are found in many carbonated drinks. These drinks are safe during exercise because contracting muscles can prevent a high rise in blood sugar levels by drawing sugar from the bloodstream without needing insulin. However, when you are not exercising, these drinks can cause very high rises in blood sugar, increasing risk for obesity and diabetes. To learn more about Dr. Mirkin and to read this blog on his website, please visit: