If you’re a baby boomer or even if you aren’t, you’ve probably heard that the best way to get ready for exercise, particularly exercise of long duration—such as a 10-mile run—is by loading up on carbohydrates. Even today, many dietitians continue to recommend eating pasta before an event to fill muscle stores with glycogen, based on the theory that you can run longer if you’ve got more “fuel in your tank.”
Like many “truths” in nutrition, this recommendation is evolving. No one can dispute the fact that taking in extra low-glycemic carbohydrates for a day or three prior to endurance competition will help fill up your muscles with glycogen, which acts as a “fuel reserve” for long-distance events. But that does not mean that a high-carbohydrate, high-starch meal, such as pasta, is just the thing to eat a couple hours before hitting the track, gym or playing field.
Quite the contrary. Research from Loughborough University in England shows that athletes in sporting events lasting more than a couple hours may benefit more from a pre-competition low-glycemic meal.
Why? Because it takes up to 24 hours to fill your muscles with glycogen (storage sugar), so the pre-event meal is not used for that purpose. The new study showed that a low-glycemic meal taken three hours prior to competition might help an athlete exercise longer by causing his/her muscles to use more fat for energy. By using more fat (and less sugar), that stored glycogen is preserved for later use, letting the athlete run longer without fatigue.
The other problem with a meal high in refined carbohydrates (typically pasta or sports drinks with high sugar content) prior to an athletic event is that it will raise insulin substantially. This easily can lead to a “crash” in energy right when you need it most. The high levels of insulin—plus the demands of the muscle cells—may bring down blood sugar too low, just when you need fuel and energy to keep on going.
Forward-thinking nutritionists have long reminded athletes that fat—not carbohydrates—is the best fuel for long-distance events (including, by the way, eight hours of recreational activity with the family!). For this reason, a meal that promotes a steady burning of fat for fuel is exactly what’s needed. The latest study is just one more confirmation of the many benefits of eating “low-glycemic” meals and snacks, a principle that’s at the foundation of Atkins.