The best time to take sugar to help you prolong your intense exercise is 30 minutes or less before you start. Researchers in Scotland showed that taking a sugared drink 30 minutes before exercise allowed the subjects to exercise at 90 percent of their maximum capacity for 12 percent longer than when they took the same sugared drink two hours before exercise (International Journal of Sport Nutrition and Exercise Metabolism, November 2013). They were able to sustain their intense exercise for the following times:
Sugared drink 30 minutes before exercise – 9 minutes
Non-sugared drink 30 minutes before exercise – 7.7 minutes
Sugared drink 120 minutes before exercise – 8 minutes
Non-sugared drink 120 minutes before exercise – 7.9 minutes
This shows that taking sugar two hours before exercise does not help you to sustain intense exercise any longer than taking nothing at all.
How long you can exercise intensely depends on how long you can keep blood sugar levels from dropping well below normal. The limiting factor to how fast you can move in athletic competition is the time it takes oxygen to get inside muscle cells. Sugar uses less oxygen than fat does to fuel your muscles, so if you can get your muscles to burn more sugar and less fat, you can move faster in competition.
• Your muscles burn both sugar and fat for energy.
• The faster you move, the higher the percentage of sugar and the lower the percentage of fat your muscles burn.
• Your muscles get sugar from the sugar stored in that muscle, from your liver, and from the sugar you eat just before or during exercise.
You have an almost infinite amount of fat stored in your body, but you have a very meager supply of sugar stored in the muscles and liver. When you run out of sugar during sports that require continued intensity, you will have to slow down.
A general rule of thumb is that all athletes need to take sugar in sports that require more than 70 minutes of intense exercise. This study shows that taking sugar two hours before competition does not provide any additional benefit. Other studies have shown that when you eat sugar before exercise, a small amount is stored in the muscles and liver as glycogen. After the muscles and liver are filled with a small amount of glycogen, all the rest of the sugar is quickly converted into fat.
This explains the failure of the outdated training strategy of “carbohydrate loading”, where athletes would gather the night before a big event and stuff themselves with pasta. They believed that they were storing huge amounts of sugar in their muscles. In reality, as soon as their muscles and liver had taken in the small amount they could hold, the rest of the meal was converted to triglycerides (fat) which just slowed them down.
The lesson to be learned from this study is that if you compete in sports that require more than 70 minutes of intense exercise, you should take some form of sugar just before or shortly after you begin your event, and continue to take in a source of sugar during your competition.