Eating and drinking just before your race: The best time to take sugar to help you prolong your intense exercise is 30 minutes or less before you start. Taking a sugar load more than 30 minutes before competition can cause a high rise in blood sugar which, in turn, causes your pancreas to release huge amounts of insulin.
Then you start your race with high insulin levels that, combined with your muscle suddenly pulling large amounts of sugar from your bloodstream, can cause low blood sugar levels that can make you feel exhausted even though you have just started your race.
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).
The researchers showed that taking sugar two hours before exercise does not help you to sustain intense exercise any longer than taking nothing at all. You can even take chocolate because it contains both sugar and caffeine.
Eating and drinking during competition: Athletes start to run out of their sugar stored in muscles after 70 minutes of intense competition, so you need to take sugar during endurance sports that last longer than 70 minutes (Medicine & Science in Sports & Exercise, July 2010). However, you can exercise at a relaxed pace for more than 3 hours without needing sugar.
Caffeine can increase the rate that sugar enters muscles by more than 26 percent (Journal of Applied Physiology, June 2006), so most athletes take their sugared dinks and foods with some source of caffeine. Ordinary beverages containing both sugar and caffeine are fine; there is no need for special sports energy drinks or gels. Caffeine improves endurance
Caution: on very rare occasions, caffeine can cause some susceptible people to develop irregular heartbeats.
Endurance Events That Last More than Three Hours
In endurance events lasting longer than three hours, you need carbohydrates, protein, fluid and salt. In addition to rich sources of sugar (sugared drinks, fruit, chocolate bars), you can eat heavily-salted potato chips, French fries, any sandwich of your choice, or anything else that you normally eat, as long as it does not make your stomach feel uncomfortable.
NO Sugared Drinks When You Are Not Exercising Intensely
You should take sugared drinks only during vigorous exercise and for up to an hour after you finish. Contracting muscles remove sugar from the bloodstream rapidly without needing much insulin. Taking sugared drinks when you are not exercising causes higher rises in blood sugar that increase risk for diabetes and cell damage. http://drmirkin.com/nutrition/sugared-drinks-cause-fatty-liver.html
Eat Carbohydrates and Protein to Recover Faster
You will recover faster by eating a high carbohydrate, high-protein meal within an hour AFTER FINISHING a race or a grueling workout, but taking the same high-protein-and-carbohydrate meal before a race or intense workout does not hasten recovery (Journal of Applied Physiology, May 2009).
Carbohydrates in the post-race meal cause a rise in blood sugar that causes the pancreas to release insulin. Insulin drives the protein building blocks (amino acids) in the meal into muscle cells to hasten healing from intense workouts.
Muscles are extraordinarily sensitive to insulin during exercise and for up to an hour after finishing exercise, so the fastest way to recover from intense workouts and races is to eat a protein- and carbohydrate-rich meal during the last part of your workout or within an hour after you finish. You can use either plant or animal sources of protein; both contain all of the essential amino acids necessary for cell growth.
The only mineral that you need during long endurance events is salt. The food you eat will supply all the potassium, calcium, and magnesium you need. You should eat salty foods during and after you finish long rides and races.
No Advantage to Restricting Sugar During Intense Training
The question had been asked whether restricting sugar during training could enhance performance by teaching the muscles to get along with less sugar. The enzymes used to convert sugar and fat to energy function just as well when sugar is taken continuously during exercise.
A study from Copenhagen, Denmark, shows that taking sugar while you exercise increases the amount of training you can do, and does not lessen the benefits of your increased training (Journal of Applied Physiology, June 2009). In this study, men trained one leg while ingesting a 6 percent sugar drink and the other leg while taking an artificially sweetened (sugarless) drink, two hours a day, on alternate days, five days a week. The legs trained with sugar had 14 percent more power and a 30 percent greater time to exhaustion. The muscles trained on sugar have no loss in the amount of stored sugar or the ability to convert food to energy.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.