by Dr. Gabe Mirkin, M.D.
Exercisers spend more than 7.5 billion dollars a year on sports drinks and sports foods because they think that they will help them exercise, train and compete better, faster and longer.
Here are my recommendations for taking food and drink during intense exercise or competition:
LASTING LESS THAN AN HOUR: fit athletes do not need to take any food or drink, except they may need water in warm weather.
LASTING MORE THAN AN HOUR: Take sugared drinks just before you begin and frequently during intense exercise.
LASTING MORE THAN THREE HOURS: Take sugared drinks before you begin and frequently during intense exercise. Eat the food of your choice (fruit or sugar- added foods such as whole grain bars, etc.), plus a source of salt. We use potato chips or peanuts. You cannot get enough salt in a drink because it would taste awful.
LASTING MORE THAN FIVE HOURS: You need water, sugar, salt, and protein. Up to ten percent of the energy to power your muscles during exercise is supplied by protein stored in muscles.
However, you do not lose enough muscle to harm performance during exercise until you have been exercising for more than five or six hours, so you do not need to take a protein food to improve performance during exercise until you have been exercising for about five hours. Protein sources include whole grain bars, nuts, meat, fish, chicken, or dairy products.
I eat whole grain bars that contain a lot of sugar and some protein just before, and sometimes during, all races lasting more than an hour.
WHY YOU NEED SUGAR DURING INTENSE OR PROLONGED EXERCISE?
How fast you can move is limited by the time it takes to bring oxygen into muscles. Since sugar requires less oxygen than fat or protein, you move faster when muscles use sugar for energy.
You have an almost infinite amount of fat for your muscles to burn for energy, but a very limited amount of sugar stored in your muscles and liver. Top athletes start to run low on sugar after an hour of intense exercise. You may start to run out of sugar before then. The only signal you will get when you start to run out of sugar is that you will slow down and have to work harder to go slower because burning mostly fat for energy will increase your oxygen requirements. Also, your muscles may start to hurt, and you may start to feel very tired.
WHY YOU NEED SALT
Even on the coldest days, you sweat when you exercise and as you keep on exercising, you will eventually run low on salt. The first sign may be slowing down as lack of salt weakens muscles. You may also suffer muscle cramps.