Dr. Gabe Mirkin's Fitness and Health E-ZineOctober 23, 2011
Muscle Sugar: Train Low, Compete High
Athletes who compete in sports requiring endurance can run or cycle faster by training their muscles to burn more sugar and less fat. Muscles use carbohydrates, fats and proteins for energy. The faster you run or cycle, the greater the percentage of sugar your muscles burn. The percentage of sugar to fat that a muscle burns is determined by enzymes in muscles that turn sugar into energy.
DEPLETION INCREASES SUGAR-BURNING ENZYMES: An athlete can increase the muscle enzymes that turn sugar into fuel by training part of the time when his muscles are low in sugar stores. Several studies have shown no benefit in performance in athletes training most of the time with low muscle sugar levels. Training all the time with low muscle sugar forces an athlete to train too slowly. An athlete is only as fast as his fastest intervals in training, so training slowly all the time would prevent an athlete from moving very fast in competition.
DEPLETION TREATS DIABETES: Several studies show that training with low muscle sugar can also help treat and prevent diabetes and obesity by depleting muscle cells first of sugar, and then of fat. Having low fat stores in muscles markedly increases the body's ability to respond to insulin and helps to lower high blood sugar levels.
HOW TO DEPLETE: You can teach your muscles to burn more fat and less sugar by: * training after skipping breakfast; * training twice a day with the second daily workout with muscles with low stored sugar, restricting carbohydrates in your diet during training; * taking prolonged workouts that empty your muscles of stored sugar; or * withholding carbohydrates after a hard workout. The key is to train with low amounts of stored muscle sugar and race with muscles full of stored sugar (Exercise and Sport Sciences Reviews, October 2010).
FOR RACES, KEEP MUSCLES FULL OF SUGAR: Hundreds of research papers show that you can increase endurance and intensity in competition by filling your muscles with sugar before you compete and then taking sugar during competition. The most efficient fuel for muscles during exercise is carbohydrates (sugar). The limiting factor for how fast you can move is the time it takes to move oxygen into muscles. Since sugar requires less oxygen than protein and fat, you move faster when muscles burn primarily sugar. How far you can run, cycle, ski, or skate depends on how much sugar you can store in your muscles before you start exercising and how long you can keep the extra sugar there. When muscles run out of their stored sugar, muscles hurt and you feel tired.Athletes in endurance events are told to cut back on their training three days before major competitions and eat extra carbohydrates. This fills their muscles with extra sugar. Then they are told to take sugar during competitions to keep up a regular sugar supply for their muscles.
TRAINING FOR MAXIMUM SUGAR USAGE: If athletes could use a special training technique to make their muscles burn a higher percentage of sugar during competition, they could go faster. They can do this by emptying their muscles of stored sugar during training. This forces muscles during training to burn a higher percentage of fat. However muscles compensate for this by trying to burn more sugar. They increase the concentration of enzymes that help to convert sugar to energy. Higher levels of sugar-burning enzymes cause muscles to burn more sugar during races. You should not try to exercise every day with low muscle sugar stores. It will make you tired all the time, slow you down and increase your chances of injuring yourself.
STRESSING AND RECOVERING: Knowledgeable athletes train by stressing and recovering. They take a hard workout on one day, feel sore on the next, and then take easier workouts until the soreness disappears. They should take very intense workouts up to three times a week, rarely on consecutive days. These intense workouts should be taken with muscles full of sugar. So you eat before your intense workouts and can even take sugar during your prolonged intense workouts. However, on your four recovery days, you may want to start your workouts without eating breakfast. If you feel excess fatigue, your muscles hurt or you have little energy, shorten your workout. If you find that you are fatigued too often and take too long to recover from workouts, abandon this training technique. It is not for you. You probably have to take in a lot of sugar during training just to keep up the intensity and volume of work that is required to be a competitive athlete.
CAUTION: If you are training with low muscle sugar stores and you feel discomfort in your muscles that worsens as you continue exercising, stop immediately. You are at high risk for an injury because muscles depleted of their stored sugar are much weaker than those full of sugar and are far more likely to become injured.
