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Glycogen: The Muscle’s Fuel

George L. Redmon Ph.D. N.D.
558 Loch Lomond Drive-Sicklerville NJ08081-(H) 856-522-6331-(O) 856-419-9066

Those who are very active will require more carbs in their diets. Because glucose is stored in your body as glycogen, if intense muscle activity occurs- such as when you engage in intense heavy workouts, you can deplete your glycogen stores.
Dr. John Matsen, N.D.        

While it is common knowledge that protein is the key material the body uses for growth and repair, Dr. John Matsen  the author of Eating Alive II reminds us that when excess protein is consumed with too few carbs, that the body starts burning protein for fuel. Not only will this accelerate muscle fatigue and discourage proper recovery, it causes increased breakdown by-products referred to as nitrogen residue. This places an unnecessary burden on the kidneys to get rid of the excessive toxic remains. While protein within normal metabolic parameters plays a key role in detoxification, physiologically, carbs are a cleaner-burning energy source, and is the body’s first preference.

Carbohydrates also are the main macronutrient used to restore glycogen. Glycogen is the hormone that is responsible for the movement or utilization of fuel rather than its storage, as opposed to insulin’s tendency to store fuel(fat). For example, simple carbohydrates like sugar will quickly raise blood glucose which stimulates the secretion of insulin to stabilize this physiological mishap. In the process the excess sugar (carbs) is stored as fat and consequently accelerates the body’s use of glycogen.

The Body Builders Paradox

 As a bodybuilder who relies heavily on muscle energy, one of the worst things you can do is let your glycogen levels get to low or become depleted. In fact, Dr. Susan M. Kleiner who has worked as a nutritional consultant for the Cleveland Brown reminds us that during high-intensity strength training reps lasting only for 1 to 3 minutes, that muscle glycogen supplies about 95% of the fuel (energy) needed to complete this set. Equally, as cited by Dr. Kleiner the more carbohydrate left in the muscle at the end of a session, the longer you will be able to continue. While the body can’t store protein, glucose, your muscle’s primary energy source can be. In fact stored glucose known as glycogen is stored in the liver and in muscle tissue and is called upon when insufficient amounts of carbohydrates are consumed. Normally the muscles can store about 1,200 calories of glycogen and the liver and about 400 calories of glycogen. This is why researchers contend that to maintain muscle energy and to keep glycogen stores replenished that carbs need to be consumed before, during and at post-workout. In fact, the two well-known sports physiologist John Ivy and Robert Portman authors of The Performance Zone states that the greatest performance benefits have been found to occur when 50g-70 g of carbs are consumed per hour of exercise to restore diminished glycogen stores .

What The Research Tells Us

 In studies conducted at the University of Texas researchers found subjects who adhered to carbohydrate supplementation were able to exercise for 3 hours at a highly charged rate at 80% VO2 max ( maximal oxygen uptake) for 33 minutes as compared to 2 minutes by subjects who were administered flavored water. These researchers attributed this to carbohydrates ability to spare muscle glycogen. In a related study appearing in the Journal of Sports Science and Medicine investigators reported that muscle glycogen synthesis was more rapid when carbohydrates were consumed immediately following exercise as opposed to waiting hours later. If fact, these researchers found that when subjects delayed carbohydrate intake for several hours the rate of glycogen creation was reduced by 50%. Furthermore, recent data indicates that when carbohydrate supplementation occurs at 15 to 30 minute intervals rather than every 2 hours that muscle glycogen storage has been found to be 30% higher.

Moreover, Dr. Liz Applegate, a faculty member of the Department of Nutrition at the University of California and a Fellow of the American College of Sports Medicine reminds us that studies show when some form of carbohydrate is consumed ½ hour before working out can extended workout time and workload capacity, delaying what is commonly referred to as hitting the wall. Conversely, research conducted at Appalachian State University suggest that enhancing glycogen storage via carbohydrate supplementation heightens immunity.  For example, marathon runners were given 60 grams of carbohydrates at a rate of 1 liter per hour. These researchers found increased activity of key cells involved with immune preservation. Other studies indicate that maintaining adequate glycogen stores reduces muscle wasting by minimizing the production of cortisol. The more glycogen levels fall, the faster cortisol is released from the adrenal glands, with one purpose in mind, the breakdown of muscle protein for fuel. On the contrary, when glycogen levels increase brain and mental fatigue is greatly delayed.

The Protein Carb Connection

It is common knowledge that carbs with protein at post workout helps drive insulin into the muscle to speed recovery. The other aspect of this biological attribute not highly publicized shows that combining protein with carbs within 30 minutes of exercise increases glycogen storage. However, the ratio must be 4:1, (4g of carbs to 1g of protein). The problem here is the fact that higher protein ratio intake slows rehydration and glycogen replenishment. However, data indicates that when carbs and protein are consumed in the above ratio’s that there is a 100% greater storage of glycogen than consuming carbs alone.

Suggested Dose: to gauge your individual carb needs based on you, researchers suggest consuming 3g to 5g of carbs for every pound of your body weight. While current data indicates that most physically active people’s diet should be 60% to 65%, carbs, resistance training athletes may need a little more.                                   



About the Author:

Applegate, L. Eat Smart Play Hard. Rodale Publishing: Emmaus PA. 2001.
Ivy, J.L., Golorth, H.W., Early post exercise muscle glycogen recovery is enhanced with a carbohydrate –protein supplement. Journal of Applied Physiology. 2002 Oct; 93(4):1337-1344.
Ivy, J.L., Regulation of muscle glycogen repletion, muscle protein synthesis and repair following exercise.  Journal of Science and Medicine.  2004; 3: 131- 138.
Ivy, J., Portman, R. The Performance Zone. Basic Health: North Bergen NJ. 2004.
Kleiner, S.M., Greenwood-Robinson, M. High  Performance Nutrition. John Wiley and Sons: New York, 1996.
Matsen, J. Understanding Glycemic Load, Better Nutrition. 2004 Aug; 25-28.
Quinn, E., Eating After Exercise-What to Eat After a Workout. Sports Medicine. 2011 Feb. accessed on line 10-04-12. 
Williams, M.B., Raven, P.B., Effects of recovery beverages on glycogen restoration and endurance exercise performance. Journal of  Strength Conditioning and Research. 2003 Feb; 17(1):12-19.