Glycogen

Glycogen is the major source of stored carbohydrates in the body.

Glycogen is stored in both the muscles and the liver.  It fuels muscles, supplies glucose to the brain, and burns fat. 

Exercise depletes glycogen stores, and a high carbohydrate diet replenishes glycogen stores.  Glycogen storage capacities vary.  The more fit you are, the more glycogen your muscles can store when you eat a well-balanced high-carbohydrate diet.  Aerobic training can help to increase your storage. 

To perform optimally, we must have adequate stores of glycogen available for training and recovery from training sessions and competitions.  Without proper amounts of carbohydrates in our diets, we face glycogen depletion.  You may have encountered the symptoms of glycogen depletion during training, which can include the following:

  • heavy legs
  • loss of focus
  • a feeling that normal training seems more difficult than usual
  • dizziness and sluggishness
  • general fatigue
  • the need to stop your session because you feel empty
  • irritability and exhaustion
  • inability to be explosive (You might seem to have only one pace left.)

Glycogen is depleted most quickly with high-intensity exercise.  You can deplete your glycogen stores completely in a strenuous ninety-minute effort.  Glycogen can fuel up to two hours of moderate to intense exercise.   For such exercise, eat early and often.  Do not wait to start fueling your body until you begin to feel depleted and tired.  Refill the tank before your car stalls on the side of the road!


 
  Athletes should not limit carbohydrates in their diet.  Glycogen depletion can affect negatively the hormones involved in recovery, which can lead to injury.