Glycogen is an important stored form of glucose that is used as an energy source during intense exercise. When glycogen stores are depleted through exercise, athletic performance decreases. The document discusses how adjusting carbohydrate intake before, during, and after exercise can help athletes increase and maintain glycogen levels, improving endurance and performance. Specifically, it recommends that athletes consume high carbohydrate meals before exercise to replenish liver and muscle glycogen, and that they consume carbohydrates during long exercises to avoid depletion. After exercise, consuming carbohydrates helps to optimize glycogen synthesis and replenish stores.

1. Glycogen and Athletic Performance
Richard A. Wang, MPH
NuLiv Science USA Inc
It is well known that prolonged and sustained high intensity exercise causes glycogen depletion in
individuals. As a result, the macro nutrient intake for active persons and athletes must be dramatically
different from those who are sedentary. This article will provide a brief overview of glycogen and the
functions it serves, as well as how it affects endurance and exercise performance. Using recent literature
and research as a reference, glycogen intake recommendations for athletes will also be discussed.
Put simply, glycogen is a polysaccharide of glucose. Glucose is obtained through the breakdown of
simple and complex carbohydrates such as corn, sugar, wheat and vegetables. Because of its availability,
glucose is one of the main sources of energy for the body. Glycogen is a much more space-efficient form
of glucose, therefore it is stored primarily in the liver and muscle cells. When performing high-intensity
exercise, your body uses these glycogen stores for energy first then starts burning triglycerides
(fats/lipids). It is estimated that glycogen concentration is around 1-2% in most individuals, although this
concentration can be increased through physical training. Increasing glycogen concentration allows
athletes to increase muscular endurance and performance.
By adjusting the frequency, amount and timing of carbohydrate intake, athletes can prevent glycogen
depletion and increase their endurance. For athletes performing long duration events such as marathon
runners and cyclists, the technique of supercompensation has been proved beneficial.
Supercompensation involves “swelling” muscle glycogen by changing diet and exercise patterns several
days before a major competitive event. Currently, there are two methods that can be use to accomplish
this: depletion/repletion, and the modified moderate approach.
The depletion/repletion approach involves depleting glycogen reserves as much as possible using a low
carbohydrate diet in combination with long bouts of exercise about 7-10 days prior to competition. On
the third day, carbohydrate intake is increased and studies have shown that glycogen stores can be
increased by as much as 50%. The modified moderate approach is a little less extreme – carbohydrates
are increased while training is tapered. This can lead to increases in glycogen storage of around 20%.
Glycogen depletion training works well for athletes who compete in one-time long distance events, but
is not recommended for those who perform consecutive competitions. For these athletes, proper
manipulation of carbohydrate availability before, during, and after training is very important. Most
strength and performance coaches advise that athletes should consume a high carbohydrate meal 3-5
hours before physical activity. This will increase liver and muscle glycogen stores that are decreased
after an overnight fast. It is estimated that 50% of liver glycogen is decreased after an hour of exercise at
75% V02 max.

2. Carbohydrate consumption during exercise that lasts longer than 45 minutes can also improve
performance. This helps athletes maintain blood glucose levels, spare liver glycogen, and increase their
motor skills. Most athletes prefer to ingest simple carbohydrates by drinking sports drinks, eating
granola bars or bananas.
Replenishing glycogen stores after exercise is extremely important. The rate of glycogen synthesis
depends on glucose transport to the muscle and the enzymes involved in glycogen synthesis. To
optimize glycogen synthesis, carbohydrates should be ingested within two hours of high intensity
exercise. Ideally, you should consume 0.7-1.0 grams of carbohydrates per kg every two hours. These
carbohydrates should be complex – rice, vegetables, oatmeal, quinoa, etc.
Supplementing with intra & post recovery products may also aid in glycogen storage and enhanced
sports performance. ActiGin has proven in a human clinical (pending publication in peer reviewed
journal) to activate more glycogen synthesis in muscle tissue, enabling prolonged peak endurance.
In conclusion, an athlete’s carbohydrate and glycogen storage can have a huge effect on their endurance
and performance. By modifying and adjusting carbohydrate levels, the optimal diet for athletes can be
achieved and their training will surely benefit.
References:
Berardi, J.M., et al (2006) Postexercise Muscle Glycogen Recovery Enhanced with a Carbohydrate -
Protein Supplement. Medicine and Science in Sports and Exercise. 38(6): 1106-13
Hawley, J.A. (2014) Manipulating Carbohydrate Availability to Promote Training Adaptation. Sport
Science Exchange. 27(134): 1-7
Rapoport B.L. (2010) Metabolic Factors Limiting Performance in Marathon Runners. PLoS Comput Biol
6(10): e1000960. doi:10.1371/journal.pcbi.1000960
Rodriguez, N.R., et al. (2010). Nutrition and Athletic Performance. Web arti cle [accessed on October 15
2014]