During exercise, your body converts your stores of glycogen into much-needed energy. However, this means that your endurance is limited by your glycogen reserves, and your body must replenish its depleted glycogen stores following your exercise. To effectively manage your glycogen, you must focus on your glycogen levels both before and after working out.
Glycogen Basics
Glycogen is the form your body uses to store glucose or sugar. Your body produces glycogen when your blood sugar level is high. Conversely, your body converts glycogen back into glucose when your blood sugar level is low, a process known as glycolysis. This process produces small amounts of energy that help fuel your body during intense or prolonged exercise. Glycogen is stored in your liver and muscle tissues. Aerobic exercise primarily targets liver glycogen, while anaerobic exercise primarily targets muscle glycogen.
Immediate Glycogen Replenishment
Replenishment of your glycogen levels is most pronounced during the two hours immediately following your workout. During this window of opportunity, you can get a jump on restoring your glycogen to pre-exercise levels. The most effective type of carbohydrates to utilize during this initial phase is simple sugars. This is because they are rapidly released into your bloodstream, maximizing their impact during the short, two-hour window.
On-Going Glycogen Replenishment
After the two-hour window, glycogen synthesis will slow down. Normally, your body will replenish around 2 percent of your glycogen per hour. However, by consuming 50 grams of carbohydrates every two hours, you can increase this rate to around 5 percent per hour. By doing so, you will enable your body to recover to pre-exercise levels of glycogen within 20 to 24 hours. During this time, you will want to consume complex carbohydrates, rather than simple sugars. Complex carbohydrates, or starches, are released more slowly into your system. Simple sugars can overwhelm your body’s capacity to synthesize glycogen, causing the excess sugar to be converted into fat.
Types of Carbohydrates
There are two basic types of simple sugars: fructose and glucose. Glucose is used to replenish muscle glycogen, while fructose replenishes liver glycogen. Therefore, for anaerobic workouts, you will want to focus on glucose supplements. For aerobic workouts, which target your liver stores of glycogen, you will want to focus on fructose supplements. You can also utilize disaccharides, which are combinations of simple sugars. However, be aware of what types of simple sugars your disaccharides are made of. After the two-hour window, polysaccharides are your best choice. You should avoid fructose as it can lead to weight gain.
Boosting Glycogen Before Exercise
Carbohydrate loading will help boost your levels of glycogen before exercise, thereby boosting your endurance. A high-carb diet that contains at least 60 percent carbohydrates will be sufficient. Super glycogen saturation is a process used by professional athletes to deplete their glycogen reserves and then consume a high-carb diet for two to three days before competing. However, this approach can be dangerous without proper training and should not be used more than three times a year or by adolescents.
References
- Exercise Prescription: Glycogen
- Stanford University School of Medicine: Glycogen
- The Sports Journal; Glycogen Replenishment After Exhaustive Exercise; Gregory Tardie, Ph.D.
- SageWood Wellness Center; Glycogen Depletion During Athletic Exercise; Mario I. Martos
- Fitness for One and All; Carbs and Glycogen; Gary Zeolla
- GlycoCharge: Rapic Glycogen Replenishment
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