Intense aerobic performance can be improved with full glycogen stores in the liver and optimal blood sugar levels. In addition, time of consumption can make all the difference in performance and assimilation of nutrients.
Physiology of Nutrient Storage
All muscles require pure glucose to perform work. The blood at any given time carries only 80 calories for performance of this work. In aerobic activities, 80 calories are usually used up in the first 15 minutes and if intense activity is performed, much sooner. In order to continue activity, one must tap their glycogen stores in the liver. The liver has the storage capacity of 300-400 calories. Since the digestive system takes up to three to four hours to replace glycogen stores once depleted, it is imperative that one eats following aerobic activities to replenish depleted stores.
When to Eat to Enhance Performance
It is important to eat well three to four hours prior to the performance of aerobic activity in order to achieve best performance. Eating right before an aerobic activity does not enhance performance. In fact, it may produce nausea, dizziness and general fatigue. The nervous system directs blood flow to the digestive system after eating. This dilatation of all the blood vessels surrounding the digestive system helps one to absorb nutrients. While the blood vessels are dilating around the digestive system they are constricted in other areas. Thus the muscles are not receiving peak blood flow for optimal performance when digestion is occurring. That is why the best athletes are those who eat well at each meal. It is best not to eat 90 minutes prior to intense aerobic activity.
Minimum Requirements for Intense Activity
Taking the physiology of minimum calories stored in the liver and the blood, if engaged in intense aerobic activity on a regular basis, a minimum of 480 calories of simple and complex carbohydrates should be ingested each day three to four hours prior to this activity for peak performance. Taking into consideration that a steady state aerobic activity by an aerobically fit individual uses fatty acid stores, the entire glycogen stores in the liver may not always be depleted with each exercise session. Fatty acids and oxygen fuel most steady state aerobic activities. However, it is not the depletion of fatty acids and oxygen that compromises aerobic performance, but the lack of blood glucose available to the muscle performing the activity.