During intense or long duration exercise periods the muscles and liver often become glycogen depleted. Glycogen is comprised of carbon (C), oxygen (O), and hydrogen (H), all molecules extracted from the carbohydrates or sugars we eat. When carbohydrates are eaten, through a specific metabolic process, the COH are broken off from these foods and reassembled in the muscles to form glycogen. Glycogen is used for short bursts of energy. The more glycogen you have the more short bursts you can perform in your weight workouts, tennis matches, etc.. And the more short bursts you enact in your training, the more glycogen is being depleted. When you fatigue from exercise, you can bet you’re low in glycogen.
The best time to replenish glycogen is immediately after a workout--I mean immediately. This is the time when your muscles are drained of their energy, glycogen that is. And the first metabolic objective mother nature has encoded is to replenish lost energy. Once energy is repleted the body shifts to a tissue repairing metabolism, also known as anabolism, which stands to reason why protein meals should follow carbohydrate meals. This refueling method increases the energy and performance for your upcoming workouts right after your last; it’s filling up you car with gas when it’s out of fuel but not necessarily going to drive it for some time. But the next time you get into your car you have a full tank of gas and can travel much farther by avoiding any unnecessary pit stops to refuel.
Waiting to consume a carbohydrate meal or drink as much as 15 - 30 minutes after exercise can dramatically narrow this glycogen repletion window of opportunity. And those who do not eat or drink a carbohydrate meal immediately after a workout are missing the ultimate opportunity to refuel themselves.
The best ways to restore glycogen is by consuming simple carbohydrates as exercise sessions are closing and (again) immediately afterwards. If you’re performing any type of marathon training sessions, or involve yourself in any other types of long activities, sip on carbohydrates frequently throughout, then after these sessions.
Carbohydrate drinks have become popular due to their convenience and taste. These products are high in the good simple carbs and are ingested very rapidly into the body. With their high glycemic response, simple sugars taken at these opportune time will combine with insulin and be shuttled into the muscles then the liver. If these carbs are taken outside the perimeters of training or exercise periods, excess body fat may develop as the muscles [most likely] will have already become filled with their glycogen needs and any spill over may accumulate as adipose tissue.
Although there are plenty of good carbohydrate drinks on the market, in my opinion, the best ones contain long chain glucose polymers, sugars with a special configuration and glycemic rating. After some simple carbs are consumed, complex carbohydrates should be eaten for the first two meals after each workout. Some great food sources of complex carbohydrates are rice, potatoes, grains, pastas, and beans.
Your protein window of opportunity begins approximately 60 - 90 minutes after exercise cessation and lasts for many hours thereafter--this depends on the intensity of the workout. Since exercise depletes glucose and glycogen, the body’s most immediate nutritional need after exercise is [again] carbohydrate.
After that, consume your protein as the body is switching from a fuel replenishing phase into a tissue rebuilding phase also know as anabolism. Never consume a protein food or drink to close to a workout. Protein, at this point, will not act as a fuel source for your workout and may hinder performance.