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There are four components of muscle recovery: restoring fluid and electrolytes, replenishing glycogen, reducing muscle and immune stress, and rebuilding muscle protein. Nutrition is vital for each of them.

Only within the last decade has the issue of muscle recovery received focused attention in the athletic community. Previously, athletes, coaches, and sports scientists were more interested in refining training methods. But by the 1990’s, training methods had been refined to their limit in virtually every sport discipline. Consequently, people became increasingly interested in finding out what athletes could do between workouts that might enhance their performance.

The subject of post-exercise nutrition drew special scrutiny. The result was a revolution in the science and practice of muscle recovery. It was discovered that not only the selection of nutrients but also the timing of nutritional intake could have a major impact on muscle recovery, for better or worse. It was even found that nutrition during exercise could enhance muscle recovery afterwards. 

Unfortunately, however, many athletes have not taken advantage of this new information. Some have not been educated about the profound effect that smart post-exercise nutrition can have on performance. Others have a general idea that they should pay attention to muscle recovery, but they have not been shown the proper methods.

There are four components of muscle recovery: restoring fluid and electrolytes, replenishing glycogen, reducing muscle and immune stress, and rebuilding muscle protein. Let's look at the role nutrition plays with respect to each component and specific guidelines for post-exercise nutrition intake.

Restoring Fluid and Electrolytes 

During exercise, water and certain minerals called electrolytes are expelled from the body through perspiration. The function of perspiration is to prevent body temperature from rising during exercise, which is important, but it comes at a cost, because water and electrolytes serve important functions within the body that they can no longer serve when they are lost. The more water the body loses, the less effective the “cooling system” of perspiration becomes. Meanwhile, the electrolyte minerals sodium, magnesium, and potassium are needed for a variety of processes ranging from nutrient transport to nerve transmission.

Consuming a sports drink containing water and electrolytes during exercise is an effective way to counteract the effects of sweating. However, it is simply impossible to restore fluid and electrolytes as quickly as they are lost during moderate- to high-intensity exercise. Athletes must therefore make up the balance by continuing to drink after completing exercise.

By weighing themselves (preferably on a scale with pounds and ounces) immediately before and after workouts, athletes can determine the amount of fluid depletion they have experienced. They should drink at least this amount of fluid in the first 30 to 45 minutes after completing a workout. Water will only do half the job. Sports drinks are a better choice because they are formulated to replace water and electrolytes in approximately the same ratio in which they are lost in sweat.

After water and electrolytes have been fully restored, athletes can switch to water for their everyday hydration needs. They can obtain minerals through food sources.

Replenishing Glycogen 

The primary fuel sources for moderate- to high-intensity exercise are glycogen stored in the muscles and liver and glucose carried to working muscles through the blood. Both glycogen and glucose are products of carbohydrate breakdown, and for this reason they are often referred to collectively as “carbohydrate fuel”.

Blood glucose is available in much more limited amounts than muscle and liver glycogen, but it can be replenished much more rapidly. It takes many hours to replenish glycogen through carbohydrate consumption, while it takes only about 20 minutes for the sugars consumed in a sports drink to pass through the stomach and become broken down into glucose in the bloodstream.

Consuming carbohydrate during exercise is essential for prolonging endurance. While an athlete cannot consume enough carbohydrate to completely halt the use of glycogen for energy, he or she can consume enough to slow its depletion significantly. Research has shown that most athletes can ingest carbohydrate at a maximum rate of 1.2 grams per minute without suffering gastrointestinal distress. But athletes can burn glycogen at more than three times this rate while exercising at near anaerobic threshold intensity. Hence, the longer an athlete exercises, the more glycogen-depleted he or she will be afterwards despite efforts to consume as much carbohydrate as possible during the workout or competition.

After exercise, the sooner the athlete begins to replenish muscle glycogen by consuming carbohydrate, the better. This is because, following exercise, the muscle cells are much more receptive to insulin, the hormone responsible for transporting glucose through the bloodstream to the liver and muscles, where it can be stored as glycogen. The body can synthesize glycogen two to three times as fast during the first two hours after exercise than it can at other times.

How much carbohydrate is needed? As a general guideline, athletes should try to consume about one gram of carbohydrate per pound of bodyweight during the first two hours of exercise. Most or all of this carbohydrate should be high-glycemic, because high-glycemic carbohydrates stimulated greater insulin release and are therefore delivered to the muscles and liver more quickly than their low-glycemic counterparts. Examples of high-glycemic carbohydrate food sources are bagels, baked potatoes, bread, Cornflakes, and raisins.

To stimulate even greater insulin release, athletes should consume about one gram of protein for every four grams of carbohydrate they consume in the two hours following exercise. For example, a 160-lb. athlete would want to consume approximately 160 grams of carbohydrate and 40 grams of protein in the first two hours after exercise. Eating more than this amount of protein will have the opposite effect, impeding glycogen replenishment by slowing gastric emptying, as will eating more than a very small amount of fat or fiber.

Most athletes are not particularly hunger right after a workout or competition. For this reason, the most practical way to kick-start glycogen replenishment following exercise is by drinking a sports drink containing carbohydrate and protein in a 4:1 ratio. In recent tests, a sports drink featuring this 4:1 ratio (Endurox R4) increased insulin levels in athletes 70% more after a workout than a conventional sports drink that contained no protein. It also increased endurance by 55% in the next workout.

Reducing Muscle and Immune System Stress

In the long-term, sports training strengthens muscles and the immune system. However, individual workouts damage muscles and can temporarily suppress immune system function. Fortunately, proper sports nutrition can minimize these effects and accelerate recovery from them.

Every athlete has experienced muscles soreness after training and, especially, competing. There are no fewer than three known causes of post-exercise muscle soreness. The primary cause is mechanical stress, which is an accumulation of microscopic tears to muscle fiber membranes and protein filaments that happen as a consequence of repetitive, intense muscle contractions. The body’s efforts to repair such damage entail increased blood flow to the area, and with increased blood flow comes inflammation, and with inflammation comes soreness.

A second cause of post-exercise muscle soreness is oxidative stress, also known as free radical damage. Oxygen is a highly reactive type of molecule. During intense exercise, an athlete’s rate of oxygen consumption increases dramatically. Many of the individual oxygen molecules consumed during exercise lose an electron and become freed radicals inside the body. These molecules are extremely unstable and must regain stability by pilfering an electron from a muscle cell membrane, thereby damage the muscle cell.

The hormone cortisol has also been linked to muscle cell damage. Cortisol is a hormone released by the adrenal glands in response to all forms of stress. Its main function is to release amino acids from muscle proteins and transport them to the liver for use as an energy source. The release of cortisol tends to occur in the latter portion of long workouts, when the preferred glycogen energy source has been depleted.

In addition to damaging muscle cells, cortisol suppresses immune system function by decreasing production of lymphocytes and antibodies. Several studies have shown a temporary (2-72 hours) decrease in immune system function in athletes following hard exercise, and cortisol is thought to be the primary culprit.

How can sports nutrition fight these negative effects of exercise? The best way to limit the release of cortisol is by consuming carbohydrate during and immediately following exercise. By doing so, athletes maintain higher levels of blood glucose, which slows the use of muscle glycogen and delays the need for the use of protein as an energy source. Again, consuming carbohydrate with protein in a 4:1 ratio can yield even more pronounced benefits by accelerating the delivery of glucose to the muscles. In one study, a 4:1 sports drink (Endurox R4) reduced post-exercise muscle damage 36% more than a conventional sports drink containing no protein.

Athletes can reduce oxidative stress by consuming a diet high in antioxidant vitamins and minerals such as vitamins A, C, and E, beta-carotene, and selenium. Several studies have shown that vitamin C supplementation reduces post-exercise muscle soreness in athletes and that vitamin E supplementation has a similar effect on indicators of post-exercise muscle damage. One way athletes can get extra antioxidants in their diet is by using a sports drink that contains them in high amounts.

Rebuilding Muscle Protein

Although not a preferred fuel source, protein is used to produce energy during prolonged exercise when muscle glycogen runs low. This process is known as catabolism. Furthermore, the high blood concentration of cortisol that is associated with catabolism also obstructs the rebuilding of muscle protein by diverting its amino acid building blocks to the liver. Because protein is an important structural element of muscles, catabolism leaves the muscles in a weakened state afterward. In order to properly recover from and adapt to this particular training stress, athletes must act quickly to rebuild muscle protein after exercise.

Earlier we discussed a physiological window of opportunity for glycogen replenishment in the two-hour period immediately following exercise. A very similar window exists for protein rebuilding, and for the same reason. Insulin is responsible for delivering both glucose and protein to muscle cells. After exercise, the muscle cells are highly receptive to insulin. In a study performed at Vanderbilt University, subjects were fed a protein-carbohydrate supplement either immediately after working out or three hours later. Members of the “early” group were found to have synthesized new muscle proteins at a much faster rate than members of the “late” group.

In a similar study, this one done at the University of Texas, subjects who consumed an amino acid-carbohydrate supplement immediately before exercise synthesized even more new muscle protein than subjects who consumed the same drink immediately after the workout. (Amino acids are the building blocks of protein.) The apparent reason for this result was that drinking the amino acid-carbohydrate drink before the workout resulted in higher blood insulin levels during the workout. Insulin is known to counteract the catabolic effect of cortisol. With greater amounts of insulin circulating to neutralize cortisol, the subjects who drank before working out were able to get more amino acids delivered to their muscle cells to rebuild proteins.

What this means is that nutritional recovery measures need to begin before workouts, or at least during them, and continue afterward. By consuming a sports drink containing carbohydrate and protein/amino acids before, during, and after workouts, athletes can ensure that their muscle proteins are rebuilt with maximum efficiency. Using a recovery drink that consists of large amounts of protein or amino acids and little or no carbohydrate is not as effective, however, because these drinks digest more slowly and result in far less insulin release than recovery drinks that contain carbohydrate and protein in the ideal 4:1 ratio.