By Leslie Bonci
Leslie Bonci, MPH, RD, is Director of the Sports Medicine Nutrition Program at the University of Pittsburgh Medical Center Health System, and a consultant to the University of Pittsburgh Department of Athletics, the Pittsburgh Steelers, Pittsburgh Ballet Theater, and several Pittsburgh-area high schools.
Training & Conditioning, 10.6, September 2000, http://www.momentummedia.com/articles/tc/tc1006/refuel.htm
If you ask any athlete about the most important role of eating for performance, the pre-game meal is the most frequently mentioned. Pre-exercise fuel can delay fatigue and improve performance (see “Event Eating” in T&C May/June 2000), but just as important is post-exercise fueling. Eating after strenuous exercise is vital for achieving the optimal recovery that enables an athlete to compete again, whether it be in two or 24 hours. Making recovery eating a planned, scheduled component of training—with the appropriate amount of nutrients delivered in a timely, efficient manner—should be a priority for all athletes. That athletes cite it less often makes it that much more important that post-exercise fueling be discussed and reinforced with both athletes and their coaches.
Exercise depletes muscle and liver glycogen stores, dehydrates the body, and increases the likelihood of muscle damage. The effects of these byproducts are cumulative and insidious. An athlete may not be aware that he or she has reached suboptimal fluid and glycogen levels until performance is adversely affected, fatigue becomes difficult to ignore, or weight loss occurs. If an athlete exercises while depleted or dehydrated, not only does performance suffer, but the risk of soft-tissue injuries increases. Post-exercise fuel in the right combination and at the appropriate time, however, can assist in muscle tissue repair, resynthesis of muscle and liver glycogen stores, and restoration of normal hydration.
Rehydration is an essential component of the recovery process, both physically and mentally. Because most of the weight lost during exercise is sweat, athletes should be weighed before and after practice, especially in situations involving temperature changes, increases in exercise intensity, duration, or number of sessions, and for young athletes undertaking rigorous exercise. The newest guidelines suggest 24 ounces of fluid for every pound lost during exercise be consumed within six hours post-exercise to assure the athlete achieving optimal hydration status. So, an athlete who loses five pounds during an exercise session or event would need to drink 120 ounces of fluid (5x24), or the equivalent of six water bottle-sized containers, to replace lost fluid. This timeline is particularly important for the athlete competing in multiple events or participating in two-a-day practices, or any sports requiring quick turnaround time. Athletes acclimating to two-a-day practices, preparing for competition, or competing in endurance events are advised to drink more than this amount over the next two days to re-establish hydration status, because, on average, it takes the body 24 to 48 hours after exhaustive endurance exercise to replace sweat loss. Not only must athletes drink a lot, but it is essential that they drink beyond thirst, since heavy exercise can blunt the thirst response, preventing the body from maximally rehydrating.
The other important component of post-exercise refueling is replenishing glycogen stores. Restoring muscle and liver glycogen stores following strenuous training will minimize the fatigue that results from repeated days of heavy training. During glycogen resynthesis, priority is given to muscles over liver stores. Muscles replace glycogen at a rate of five percent per hour, and it takes 20 to 24 hours post-exercise for the body to replenish muscle glycogen stores maximally. Since the energy demands of training exceed those of competition, post-exercise eating needs to be a routine part of every athlete’s training regimen and not just something that’s done in a competition situation.
Timing of post-exercise refueling is an essential part of the recovery process, as muscles are most receptive to fuel within 15 minutes after exercise, when the enzymes that produce glycogen are most active and can most effectively replace depleted glycogen stores. The lower the muscle glycogen stores, the faster the rate of recovery, but a delay in intake of post-exercise fuel will slow the recovery rate. In part, this is because the blood flow to the muscles is much greater post-exercise, enhancing glycogen repletion. Failure to capitalize on this opportu-nity delays recovery and will impair performance, and possibly increase the risk of injury.
Since exhaustive, intense exercise can suppress not only thirst, as mentioned earlier, but appetite, an athlete may complain of an inability or lack of desire to eat after activity. To overcome these objections, athletes should be encouraged to eat and drink something they enjoy, but most importantly, the food needs to be easily prepared and easily accessible. Most athletes are disciplined when it comes to bringing their foot gear, uniform, and other equipment necessary for their sport. They should likewise be encouraged to include appropriate refueling foods and drinks on their equipment lists. Remind them to pack a water bottle, some packets of powdered lemonade or fruit drink mix, a sports drink, if desired, and something to eat that is non-perishable. Good choices include:
• sports or breakfast bars
• peanut butter or cheese crackers
• dry cereal
• trail mix with cereal, nuts, and
• granola or cereal bars
• graham crackers.
If it is possible to keep items cold, athletes could consider one of the following:
• cans of a high-carbohydrate drink (sports drink with at least 50 grams of carbohydrate per serving)
• milk, to which a chocolate powder, or powdered instant breakfast could be added.
For cold weather, warm foods post-exercise can expedite blood flow to the extremities. A thermos filled with hot cocoa or access to hot water to add to an instant cup of soup or instant oatmeal can make a warming, nourishing post-exercise fuel.
KEY NUTRIENTS FOR RECOVERY
The goal of post-exercise eating is to restore hydration status and glycogen levels as quickly and efficiently as possible. Research has shown that for athletes involved in intense exercise, especially of long duration, water alone may not be the most optimal post-activity beverage, as the body experiences not only fluid loss but electrolyte and carbohydrate loss as well. Thus, taking in enough carbohydrate and fluid containing electrolytes are the most important elements to address in post-activity refueling.
In a two-hour exercise session, fluid loss through sweat can exceed four to five quarts. In addition to water, one pound of sweat contains 80 to 100 milligrams of potassium and 400 to 700 milligrams of sodium. In a two- to three-hour exercise session, an individual can lose up to 300 to 800 milligrams of potassium and 1800 to 5600 milligrams of sodium. The answer is not sodium or potassium tablets, but foods and fluids that provide the depleted electrolytes.
Consuming adequate carbohydrate post-exercise is essential for restoring muscle glycogen levels, regardless of whether the activity is primarily aerobic or anaerobic. There is no benefit to a low-carbohydrate diet for an athlete, as it can contribute to chronic fatigue, slower recovery, and increased risk of injury. Despite what some believe, the body cannot efficiently replete muscle glycogen with protein! (Protein may play a role, however, as discussed later.) Carbohydrate, in the right amount and type, however, can optimize muscle glycogen stores. Foods with a moderate-to-high glycemic index (a carbohydrate-rich food’s ability to raise blood glucose) may enhance muscle glycogen stores post-exercise.
The goal is to drink and/or eat at least 50 grams of carbohydrate as soon as possible post-exercise. This should be followed by a carbohydrate-rich meal two hours post-exercise. The maximum level of carbohydrate intake seems to be 500 to 700 grams a day, above which one will get little, if any, added contribution to glycogen storage or improvement in athletic performance. Unlimited carbohydrate intake can also lead to increased weight. In terms of the number of meals, the most important factor is meeting the carbohydrate requirements. Smaller, more frequent meals may be easier to tolerate for some athletes, but as long as he or she meets the goals in consuming the appropriate amount of carbohydrates, the number of meals is irrelevant. Athletes also need to experiment with these foods for taste preference, tolerability, and effect; record what foods work best; and ensure that these items are available.
Intensity and duration of the workout or competition, as well as ambient temperature, can have an effect on the types of recovery foods chosen. In colder months, hot cocoa and a muffin may be more appealing, whereas in hot, humid weather, a fruit smoothie may be more palatable.
When it comes to choosing liquids versus solids for effectiveness and absorption of carbohydrates, athletes needn’t worry. Liquid and solid carbohydrate-rich foods of comparable carbohydrate content will result in a similar rate of glycogen resynthesis. Many fruits, however, provide both carbohydrate and fluid and can be used to satisfy rehydration and glycogen repletion simultaneously. Good choices include grapes, blueberries, apples, peaches, celery, strawberries, melon, tomatoes, oranges, and cherries.
Not all carbohydrates are created equal, however—the type of carbohydrate selected for recovery may influence the rate of recovery. Carbohydrate-rich foods containing glucose or sucrose may be twice as effective as those containing fructose in restoring muscle glycogen post-exercise. This is because fructose is converted to liver glycogen, whereas glucose is converted to muscle glycogen. From a practical standpoint, it is prudent to advise an athlete to include a variety of carbohydrates post-exercise. For example, even though fruit contains fructose, it can be very refreshing and provides fluid to aid in rehydration. So, encouraging consumption of a piece of fruit with another carbohydrate-rich food, such as a bagel or handful of sweetened cereal, will encourage both fluid repletion and glycogen resynthesis.
Some studies have suggested that a mix of carbohydrate and protein in a 3:1 ratio post-exercise may replenish muscle glycogen more rapidly and promote muscle tissue repair. Adding protein to the post-exercise fuel results in a greater secretion of insulin than carbohydrate or protein alone. A 3:1 ratio of carbohydrate to protein post-strength training can stimulate muscle growth due to the release of insulin and growth hormone. For the strength athlete who downs the protein shakes after his or her workouts, adding some carbohydrate to the shake, such as juice, fruit, or pudding mix, and having a handful of cereal on the side, would change the composition of the post-workout meal and enhance muscle development.
THE BEVERAGE CART
As mentioned previously, water alone may not be the best recovery fluid. In addition to not providing much-needed electrolytes, relying solely on plain water as a post-exercise beverage can cause a drop in plasma osmolality, which can suppress thirst and increase urine output, causing additional fluid loss. A post-exercise beverage that contains sodium or consuming a salty food with a post-activity fluid helps to retain water in the extracellular compartments, thereby decreasing urine production without decreasing thirst. Carbohydrate-containing fluids will help to replenish glycogen stores, while the electrolytes, sodium, and potassium expedite rehydration.
Athletes should avoid alcohol, caffeine, and carbonated beverages following strenuous exercise. Alcohol post-exercise can impede recovery by hampering the body’s attempt to rehydrate, and it can interfere with the body’s ability to replenish glycogen and impair the tissue-repair process. Alcohol also promotes vasodilation, which can cause an increase in body-heat loss in cold weather, increasing susceptibility to hypothermia. And, it is a diuretic, causing further dehydration.
Caffeine is also a diuretic, resulting in only 50-percent fluid retention, and is therefore not an appropriate post-exercise fluid choice. Carbonated beverages are not the optimal choice either, as an athlete may feel full before optimally rehydrating. A good rule of thumb is juice first, beer, soda, or latte later! Another point to consider is the temperature of the beverage. Cool drinks may permit increased intake over ice-cold beverages.
SUPPLEMENTS FOR RECOVERY
Although there are no definitive studies demonstrating the performance-enhancing effects of vitamin-mineral supplementation, achieving optimal intake of micronutrients may reduce exercise-induced tissue damage. A general multivitamin-mineral supplement that is age-specific may be a good insurance policy, provided it is taken on a daily basis and is not a replacement for food.
Strenuous endurance exercise can depress glutamine levels, and glutamine supplementation may decrease muscle damage and expedite recovery. The recommendations are 0.09 to 0.27 grams of glutamine per pound body weight. For a 120-pound athlete, this would be 10 to 32 grams of glutamine per day. While there are readily available glutamine supplements, glutamine by itself is poorly absorbed, and it is better utilized in a product containing other amino acids or a food containing glutamine. Some good sources include pork chops, steak, chicken breast, salmon, skim milk, dried beans, and eggs.
Some studies have looked at ciwujia for its ability to expedite recovery, at a dose of 800 milligrams per day. The effects of long-term use are unknown, and as with other herbal products, purity and dosing remain issues.
WORDS OF WISDOM
The bottom line is that eating should be considered a part of performance enhancement. Athletes need to plan and schedule their post-activity snacks and meals with even more focus than the pre-competition eating, since training occurs at least once a day, whereas competition may only be a few times per week. At the high school level, parents and booster clubs can participate in handling the postgame snacks. At any level, handing a large glass of fluid and a sports bar to athletes after workouts or having food available and visible can be a great reminder to refuel. Take advantage of postgame wrap-ups to encourage players to eat and drink.
Achieving optimal hydration and glycogen repletion should be a goal for every athlete. Taking a proactive approach to eating by encouraging athletes to preplan and make time for post-exercise eating will enable an athlete to perform at his or her best, not just today, but every day.
All past T&C articles mentioned above—and any T&C articles on nutrition going back to 1996—can be found on our Web site at by typing in the keyword “nutrition.”