Brian B. Parr, Ph.D.
Maybe you saw an ad for a sports drink telling you that you really can’t exercise without “it.” Or maybe it was the sign in the locker room at the gym reminding you “your workout isn’t complete” without a special recovery beverage from the juice bar that got you curious. Now you are asking yourself “what is in these drinks and do I need one to meet my training goals?” Fortunately, the results of research on sports drinks and recovery beverages can help answer these questions.
Sports drinks, designed to be used during exercise, are a combination of water, carbohydrates (sugar), salt, and other electrolytes. These drinks are formulated for athletes who are competing in or training for long-duration events. The water is needed to replace sweat loss and maintain plasma volume. The sugar, typically sucrose, glucose, or fructose, helps maintain blood glucose, a primary fuel used by the muscle during intense exercise. In addition to replacing what is lost in sweat, the salt also enhances water and glucose absorption and stimulates thirst.
Recovery beverages generally contain some combination of carbohydrates and protein and come in liquid, shake, or smoothie form. There are also energy bars specifically formulated for use after exercise. The carbohydrates replenish muscle glycogen, a storage form of glucose used as a fuel during intense exercise, and the protein provides amino acids necessary for muscle repair and growth.
Intense endurance training (think competitive runners and cyclists) relies heavily on muscle glycogen as a fuel. Muscle glycogen is a storage form of glucose, a sugar that the muscle converts into energy. During prolonged training sessions that last at least 60–90 minutes, muscle glycogen levels can be severely depleted. Carbohydrates consumed at regular intervals during exercise can maintain glucose delivery to the muscle despite this decline, and after exercise carbohydrates can replenish muscle glycogen levels.
It turns out that the best time to consume carbohydrates to restore muscle glycogen levels is immediately following exercise. It has also been shown that combining the carbohydrates with some protein results in more rapid muscle glycogen synthesis. A recovery drink following an intense exercise session makes good sense for people who are engaged in endurance training for competition.
Athletes who are engaging in intense resistance training to build muscle mass and strength may also benefit from a recovery drink. Weight training stimulates protein synthesis in the muscle. As new muscle protein is formed, both strength and muscle size are increased. It makes sense that consuming additional protein would be beneficial. Research shows that combining the protein with carbohydrates increases muscle protein synthesis. Just as with endurance training, the muscle is most responsive to the extra protein immediately following exercise. Again, for people who are actively training to gain muscle mass and strength, a recovery beverage may be helpful.
But what about people who engage in exercise to improve their fitness or to lose weight? The benefits of these supplements during high intensity exercise exists because the intense endurance or strength training causes changes in the muscle that allow the extra carbohydrates and protein to have a positive effect. Training at a lower intensity is unlikely to create this stimulus in the muscle, so these nutrients may not have a significant benefit. Simply put, most people don’t train hard or long enough to need a sports drink during, or a recovery drink after, exercise.
For most people, drinking water during and after exercise is sufficient. There is little risk of harm in consuming a sports drink or recovery supplement, even if you don’t need one, but these supplements can be high in calories, especially in shake or smoothie form. It is entirely possible to consume more calories in a sports drink or recovery beverage than you burned during exercise. If you are exercising to manage your weight this could interfere with weight loss and may even lead to weight gain.
Other Options for Post-Exercise Nutrition
Even if you do exercise at an intensity that is high enough to warrant post-exercise nutrition you don’t necessarily need a specialized supplement. Sports drinks are popular in part because they are formulated to provide a convenient way to get water and carbohydrates during exercise. But you could get a similar result from consuming almost any beverage that contains carbohydrates, including juice or soda. Some athletes even consume solid food, such as energy bars or fruit, during prolonged events.
Research also shows that chocolate milk is just as effective as more expensive supplements for replenishing muscle glycogen and promoting muscle protein synthesis following exercise! It turns out that the mix of carbohydrate and protein in chocolate milk closely matches that in many supplements. In fact, consuming any food or drink containing carbohydrate and protein – a peanut butter sandwich, for example – shortly after exercise will work.
Keep in mind that if you eat a diet that contains adequate levels of carbohydrate and protein, supplements before or after exercise may not be necessary. Furthermore, consuming carbohydrate and protein supplements will not make up for an inadequate diet. The goal should be to supplement a diet that contains sufficient energy, carbohydrate, and protein with sports drinks and recovery beverages. If you do choose to consume sports drinks or recovery beverages be aware that some may contain other nutrients that have not been shown to improve performance.
Finally, these supplements have been shown to enhance exercise performance and adaptations to training. Most of the improvements are a result of the training, not the additional nutrients. The point is that supplements should be used to enhance, not replace, training or good nutrition.
Hydration After Intense Exercise
The purpose of drinking during exercise is to best prevent a water deficit that results in more than 2% body weight. When done properly it works well but hydration doesn’t stop there. Often sweat rates exceed the rate the stomach can empty and diffuse the fluid taken in. This means post-workout hydration is essential to complete the hydration process.
It is unrealistic to assume one can fully recover or replenish instantly after workout completion. Focus on rehydration for as long after as it took to complete the workout or event. If you were in motion for 3 hours then think about rehydrating properly for 3 hours after. An additional 1-2 electrolyte supplements will be sufficient post-workout and then continue your efforts with plain water. Given ample time, intake of balanced meals and water, hydration will be fully restored. Clear to light yellow urine output signals you’re on the right track.
Hydration should be on an endurance athlete’s radar daily, training or not. For good health and better running, become best friends with an eco-friendly water bottle.
The preceding excerpt is from Nutrition for Everyday Endurance by Rebecca Turner, MS, RD, CSSD, LD, which will be published in 2014. For more information visit www.RUNNERS-FUEL.com.