Sport drinks have been popular for many years among serious athletes who rely on them to improve performance. The first of these products, Gatorade, was introduced in the 1970s, and has since been joined by an astounding assortment of specialized drinks. Now these lightly flavored, fortified beverages have made their way from gyms and playing fields to the diet of the average consumer.
Despite their mainstream acceptance, they are still designed with the athlete in mind. The vast majority of sports drinks are formulated to replace the fluids, electrolytes and carbohydrates lost through exercise. Other drinks are designed to help athletes with carbohydrate loading before an event. When used as intended, sport drinks fit in with the simplest and most important part of any athlete's daily regimen -- maintaining proper hydration levels. The advantage that sport drinks have over plain water is that they not only quench thirst, but also refuel working muscles as well.
There are three different situations in which an athlete uses sports drinks, thus there are three basic differences in the formulations of these drinks:
* Carbohydrate-loading drinks -- used in the days leading up to a competition, they should provide 50 or more grams of carbohydrates per 8-oz. serving.
* Rehydrating or fluid replacement drinks used during exercise they should contain between 14-17 grams of carbohydrates per 8-oz. serving.
* Recovery drinks -- used after exercise, they offer a concentration of carbohydrates that falls in between the others and is supplemented with protein.
A great deal of research has been done on sports drinks, both to gauge their effectiveness and to find the optimal formulation for these beverages. When tested against placebos and plain water, results have repeatedly shown that athletes using sports drinks had a significant improvement in performance over those not using them. Studies have also shown that flavoring, sweetness and the presence of sodium chloride in sports drinks increased voluntary fluid intake.
This is a crucial feature, not only for optimizing performance, but also for preventing dehydration. When athletes begin exercise with a low volume of body water or neglect to replace water lost though sweat, they will soon feel the effects of dehydration. The most immediate symptoms of this include impaired cardiovascular function and impaired temperature regulation, both of which will lead to noticeable decreases in performance levels.
For exercise of a short duration (i.e., less than an hour), it's possible to replenish what the body loses through sweat with plain cool water. This is not to say that a sport drink will not provide an extra edge, but with proper training and eating habits, there should be enough energy stored as liver and muscle glycogen to power through the exercise. When exercise lasts longer than an hour, or optimum performance is critical, a sports drink will help.
In one study conducted on cyclists, they were instructed to ride at 80% of their maximum for 50 minutes and then sprint for 9-12 minutes. The subjects who drank enough water to replace 80% of their fluid losses (1,330 ml) experienced a 6% improvement over those who drank only 200 ml of water. However, those who drank 1,330 ml of a sports drink showed a 12% improvement in performance. From these results, the authors concluded that the benefits of hydration and additional carbohydrate intake were additive.
Another study on the effects of carbohydrate intake during exercise of longer duration showed that when a carbohydrate solution containing a combination of sucrose, glucose, fructose and maltodextrin was taken, exercise performance improved. Varying concentrations were tested and it was found that higher intake rates of up to 60-75 gs/hour produced the best results with no added performance benefit when subjects were given levels greater than that. It is crucial that athletes understand their carbohydrate needs in order to maximize the potential benefits they can gain from sports drinks.
CARB-LOADING DRINKS
Carbohydrate loading drinks were developed specifically for endurance athletes who need to store extra carbohydrates prior to a long event. The more carbohydrates an athlete can store, the longer he or she can delay the onset of fatigue. Carbo-loading drinks are used in the last three days prior to an event. The advantage that they have over traditional methods of carbo-loading is that they can provide the body with an easily absorbed source of carbs without all of the bulk found in traditional foods, such as pasta and rice. Aside from carbs, these drinks usually contain some fat and protein that mimics the nutritional composition of a meal. Look for them to provide about 200 calories and 50 or more grams of carbs per 8-oz. serving. A note of caution -- more than 3 gs of fat per serving could slow absorption and lead to dehydration.
FLUID REPLACEMENT DRINKS
The primary purpose of these drinks is to replenish the body's fluid supply. Fluid replacement drinks with a 7% carbohydrate solution work best for rehydrating and providing maximum sustained performance levels. Look for a ratio of 4:1 complex to simple carbs. The first ingredient on the label should be maltodextrin or glucose polymers, followed by fructose. Be cautious of less expensive sports drinks as well as fruit juices, since these have simple sugars that can upset blood sugar levels and cause dehydration.
RECOVERY DRINKS
Recovery drinks are designed to maximize post-exercise refueling of muscle glycogen. The results of recent studies have shown that protein synthesis is an important component of post-exercise muscle recovery. A unique function of recovery drinks is that they can supply the fatigued and depleted muscle with protein which may enhance that repair process, promoting greater recovery of muscle energy and muscle protein re-synthesis. If protein is not replaced soon after exercise, this may result in a loss of muscle mass and greatly delayed recovery time. The addition of amino acids also aids in cell repair and synthesis.
Recovery drinks should be used as soon as possible after exercising, since research shows that in the hours immediately following vigorous exercise, ingested carbs are converted into muscle glycogen at about 3 times the normal rate. It takes the body up to 48 hours to completely replace muscle glycogen stores, so it's important, especially for athletes training daily or participating in multi-day events, to take advantage of this opportunity to get a jump start on their recovery. An added benefit of these drinks is that the rapid repletion of muscle glycogen stores may help to prevent muscle soreness.
There's an easy formula to calculate how many grams of carbs an athlete needs to consume in a recovery drink - use 1/2 gram of carbs/pound of body weight. Thus, a 150-lb. person would need 75 g of carbs.
WHO SHOULD USE SPORTS DRINKS?
Endurance athletes -- such as cyclists, long distance runners and triathletes -- will benefit the most from the performance enhancing abilities of all three types of sports drinks. The carb content of rehydrating formulations makes them especially useful for people who either can not or do not want to break up a workout or race to take the time to eat solid food. They also provide an added advantage over solid forms of carbs, because the body can absorb them faster, thus they provide quicker energy. This makes them ideal for people involved in sporting tournaments who will play more than one game per day or over a period of days. The supplemental energy and electrolyte boost is crucial when athletic events don't allow for a normal meal schedule.
PICKING THE RIGHT ONE
The most important function of a sports drink is to enable the user to rapidly replace lost fluids and enhance performance. These drinks should contain no carbonation or caffeine, and provide just the right amount of carbs and electrolytes.
The carbs should come from a combination of glucose, sucrose and fructose. Avoid sport drinks that contain fructose as the only source of energy. Fructose can cause an upset stomach and is a slow energy source, since it must first be converted to glucose before it can be used by the body. This means that the energy derived from fructose will not be available to the body as quickly as energy coming from other carbs. Make sure that the carb content matches the needs of the individual athlete.
Electrolytes serve important regulatory functions within the body, so it's just as important to replace them as carbs. This should be done in proportion to the amount lost in sweat. Look for around 100 mg of sodium per 8-oz. serving -- an ideal amount to enhance taste, optimize absorption and maintain body fluids. The same is true of potassium, magnesium chloride and other minerals. Some or all of them should be present in a sports drink.
HOW MUCH TO DRINK AND WHEN
It is important for athletes to drink fluids before, during and after practice and competition. Under most circumstances, they should drink at least 16 oz. of fluid before sleeping on the night before exercise and at least another 16 oz. first thing in the morning to help ensure adequate hydration levels. They should also top off fluid stores by drinking at intervals of 1 hour and then 20 minutes before the exercise starts.
Carbo-loading drinks can be used the night before, but should be avoided in the hours before exercise. The large amounts of sugars they contain can slow down the stomach-emptying process and cause severe stomach distress, making exercise very uncomfortable. In the four hours directly preceding an event, athletes should stick with water or a diluted sports drink with low carb levels.
CONCLUSION
Energy and convenience are the main advantages of sports drinks. By helping athletes maintain proper hydration and allowing them to keep performing at optimum levels, sports drinks perform a critical function that is not easily duplicated with other foods. Sports drinks will offer the greatest benefits to athletes who use the type of beverage that best satisfies the demands of their sport.
Christopher Nellen is an avid triathlete, and competes on the national level in both swimming and lifeguarding events. Since 1987, he has been a member of the Jones Beach (NY) Lifeguard Competition Team, of which he was captain. A winner of the New York State Masters Long-Distance Swimming Championship for the past two years, Chris coaches Masters swimmers. He is also certified in CPR.
