Sports Drinks

Gabe Mirkin, M.D.

Exercisers spend millions of dollars on special sports drinks, even though none increase endurance more than the food from which they are made (1).

You become tired during exercise because you run low on fluids, salt and calories. As long as you replace these three components, you do not need to pay extra for a sport drink.

If you are going to exercise for more than 25 minutes, you can increase your endurance by drinking fluids. If you are going to exercise for more than 45 minutes, you can increase your endurance with sugared drinks, which provide a quick source of calories. Sugared drinks such as fruit juices, soft drinks and sports drinks can be absorbed just as rapidly as water.

When you exercise, you lose water through sweat. Sweat contains much less salt than blood does, so you lose far more water than salt, which causes blood levels of salt to rise. You have to lose more than two pints of water for the salt concentration in your blood to rise high enough to make you feel thirsty. By the time you feel thirst, it is too late to catch up on your fluid loss and you will have to stop exercising. By then you are dehydrated and you may become nauseous, get muscle cramps, or feel dizzy. If you ignore the warning signs of dehydration, you can convulse and pass out.

Eating salt stimulates you to drink, and raises your blood salt level high enough to make you feel thirsty and able to retain fluid. Some sports drinks contain salt, but most people don't like the taste of a salty drink, so the salt content is usually too low to meet your needs for salt during heavy exercise. The potassium listed as an ingredient in some sports drinks is irrelevant since you will not become potassium deficient from exercise, and you get plenty of potassium in virtually all foods.

Previous studies showing that temperature or carbonation affect absorption have been not been supported by more recent research. Your drink can be chilled or warm, as you prefer. If you prefer the taste of a sports drink over other beverages, use it. If your favorite beverage is a cola, iced tea, lemonade or plain water, that's what you should drink when you exercise. Research overwhelmingly shows that you will drink the most of the fluid you like best.

Since your drink won't supply enough salt to meet your needs when you exercise for several hours, you'll also need to eat salted peanuts, potato chips or anything else with salt that tastes good to you. For calories, it doesn't make much difference what you eat as long as it doesn't remain too long in your stomach and cause intestinal discomfort.

When you're not exercising, don't get in the habit of using sports drinks or any other sugared drinks to quench thirst. They'll add up to a lot of calories with little other nutritional value. Use plain water or other calorie-free beverages instead.

JS Coombes, KL Hamilton. The effectiveness of commercially available sports drinks. Sports Medicine, 2000, Vol 29, Iss 3, pp 181-209.Address Coombes JS, Univ Tasmania, Ctr Human Movement, POB 1214, Launceston, Tas 7250, AUSTRALIA

Comparison of Sports Drinks and Other Fluids for Exercise in Hot Weather

Brand (8 oz. serving) / Calories / Sugar / Sodium / Cost/8oz
Gatorade / 50 / 14g / 110mg / $.40
Recharge / 70 / 17g / 25mg / .55
Powerade / 70 / 19g / 55mg / .33
AllSport / 70 / 19g / 55mg / .42
SuperJuice (FreshSamantha) / 140 / 30g / 0 / 1.25
CranApple (Ocean Spray) / 160 / 40g / 35mg / .55
Fruitopia / 110 / 30g / 80mg / .40
Iced Tea (Lipton) / 80 / 22g / 50mg / .25
Pepsi / 100 / 27g / 25mg / .25
Water / 0 / 0 / 0 / 0-.25
Snacks - 1 oz serving
Salted peanuts / 180 / 0 / 100mg / .25
Salted sunflower seeds / 190 / 0 / 230mg / .25
Source: Product labels

http://www.drmirkin.com/fitness/8341.html 11/03/2009

Scientific Basis of Sports Drink Efficacy

Robert Murray has another in our series of sports nutrition articles from Gatorade

Published Wednesday, August 23, 2006

Endurance athletes can choose from a number of sports drinks that offer a wide variety of nutrients including carbohydrates, electrolytes (minerals), vitamins, protein, and amino acids. Yet science is fully supportive only of a well-balanced combination of carbohydrates and electrolytes for providing meaningful benefits to athletes while they exercise (post-exercise "recovery" nutrition is a different issue).
Elite athletes expect The Gatorade Company to provide exactly what they need to meet the demands of training and competition. That's why science will always play an essential role in developing and evaluating the effectiveness of Gatorade products. The purpose of this brief overview is to highlight the scientific thinking that underlies the Gatorade formula.

Since 1985, the Gatorade Sports Science Institute (GSSI) has been conducting research, helping fund research at major universities, creating educational materials, and sponsoring scientific meetings all designed to help athletes optimize their performance and safeguard their health. In addition, GSSI research leads to the development of nutrition products to provide athletes with the fluids and fuels they need to train and compete, and establishes and maintains the scientific standard for the Gatorade business. The institute is staffed by experienced sports scientists and nutritionists who carry out the scientific studies required to develop the best practical advice and the best products to meet the hydration and nutrition needs of athletes. GSSI has supported hundreds of sports science and nutrition conferences around the world and www.gssiweb.org continues to offer the latest information on a wide variety of topics in sports science, sports medicine, and sports nutrition.
Scientifically Tested and Athletically Proven
Research has consistently shown that there are many exercise occasions when a sports drink provides benefits superior to water but no athletic occasion when water is superior to a properly formulated sports drink. The primary benefit of a sports drink when compared to water is better exercise performance. Performance is improved with a sports drink, like Gatorade, compared with water for two reasons: properly formulated sports drinks help maintain hydration and provide extra energy. A scientifically balanced combination of carbohydrates and eIectrolytes encourages drinking, is absorbed into the body quickly, helps maintain fluid balance, and provides energy to working muscles. That potent combination allows athletes to push themselves longer and harder than they can when drinking water alone.


The amount and types of carbohydrates used in a sports drink are critical in optimizing the drink’s ability to improve performance. Research shows that a blend of simple carbohydrates (e.g., sucrose, glucose, fructose) is most effective in stimulating rapid absorption and enhancing carbohydrate oxidation, two important considerations whenever athletes are training and competing. In the small intestine, multiple types of carbohydrate stimulate the fastest fluid absorption, and that helps sustain important cardiovascular functions and helps reduce the risk of gastrointestinal distress during vigorous exercise.
Whenever muscles work hard, they rely predominantly on carbohydrate as fuel.The same blend of carbohydrates that stimulates rapid absorption also maximizes carbohydrate oxidation, and that’s a good thing for sustaining high-intensity exercise.But it is possible to have too much – or too little – of a good thing, and that’s why a properly formulated sports drink has the right amount of carbohydrate – not too much and not too little. Too much carbohydrate overwhelms the intestine’s ability to absorb it and the muscle’s ability to oxidize (burn) it. Too little carbohydrate (too few calories) doesn’t provide enough extra energy to benefit performance. Gatorade has a carbohydrate concentration of six percent (60 grams per liter, or about 14 grams per eight ounces) because research has indicated that level appears to provide the optimal amount of carbohydrate needed for palatability, rapid gastric emptying and intestinal absorption, as well as for the enhanced carbohydrate oxidation required for improved performance.
Research also verifies the need for sodium and other electrolytes in a properly formulated sports drink. Replacing the electrolytes lost in sweat aids overall hydration because of the osmotic properties of the electrolytes (in this case, “osmotic properties” refers to the ability of electrolytes to hold onto fluid in the blood and muscles). Sodium is most critical in this regard because of the singular role it plays in maintaining fluid balance. Ingesting sodium in a sports drink like Gatorade Thirst Quencher or the Gatorade Endurance Formula (contains roughly twice the sodium of regular Gatorade) helps maintain the osmotic drive to drink, stimulating greater voluntary fluid intake than is achieved when only plain water is ingested. Once in the bloodstream, sodium helps maintain blood volume at higher levels than can be achieved when only plain water is consumed. This is particularly important because a higher blood volume translates into a lower heart rate and greater blood flow to muscle and skin, all of which are essential in helping sustain performance. Ingesting sodium in a sports drink also reduces fluid loss via the kidneys, an additional benefit to hydration. However, not all sports drinks contain adequate amounts of sodium and other minerals. It is recommended that a sports drink deliver at least 70 mg of sodium per 8-oz serving (18 mmol/L) to provide sufficient osmotic impact to benefit hydration.Gatorade Thirst Quencher provides 110 mg of sodium per 8-oz serving, while the Gatorade Endurance Formula provides 200 mg.
Other Ingredients: Scientifically Tested yet Unproven
Athletes are always searching for a performance edge, so the appeal of new ingredients is understandable. But what does science say about other ingredients that some sports drinks offer? The answer to that question is that science shows that there either is no benefit associated with a particular ingredient or that the results of research are inconclusive. For example, research clearly shows either that there are no immediate benefits to adding vitamins to a sport drink because, although vitamins are good for the body as part of a balanced diet, they cannot be incorporated quickly enough into the body to provide any benefit during exercise.
The value of adding protein to a sports drink is another issue where the existing science is inconclusive. “Inconclusive” means that there is not enough consistency among the high-quality published research studies to confidently conclude that protein ingested during exercise provides a benefit. There are always scientific studies on both sides of any issue, so it is important to keep in mind that an accurate scientific conclusion is not developed simply by counting the number of studies on either side of the fence. Arriving at an accurate conclusion requires careful examination of the quality and the quantity of research in a particular area. In the case of protein, the vast majority of the best-quality studies show no performance benefit when protein is ingested during exercise.
Some athletes use caffeine to try to gain a performance edge. Research has shown that 200 mg of caffeine (by comparison, there is about 50 mg of caffeine in a 12-oz cola and 125 mg in 12 ounces of coffee ) taken before endurance exercise improves the performance of most subjects. However, at caffeine doses lower than 200 mg, the effects on performance are inconsistent. In other words, there isn’t a clear scientific consensus about the effects of ingesting low doses of caffeine and there won’t be until more research is completed. It is important to keep in mind that, the responses to caffeine ingestion vary widely among people.Some people tolerate caffeine without incident, while others can experience increased heart rate, increased blood pressure, heart rate abnormalities, diuresis (increased urine loss), anxiety, and jitters. Large doses of caffeine are accompanied by a greater risk of these side effects.

Science that matters
Relying on published science to help draw a conclusion is always an important step to take, but it is not the only step. Conducting additional research and consulting with experts in the field are also relied upon to help reach the conclusion that some ingredients have no place in a sports drink consumed during exercise.


Gatorade is formulated to provide everything that we know an athlete’s body needs during exercise – and nothing more. That said, The Gatorade Company is always looking for ways to help athletes perform at their peak and relies on research conducted by the Gatorade Sports Science Institute and at leading universities to help identify new approaches to sports nutrition. GSSI scientists constantly study potential new ingredients that might provide benefits to athletes and GSSI continues to depend on top-notch science to assess the effectiveness and the safety of the functional ingredients that go into Gatorade products.
Robert Murray, Ph.D., FACSM, is the Director of the Gatorade Sports Science Institute

References

1Jeukendrup, A.E. Carbohydrate intake during exercise and performance. Nutrition, 20:669-677, 2004.

2Sports Drinks: Basic Science and Practical Aspects. Maughan, RJ and R Murray, eds. Boca Raton, FL: CRC Press, 2001.

3Cheuvront et al. Branched-chain amino acid supplementation and human performance when hypohydrated in the heat. J Appl Physiol, 97:1275-1282, 2004.

4Wemple, R.D., Lamb D.R., McKeever, K.H. Caffeine vs caffeine-free sports drinks: Effects on urine production at rest and during prolonged exercise. Int J Sports Me,d 18:40-6, 1997.

5Casa et. al. National Athletic Trainer’s Assoication Position Statement: Fluid Replacement for Athletes. J Athl Train, 35(2):212-224, 2000

http://ironman.com/training/nutrition/robert-murray-has-another-in-our-series-of-sports-nutrition-articles-from-gatorade 11/03/09