|Sports & Energy Drinks: Answers for Fitness Professionals
Jerry J. Mayo, Ph.D., R.D. and Len Kravitz, Ph.D.
Fitness professionals routinely field questions from clients concerning the use of sports and energy drinks. Sports drinks are designed to be consumed before, during or after exercise. As the name implies, energy drinks have arisen to deliver a proposed 'jolt' of energy to a person's daily life. This article will provide background content, helpful information and contemporary research about sports and energy drinks.
The History Sports and Energy Drinks
The unique origin of sports drinks dates back to the summer of 1965, when a University of Florida Gator's assistant football coach asked a team of university physicians (led by Dr. Robert Cade) to determine why the heat was affecting so many of their athletes (www.gatorade.com/history). From their research it was discovered that the fluids, electrolytes and carbohydrates the players lost during practice and competition were not being adequately replenished. The scientists used these findings to formulate a carbohydrate-electrolyte beverage called Gatorade. The following year, the Gators went 9-2 and won the Orange Bowl. Other colleges, hoping for similar results, soon began ordering batches of Gatorade and the sports drink industry was born.
The first energy drink may well have started in Scotland in 1901 under the name 'Iron Brew, which was subsequently changes to Irn-Bru (http://en.wikipedia.org/wiki/Irn-Bru). It is currently advertised as Scotland's other National Drink (referring to whiskey). In Japan, Taisho Pharmaceuticals introduced a drink called Lipovitan-D in 1962. It contained a blend of B-vitamins and taurine, which are proposed ingredients intended to bolster energy and concentration (Penalty, 2006). Then in 1987 an Austrian named Dietrich Mateschitz furthered this idea by combining sugar and caffeine, formulating Red Bull. The popularity of Red Bull quickly spread in Europe and a decade later appeared on the U.S. market. Today, energy drinks are extremely popular with over 500 brands appearing on the market in 2006 alone (Boyle, 2006).
Sports Drink Basics
Since its beginning over forty years ago, the three main goals of sports drinks remain unchanged: (1) to prevent dehydration, (2) to replace electrolytes lost in sweat, and (3) to provide carbohydrate for use during exercise (Coombs and Hamilton, 2000). Table 1 lists selected sports drinks and provides the key nutritional facts of each. Most commercial sports drinks provide 50-80 calories and contain 14-17 grams of carbohydrate per 8 ounces (Stover and Murray, 2007). This corresponds to a 6-8% carbohydrate solution which has been shown to maximize gastric emptying, enhance fluid absorption from the intestine, as well as supply energy to the working muscle (Coombs and Hamilton, 2000; Sawka et al., 2007). Electrolyte concentrations found in sports drinks differ based on the manufacturer. Sodium and potassium are added in small amounts to replace losses due to sweating, conserve fluid in the muscle cell and in combination with carbohydrates to improve palatability of the beverage (Sawka et al., 2007). Flavor, temperature (cooled), and sodium content of a beverage make these drinks very appealing, thus enhancing the total amount of fluid consumed (Coombs and Hamilton, 2000). Some sports drink varieties also include protein, vitamins and minerals.
Sports Drink Guidelines
Here are 5 key points recapping the recent American College of Sports Medicine exercise and fluid replacement guidelines (Sawka et al., 2007).
1) To ensure clients are properly pre-hydrated for exercise, drink 5-7 milliliters of fluid per kilogram of body weight 2-4 hours prior to exercise.
2) If needed, eat a lightly salted snack or small meal containing sodium a couple of hours before exercise to correct any electrolyte imbalances.
3) During exercise e 1 hour, a sports drink may be used to meet the hydration, electrolyte, and carbohydrate needs of your clients.
4) Consume some carbohydrate energy (food or sports drink) to help fuel ongoing endurance exercise.
5) Clients exercising in a hot, humid environment or who are heavy sweaters may benefit in consuming a carbohydrate-electrolyte solution during shorter bouts of exercise.
The amount of carbohydrate needed to maintain blood glucose levels during lengthy exercise sessions typically ranges from 30-60 grams per hour (Manore et al., 2000; Sawka et al., 2007). To achieve this from a sports beverage clients would need to consume 2-4 cups (16-32 oz.) per hour. Sawka et al. suggest that carbohydrate and electrolyte needs could also be partially or totally met by nonfluid sources like energy bars or gels. The key is to develop a fluid replacement strategy during exercise that meets the needs for your client.
The ABCs of Energy Drinks
As of 2006, the energy drink market had become a 5.7 billion dollar industry (Boyle, 2006). With names like AMP, Full Throttle, and Cocaine these drinks appear to be appealing to a younger population (or those wishing to feel younger). Table 2 provides key nutritional information of selected energy drinks. As the table describes, caffeine and sugar are the primary ingredients. Additionally, these beverages contain a 'cocktail' of supplemental ingredients, such as herbal extracts (ginseng, guarana, and ginko biloba), amino acids, derivatives (such as taurine and carnitine) and B vitamins. Some client questions about energy drinks include the following;
1) How much caffeine and sugar do energy drinks contain?
The amount of caffeine varies but typically its 70-140 mg per 8 ounces (Malinauskas et al., 2007). For reference, one cup of coffee contains about 100 mg. In general, most energy drinks contain 25-35 grams of sugar per 8 ounces. This equates to 6-9 teaspoons of sugar (four grams per teaspoon). Fortunately, many manufacturers do offer consumers a sugar-free alternative (Malinauskas et al., 2007). One additional point to note is that a majority of energy drinks consist of two or more servings per container.
2) Why are energy drinks so popular?
Malinauskas et al. (2007) examined the energy drink consumption patterns of nearly 500 college students and found that over half (51%) surveyed consumed more than one energy drinks per month. Interestingly, the three primary reasons given for consumption were to remedy insufficient sleep (67%), increase general feelings of energy (65%) and drink with alcohol while partying (54%).
3) Do energy drinks actually help improve energy?
Caffeine, the principal active ingredient in energy drinks, is a central nervous system stimulant and has been used for decades to increase alertness. Caffeine, when given in a large enough dose, can cause one to feel 'energized.' Smit and co-workers (2004) had 271 volunteers perform fatiguing cognitive tasks after consuming an energy drink containing 75 mg of caffeine or a placebo. The researchers commented the energy drink showed clear energizing effects compared to a placebo
for up to 90 minutes after consumption.
4) Can energy drinks improve exercise performance?
Few studies have been conducted testing the performance effects of using commercially available energy drinks. So far, the findings of these studies are inconsistent (Forbes et al., 2007; Pasiakos, et al., 2005; Umaña-Alvarado and Moncada-Jiménez, 2005). More research is needed in this area but from the current literature the use of energy drinks to achieve improved exercise performance seems impractical.
5) Are there side effects to consuming energy drinks?
Some of factors that determine the effect energy drinks (primarily caffeine) have on the human body include age, weight, caffeine tolerance, habituation and dose (Sokmen, 2008). The high levels of caffeine found in energy drinks can cause nervousness, headache, increased blood pressure and elevated heart rate. Of the energy drink users studied by Malinauskas et al. (2007), 29% experienced energy 'jolts' and then crash episodes, 22% experienced headaches and 19% reported heart palpitations.
Sports beverages and energy drinks are definitely here to stay. It is hoped that personal trainers and fitness professionals can use this article content to effectively educate clients, and help them make informed decisions regarding the appropriate use of these drinks.
Boyle, M. and Castillo, D.V. (2006). Monster on the Loose. Fortune. Vol. 154, pp.116-122.
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Forbes, S.C., Candow, D.G., Little, J.P., Magnus, C. and Chilibeck, P.D. (2007). Effects of Red Bull energy drink on repeated wingate cycle performance and bench press muscular endurance. International Journal of Sports Nutrition and Exercise Metabolism. Vol. 17, pp. 433-444.
http://www.gatorade.com/history Retrieved July 2008
http://en.wikipedia.org/wiki/Irn-Bru Retrieved July 2008
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Retrieved July 2008
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Stover, B. and Murray, B. (2007). Drink Up! The science of hydration. ACSM's Health & Fitness Journal. Vol. 11, pp. 7-12.
Umaña-Alvarado, M. and Moncada-Jiménez, J. (2005). The effect of an energy drink on cycling performance in male athletes. Medicine & Science in Sports and Exercise. Vol. 37, S38.