According to a June 19, 2006 story in the New York Times, $1.83 billion worth of energy drinks were sold in 2005. And, a 2005 survey found that 62% of people ages 18-24 reported having used an energy drink during previous week.

So, what's the difference between "energy" drinks and "sports" drinks? Aren't these just different names for the same category of beverage?

No. Energy drinks and sports drinks are clearly different, though, admittedly, there is quite a bit of overlap. One of the most popular energy drinks on the market is Red Bull® while Gatorade® is the original sports drink.

In my mind, there are 3 main ways to distinguish between energy drinks and true sports drinks:

• Caffeine content
• Carbohydrate content
• Other ingredients

CAFFEINE CONTENT

Generally, beverages categorized as energy drinks contain a lot of caffeine while sports drinks contain little or none. For example, Red Bull® contains 77 mg caffeine (per 8 oz.) while none of the Gatorade® products contain caffeine.

The exact caffeine amount should be listed on the label. But, note that guarana and kola nut are herbal sources of caffeine. Even if the label states "guarana 100 mg", you still do not know how much caffeine that represents. Reference texts state that the caffeine content of guarana can range from 3% to more than 5%. The amount of caffeine in kola nut is even more difficult to determine.

CARBOHYDRATE CONTENT

Another distinction between energy drinks and sports drinks is the amount of carbs. In energy drinks, the carbohydrate concentration is typically much higher than in sports drinks. Extensive research over the past 20 years shows that the optimum carbohydrate concentration of a sports drink is 6-8% (see Sports Drinks and Recovery Drinks). When the carbohydrate concentration in a beverage is 8% or higher, the rate of gastric emptying slows (Murray R, et al. 1999) (Shi X, et al. 2004). This can cause stomach cramps (or worse) during a race.

The carbohydrate concentration of most energy drinks ranges 11-15%, making them risky for consumption during competition. Energy drinks are not much different than soft drinks such as Coca-Cola® or Mountain Dew®, except for the fact that energy drinks often contain other substances such as herbs, amino acids, and vitamins.

OTHER INGREDIENTS

The third way to differentiate energy drinks from sports drinks is to look for lots of additional ingredients. Sports drinks are generally a simple combination of carbs (glucose, fructose) and electrolytes (sodium, potassium). Period.

Energy drinks often have a variety of other ingredients that you don't need to consume during a triathlon or marathon or 3-hr tennis match. These might include vitamins, amino acids, herbs, or other substances.

READ THE LABEL

Still, it's easy to get confused. Athletes should learn to read the ingredients label and not simply consider the product's name or marketing pitch. For example, Gatorade® calls its Performance Series sports beverage an "energy drink" while the tag-line on Powerade's® label is currently "liquid hydration + energy drink". However, these beverages contain no caffeine, and the carbohydrate concentration is acceptable, so I consider them to be sports drinks.

Also confusing is Arizona Beverage's "Low Carb Extreme Energy Shot". Its carbohydrate concentration is only 1.25%. Even though it doesn't violate the rule "carbohydrate concentration in sports drinks should be no higher than 8%", it is clearly an energy drink, since it contains a ton of caffeine. Also, the carbohydrate concentration is too low for that to be a significant source of energy. Thus, most of the "energy" in this drink comes from caffeine.

Space does not permit listing them all, but several energy drinks are listed below:

Caffeine-Based Energy Drinks:

(quantities listed are per 8 oz serving and are based on actual product labels, March 2006):

WHY ATHLETES SHOULD AVOID (CAFFEINE-BASED) ENERGY DRINKS

Athletes, particularly those who engage in aerobic events, should avoid energy drinks for the following reasons:

• Too Much Caffeine: The label "energy drinks" is somewhat misleading. While a person may feel energized after drinking one of these beverages, most of that sensation comes from the caffeine component. Nevertheless, caffeine is one of the most extensively researched pharmacologic substances and there is plenty of evidence showing that caffeine can improve athletic performance. So, why condemn energy drinks just because they contain caffeine? Shouldn't we assume energy drinks are probably beneficial for athletes, too?

Certainly, it's true that caffeine is ergogenic; this has been proven in many studies. And, some limited research does show that an energy drink can improve exercise performance (see below).

But, athletes need to realize that some sports governing groups (NCAA, for example) can disqualify them from competition if there is too much caffeine in their system. (In 2004, the World Anti-Doping Agency (WADA) took caffeine off its list of banned substances. In September 2005, they announced that they were not going to change that decision, though, they stated they were watching it very closely...).

And, as almost anyone who drinks caffeinated beverages knows, when the effects of caffeine wear off, you feel even more sluggish than before.

• Carbohydrate Content Is Too High: As mentioned above, the ideal carbohydrate concentration in a sports drink is 6-8%. The carbohydrate concentration in most energy drinks is much higher than that.

• Carbonation: Another strike against energy drinks: most are carbonated. While some research shows that carbonation does not impair gastric emptying (Zachwieja JJ, et al. 1992), it may set you up for stomach cramps. Unless you are 100% certain that drinking carbonated beverages before, or during, a race won't bother you, avoid all carbonated beverages for at least 4 hours before the start of a race.

• Volume: Many energy drinks are sold in small cans. When you are perspiring heavily, you need to take-in a lot of fluid. Eight ounces isn't going to get the job done. And you wouldn't want to consume multiple cans of most energy drinks. One liter (1000 ml) of Red Bull®, for example, would give you 320 mg of caffeine - equivalent to about 3-4 cups of coffee. The diuretic effects of caffeine, though mild, can interfere with the process of rehydration.

• Unwanted Ingredients: Most energy drinks contain ingredients that athletes don't need....at least, not while exercising. Sure, your body needs vitamins, but these don't need to be supplied while you are running a half-marathon. But, you say, they can't hurt, right? Wrong. What if they cause stomach cramps and you can't finish the race? For example, Red Bull® contains niacin. In high doses, niacin causes cutaneous flushing. This might disrupt temperature regulation during exercise in the cold. Some vitamins taken in excess can be very serious.

Athletes should definitely watch out for energy drinks that contain bitter orange, which is an herbal source for the drug synephrine. Some manufacturers are adding bitter orange in place of ephedra, since ephedra was removed from the market in 2004.

RESEARCH ON THE EFFECTS OF RED BULL® ON EXERCISE PERFORMANCE

Despite the concerns and issues listed above, I did find one study that evaluated the effects of Red Bull® on aerobic and anaerobic exercise performance in young, healthy adults.

In this study, subjects aged 18-35 yrs consumed 250 ml of Red Bull® or carbonated water. The study showed that reaction time was faster and aerobic endurance was longer after consumption of Red Bull® compared to carbonated water. The improvement in aerobic endurance amounted to 92.9 seconds; the improvement in anaerobic endurance was roughly 1 second (Alford C, et al. 2001).

Admittedly, these improvements could be substantial in a race. However, this study used cycling as the exercise test. I doubt that any serious runner would use a sports beverage with a carbohydrate concentration above 8% during a race, particularly if that beverage was carbonated. In fact, in 1 study involving sprinting, shuttle runs, and vertical jumping, even an 8% carbohydrate beverage caused more GI upset than the 6% solution (Shi X, et al. 2004).

SUMMARY

It's important that athletes can differentiate caffeine-based energy drinks from true sports drinks that have a proper amount of carbs and electrolytes. While some weight-lifters may love the kick that energy drinks give them, aerobic athletes should avoid energy drinks.

FOR MORE INFORMATION

The August 2005 issue of Runner's World magazine has a brief review of energy drinks, though it does not provide specific ingredient amounts. A better review, though older, is available at the Gatorade Sports Science Institute web site: Sports Science Exchange #84. This was published in 2002.

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REFERENCES

Alford C, Cox H, Wescott R. The effects of Red Bull Energy Drink on human performance and mood. Amino Acids 2001;21:139-150. Abstract

Murray R, Baroli W, Stofan J, et al. A comparison of the gastric emptying characteristics of selected sports drinks. Int J Sports Nutr 1999;9:263-274. Abstract

Shi X, Horn MK, Osterberg KL, et al. Gastrointestinal discomfort during intermittent high-intensity exercise: effect of carbohydrate-electrolyte beverage. Int J Sport Nutr Exerc Metab 2004;14:673-683. Abstract

Zachwieja JJ, Costill DL, Beard GC, et al. The effects of a carbonated carbohydrate drink on gastric emptying, gastrointestinal distress, and exercise performance. Int J Sport Nutr 1992;2:239-250. Abstract

ABOUT THE AUTHOR

Stan Reents, PharmD, is a former healthcare professional. He holds Personal Trainer and Lifestyle Counselor certifications from the American Council on Exercise and has been certified as a tennis coach by USTA. He is the author of Sport and Exercise Pharmacology (published by Human Kinetics).  He can be reached at: Editor@athleteinme.com.

DISCLOSURE: Neither the author, nor AthleteInMe LLC, has any financial relationships with any of the products or manufacturers mentioned in this review.