Carbohydrates

Most energy drinks contain anywhere from 27-40g of carbohydrate from sugar. The concentration of these carbohydrates is very high ranging from 20-25%. Sport drinks typically have a concentration between 4-6%. Research by Ryan et al., demonstrated that high concentrations of carbohydrate such as glucose, sucrose, maltodextrins, fructose, and/or galactose will slow the rate at which fluid is absorbed from the intestine into the blood. For sports where fluid replacement due to sweat loss is critical, these drinks may retard the rehydration process. In addition, consuming high concentrations of carbohydrate too soon before or during exercise can result in gastrointestinal distress and may have a laxative effect.

Caffeine and Herbs

Energy drinks contain caffeine or herbal forms of caffeine like guarana seeds, kola nut and yerba mate leaves. Herbal doesn’t mean healthier. Due to processing, it is sometimes impossible to know the exact amounts of herbal caffeine that are in the drinks. The dose of caffeine is not always apparent on the label and may be high enough to place the athlete at risk for a positive doping test for caffeine.

Caffeine stimulates the central nervous system and provides a temporary feeling of being “energized.” In 2001, Graham demonstrated that caffeine at a dose of about 6 mg/kg body weight (e.g., 490 mg for a 180-lb person) has often proved effective at enhancing exercise performance lasting from 1-120 min. Although this may be the case, it is not a magic bullet. Caffeine in large doses may make some athletes feel light headed, jittery, disoriented and nauseous and may cause diuretic and laxative effects

Other herbs added may include echinacea, ginkgo biloba, ginseng, ciwujia, hydroxycitrate, ephedra and St. John’s Wort. Companies may claim they aid in boosting the immune system, weight loss and memory. These ingredients are typically in small amounts, but even in larger amounts there is little evidence that any of them can benefit performance. Standardization and purity of these herbs is not always reliable. Mislabeled products could result in positive doping and potentially serious side effects if herbs interact with athletes medications.

Energy Drinks

Some energy drinks have also added vitamins and minerals to their formulations. One national brand contains 3000% of the recommended daily value for vitamin B12 and another brand contains 250% of the amount needed for vitamin B6. B vitamins are water soluble and thus excess amounts are excreted in the urine. It’s important that athletes recognize that energy drinks should not be considered a well balanced meal replacement or a multivitamin supplement. A multivitamin-mineral supplement will be a far less costly and more effective alternative to a fortified beverage.

The energy-drink category is a multimillion dollar industry. Companies are sponsoring athletes and teams and drinks are becoming widely available. It’s important to remember that they are not an adequate substitute for the time, training, rest, recovery, and fueling required for sports. Educating athletes about these products is critical for their health, safety, and sport performance.

Practical Application

Leslie Bonci, M.P.H., R.D. a University of Utah professor and sport dietitian developed practical guidelines for athletes interested in energy drinks.

Being optimally “energized” requires a suitable level of physical activity, adequate sleep, effective fueling and hydration strategies, and probably other unknown factors that affect neurochemicals in the brain. An energy drink alone will never make up for all of these elements. When it comes to choosing any food or beverage product, athletes must be skeptical consumers and ask questions before buying. Here are some guidelines:

• Label reading is necessary!
• Athletes using medications should avoid any product that contains herbs.
• If there is no Nutrition Facts or Supplement Facts panel, athletes should not buy the product.
• Athletes need to know if the ingredients are legal and safe.
• Athletes should examine the Nutrition Facts panel for the total carbohydrate content as well as calories.
• Avoid the product if the evidence for claims is non-existent, incomplete, or unsubstantiated!
• If it sounds too good to be true, chances are that it probably is!

Should I drink a sports drink?

Sports drinks have been researched extensively and generally provide an excellent alternative to plain water for hard working athletes. During intense aerobic exercise, the body’s preferred source of fuel is carbohydrate (rather than fat or protein) due to the efficiency of energy transfer to fatigued muscles. The majority of sports drinks are formulated to deliver carbohydrates, electrolytes and fluids in such a way that will minimize stomach upset and maximize intestinal absorption. When compared with water, the flavor of sports drinks typically entices athletes to drink more, thus aiding the hydration process.

References:

Ryan, A.J., G.P. Lambert, X. Shi, R.T. Chang, R.W. Summers, and C.V. Gisolfi (1998). Effect of hypohydration on gastric emptying and intestinal absorption during exercise.

Graham, T.E. (2001). Caffeine and exercise: metabolism, endurance, and performance.

Leslie Bonci, M.P.H., R.D. Energy drinks: Help, Harm or Hype?

J. Appl. Physiol. Sports Med. 31:785-807. Sports Science Exchange 8 Volume 15 (2002) No 1.

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