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Effectiveness of Carbohydrate-Protein

Sports Drinks on

Endurance Performance


By Marissa Nolan

Date: 10/14/2006


The use of performance enhancing sports products is evident across all levels of athletics, from elite competition to recreational activities.  The widespread use of the major carbohydrate sports drink, Gatorade and its proven enhancement of athletic performance, led to the support of further scientific research.  Advertised claims about the effectiveness of carbohydrate sports drinks were made available to the public through various forms of media.  Increased public interest in performance enhancing beverages resulted.  Experimental studies successfully manufactured scientific evidence to support the claims about the effectiveness of carbohydrate-only sports drinks. 

Specific areas of research were based upon the idea that significant improvement in endurance performance could be achieved through the consumption of carbohydrate-only sports drinks, in comparison to the use of water and placebo drinks.  Carbohydrate-only sports drinks were found to improve endurance performance by replenishing fluid lost through perspiration during exercise, and most importantly, providing the muscles with carbohydrate than can be converted and stored for energy during exercise.  Naturally many athletes figured that by taking in as much of these sports enhancement sports drinks as possible, they could maximize their level of performance.  However, researchers discovered that there was a limit to the effectiveness of the carbohydrate-only sports drink, in that increased levels of concentration above 6-10% were ineffective.  Above the level of 6-10% concentration of carbohydrates in sports drinks was found to provide no additional benefits to athletic performance (Coggan, A. R., and E. F. Coyle, 1991).   Now that limits were drawn on the effectiveness of carbohydrate-only sports drinks, researchers set out to investigate new performance enhancing beverages, one of which was the carbohydrate-protein sports drink.

With astounding amounts of scientific research to support the effectiveness of carbohydrate-only sports drinks and the new found limitations of the product, researchers set out to determine the effects of addition of other supplements to the already effective carbohydrate-only sports drinks.  Various companies have experimented with the addition of different supplements to carbohydrate beverages.  The goals of these revamped sports drinks are to maximize the proven performance benefits of carbohydrate beverages, while offering new aspects of performance enhancement on their own.  This research paper will look at the more specific application of sports drinks, in detailing the analysis of the effectiveness of carbohydrate-protein on the performance of endurance athletes.

            Before diving into the depth of information about specific carbohydrate-protein beverages, proposed effectiveness of those available products, and supporting or contradicting evidence about effectiveness, it may be helpful to review some background about endurance sports.  In order to understand the proposed effectiveness of carbohydrate-protein sports drinks, it is helpful to obtain some basic understanding of the energy metabolism process which occurs during endurance exercise.


Basic Overview of Energy Metabolism During Endurance Sports

            Digestion is the efficient process that allows for the food to be eaten and transformed into nutrients.  Nutrients, which include carbohydrates, fats and proteins, are converted into energy an athlete to use during endurance activity.  The demands placed on the digestive system of an athlete may interfere with the processes necessary for the conversion of food into energy.  Timing is of great importance for endurance athletes.  Food intake during endurance exercise must occur at certain times to insure the availability of energy needed for successful level of endurance performance.  Endurance sports require a certain amount of energy that cannot be immediately stored within the body.  Therefore, the body must generate energy from other sources.   

During endurance activities, an athlete’s body has three available sources, or nutrients, for energy metabolism.  The metabolism of these nutrients is activated at different times during endurance activity.  The ease of digestion of carbohydrates makes it the first choice for energy during the prolonged exercise.  However, the use of protein for energy increases as an athlete increases the intensity of exercise.  Therefore as an athlete improves endurance performance the utilization of protein as a source improves. Better utilization of protein as an energy source results in longer storage of carbohydrate and more efficient energy regulation.  In addition to the utilization of protein as a fuel, fat may also be used as a fuel in order to spare muscle glycogen.  In fact, it is only after about one hour of steady pace exercise that fats are available for use as energy sources.  Therefore, endurance athletes may benefit from the consumption of nutrients other than carbohydrate during prolonged exercise (Peterson, 1996). 


Claims about the Effectiveness of Carbohydrate-Protein Sports Drinks

            Several companies have developed a line of carbohydrate-protein sports drinks in hopes of the product gaining the same amount of popularity that the current carbohydrate-only sports drinks, such as Gatorade and Powerade, now possess.  Among the most popular carbohydrate-protein drinks on the market today is AcceleradeAccelerade claims to be the first carbohydrate-protein sports drink to contain their patented ratio of 4 grams of carbohydrate to 1 gram of protein.  They also claim that the amount of protein used in the product helps to provide more carbohydrate to the working muscles during exercise.  In fact, they have proven scientific studies to show that consumption of their carbohydrate-protein drink shows improved endurance by 24% over carbohydrate-only sports drinks and 57% over water only.  In addition, Accelerade claims that the protein added to their sports drinks helps to speed up muscle recovery and spare the breakdown of muscle tissue during endurance exercise.  More importantly, Accelerade claims that the use of their product can delay the onset of muscle fatigue, thereby reducing the occurrence of injuries.  Many endurance athletes experience intense levels during both training and competition.  Therefore, the use of carbohydrate-protein sports drinks will not only provide improvements in endurance, but also allow the endurance athlete to consistently perform at their top level in order to maximize their performance ( ).



Evidence to Support the Effectiveness of Carbohydrate-Protein Sports Drinks

            The most recent evidence in the support of carbohydrate-protein sports drinks is provided by the recent study published in the Med Sci Sports Exerc (Saunders, M., Kane, M., Todd, M., 2004).  The double-blind study, conducted by Saunders et al., determined the effects of carbohydrate-protein beverages on performance during endurance cycling and the levels of post-exercise muscle damage.  Fifteen male cyclists participated in the study which involved riding a cycle ergometer during two phases of evaluation.  During each evaluation the subject was randomly assigned either a carbohydrate-only beverage or a carbohydrate-protein beverage every fifteen minutes of exercise, as well as a dose at the end of the phase of exercise.  The administration of the beverage was reversed in the second phase of the evaluation so that it was opposite of that given during the first phase.  The carbohydrate-only drink matched exactly the same concentration of carbohydrate as the carbohydrate-protein drink.  The first phase of evaluation involved cycling for over an hour at 75 % VO2 max.  VO2 max was defined as a level at reduced muscle glycogen levels could have contributed to fatigue of the subject.  Following a 12 to 15 hour break, the subject performed the second phase of evaluation which entailed riding to exhaustion at 85 % VO2 max.  In addition, the lactic acid and glucose levels were evaluated through blood samples were taken prior to exercise, every thirty minutes during, and post-exercise. 

In conclusion of the experiment conducted by Saunders et al., researchers concluded that there was a significant increase in endurance in subjects who consumed the carbohydrate-protein drink in comparison to those who consumed the carbohydrate-only drink.  In fact, during the first phase of the experiment subjects who were administered the carbohydrate-protein beverage lasting 29% longer than those administered the carbohydrate-only beverage.  Results from the second phase of the experiment were similar, with carbohydrate-protein consumers lasted 40% longer than those consuming the carbohydrate-only beverage.  Therefore, the results of the study provide scientific support for the enhancement of endurance provided by the consumption of carbohydrate-protein drinks. 

One particular study done by Williams et al. (Williams, M. B., P. B. Raven, D. L. Fogt, and J. L. Ivy, 2003) also found improvements in endurance, resulting from the consumption of carbohydrate-protein beverages.  The study, published in Strength Cond. Res., involved the participation of eight cyclists in two trials of a two-hour endurance ride.  The two hour long ride was performed at a level, ranging from about 65 to 75 % VO2 max, so as to deplete stores of muscle glycogen.  Subjects were given either a carbohydrate-protein beverage or a carbohydrate-only beverage immediately before and after the trials.  The two randomized trials were separated by anywhere from 7 to15 days, allowing for enough analysis of muscle glycogen and fatigue before the second trial.     

Results of the study by Williams et al. found that there was greater muscle glycogen storage, as much as 128 %, following consumption of the carbohydrate-protein drink in comparison to the carbohydrate-only drink.  Similar results were found in a study published in Am. J. Clin. Nutr. as well

(Van Loon, L. T., W. H. Saris, and M. Kruijishoop, 2000).  As a result of the greater amount of glycogen storage when using the carbohydrate-protein drink, the subject would have more energy to utilize during the rest of the endurance activity.  Therefore, the subjects who consumed the carbohydrate-only beverage would run out of energy a lot faster than those who consumed the carbohydrate-protein beverage.  As a result, faster times to fatigue for those who were administered the carbohydrate-only drink.  Based on the results of the experiment, the researchers concluded that the rate at which an athlete is administered carbohydrate-protein drinks will determine the level of muscle glycogen replenishment.  Therefore, Williams et al. suggest that carbohydrate-protein drinks be used to quickly restore levels of muscle glycogen following prolonged exercise.  Further more, results of this particular study support the results found in the previous study conducted by Sanders et al (Saunders, M., Kane, M., Todd, M., 2004), where researchers found that carbohydrate-protein drinkers possessed higher levels of endurance than carbohydrate-only drinkers.


Evidence to Challenge the Effectiveness of Carbohydrate-Protein Sports Drinks

The previously mentioned study published in the Med Sci Sports Exerc. (Saunders, M., Kane, M., Todd, M., 2004), also provided challenging evidence as to the effectiveness of carbohydrate-protein sports drinks.  Researchers speculate as to the influence of the additional calories added to the carbohydrate-protein beverage as compared to the carbohydrate-only beverage with about 190 calories less without the addition of protein.  The additional calories found in the carbohydrate-protein drink could provide a greater benefit than the carbohydrate-only drink during endurance sports as a result of the simple fact that more calories, provides the athlete with a greater source of energy for activity.  Therefore, the carbohydrate-protein drink could provide a greater benefit because of its greater amount of overall calories.  Researchers suggest that a carbohydrate-protein drink could be as effective as a carbohydrate-only drink of the same amount of calories.  Additional research is needed to determine whether or not the benefits of carbohydrate-protein beverages are derived from the actual inclusion of protein or the greater calorie amount.  Also, further research is needed to examine the exact influences of additional calories to sports drinks and their effective improvement on endurance performance.


Precautions Concerning Use of Carbohydrate-Protein Sports Drinks

            Both serious athletes and interested consumers should be careful about using carbohydrate-protein sports drinks.  Excessive consumption of these products can result in dehydration and upset stomach during exercise.  If too high of a concentration of carbohydrates is consumed during exercise, then it may result in the delay of digestion and early onset of fatigue (  Although high levels of protein have not been linked to kidney damage in healthy individuals, it may cause brittle bones and reduced testosterone levels in some individuals (  Overall, athletes should be aware that the excessive consumption of any performance enhancing product may have long-term side effects which may not readily known.  If a competitive endurance athlete chooses to use a certain carbohydrate-protein beverage during competition, it is advised that they first experiment with specific products during training sessions.  Certain products may work better for some individuals than for others, so it may be best to personally experiment with products than listening to the testimonials of other endurance athletes.  To maximize sports performance, athletes should focus on eating well-balanced meals in during competitive season and also during the off-season.  Although sports drinks do help to provide energy during prolonged exercise, a healthy diet and consistent training are requirements for any successful athlete.


Providers of Information about Carbohydrate-Protein Sports Drinks

            Depending on the source, information may not come from a legitimate source.  Often enough many companies, in hopes of selling their product, may use testimonials to help sell their product instead of presenting sound scientific evidence to back their claims.  These companies support false claims about the effectiveness of carbohydrate-protein beverages. Also, many products may differ in the concentrations of available nutrients in the product.  Sometimes the public is fooled into committing to the use of a product without even researching it.  On the other hand, there are sources such as this one which provide the reader with facts from scientific research and publication, as well as provide a personal opinion based on reviewed research. 



            Both athletes and companies alike are in search of a new supplement to enhance endurance performance.  While the use of carbohydrate sports drinks was once a choice of few athletes, the proven effectiveness of the product has resulted in the widespread use of the supplement amongst all range of athletes, but especially endurance athletes.  Endurance athletes require massive amounts of energy during prolonged exercise.  Such large amounts of energy require consumption of additional calories, and thus additional nutrients, such as carbohydrates.  Carbohydrates are the primary source for energy during endurance activity, while protein often serves as an intermediary source of energy.  Overall, there is enough evidence to support the claim that the consumption of protein in addition to carbohydrate during exercise may enhance the available energy stores during endurance activity.

One significant piece of evidence, which may lend the most support to the effectiveness of carbohydrate-protein drinks, is the same thing that restrains some researchers from proclaiming the use of carbohydrate-protein drinks during endurance activity.  This piece of evidence is the additional calories available in carbohydrate-protein drinks in comparison to carbohydrate-only drinks.  Further research needs to be conducted to determine whether it is the additional calories that make carbohydrate-protein drinks more effective or if it is the presence of protein.  Sufficient evidence is also available to support the idea that carbohydrate-protein drinks are far more efficient in providing post exercise benefits, such as faster muscle glycogen replenishment, than carbohydrate-only drinks. 

In conclusion, it may be most efficient for the endurance athlete to use carbohydrate-protein drinks during exercise to allow for muscle glycogen to be spared.  In addition, the endurance athlete would also benefit from the post exercise effectiveness of carbohydrate-protein drinks on the rate of muscle glycogen replenishment.  However, the effectiveness of carbohydrate-only sports drinks should not be ignored.  Therefore, an endurance athlete should consume carbohydrate-only drinks as well.  The use of carbohydrate-only sports drinks should be utilized prior to exercise, to allow for maximum levels of muscle glycogen stores during endurance activity.  It is also recommended that the endurance athlete use a carbohydrate-protein drink in the later part of an endurance activity, as well as consumption of a carbohydrate-protein drink after an endurance activity to maximize the rate of post exercise muscle glycogen recovery.




Coggan, A. R., and E. F. Coyle. Carbohydrate ingestion during prolonged exercise:

effects on metabolism and performance. Exerc. Sport Sci. Rev. 19:1-40, 1991.

Peterson, Marilyn. A Guide to Sports Nutrition – Eat to Compete. Mosby – Year Book,

Inc.: New York, 129-134, 1996.

Saunders, M., M. Kane, and M. K. Todd. Effects of a carbohydrate-protein beverage on

cycling endurance and muscle damage. Med Sci Sports Exerc. 36:7: 1233-

1238, 2004.

Van Loon, L. J., W.H. Saris, and M. Kruijshoop. Maximizing post exercise glycogen

synthesis: carbohydrate supplementation and the application of amino acid or

protein hydrolysate mixtures. Am. J. Clin. Nutr. 72:106-111, 2000.

Williams, M. B., P. B. Raven, D. L. Fogt, and J. L. Ivy. Effects of recovery beverages

on glycogen restoration and endurance exercise performance. J. Strength Cond.

Res. 17:12-19, 2003.



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