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Do protein sport drinks really work? If the consideration is protein drinks and protein-rich mini-meals consumed immediately after a strenuous workout, the answer is an unequivocal “yes.”

The Right Protein Drink at the Right Time

If the consideration is a protein drink consumed during exercise, however, the answer is “probably not,” unless you are an elite athlete.

Protein is essential to muscles in recovery

Exercise physiologists universally agree that protein is essential to muscles in recovery after strenuous exercise. A really hard workout has a number of potentially detrimental effects on the body:
  • Muscles are damaged and have to rebuild themselves.
  • The muscle storage form of glucose, glycogen, is depleted and has to be restored. Glycogen is what “pumps up” muscles, and if they don't have glycogen, they are not large.
  • Bloodstream concentrations of the stress hormone cortisol soar.
  • The immune system is compromised, and the body is primed to break down proteins in healthy tissue in order to provide the amino acids needed to repair proteins in muscle.
Fortunately, the body can deal with all of these problems in a matter of minutes with the right post-workout nutrition. Protein drinks to be consumed after exercise usually contain some mixture of complete protein in an easily digestible form, such as whey powder, plus simple sugars, glucose preferred over sucrose, since glucose is absorbed more quickly. If the body receives amino acids and glucose in the 30 to 120 minutes after exercise, it switches from a catabolic, break-down mode to an anabolic, build-up mode, reducing stress, boosting the immune system, and helping muscles rebuild themselves to a stronger and larger form.

What Is in a Protein Drink?

The key quality in a post-workout protein drink is that it has to be fast-acting. Insulin receptors on the surfaces of the muscles are activated by strenuous exercise to absorb glucose to make glycogen for only a short time after exercise. Briefly, a muscle that has been worked out to its limits becomes 50 times more sensitive to the action of insulin from the bloodstream (a quality that makes resistance exercise a boon for diabetics). If the sugars aren't in the bloodstream while the muscle is primed to react to them, however, then both sugar for pumping up the muscle and amino acids for rebuilding and reshaping its fibers will not be absorbed, and exercise makes the muscle weaker, not stronger.

Protein drinks have to be fast-acting to work effectively

The key to success for any post-exercise protein drink is that it has to be fast-acting. The muscles cannot wait for the digestive tract to spend hours or even days to break down the drink into amino acids and glucose. That is why most workout drinks are made with whey, the 20 per cent of milk protein that is digested fast. Whey is also the part of the milk protein that is least likely to trigger an allergy; most milk allergies are activated by the casein that makes up the other 80 per cent of milk protein.

Manufacturers treat the whey protein so it is very easily digested. They add glucose and maltodextrin, the latter a form of sugar that breaks down into glucose even more quickly than table sugar. All of these post-workout foods are exactly right for hungry muscles, but they are not essential to good nutrition at any other time.

Hydration is important, too

There is one more ingredient in a successful after-workout pick-me-up that often is overlooked. That ingredient is water. The glycogen that “pumps up” muscles is made by combining one molecule of glucose with four molecules of water. If you are dehydrated after exercise and you fail to rehydrate with water and electrolytes, no amount of glucose and amino acids is going to help your muscles grow.

But What About Protein Drinks During Exercise?

Some athletes and their trainers take the idea of post-workout repletion of protein a step further and advocate taking protein drinks during exercise. The kind of exercise to which they refer is a longer session of endurance exercise, such as running a marathon or participating in a long-distance bike race. The scientific evidence for the use of protein drinks during exercise, however, just is not there.

Scientists at the University of Birmingham in England publishing in the Journal of the American College of Sports Medicine found that giving cyclists a protein drink during warmup and race offered no benefits over giving cyclists an energy drink without the added whey. Muscles showed just as many markers of broken-down tissue at the end of the race whether the cyclists drank the protein drink or not, and racers who took the protein drink did not have greater speed or power during the race.

On the other hand, scientists at the University of Texas at Austin publishing in the Journal of Strength and Conditioning Research report that cyclists racing at maximum intensity may get a few more minutes of racing time if they drink a low-carbohydrate, low-calorie protein drink while they race. These effects were only observed in well-trained athletes exercising at the limits of their performance for several hours.

So when does a protein drink benefit ordinary exercisers most?

Scientists are not quite sure how to interpret the results of the University of Texas study. It may be that reducing the number of calories in the drink taken during the workout shifts the metabolism so that protein is burned as fuel instead of carbohydrate. If this is the case, then the protein is certainly not protecting muscles from breakdown and tissue damage, and better results could be obtained by simply using a straight sugar-based energy drink.

Or it could be that the reason protein during a workout enhanced the performance of the University of Texas athletes was that they were exercising at peak capacity. People who are not as fit as athletes, or who are not fit at all, reach peak capacity at much lower levels of speed and power. Maybe low-calorie, high-protein drinks could be useful for anyone doing exercise and trying to perform just a little better.

If you are not an elite athlete, however, you are going to be much more concerned about making sure that your muscles grow in response to exercise than in shaving off that 30 seconds or 1 minute off your time in a marathon race. For you, the best way to use protein drinks is after your workout, with adequate amounts of water to replace fluids lost as sweat, making sure your drink contains both complete protein and at least a small amount of sugar.

  • Ferguson-Stegall L, McCleave EL, Ding Z, Kammer LM, Wang B, Doerner PG, Liu Y, Ivy JL. The effect of a low carbohydrate beverage with added protein on cycling endurance performance in trained athletes. J Strength Cond Res. 2010 Oct, 24(10):2577-86
  • Photo courtesy of David Goehring by Flickr :