Hot Controversy: Does Your Sports Drink Need Protein?

One look at the sports drink coolers in your convenience store is enough to make your head spin. Bottles advertise endurance, recovery, added protein, low calories, and—this one wins the “defeating the purpose” award of the century—no calories.

One of the most hotly debated controversies within the sports nutrition community is adding protein to improve endurance. The argument has some merit: Some studies show protein-spiked sports drinks improve endurance athletes’ performance by almost one-third when slurped down during a workout. And a 2010 meta-analysis of all the research found endurance athletes who drank sports drinks with protein performed 9 percent better than when they drank carbs alone.

However, some researchers argue that the methods used in those studies don’t translate into real-world results.

So should you pick a sports drink with protein? Here’s the state of the science.

Carbs Fuel Long Cardio Workouts
First, some sports-drink 101. “Water, sugar, and salt are the key ingredients in sports drinks,” says Martin Gibala, Ph.D., professor and chair of the department of kinesiology at McMaster University in Canada. During workouts 90 minutes or longer, water rehydrates you, sugar replenishes the glucose or glycogen your muscles use for energy, and salt helps distribute those fluids throughout the body.

As sports drinks have gained popularity over the past decades, protein wasn’t a top prospect because it’s not a good fuel source. During longer workouts your body burns through all its glucose and then turns to fat, with protein entering the equation “as a last resort,” says Rebecca L. Stearns, M.A., A.T.C., from the University of Connecticut’s Korey Stringer Institute, who’s the lead author of the meta-analysis. (Your body does convert some protein into glucose in the early stages, but it’s not much, Gibala explains.)

But in recent years, researchers have found that consuming protein after endurance exercise helps you recover—a statement that should come as surprise to any Men’s Health reader. In fact, there’s now a “slew of evidence” that protein stitches back together muscles damaged by a tough ride or race, says Stearns.

Protein Surprises Researchers
A funny thing happened when researchers were delving into protein’s recovery benefits. Take a study by Michael J. Saunders, Ph.D., of James Madison University in Harrisonburg, Virginia. He had athletes drink either a standard sports drink or one spiked with protein during two hard cycling efforts, 12 to 15 hours apart.

“To my surprise, the cyclists rode 29 percent longer in the initial ride when receiving the carbohydrate/protein drink, as well as performing better in the subsequent exercise bout,” he says.

This study, published in 2004, came on the heels of a 2003 study with similar results, led by John Ivy, Ph.D., professor of Kinesiology and Health Education at the University of Texas. Since then, both Saunders’ and Ivy’s labs—among a couple of others—have published additional research finding protein boosts endurance efforts.

On the flip side, other results show no perks for protein whatsoever. For example, a 2010 study in Medicine & Science in Sports & Exercise found no difference in 12 cyclists’ performance when they were given a carb-protein vs. carb-only beverage. Lead author Asker Jeukendrup, Ph.D.—who recently left the University of Birmingham to become Global Senior Director of the Gatorade Sports Science Institute—says, “purely for performance reasons, I don’t think protein does anything.” Gibala’s research has also failed to find an effect.


Carbs vs. Calories
Why would similar studies lead to opposite results? First, there’s the question of what else is in the sport bottle. “When you add protein to a drink, you’re also changing the caloric content,” Stearns says. Some studies—like Ivy’s and Saunders’ first two—added protein without adjusting the amount of carbohydrates, so the protein formulas were higher in calories.

The meta-analysis found that in studies where the compared drinks had the same number of calories, performance improved by only about 3 percent.

Performance, Defined
There’s also a bigger question for the whole field of exercise science. What exactly is endurance performance, anyway? Is it the ability to push as hard as you can for as long as you can? Or is it covering a set amount of ground—10 miles, 100 miles—as quickly as possible?

Some studies, including most of Ivy’s, take the first route. They ask cyclists to pedal hard and fast until they just can’t make it through one more revolution. This is called time to exhaustion, and because there’s no finish line to push toward it eliminates some of the psychological factors that influence effort. For example, trained athletes tend to hold back at first; at the end, “they will speed up when they know they can safely complete the race,” Ivy says.

Time to exhaustion tells you a lot about preventing fatigue, an important component of endurance. But the results aren’t directly applicable to what happens to you during a competition. “Although you would certainly expect that a 29 percent improvement in time to exhaustion would translate to improved race performance, it would be inappropriate to assume you would get 29 percent faster,” Saunders says.

And as Jeukendrup points out, “there are no Olympic medals for events where you have to go as long as possible,” which is why he’s used a different approach. Most endurance athletic competitions—like your average 10K or marathon—are time trials, where study participants are timed while racing a set distance. In most cases, you’d want a study to look as much like what you’ll be doing in the field (or on the track) as possible, Stearns says. When her meta-analysis looked only at time-trial studies, it found no benefit to protein use.

Pinpointing Protein’s Perks
When asked why opinions on the topic are so divergent, Jeukendrup says some researchers “almost religiously believe” in adding protein to sports drinks, despite the fact that there’s no physiological reason it would help.

Gibala likens the search for the origin of protein’s benefits to “chasing a ghost,” and he hasn’t been able to find it, even in samples of athletes’ muscle tissue. Jeukendrup has looked at blood samples and seen no differences between athletes fueled by protein and carbs or carbs alone.

Ivy, Saunders, and others have hypothesized that protein improves hydration, alters brain chemicals that control fatigue, reduces the amount of muscle damage, and increases the amount of insulin in your blood, which could help you use carbohydrates more efficiently. Ivy says, “what the protein is actually doing, we don’t know—there are a couple of studies we need to do to find out.”

“It’s easy to speculate on mechanisms and then not try to measure them,” Gibala says. “What we’ve tried to do is actually test these mechanisms, and we don’t find any support for the claims that have been made for how protein might be working.”

Is Protein Right for You?
All of this debate may leave you in a bit of a lurch about what to put in your water bottle. Here are some situations where it might be worth a shot:
• If you’re trying to cut back on carbs without completely sacrificing performance. Another of Ivy’s recent studies found swapping a high-carb beverage for a low-cal, low-carb blend with protein didn’t diminish time to exhaustion. Drink to try: PureSport, which Ivy helped develop (15g carbs and 6g protein per 16-oz. serving).
• If you like it better. Protein drinks definitely don’t feel the same in your mouth as carb-only formulas. “There are considerable differences in personal tastes and tolerances, and even the ‘best’ sports drink cannot convey its benefits if you don’t drink it,” Saunders says. Drink to try: Accelerade (21g carbs and 5g protein per 12-oz. serving).
• After a hard workout. Getting 10g to 20g protein within 30 to 60 minutes after exercise “will help promote muscle recovery and replenish depleted glycogen stores until an athlete’s next meal,” says Jeukendrup. Drink to try: Gatorade Recover (7g carbs and 8g protein per 8-ounce serving).