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Think stomach distress is a necessary evil of high-octane training and racing? Not so fast: A couple of high-profile sports scientists may have your perfect (and pro athlete-vetted) solution.
As a researcher at the University of Colorado, Boulder, Allen Lim studied ways to measure and improve cycling performance. After earning his Ph.D. in 2005, he left academia to apply his knowledge to the field of play, and signed on as the director of Sport Science at Team Garmin, a professional cycling team. He quickly realized team members were struggling with the carbohydrate-and-electrolyte formula of the typical sports drink.
“We had this consistent, ubiquitous complaint that our sports drink was making our athletes sick,” says Lim. “They would get the classic gut rot or bloating or upset stomach.” Even though many kinds of sports drinks have been proven effective in the laboratory, his Garmin cyclists had a different problem with their beverage. They drank so much of it to refuel they developed gastric distress, particularly when forced to drink extra fluids during long, hot races. So Lim advised they do what a lot of endurance athletes do—water down their drinks. It solved the gastric problem, but it also reduced the amount of calories and sodium they were getting during a long bike race. Lim went searching for another solution.
Stacy Sims landed on the topic for her sports nutrition Ph.D. research during the bike leg of Ironman Hawaii in 2000. The 27-year-old Kiwi started bloating on the way back from Hawi, a symptom she later attributed to hyponatremia, a condition resulting from a water/sodium imbalance. After failing to find the right balance on the race course, she returned to the University of Otago in New Zealand with a newfound interest in fluid balance physiology. Like Lim would a few years later, Sims found that the common practice of relying on sports drink for hydration and all the calories required by an athlete did not work in hot conditions. Following lab and field studies, she arrived at a paradigm-shifting conclusion: Hydration needs to be separate from fuel.
Each athlete has his or her individual recipe that balances the three basic components of sports nutrition—water, electrolyte and calories. (Sports nutrition, of course, is more complicated than just three elements, and many other variables including protein have been shown to improve performance and recovery, but these three are fundamental.) Considerations such as an athlete’s size, sweat rate and performance level, the weather on race day and many other factors change the quantity of these three components needed to maximize performance. If a person relies on the contents in their bottles to meet both their fuel and hydration needs, either the electrolytes, water or calories an athlete requires is going to be sacrificed for the others. Too much substance in the drink forces “water to flow from the blood to the gut to dilute [the drink or gel] to be absorbed,” says Sims, which creates “effective dehydration” by removing water from the blood as well as bloating or indigestion. You end up with a compromised nutrition strategy that Sims semi-jokingly compares to a sofa bed. “It’s not a good bed and it’s not a good sofa,” she says.
Lim’s frustration with fueling and hydrating the cycling team was growing when he met Sims in May 2009. Sims says they “spoke the same language” in their academic approach to sports nutrition, and Lim invited her to a six-week training camp prior to the Tour de France to help Team Garmin refine their nutrition strategy. The riders already relied on solid food for part of their caloric intake, but they further separated “hydration into the bottle, and fuel in the pocket,” Sims said . They wanted a drink optimized solely to hydrate the cyclists, not to meet their caloric needs. They examined the academic literature to find the combination of sugars that led to the fastest absorption of water by the body, but rather than adopt a formula straight from the textbooks, they looked to improve it.
“One of the problems that has been happening in the sports nutrition world is that we often think we’re smarter than nature, that we can basically address the needs of some biochemical pathway rather than address the needs of a whole human being,” says Lim. So rather than using the combination that fits an academic model of exercise physiology, they used a method that some scientists may balk at: They tried a bunch of options and asked the athletes which worked best. “We began experimenting with all sorts of sugars, from maltodextrin to fructose to sucrose to glucose and combinations thereof,” says Lim. They arrived at a 4 percent carbohydrate solution, 90 calories per 20 ounces of water. They also played with electrolyte quantity and type.
They found a combination that was the “most un-offensive” to the athletes and stuck with it. Their solution had fewer calories than most sports drinks, and a lot more sodium. To make up for the calories the athletes used to get through their beverage, the riders had to increase the amount of food they ate. Instead of semi-solid options such as gels and chews, they opted for real foods such as bars and home-cooked snacks like rice balls and salted potatoes. Chews and gels still had a place on very hot days.
Lim started making small batches of this new drink powder formula in the kitchen of his Boulder apartment. He walked them over to the local hardware store in a (food-safe) paint bucket to thoroughly mix the ingredients using the paint shaker. Then he would bag the mix in Ziplocs and ship them to the cycling team in Europe. This home-baked supply chain continued for two years. Lim says he never intended to market or sell the product, but word spread through the pro cycling world and other teams slowly started to ask for “the secret drink mix,” as it was called. Lim and Sims founded Skratch Labs and started selling the drink mix, and earlier this year Sims left and launched her own company, Osmo Nutrition.
The Skratch Labs and Osmo formulas have many differences from the more established brands, but you don’t have to buy these products to buy into the philosophy. Many beverages can be modified to reflect the core idea, which is to drink for hydration and eat for fuel. Applying this theory to multisport is the next frontier, and triathletes—including pro Rasmus Henning—are already starting to successfully adopt this practice. If you want to follow suit, Sims recommends eating solid foods on the bike, then shifting to semi-solids such as chews for the first half of the run, then going back to liquid calories from sources such as sports drink and Coke for the last portion of a race. If you struggle with gastric distress, especially on hot days, this method could be the solution you’ve been seeking.
Apply It: Dilute your drink
From the field: The American College of Sports Medicine says, “Sports beverages for use during prolonged exercise should generally contain 4–8 percent carbohydrate,” but Lim believes that range extends much too high. He found the Team Garmin cyclists were best able to stay hydrated and fueled when drinking a 4 percent carbohydrate solution. Anything above that, he found, led to slower absorption and gut cramping. That means no more than 90 calories in a 20-ounce water bottle.
From the lab: Gatorade Sports Science Institute director Xiaocai Shi, Ph.D., reviewed five decades’ worth of sports drink research and concluded that “CHO (carbohydrate) concentration is negatively related to water absorption,” particularly above an 8 percent carbohydrate solution, or 180 calories per 20 ounces of water. That means a drink with low carbohydrate concentration can be absorbed more quickly than one with more carbs, corroborating Lim’s concept but stating a much higher limit than Lim recommends.
Do it: Measure out 90 calories’ worth of your favorite drink powder and mix it with 20 ounces of water. If you prefer a pre-mixed sports drink, estimate the volume that contains 90 calories of carbohydrate and top off with water.
Dr. Gatorade’s Take
Robert Murray, Ph.D., director of the Gatorade Sports Science Institute from 1985-2008 agrees with some of Lim’s and Sims’ ideas, but not all. The experienced sports nutrition scientist weighs in on the tenets of this new refueling strategy.
Dilute the drink: Disagree
Murray’s research and experience shows that drinks with Lim’s suggested 4 percent carbohydrate solution are not absorbed faster than more concentrated versions. “Sports drinks containing up to 6–7 percent carbohydrate (130-150 calories per 20 ounces) empty from the stomach and are absorbed at similar rates, so there’s no absorption advantage to diluting sports drinks,” he says.
Apply It: Take extra sodium
From the field: Both sweat rate and the amount of salt lost through sweat vary widely from person to person. Lim says losing 350–400mg per half-liter of sweat is typical; Gatorade’s Murray says it’s closer to 500mg. Either way, that’s a lot of salt. Heat and humidity result in even greater salt loss per hour. Although arriving at a concrete number for the amount of sodium a person loses involves lab testing, Lim says sports drinks in general have insufficient quantities to optimally hydrate most athletes. “No sports drinks we could find had the right amount of sodium, so we were adding back our own sodium,” he says. “If you’re losing that much salt in your sweat and you’re just drinking water, or you’re drinking a fluid that doesn’t have that same amount of sodium, you’re going to dilute the sodium in your bloodstream. And when that happens you can get some very funky problems. This is all in the category of hyponatremia.”
From the lab: Many studies show that taking sodium during long-lasting endurance exercise prevents athletes from losing weight, implying they become less dehydrated. Improved performance, however, isn’t always tied to ingesting a lot of sodium.
Do it: A 20-ounce serving of Lim’s Skratch Labs Exercise Hydration Mix has 366mg of sodium. Most individuals need between 500 and 1,000mg of sodium per hour. If you use another mix with less salt, supplement your sodium intake with electrolyte pills or by adding an effervescent electrolyte supplement such as Nuun to your drink.
Dr. Gatorade’s Take
Add more sodium: Agree
Gatorade’s Endurance Formula, which Murray helped create, contains 500mg of sodium in a 20-ounce serving. “There is absolutely nothing wrong with favoring sodium replacement over carbohydrate supply for endurance athletes,” he says. “There are lots of different ways to ingest carbs, but fewer ways to consume sodium in palatable quantities balanced with water intake.” So keep the salt coming; the experts agree on this one.
Apply It: Eat solid foods
From the field: Lim advocates eating “real, actual food” instead of engineered sports nutrition products. “Rice cakes work really well,” Lim says. “We use a recipe that’s just sushi rice with coconut, currants and a little bit of chocolate.” Ingesting solid food “allows fluid to go around it and get absorbed” rather than mix completely in the gut. Dr. Robert Sallis, who has been involved with the Ironman Hawaii medical tent since 1996, asserts “it was very clear that the ones who were in [the med tent] with GI upset were eating way more solid food and larger quantities.” He does however support eating limited quantities to supplement liquid calories.
From the lab: A 2010 study from the University of Birmingham, England found “carbohydrates from a solid bar are effectively oxidized (digested) during exercise and can be a practical form of supplementation alongside other forms of carbohydrate.”
Do it: Lim and chef Biju Thomas wrote The Feed Zone Cookbook to share the recipes they use to fuel cyclists as they train, race and recover. Sims also suggests consuming solid foods such as bars, non-fat brownie bites or small pieces of a sandwich.
Dr. Gatorade’s Take
Eat real food: Disagree
Sims and Lim found that the Garmin cyclists experience fewer gastric problems when they ate solid foods like bars, but Murray has observed the opposite. “In my experience, endurance athletes who experience the Three B’s—burping, bloating and barfing—do so because they either drank too little or ate too much.”