Humans evolved to run, hunt and gather. The science of post-exercise recovery reveals how our bodies also adapted to quickly rebuild.
By Kim McDonald
Humans evolved to run, hunt and gather. The science of post-exercise recovery reveals how our bodies also adapted to quickly rebuild.
By Kim McDonald
Eight thousand to 10,000 calories. For an elite triathlete finishing an Ironman in the eight-to-nine-hour range, that’s how many calories will be burned while swimming 2.4 miles, cycling 112 miles and running a marathon. If you could stomach it, you could replace those calories after the race by eating 15 Whoppers, 18 Big Macs or—if you wanted a healthier option—35 Carl’s Jr. Grilled Chicken Salads. But recovering properly after exercise isn’t simply about replacing lost calories. It’s about what you consume and when.
During the early days of Ironman, the pioneers of triathlon fueled themselves on the windy and hot Kona, Hawaii, course with Gatorade, water, bananas, figs and boiled potatoes with salt wrapped in foil. When the race was over, the menu of choice was burgers and fries—washed down, of course, with lots of beer.
"I thought I was a smart guy coming out of college, but we honestly didn’t know anything," said six-time Ironman world champion Dave Scott, about race nutrition in the early 1980s. "I ate mounds of simple carbs, and we’d grab a bucket of bananas and figs and try to survive an Ironman. I used to tuck six to seven bananas in my back pocket during a race, and they’d just be bouncing around, getting soft. I also thought all fat was bad, so I avoided foods like nuts, avocados, salmon and coconut oil. I didn’t eat eggs or cheese for a long period of time. As a result, my training fluctuated a lot, and my recovery was stunted."
Sports nutrition has come a long way since the 1980s, when athletes used trial and error to experiment with different diets and drinks to see what worked and what didn’t. They just hoped they didn’t "bonk" during an important race—when their blood glucose levels plummeted and their brains got so hazy they would have to walk to the finish.
Scientists now know much more about how to fuel the human body during and after exercise. Eating properly to reach your potential as an athlete is now like taking care of a high-performance race car, says John Ivy, Ph.D., a professor of exercise physiology at the University of Texas at Austin, who is one of the world’s foremost experts on sports nutrition. If you subsist on low-octane fuel, your engine will sputter. But if you take in the proper fuel at the right times, he adds, your running, cycling and swimming performances can improve by up to 15 percent.
John Ivy, Ph.D. and professor of exercise physiology at the University of Texas at Austin. Ivy is credited a one of the world’s foremost experts on sports nutrition, and discovered the key breakthroughs in the field of recovery.
Adapting to life on the Serengeti for our hunter-gatherers ancestors wasn’t much different from finishing a marathon, Ironman or 100-mile Gran Fondo. After hours spent stalking game on foot, humans needed to recover quickly. If they didn’t, the hunters would become prey for lions and other predators. These prehistoric athletes also needed to refuel their muscles efficiently on a minimal diet and adapt to the daily demands placed on their bodies.
"If you think about how we evolved, we’ve always been an active species," says Ivy. "To hunt and to kill you have to be physically active. And once you kill and eat, you have to recover quickly. If you don’t recover quickly, then you become the prey. So our bodies have adapted to recovering quickly and the perfect example of this is if we exercise really hard and take in carbohydrate right away, the carbohydrate bypasses our liver (which stores the highest concentration of carbohydrate fuel) and goes right into the muscles to be stored as glycogen, which is a ready and rapid source of fuel for the muscles. In this way, the muscles are given priority to the carbohydrate consumed. This allows the muscles to be ready to respond to any emergency that may arise soon after being stressed."
In the 1980s, Ivy discovered from experiments with athletes riding on stationary bikes that the way we evolved as hunter-gathers, the way our muscles were optimally primed for life on the Serengeti, is to feed them within one hour of exercise. That’s because elevated levels of the hormone insulin from eating carbs soon after exercising convert the carbs into glycogen in the muscles three times faster than at other times. Once you miss that 60-minute window, no matter how much you eat, much of the extra fuel is converted to fat instead of carbohydrate.
"Timing makes a big difference in how effective the nutrients are," explains Ivy. "Post-exercise, the body is set up to use nutrients very effectively in the recovery process—this has to do with cellular changes and hormonal changes that occur during exercise."
Are you ready for some real science? John Ivy, Ph.D., goes full nerd on recovery nutrition.
When we exercise hard and deplete glycogen, changes occur in our muscles to increase the efficiency of carbohydrate uptake, such as a greater sensitivity to insulin. Our muscle cells also become more receptive to taking in amino acids—the building blocks of protein—to make more muscle.
For weightlifters, protein synthesis is critical for building muscle mass. But it’s also essential, Ivy says, for endurance athletes who need to increase the density of a muscle cell’s energy-producing factories, called mitochondria, as well as the number of oxygen-carrying red blood cells. Both processes depend on getting glucose and protein into the body, and within an hour after exercise, says Ivy, “you can get these nutrients into the appropriate cells very rapidly because the cell is programed for rapid protein synthesis and you get a rapid training adaptation.”
Until the 1990s, drinks containing simple sugars and electrolytes—the formula of the original Gatorade drink developed in 1965 at the University of Florida to replace the sweat lost by football players on the Gators team—were the primary means by which long-distance athletes kept hydrated and prevented themselves from bonking before and after exercise. Then in the early 1990s, Ivy stumbled upon the second key to refueling. Realizing that certain kinds of amino acids increased the production of insulin in our bodies, Ivy added a small amount of protein (which our bodies break down to amino acids) to the carbs he gave his study subjects after exercise. The result? Glycogen synthesis increased dramatically. In that study, published in the Journal of Applied Physiology in 1992, Ivy and his colleagues found that refueling muscles with a mixture of 1 gram of protein to every 3 to 5 grams of carbohydrate allowed athletes to store 38 percent more glycogen in their muscle cells—where the body can most easily access carbs for emergency fuel—during the first four hours of recovery than consuming just carbs and three times more than with protein alone.
“When you take in both carbs and proteins post-exercise, you raise insulin levels, which stimulates a greater muscle glycogen storage and protein synthesis,” Ivy explains. He and other scientists worked with PacificHealth Labs in the late 1990s to produce Endurox R4, the first post-exercise sports drink containing protein, which provided a mixture of carbs to protein in a 4 to 1 ratio to enhance recovery and training adaptation, and which later ushered in the recovery drink revolution. Since then, Ivy has continued to conduct studies on the effect of various kinds of carb-protein supplements on athletic performance, including revisiting post-workout recovery in 2011.
Photo: Brad Kaminski
The carb-protein supplement Ivy investigated in that study wasn’t an expensive drink formula, but an everyday product found in neighborhood groceries and convenience stores: low-fat chocolate milk. Its ratio of carbs to protein is 3.25 to 1, within the window ideal for recovery.
In Ivy’s study, 35 previously untrained individuals were trained for four and a half weeks on stationary bicycles for 60 minutes a day, five days a week. Within an hour after every training session, the subjects were given either a placebo (flavored water), low-fat chocolate milk or a carbohydrate sports drink containing the same amount of calories as the chocolate milk, then were asked not to eat anything for three hours after exercise.
“What we found was that the VO2 max (a measure of aerobic fitness) in the individuals that drank the chocolate milk increased twice as fast as the group that got the placebo and the group that got the carbohydrate supplement,” says Ivy. “If you don’t take anything in or take just carbohydrate in, you don’t adapt as fast because the protein and carbohydrate together promote protein synthesis. And the reason VO2 max went up was due to a greater red blood cell mass.”
Not only did VO2 max dramatically increase among the chocolate milk drinkers, but as a group they gained more muscle and lost more fat than the other two groups. Why? Ivy speculates the greater protein synthesis and glycogen storage in the muscles of the chocolate milk drinkers not only helped them build more lean body mass, but allowed them to burn more calories after exercise than the other two groups of exercisers. “Those are two energy-requiring processes,” he says. “During that time you’re burning more fat to promote these processes, so you maintain a higher metabolic rate.”
Endurance athletes who competed in the 1980s and in the decades before lacked not only the knowledge of what to eat when, but the wide array of carefully formulated sports drinks, bars, gels, blocks and recovery products that now can be purchased in any store. Yet despite the convenience and popularity of these products, which make up the $12-billion-a-year nutritional supplement industry in the United States, many top cyclists, runners and triathletes are trading in their packaged drinks and bars for real food when training and racing.
“Every athlete I've worked with has and does eat real food when they train and race,” says Allen Lim, Ph.D., an exercise physiologist who’s worked with top professional cycling teams and is co-founder of Skratch Labs (www.skratchlabs.com).
In the books The Feed Zone Cookbook and Feed Zone Portables, Lim and chef Bijou Thomas make the case for why carrying real food in your jersey pocket is superior in many cases to nutritional supplements: Real food is easier to digest than dry, prepackaged bars because of its higher water content; it doesn’t overwhelm the small intestine like some concentrated sports drinks; and it doesn’t have preservatives that can have a laxative effect on the GI system during exercise.
“I think the most important reason why real food is better is because it just tastes better,” adds Lim. “Ultimately, we're humans and most of us love great food. In fact, the very process of digestion begins when we smell or see delicious food. Those sensory cues cause us to salivate and prime our GI tract to receive and process food through the release of a number of hormones and digestive enzymes. This first step is critical and one that is not always initiated by the deconstructed, processed and pre-packaged bars, blocks or gels that are common sources of calories for athletes. The bottom line is that simply drinking our calories or relying on pre-packaged foods isn't all that inspiring—a fact that can have some real physiological consequences. All things being equal, I'd rather eat something that has been freshly prepared.”
After exercise, as a real-food alternative to prepared recovery drinks, Lim says low-fat chocolate milk is an excellent choice.
“Low-fat chocolate milk is calorie-dense, has a good amount of protein, and is super convenient—all of which can be great immediately after a hard bout of exercise if someone is looking to refuel and optimize recovery for the next day,” he says. “More importantly, it tastes great and is just as convenient and easier to find compared to equivalent recovery drink products. Big picture: If you're hungry after a hard workout, low-fat chocolate milk probably works just as well as any protein recovery drink on the market and is, for most people, a more enjoyable option.”
Why Real Food is the Best Fuel
Eat a big, high-carb breakfast when you get up in the morning, a high-carb lunch with some protein before mid-day and a smaller, low-carb, protein-rich dinner. And limit the amount of snacking. That, in a nutshell, is the advice Ivy gives to athletes who want to perform at their very best.
“Balancing energy expenditure during the day and also what you eat and when are very important,” he explains. “There’s a high relationship to obesity and not eating breakfast. Eating most of your calories at supper and after supper is also highly related to obesity. You want to have three basic meals a day. You don’t want to skip breakfast. And you want to eat the majority of your calories before the mid-afternoon.”
The reason is that while we’re sleeping, our bodies are burning glycogen stores and breaking down protein from our body to maintain blood glucose levels to keep our brains functioning. As a result, we need to “break the fast” with breakfast and replenish our carbohydrate stores as soon as we get up. Conversely, since most of our muscle building and other protein synthesis activity occur at night when our growth hormone levels are at their highest, Ivy says it’s important to have sufficient protein before going to bed. “Normally people are protein deficient or have a net negative protein balance during the night,” he adds, “but you can reverse that by having a high-protein supplement, about 30 to 40 grams of protein, before going to bed.”
Lim supports that advice and his favorite recipes for breakfast, lunch and dinner from The Feed Zone Cookbook follow Ivy’s prescriptions.
Republished with permission of VeloPress from The Feed Zone Cookbook. Try more recipes at www.feedzonecookbook.com.
Photo credit: Courtesy VeloPress
Most athletes are aware of the boom endurance sports have experienced in the past three decades. What they may not realize is that as recently as the mid-1980s, athletes were not armed with the knowledge or the arsenal of sports-nutrition products that athletes have today.
Early triathletes such as Dave Scott fueled with bananas and figs—not only because he admittedly didn’t know better, but also because such options were all that were available to athletes. Fueling during the race was a challenge, and recovery was a mere afterthought.
Research conducted by Ivy and other physiologists paired with field testing by experts including Lim has led endurance athletes away from figs and bananas to pre-packaged sports drinks and now back to natural foods as a fuel source.
Just as low-fat chocolate milk existed long before we discovered it was a perfect recovery beverage, our bodies were designed to recover. They always have been. We now know how to utilize our natural biology to our advantage—we just had to figure out how it works.
This piece supported by Chocolate Milk