I’ve had two colds this winter and both hit me within days of finishing a 12- to 14-mile run. Like many weekend warriors, I’m training for a marathon, so in addition to my Saturday long run, I’m exercising for about an hour five days a week, and I wondered if there was a connection.
In fact while studies show exercising 30-45 minutes most days of the week cuts your chances of getting a cold in half, according to public health specialist David C. Nieman, your odds go up six-fold when you’re exercising for more than 90 minutes, including running, cycling, or even swimming at a racing pace.
That’s because this kind of high-intensity endurance exercise has the potential to put an enormous amount of stress on the body, making it more difficult for your body to fight off viruses, said Nieman, director of the University of North Carolina’s Human Performance Lab. We’re exposed to viruses all the time, especially now during flu season, he added, but if you compromise your body’s ability to fight back, you’ve created an "open window” for getting sick.
What happens is in general people aren’t able to store large amounts of carbohydrates, our body’s most efficient energy source, and we run out relatively quickly during high-intensity exercise lasting between 75 to 90 minutes, Nieman said. If you don’t replace your body’s glycogen, or stored carbohydrates, he said, your body can go into a red-flag alarm state impairing your body’s ability to fight off bugs.
To make matters worse, when glycogen drops to very low levels, Nieman said, the body is forced to start using other fuel sources, including protein stored in the muscle and other areas, further compromising the body’s immune system.
Sounds simple, right? Replace carbs and you’re good to go?
The problem is many people just don’t do it, Nieman said. Often that’s because they don’t have an appetite when they run, or their digestive systems have not adapted to taking in carbs as frequently as they need to, or they haven’t developed a good method for taking in what they need without cutting into their race pace.
So while it’s true that carbs are the main actor in closing that window, protein may play a role in helping reduce the risk of upper respiratory tract viral infections during high-intensity endurance exercise, according to Kelly R. Jones, a Philadelphia-based registered dietitian and sports dietetics specialist.
Mostly that’s because adding amino acids, or protein, can help replenish glycogen faster, but it’s also because some proteins, specifically arginine and glutamine and branched-chain amino acids (BCAAs), are energy sources for our immune system, according to Jones.
Arginine stimulates the activity of our natural killer immune cells, Jones said, and like glutamine, while we do get some in our diet through protein-rich foods we also create these amino acids in our skeletal muscle cells. Under normal circumstances we don’t have a problem with these amino acids, Jones added, but when the body is experiencing extreme physiological stress, which could be any sort of trauma or endurance exercise over two hours, our levels drop.
In addition, Jones maintains that while there is not enough scientific evidence to recommend glutamine supplements for immune support, some research shows that BCAAs can help to support glutamine levels. “Consuming BCAAs either right before exercise or during extreme endurance exercise along with the appropriate amount of carbohydrates should keep your glutamine levels from dropping,” Jones said.
Jones advises her clients to ensure their diets are rich in poultry, fish, eggs, dairy, and meat, which contain all of the amino acids that support high-intensity endurance exercise. Soy is the best option for vegetarians, she said, but she recommends other vegetarian sources, too.
Jones said it’s not necessary to eat protein during a workout for most individuals. If you’re engaging in high-intensity exercise longer than two hours, however, and if it gets hard to consume enough carbohydrates, having a few grams of protein per hour might be helpful.
That’s where a BCAA supplement might come into play, Jones said. Otherwise she advises clients to mix a pasteurized egg white into their water or other beverage they might carry with them on a fuel belt.
“It doesn’t take a lot to make a difference,” according to Jones, “maybe 3 to 6 grams per hour.” You just want to be sure you’ve bought pure egg whites in a container that says the product has been pasteurized, a high-heat process that kills bacteria. One pasteurized egg white, or two tablespoons, provides about 3.6 grams of protein.
“What a lot of research shows and what I’m always recommending is if you eat enough carbohydrates throughout the day then you’re saving your protein from being used as an energy source,” Jones said. But with an endurance athlete that’s where sometimes that’s not enough. Adding in protein for the longer term can be helpful, Jones said.
And both Nieman and Jones recommend replenishing carbohydrates and adding protein within an hour after exercise whether it’s endurance or strength training.
“That’s when your muscles are most sensitive to absorbing nutrients for recovery,” according to Jones, “and your heart rate is still up so you’re going to deliver the nutrients quickly to where they need to go.”
Vegetarian foods rich in arginine, glutamine, and BCAAs
Arginine: soy/edamame, lentils, quinoa, pumpkin seeds, spirulina, peanuts, walnuts
Glutamine: soy and other legumes,raw spinach,raw cabbage, beets
BCAAs: soy, quinoa, hemp, , almonds, brazil nuts, buckwheat, pumpkin seeds
For information on fueling your exercise with sports energy products, see What Exactly Is In Your Little Pouch Of Gu Energy Gel? and What You’re Drinking When You Have NUUN Active