How many times have you completed the best training efforts of your life only to come down with a cold right afterward, or even worse, the day or two before your big competition? Or perhaps you get knocked off track every winter with a never-ending cold or the flu?
For the most part, exercise seems to create a protective shield against catching colds and other upper respiratory tract infections (URTIs). Studies on runners, for example, reveal that they generally report suffering from fewer colds when compared to sedentary people.
If you’re like many athletes, you pop vitamin C, zinc or glutamine – nutrients commonly linked with the immune system – in hopes of preventing illness. Or you may load up on the popular cold-prevention herb Echinacea as soon as the cold season begins.
Most likely, you have overlooked one of the simplest, but most effective means (besides
frequent hand-washing) of bolstering your immune system and thwarting the common cold: paying attention to what and when you eat.
The Power of Carbohydrates
Despite testimonials from famous sports people and overzealous manufacturers, scientists find little conclusive evidence that Vitamin C, zinc, glutamine or other popular supplements like Echinacea protect immune systems from being suppressed by prolonged or intensive bouts of exercise. Scientists have found one thing, however, that can turn it around – consuming carbohydrates during exercise.
Carbohydrates consumed during exercise (e.g., a sports drink) appear to boost the immune system by preventing precipitous dips in blood sugar. When your blood sugar level falls, your body responds by releasing large quantities of cortisol and other powerful stress hormones. Typically elevated after prolonged or intense exercise, cortisol profoundly suppresses immune function.
In other words, take sugar in and keep your glucose up during exercise and your cortisol levels will be significantly lower. That alone may be the edge you need to avoid catching a cold or being slowed down with a sore throat or the flu.
Exercise Immunology
Immunologists have found athletes’ immune systems are suppressed after exercise – especially after particularly prolonged, intense bouts. Depending on other factors, such as poor eating habits, inadequate sleep or mental stress, an intense or long exercise session may be the final blow to an overtaxed immune system. This is when viruses and bacteria can gain a foothold, disrupting your training schedule or racing plans.
If you exercise for an hour or less, drinking water during your workout should be sufficient. Follow-up by eating a well-balanced meal composed of carbohydrate and protein-rich foods. If you’re going longer than that (especially past the 90-minute threshold) or you’re tackling a particularly strenuous workout, use a sports drink during and immediately following exercise. This will prevent or at least help delay dehydration, glycogen depletion and a low blood sugar level, all of which are interpreted by your brain as stressors.
Day to Day Counter-Measures
How you typically consume your calories throughout the day can also greatly affect your immune system. For example, consuming 80 percent of the food (and calories) you need during the evening after you’re done exercising means you’re not in energy balance during the day.
To normalize your blood sugar level during the day, closely balance the calories you consume with the calories you expend. This means thinking about your energy needs on an hour-to-hour basis. Have healthy foods on hand so you don’t have to raid the nearest vending machine or fast food restaurant when you get the munchies. Besides feeling better and having more energy to train, your immune system will be in better shape to fight off the latest cold making the rounds.
Suzanne Girard Eberle, MS, RD, is a sports dietitian in Portland, Ore.
A former elite runner and the author of Endurance Sports Nutrition,
she can be contacted about sports nutrition consults
and speaking opportunities at Ebcruz@aol.com
Eat, Drink, Win!
“If you frequently ponder nutrition questions about triathlon or any other endurance sport, this book is your nutriment grail.”
-Triathlete magazine
Endurance Sports Nutrition is available at major bookstores, www.humankinetics.com or directly from the author at $15 plus $2 shipping/handling per copy.
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