1) Are you racing more than twice a month?
2) Are you exposed to air pollution and/or sun during exercise?
3) Does your diet eliminate one or more food groups (animal protein sources, dairy, grains, fruit and vegetables)?
Exercise and free radicals
"Exercise wreaks havoc on your body." That's what one popular endurance sport supplement website claims. Havoc? Can exercise really be that bad for you?
Ramping up the body's metabolic rate does cause an increase in the production of free radicals, which are reactive chemicals that can harm membranes of the muscle cells unless the body's natural defenses are adequate. Even when we're taking it easy, our environment can intensify metabolic stress because of air pollutants we breathe in dust and exhaust. In the summer, harmful UV rays from the sun add to free radical production. Clearly, endurance athletes who exercise outside are regularly exposed to free radicals. But from this can one seriously conclude that exercise is harmful to their health?
No pain, no gain
Despite the fact that revving up metabolism during exercise produces free radicals, continuously taking megadoses of antioxidant vitamins has not been proven to be beneficial for endurance athletes.
When researchers at the U.S. Olympic Committee, Sport Performance and Olympic Training Center in Chula Vista, California, did a meta-analysis of studies where 1,000 mg per day of vitamin C were taken long-term, they found performance was actually decreased. Although unproven, they attributed the decrease to a reduction in beneficial training adaptations stimulated by exercise stress.
Similarly, other trials with vitamin C and E have shown that supplementation with high dose combinations for four weeks prior to a 2.5-hour bout of exercise did not improve markers of oxidative stress, and in fact higher levels of cortisol were found in the supplemented group when compared to non-supplemented athletes. Researchers in the combination trial hypothesized that the higher cortisol levels found in the supplemented group were caused by down regulation of the body's natural antioxidant defenses.
Long-term vs. short-term
While there is little scientific support for chronic use of high dose antioxidant supplementation, the situation may be different for very short-term supplement use immediately before or following intense exercise. According to a recent meta-analysis of double-blind, randomized studies published in The American Journal of Nutrition, a vitamin C supplement of at least 200 mg per day taken by 584 endurance athletes (marathon runners, Nordic skiers and soldiers participating in subarctic exercises) reduced the incidence of the common cold by 52 percent.
Other research has demonstrated that taking 1,000 mg of vitamin C in a single day is more effective than two weeks of supplementation in reducing exercise-induced metabolic stress.
Real diet vs. supplements
What is available on race day or during a century bicycling tour is often not the ideal free-radical squelching diet that can balance out the metabolic exercise stress. Summer bicycle tours advertise brats, burgers and beer with the only vegetables available being potato chips or corn on the cob. (If it's a high-quality refreshment spread, maybe there's sauerkraut and onions.) Few athletes turn down the free coupons for soda or beer as a reward for their efforts.
Many endurance athletes love their sports because they can enjoy all the good eats that go along with their events. Quality is an issue, however. It is very easy to eat a lot and stay in caloric balance but still do significant damage to your muscles and heart.
Striking a balance between having a good time and providing nutrients to repair muscles and replace depleted nutrients is essential.
Five smart nutrition practices
1) Skip the Belgian waffles or pancakes. Start the day with nutrient dense, high antioxidant foods: oatmeal with fruit and a sprinkle of nuts; plain yogurt with berries; whole grain toast and natural peanut butter; fruit and nut granola; cinnamon toasted quinoa with berries, honey and soy milk.
2) Include two servings of a high vitamin C food or beverage as a snack or in a meal daily. Orange juice is often too acidic before a race while fresh oranges are usually tolerable. Other high vitamin C foods include kiwi, kale, broccoli, bell peppers, papaya, strawberries and cauliflower.
3) Consume antioxidants shortly after high intensity or prolonged exercise, say of 2.5 hours or more. The options include drinking a) a fruit or veggie smoothie, b) a commercial recovery drink fortified with antioxidant vitamins, c) a large V-8 vegetable juice cocktail, d) indulging in fresh strawberries or kiwi dipped in dark chocolate or e) eating pizza topped with roasted peppers, tomato and onion.
Off-setting metabolic and environmental stress is an ongoing process for endurance athletes. If you would rather not rely on antioxidant supplements, then follow a diet that contains a high amount of phytochemicals from fruits and vegetables, whole grains and legumes every day.
If it were up to me, all silent sports event directors would serve strawberries, kiwi, good quality red wine, pickled herring and whole grain crackers to boost antioxidants and omega-3 fats. And lots of dark chocolate!
Donna Marlor, MA, RD, CSSD, is a registered dietician specializing in nutrition for endurance exercise and weight management. She offers motivational coaching and behavioral skills training to change eating patterns. Marlor is a consultant to the Olympic Education Center in Marquette, Michigan, and works with many individual athletes from novice to elite. A former collegiate alpine and Nordic skier, Marlor still enjoys master's level competition as a skier and runner as well as spending time with her family and chocolate Lab in the Upper Peninsula. She can be reached viawww.DonnaMarlor.com and at 906/360-9049.