Q. What should I take to boost my immune system?
A. Moderate exercise actually boosts your immune system; moderate exercisers have no need to take immune-boosting supplements. Hard, exhaustive exercise, in comparison, contributes to inflammation, oxidative stress, and immune dysfunction. But if you are healthy, well fed, and well rested, your immune system can handle the stress. Supplements will not boost your immune function above normal levels.
If you undereat and fail to consume adequate protein or carbs after exercise (as happens with dieters or athletes who are "too busy" to eat), immune response drops. The best supplement to take to counter this response is adequate food--carb-protein combinations, like chocolate milk or a meal.
Quercetin (a bioactive compound found in red apples) is touted to boost the immune system. However, research suggests quercetin works best in "cocktails," the way it naturally come in foods. That is, a quercetin supplement, by itself, is less effective than when quercetin is combined with other bioactive compounds, such as fish oil and green tea extract.
Q. Should I train on a high fat diet to enhance fat-burning?
A. By burning more fat, athletes are able to burn fewer carbs and thereby spare their limited glycogen stores. Supposedly, this should enhance endurance, given that glycogen depletion is associated with fatigue. Yet, the practice has yet to translate into improved performance. The best way to enhance endurance is to consume carbs during extended exercise.
Q. Should I train with low glycogen stores, and then compete when carbo-loaded?
A. While the "train low, compete high" method is an interesting concept, research has yet to prove it will enhance performance. Theoretically, training "low" stimulates physiological adaptations that spare muscle glycogen and allow greater endurance. The problems are:
1) athletes are unable to train at a high intensity when their muscles are glycogen depleted.
2) training with glycogen-depleted muscles increases the risk of injury.
Bottom line: Eat carbs daily for well-fueled muscles that allow you to train hard.
Q. What dose of caffeine is best to enhance performance?
A. Although responses to caffeine vary greatly from person to person, a suggested dose equates to a 12-oz. mug of coffee one hour pre-exercise. (More precisely, consume 1.5 mg caffeine per pound of body weight (3 mg/kg)--or about 225 mg for a 150-lb athlete. Higher doses of caffeine offer no performance advantages and can create the disadvantage of sleep problems that end up hurting performance. Enough is enough; more caffeine is not better!
Q. Do I need to worry about contamination in commercial sports supplements like protein powders?
A. Yes! A survey of 634 nutrition supplements indicates about 15 percent included a banned substance, even though the supplement came from a factory that did not even manufacture banned substances (i.e., steroids, ephedrine). The contaminants make the products "work" (read that, "sell better"). The products most likely to be contaminated with illegal compounds include bodybuilding supplements and weight loss products. Buyer beware!
Q. Where can I find a sports dietitian to help me eat to win?
A. For a board certified specialist in sports dietetics (CSSD) in the US, use the referral network at www.SCANdpg.org. With a personalized eating program that optimizes your fueling practices, you'll gain a winning edge!