Some years ago a football coach asked us if feeding royal jelly to his team would improve its performance. When we told him the only proven function of royal jelly is to feminize bees, and that its effect-feminizing or otherwise-on humans is unknown, the coach quickly lost interest.
Weekend sports enthusiasts and competitive athletes alike hungrily consume such substances in hopes of bolstering their prowess. Each year millions of dollars go toward amino-acid mixtures, ``energy replacers`` and vitamin and mineral supplements for which there is no proven or even likely benefit.
In the last two decades, research on maximizing human physical capacity has intensified. Much effort centers on gauging the merits of the ``training`` diet. Recently the American Dietetic Association issued a position paper on nutrition and physical fitness and athletic performance for adults. The bottom line is that while we now know more about the physiology of exercise, sensible dietary recommendations for competitive athletes have changed little over time.
One fact is clear: Athletes whose weight is normal need more calories than sedentary individuals of the same size. While it is generally recommended that we eat more complex carbohydrates and less fat, this is particularly true for the competitive athlete. Complex carbohydrates help promote storage of glycogen-muscle starch-which is important in endurance contests.
But advice regarding ``carbohydrate loading,`` or packing the muscles with glycogen, has been modified. Increasing glycogen stores enhances performance by providing greater energy reserves to draw on during
competition. That allows the athlete to maintain a high intensity of exercise. As originally prescribed, athletes first depleted their muscle stores and then ate enormous amounts of carbohydrate for several days before an event. But there were side effects: Repeated loading was associated with depression, lethargy and loss of muscle tissue. Chest pain, abnormal electrocardiograms and other problems also were reported, so the procedure was modified.
Nowadays, athletes are advised to consume hefty portions of carbohydrate throughout the training period, and to use carbohydrate loading judiciously. Beginning a week before a competition, they are counseled to taper their activity, with complete rest the day before the event, and to slowly increase carbohydrate consumption from about 350 grams a day to as much as 550 grams, or 2,200 calories of carbohydrate for the three days prior to the event.
To put that figure into perspective, a pound of spaghetti contains 340 grams of carbohydrate. Athletes whose caloric requirements are very high may need to consume more.
Carbohydrate loading has specific uses. It is beneficial only in endurance events lasting more than 90 minutes or in multiple competitions. It should be used only three or four times a year, and should not be practiced by young children or teen-agers, or without medical consultation by athletes who have diabetes or hypertriglyceridemia.
Unlike carbohydrate loading, packing the diet with protein has no known benefit, despite the plethora of products suggesting otherwise. Research indicates that current Recommended Dietary Allowances for endurance athletes may be slightly higher than for nonathletes. But athletes who eat enough calories to meet their energy needs are consuming well above that amount anyway. The idea that very high protein diets are necessary for muscle building is totally unfounded and possibly harmful.
Similarly, athletes don`t need special vitamin and mineral supplements except in very specific, highly individualized situations. For example, young female athletes who do not menstruate regularly may be at risk of losing calcium from bone, and might be prescribed supplements to offset losses.
Anemia is another common problem facing female athletes. But again, it is recommended that supplements be prescribed only after an evaluation of an individual`s iron stores and should not be viewed as self-help measures by weekend athletes. Mega-nutrient capsules and powders are unnecessary for either competitive athletes or for those who simply enjoy regular physical activity.
Conversely, adequate fluids are essential to athletic performance. Because vigorous exercise may blunt the thirst mechanism, regular fluid consumption should be scheduled. Athletes are advised to take 2 cups of fluid about 2 hours before exertion, and another 2 cups 15 to 20 minutes before endurance exercise. If it is especially warm, small amounts of fluid should be consumed every 10 or 15 minutes. For most people who are undertaking normal exercise at moderate temperatures, the fluid of choice is plain, cool water. Heavy exercise or extreme heat may call for a low-dose supplemental electrolyte replacement during endurance competition.