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Sports Nutrition Update: News from ACSM

The American College of Sports Medicine (ACSM) is the nation's largest professional organization for exercise scientists, sports nutritionists and other sports medicine specialists. Every May, experts from around the country and the world gather to present the latest information at the ACSM convention. The following are some highlights from the May, 2002 meeting in St. Louis.

Protein
Bodybuilders commonly wonder when is the best time to eat protein to optimize muscular growth. The latest research suggests having some amino acids (the building blocks of protein) circulating in the blood while you are exercising can optimize the muscle-building process. This simply means eating a pre-exercise snack that includes a combination of carb (for energy) and protein (for muscle building): cereal with milk, yogurt and a banana, bagel with peanut butter, trail mix (nuts and dried fruit), or a turkey sandwich. You need not run to the store to buy the latest protein bars or drinks; standard foods can do the job just fine!

Amenorrhea
Exercise scientists have questioned why some female athletes stop menstruating and others maintain regular menstrual periods despite a rigorous exercise program. According to Dr. Anne Loucks of Ohio University, amenorrhea (loss of the menstrual period) is caused by undereating. Women with amenorrhea fail to increase their calorie intake to account for the calories they burn during exercise. When the brain detects an energy deficiency, it immediately turns off the reproductive system.

If untreated, amenorrhea can lead to poor bone health, stress fractures and premature osteoporosis. The solution is to eat more calories, preferably a nice balance of whole grains, lean protein-rich foods, lowfat dairy products and healthful fats (salmon, nuts, peanut butter). For example, calories can be added by enjoying a yogurt for a morning snack the first week, then a half-cup of beans on a lunchtime salad the next week, potato with dinner the third week, etc. By gradually increasing calories over the course of three to five weeks, a woman can reverse the situation and not only be healthier (as indicated by regular menses) but also feel better and be better fueled for stronger workouts. Because these are not excess calories, they are unlikely to cause the women to "get fat." Rather, the body burns the fuel and becomes fully functional, as opposed to shutting down to conserve energy.

Anemia
Iron deficiency anemia ( "iron poor blood") is a cause of needless fatigue, primarily among female athletes. Women are more likely to suffer from anemia than are men, because women tend to eat less red meat (the best source of dietary iron), lose iron via menstrual bleeding, and skip breakfast (i.e., fail to eat iron-enriched breakfast cereals). A little bit of iron can also be lost via sweat or intestinal bleeding but, according to Dr. Randy Eichner of the University of Oklahoma, this loss is minimal. Dr. Eichner believes sports do not cause anemia but rather sports unmask it. That is, a sedentary woman could be unaffected by having mild anemia, whereas the active woman would notice a difference in physical performance. Regular blood tests in competitive athletes can help detect shifts in iron levels and prevent anemia.

Epidemic of obesity
Obesity is a major public health concern: 25% of children are now classified as overweight (or at risk of overweight); 61% of American adults are overweight or obese. Sedentary behavior is a contributing factor. Because 73% of kids ages 12 to 17 years spend a significant amount of time surfing the Internet, websites are an excellent way to reach this audience. A new site, www.kidnetic.com, is helping kids and families get positive messages about ways to be more active and fuel their bodies healthfully. The program designers studied what motivates kids (looking better, performing better, having more energy to do fun things). Hence, the content focuses on these fitness "pay offs." Hopefully, this obesity prevention program will also pay off!

Muscle cramps
Anyone who has ever experienced severe muscle cramps wants to know how to prevent them. According to Dr. Michael Bergeron of the Medical College of Georgia, salt is a key cramp preventer. Having worked with numerous tennis players who exercise in extreme heat, Dr. Bergeron noticed the athletes who suffer from cramps could resolve the problem by adding more salt to their daily diets. Case in point: a tennis player who regularly cramped badly, despite drinking plenty of fluids. His father had high blood pressure and consequently, the entire family ate a low sodium diet. Once the player started eating more pretzels, table salt and sports drinks, the cramping problem dissipated.

Dr. Martin Schwellnus of the University of Cape Town Medical School in South Africa offers another theory based on science rather than anecdotes. He believes cramps occur when the muscles are fatigued. A nerve malfunction creates an imbalance between muscle excitation and inhibition; the muscle doesn't relax. His solution: stretch the cramp.

Overhydration
In the effort to prevent muscle cramps and dehydration, some endurance athletes drink copious amounts of fluids, so much so they dilute their blood to the point sodium levels are dangerously low. This often occurs in slower marathoners who take the advice to drink at every water station. Excess water, in combination with a low salt diet, increases the risk of suffering from hyponatremia (low blood sodium); the athlete becomes tired, nauseous, disoriented or even worse (a seizure). The solution: Don't avoid salt and don't drink if your stomach is sloshing!

Exercise and weight loss
The myth is, if you add on exercise you'll lose body fat. The truth is, if you create a calorie deficit, you'll lose body fat. In a study with previously sedentary overweight males and females (average ages 22-24 years) who exercised 5 times a week for 16 months with no dietary restrictions, the men lost 12 lb. (body fat dropped 27 to 22%); they failed to eat enough to compensate for the extra calories burned. The women, however, had no significant weight or body fat changes; their appetites kept up with their calorie expenditure.

In a study with 220 women (ages 35-45), changes in calorie intake (i.e., eating less food) were more closely related to changes in body fatness than were changes in exercise. This means: remember to subtract food, not just add on exercise!

Nancy Clark, MS, RD is Director of Nutrition Services at SportsMedicine Associates in Brookline MA. She is author of Nancy Clark's Sports Nutrition Guidebook, Second Edition ($23) and her new Food Guide for Marathoners: Tips for Everyday Champions ($20). Both are available via www.nancyclarkrd.com or by sending a check to Sports Nutrition Materials, 830 Boylston St #205, Brookline MA 02467.