Tips from Nancy Clark
Sports Nutrition Update: News from ACSM
The American College of Sports Medicine (ACSM) is the nation's
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
the ACSM convention. The following are some highlights from the
2002 meeting in St. Louis.
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!
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
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,
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
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!
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.
nerve malfunction creates an imbalance between muscle excitation
inhibition; the muscle doesn't relax. His solution: stretch the
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
eating less food) were more closely related to changes in body fatness
than were changes in exercise. This means: remember to subtract
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.
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