Tips from Nancy Clark
2001 Nutrition and Health News from ACSM
At this year's meeting of the American College of Sports Medicine
(ACSM, the nation's leading group of sports medicine professionals),
over 5,000 members gathered in Baltimore to learn the latest research
regarding health, exercise and sports medicine. The following are
some highlights that might be of interest to you.
IMPORTANCE OF EXERCISE
We all know that exercise is health-protective, but just how much
does exercise impact health? One study with about 26,000 men indicates
those who exercised had lower rates of death from cancer than those
who exercised less. This held true even for smokers. If you have
friends who smoke, tell them to at least exercise and be fit!
Exercise can save corporations millions of dollars on medical expenses.
In a three-year study of the effectiveness of a corporate wellness
challenge, 700 employees earned points for doing regular exercise,
reducing cholesterol levels, body fat and blood pressure plus attending
health education programs. The employees got paid $350 per person
for completing the program. Incentive payouts of $400,000 yielded
net savings of $1.6 million for the three year period ($762 per
participant per year). The program contributed to reduced health
care costs, less absenteeism and reduced workers compensation costs.
Exercise is less expensive than medicine!
One "innovative" way to become fit is to get a dog and
walk it. But even dog owners need guidelines. A survey of 410 dog
owners suggest 58% did not walk their dogs regularly, and only 22%
walked their dogs for more than 2 hours per week--not long enough!
This lack of exercise has implications for the health of both the
dog and the owner. Fido, start begging to go for a walk!
The benefits of exercise extend into cancer recovery. Chemotherapy
and radiation treatment are known to cause fatigue and reduced physical
activity, as well as reduced immune function. In a study with 11
breast cancer patients who did strength training (1-3 sets) and
aerobic exercise (15-20 minutes) for three months after radiation
treatment, the women showed improved immune function (as measured
by recovery of lymphocytes).
Exercise has psychological benefits as well for cancer patients.
In another study of 40 women in recovery from breast cancer, those
who walked regularly experienced less body dissatisfaction and physique
anxiety; they felt better about their bodies and reported improved
health-related quality of life. Integrating physical activity into
cancer treatment programs has meaningful implications.
If you lose 2-3% of your body weight pre-post exercise, you compromise
your ability to perform at your best. Yet, many athletes fail to
drink enough fluids. In a simulated 10 mile running race, the athletes
drank only 30% of what they lost via sweat and became 2% dehydrated.
This study underscores the need to adhere to a predetermined fluid
schedule. By knowing your sweat rate (as determined by weighing
yourself naked before and after exercise), you can then know how
much to drink. Theoretically, if you lose 1 pound of sweat per hour
of exercise, you should target consuming 1 pound of fluid (16 ounces)
per hour during your next exercise bouts. In reality, you may not
need/be able to tolerate quite that much because your body has inner
water that gets released during exercise--about 3 grams water become
available /gram muscle glycogen used during exercise--but at least
you'll have a baseline fluid target. By experimenting during training,
you can learn how much fluid you can actually tolerate during exercise
in different temperatures.
A survey of almost 250 collegiate athletes at U Mass-Amherst indicates
that prior to exercise, 13% of the athletes were considered underhydrated
(based on the concentration of their urine). Sixty-nine percent
were acceptably hydrated, and only 17% were well hydrated. Men were
more likely than women to be underhydrated. The bottom line: Be
responsible--consume enough fluids!
Exercise scientists have validated that an accurate way to tell
if you have had enough fluids is to simply monitor the color of
your urine. The darker the color, the greater the level of dehydration.
In a 30 mile mountain bike race (completed with no fluids other
than "tanking up" beforehand), the athletes ended with
a very small volume of dark-colored urine that was indicative of
Overhydration also deserves mention. Among "slow athletes"
(such as participants in >5-hour fund-raising marathons), medics
are noticing more and more disoriented participants with a vacant
stare. The problem: overhydration. These slow athletes take the
advice "drink often" to the extreme. Hints: 1. Do not
add water to a sloshing stomach. 2. Consume sodium-containing sports
drinks and foods (as compared to consuming only water).
As for what's acceptable to drink during exercise, a study with
ever-popular Coca Cola validated what athletes have been doing for
years. Cyclists traded sports drink for Coke after 1.5-2 hours of
hard biking and again during the final 30-minute sprint. They enjoyed
a stronger performance than when they had no caffeine. The combination
of caffeine + sugary fluid (be it Coke or a sports drink + caffeine)
yielded a stronger finish.
BODY FAT / WEIGHT
Weight is forever a concern of athletes, and overweight / obesity
is a national public health concern. Researchers are particularly
interested in the effect of exercise on weight management. Overweight
people commonly believe they have to exercise vigorously to achieve
weight loss. In a 16 week study with overweight people assigned
to one of 3 programs (diet plus: vigorous exercise OR intermittent
10-minute bouts of vigorous exercise OR simply increased activity
in their daily lifestyle), the subjects averaged 1 lb. weight loss
/ week and all experienced similar health benefits (reduced blood
pressure, blood lipids). The bottom line: Simple daily activity
has a positive impact on weight and health. Not everyone wants to
exercise vigorously (nor needs to exercise vigorously). But most
of us can park the car further away, take more stairs and fewer
elevators, and sweep the kitchen floor with more effort. Small bouts
of activity count; they burn calories and improve health.
Take heed: Doing regular exercise does not always equate to weight
loss. In a 16 month study, overweight women who exercised 5 days/week
for 45 minutes did not lose weight (but they did improve fitness).
The women failed to create the calorie deficit needed to lose body
fat. Apparently they were less active during other parts of the
Nancy Clark, MS, RD specializes in nutrition for
sports and exercise. She counsels both competitive and casual exercisers
at SportsMedicine Associates in Brookline MA (617-739-2003). Her
popular book, Nancy Clark's Sports Nutrition Guidebook, Second Edition,
is available via www.nancyclarkrd.com.
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