If you are looking for sports nutrition information, a likely
source is the American College of Sports Medicine (ACSM), the
nation's largest group of exercise scientists and sports
medicine professionals. (See www.acsm.org for more
information.) The following bits of nutrition information
presented at ACSM's annual meeting in Indianapolis (June 2-5,
2004) offer just a taste of what was discussed.Food:
If you want to save money on pre-exercise
snacks, consider eating "real" food. Trained cyclists performed
just as well whether they ate raisins or sports gel 45 minutes
before an exercise test. The approximately 300 calories (0.5
grams carb/lb) of pre-exercise carbohydrate from either source
did the same job and no one complained of intestinal problems
during the raisin trial! At one-fifth the cost of gels and a
stronger source of nutrition, raisins can be a good sports
energizer at a bargain price.
Fluids:
Many commercial sports drinks claim to
enhance performance and recovery, but the claims can sometimes
be questioned. Case in point: Endurox. Subjects consumed R4
Endurox, Powerade, or a no-calorie placebo before, during, and
immediately after an exercise test that involved biking
moderately hard for 45 minutes, performing an incremental test
to fatigue, resting for 15 minutes, and doing another
incremental test to fatigue. When the subjects consumed the
Endurox, they fatigued slightly earlier than when they had the
placebo or Powerade.
Caffeine:
Athletes are typically advised to refrain
from
consuming caffeinated beverages before and during hard exercise
in the heat, based on the (now outdated) theory that caffeine
has a dehydrating effect. When 59 healthy males (whose bodies
were accustomed to caffeine) consumed differing amounts of
caffeine, the caffeine did not threaten hydration status nor
tolerance to the heat. The group who consumed 1.5 mg
caffeine/lb body weight (about a 12-ounce mug of coffee)
actually performed longer than the no-caffeine group (86 vs 75
minutes). This suggests caffeine offers an ergogenic effect and
can be effective, even when used in the heat.
Illegal drugs:
If you are a collegiate, Olympic, or
professional athlete, take heed: about twenty-five percent of
supplements are contaminated with muscle-building substances
that are prohibited by the IOC and NCAA. What appears to be
a "legal" sports supplement may not be legal, after all.
Recovery:
After a hard workout, athletes need to
consume carbs
to refuel their glycogen-depleted muscles. The question arises:
does adding protein to the carbohydrates enhance the rate of
post-exercise glycogen storage and thereby enable stronger
performance in the next bout of exercise? Two studies suggest
no significant improvement in run times to exhaustion in a bout
of exercise performed either two or four hours after the first
bout, when the subjects refueled after the first exercise bout
with a carb-protein recovery drink. Yet, the carb-protein
recovery beverage did contribute to lower ratings of muscle
soreness. The researchers want to investigate whether the
addition of pre-, during, and post-exercise protein enhances
muscle repair, thereby reducing muscle soreness. A refueling
study with chocolate milk indicates it is an effective recovery
drink, similar to commercial carb-protein drinks.
Dehydration:
Most athletes are well versed on the
importance of
drinking enough fluids before, during, and after exercise in
the heat. Despite this knowledge, problems with dehydration
abound. A study with professional basketball players who
performed two-a-day workouts shows they started their first
practice of the day inadequately hydrated and remained that way
into the second practice session. This hypohydration existed
even though they lost only a modest amount of sweat, about 0.85
liters/hour of sweat.
In comparison, college football players lost about 1.8
liters/hour of sweat (a total of 4.1 liters per day) in
moderately hot weather. The football players also failed to
replace all the sweat losses and experienced mild dehydration.
Youth soccer players (ages 12-13) attending a summer soccer
camp failed to drink enough fluids, even though the coaches
encouraged them to do so and positioned cool fluids nearby. The
studies suggest high-performing athletes need to pay more
attention to their hydration needs. A simple drinking strategy
to improve hydration status is to drink 20 ounces of fluid
after dinner and before bed, then again before practice in the
morning.
Anemia:
Iron deficiency anemia and the precursor,
low serum
ferritin levels, threaten optimal athletic performance. A study
of 46 competitive 13-year-old swimmers indicates twenty-three
percent of the boys and fifty-five percent of the girls had low
serum ferritin. Given that more than one-third of these
swimmers presented with low ferritin, youth athletes should be
encouraged to eat iron-rich foods (enriched cereals, lean
meats) to prevent the development of anemia. Some may even need
iron supplements to keep up with their body's increased demand
for iron due to growth and the expansion of blood volume.
Junk food:
Despite eating more than 4,000 calories
per day,
many collegiate football players eat too little fruit,
vegetables, and dairy foods. A survey of 50 players suggests
they consumed fifty-nine percent of their energy from sugar and
fat. No wonder many had low intakes of calcium, magnesium,
fiber, and vitamins A, E, and folate.
Meat:
Among female collegiate athletes from a
variety of
sports, sixty-one percent consumed inadequate high quality
protein (from meat, fish, poultry, eggs, and dairy). Some of
these women limited their intake of animal protein in an effort
to reduce their intake of dietary fat and, hopefully, reduce
their body fat. Yet, dietary fat intake was not related to
percent body fat in this study. Female athletes should focus on
eating well (including adequate protein) without worrying about
gaining weight.
Pedometers:
Pedometers can be useful with weight
reduction
programs. By wearing a pedometer, people can obtain data
regarding their activity level. For example, in a group of 552
overweight older women (ages 45-75) who did no regular
exercise, the average step count was about 5,300 per day. Only
three percent of the women accumulated more than 10,000 steps
per day, a popular recommendation for a physically active
lifestyle. In comparison, fewer than 5,000 steps per day has
been defined as sedentarism.
Does knowledge about personal sedentarism inspire greater
activity level? Doubtful, according to a study with 41
overweight, lower income women (ages 40-65) who wore pedometers
for three months. Each woman received a weekly phone call,
encouraging her to increase her steps by ten percent each week
with a goal of 10,000 steps per day by the end of three months.
More than half of the women did not increase their steps by
more than 1,000 from baseline. Knowledge does not always turn
into action.
How accurate are the pedometers that estimate calories burned
with walking? In a study with 21 students who walked/jogged on
a treadmill while wearing a pedometer and simultaneously
getting their energy expenditure measured via a metabolic cart,
the pedometer overestimated calorie expenditure by 70-95
cals/hour.
Sports Nutritionist Nancy Clark, RD counsels casual and
competitive athletes at her private practice in Healthworks
Fitness Center in Chestnut Hill, MA (617-383-6100). Her best-
selling Sports Nutrition Guidebook, Third Edition ($23) and
Food Guide for Marathoners: Tips for Everyday Champions ($20)
are available by sending a check to Sports Nutrition Services,
PO Box 650124, Newton MA 02465 or ordering through
www.nancyclarkrd.com.