March 2008
Sports
Nutrition for Young Athletes: Vital to Victory
By Pamela M. Nisevich, MS, RD, LD
Today’s Dietitian
Vol. 10 No. 3 P. 44
By analyzing their diets and coaching them
on the most valuable nutrients, RDs can help their young athletic
clients play to the best of their competitive ability.
A young athlete enters an RD’s office
and turns in his three-day food record. He’s proud of
himself for “improving” his diet, but as the RD
reviews his intake, she grows increasingly disturbed. The athlete
fuels at breakfast with two Super Donuts; regardless of the
touted extra protein, vitamins, and minerals, he’s not
off to a good start. The RD is equally unimpressed with his
lunch choices: a deli sandwich on white bread with three packets
of mayonnaise, a 16-ounce juice, a small bag of potato chips,
and a 6-ounce blueberry muffin. Ten minutes before a big game,
he downs 12 ounces of Coke and a chocolate chip cookie and,
more than three hours after the final whistle, finally recovers
with a foot-long cheesesteak and large order of fries.
After reviewing his intake, the RD wonders how
to break it to this young man with “improved nutrition”
that there is nothing super about donuts, blueberry muffins
do not count as a fruit serving, and fries are not a vegetable.
But before criticizing him for his precompetition meal of high-fructose
corn syrup and fat, she remembers having the same poor eating
habits when she was a young athlete, constantly on the run and
at the mercy of whatever the school vending machine and cafeteria
offered.
Sports Nutrition:
Critical to Success
All athletes strive to compete at the top of their game but,
unbeknownst to many of them, their performance relies on their
nutritional status. Jenna A. Bell-Wilson, PhD, RD, CSSD, who
is a certified specialist in sports dietetics in Arlington,
Mass., says that young athletes with inadequate diets may have
insufficient fuel for workouts, nutrient deficiencies that can
lead to illness or fatigue, a decrement in bone growth and maintenance,
and may not reach their potential for muscle growth. All of
these will be reflected in their performance, regardless of
their determination.
Despite the recognition that young athletes
need to pay greater attention to their fuel consumption, recent
research suggests that many youths struggle with energy balance,
experiencing an energy deficit or surplus. We are all too familiar
with this energy surplus, known as overweight or obesity—but
that crisis is not the focus of this article. The concern is
that many young athletes require greater amounts of nutrients
but remain uninformed or unconcerned about their nutrition needs
or simply feel powerless to improve their nutritional status.
RDs can help young athletes overcome these problems.
The number of young athletes in the United States
is increasing and estimates are that approximately 30 to 45
million youths aged 6 to 18 participate in some form of athletics.1
These young athletes turn to coaches, parents, teammates, and
health professionals for nutrition guidance. RDs, especially
those who are certified specialists in sports dietetics, guide
athletes to be leaner, stronger, and able to withstand the rigors
of training and competition. RDs can offer superior advice because
they are more cognizant of research findings and are equipped
with clinical and counseling skills to aid in a young athlete’s
quest for improvement. By helping athletes improve their diet,
RDs can eliminate obstacles to better health and nutrition and
thereby help athletes push their limits and reach their full
potential.
Nutrition professionals can aid young athletes
in their quest for victory by recognizing that children and
adolescents generally need more calories and protein per pound
of body weight than many adults. It is a well-known fact that
children need this extra energy to grow, fully develop, and
thrive. Nutrient needs further elevate and reach their peak
during adolescence.2 Potential differences in nutrition needs
between a typical child or adolescent and an athletic child
or adolescent likely exist but are not entirely clear. Limited
studies of energy balance in young athletes have been published,
and conservative recommendations have been made. But self-reported
diet records of young athletes often indicate that intake of
energy, carbohydrate, and select micronutrients may be below
recommended levels. RDs must be aware that these deficiencies
exist and are especially apparent in athletes involved in sports
that focus on body composition and appearance.3
Proper Intake of Macronutrients and
Micronutrients
Critical Micronutrients
Current research and trends point to deficiencies in calcium,
iron, folate, vitamin B6, and zinc for young athletes. The functions,
risks of deficiency, and recommendations for each vital micronutrient
follow.
Calcium
Proper intake of calcium is needed to support bone growth, increase
bone mass, and aid in nerve impulses and muscle contraction.4
Poor calcium intake can lead to decreased bone mass and consequential
increased risk for stress fractures and other bone-related injuries.1
Because a young athlete’s growing bones cannot handle
as much stress as an adult’s mature bones, optimum bone
health is critical; overuse and overtraining injuries are more
apt to occur in a pediatric or adolescent athlete. To ensure
proper bone health, keep in mind that the adequate intake of
calcium for children aged 9 to 18 is 1,300 milligrams per day.5
Iron
While iron is noted for its oxygen-carrying capacity, it is
also a major player in the energy metabolism of carbohydrate,
protein, and fats. For this reason, young athletes with iron-deficiency
anemia may experience performance inhibition ranging from decreased
work capacity to extreme fatigue, impaired immune function,
and impaired cognitive reasoning. Because iron deficiency is
one of the most common nutrient deficiencies in the world, it
is imperative that professionals working with young athletes
are aware of the athlete’s iron intake.
On the other hand, it is important to note that
iron toxicity is the most common cause of poisoning death in
young children. If you want to avoid recommending a supplement,
you can recommend food items that are high in iron, such as
red meat and enriched cereals and grains, coupled with fruits
and vegetables that are high in vitamin C, which aids in iron
absorption.
B Vitamins
Both vitamin B6 (pyridoxine) and folate are members of the B-complex
of vitamins and are critical components of energy metabolism
and blood health.4 Both are critical for amino acid metabolism
and good sources of each are enriched grain products and assorted
animal products. Research differs on whether there are changes
in folate and vitamin B6 levels during periods of heavy training.
However, the conclusion is usually that exercise does not increase
the requirements for these nutrients and the dietary reference
intake should be followed.6 In general, a B-complex deficiency
can lead to fatigue, muscle soreness, apathy, and loss of cognitive
function.
Zinc
While an extreme zinc deficiency is uncommon in the United States,
athletes are at risk due to poor consumption of foods rich in
this mineral. Zinc plays a role in more than 300 enzymatic reactions
in the body and is critical for wound healing, tissue growth
and maintenance, and immune function. Various studies have shown
that zinc status directly affects basal metabolic rate, thyroid
hormone levels, and protein utilization; thus, zinc is critical
to athletes. Dietary protein enhances zinc absorption, and athletes
who are most at risk of a deficiency may be vegetarians or those
who primarily eat a grain-based diet. With the myriad critical
functions to which zinc is linked, consumption of adequate levels
of zinc should be stressed.6
Critical Macronutrients
With an increase in energy expenditure comes a subsequent need
for an increase in the intake of carbohydrate, protein, and
fat. Current research and trends point to deficiencies in overall
total energy and carbohydrate intake. Also of concern is deficient
fluid intake and consequent altered hydration status of young
athletes. The functions, risks of deficiency, and recommendations
for each vital macronutrient follows.
Carbohydrate
In athletes, poor carbohydrate intake results in inadequate
glycogen stores and premature fatigue, which not only compromises
performance but also forces the body to rely on another source
for fuel: protein. Glucose from carbohydrate sources is essential
to most body functions during exercise. If glucose is not available
for use as fuel during physical activity, the body will take
from its protein stores for energy via gluconeogenesis. Because
carbohydrate is the preferred fuel for athletic performance,
approximately 55% of total daily calories should come from carbohydrate.
The young athlete has the capacity to store carbohydrate in
the form of glycogen, but this capacity is limited, so carbohydrate
must be consumed daily. Carbohydrate needs are based on body
weight and intensity of activity. The American Dietetic Association
(ADA) has set the following recommendations for the young athlete:
• 3 to 5 grams of carbohydrate per kilogram
for very light intensity training;
• 5 to 8 grams of carbohydrate per kilogram
for moderate or heavy training;
• 8 to 9 grams of carbohydrate per kilogram
for preevent loading (24 to 48 hours prior); and
• 1.7 grams of carbohydrate per kilogram
for postevent refueling (within two to three hours).7
Protein
Protein is an essential part of the young athlete’s diet,
and the role of protein for youth includes building, maintaining,
and repairing muscle and other body tissues.7 It should be noted
that an adequate protein intake with inadequate caloric intake
prohibits protein balance, even when the recommended daily allowance
for protein is consumed.8 Therefore, it is critical that young
athletes consume enough calories to maintain body weight.
While adult endurance and strength athletes
may need more protein per pound of body weight, additional protein
needs for young athletes have not been specifically evaluated.
However, the ADA has set the following recommendations:
• Athletes who have just begun a training
program require 1 to 1.5 grams per kilogram per day of protein.
• Athletes participating in endurance
sports require 1.2 to 1.4 grams per kilogram per day of protein.
• Athletes who restrict calories must
be certain to consume adequate protein for muscle building and
repair. A minimum of 1.4 grams per kilogram per day is recommended.
• Vegetarian and vegan athletes should be counseled to
ensure that adequate intake of protein is consumed from plant
sources.
• Consuming an overabundance of protein
can lead to dehydration, weight gain, and increased calcium
loss. This is critical to monitor as research shows that the
population of young athletes is already at risk for calcium
deficiency.7
Fat
While carbohydrate is often spotlighted as the preferred fuel
for sports, there are some bodies of research suggesting that
lipid or fat may be the preferred fuel for children. This may
be due to the higher rate of fat oxidation in children.9 As
a major energy source, fat is essential for light- to moderate-intensity
exercise and for endurance exercise. Below are some easy-to-follow
guidelines for consumption of fats:
• While a low-fat diet can be followed,
it is important that young athletes consume an average of 20%
to 30% of calories from fat.
• Like adults, young athletes should aim
to significantly lower the amount of saturated and trans fat
in their diet. The focus should be on an intake of healthy fat
from plant oils and soft margarines made with vegetable oils
and on limiting the amounts of fried and processed foods.
Fluid
Maintaining fluid balance is critical for the young athlete.
As rates of youth participation in endurance events climb, legitimate
concerns about fluid status have arisen. Aside from the risk
of heat-related illness, dehydration is strongly associated
with fatigue during exercise. This risk is increased in certain
environmental conditions such as high heat and humidity.
Compared with adults, young athletes may be
at a higher risk for altered fluid status for several reasons:
Children experience greater heat stress and heat accumulation,
and they have a greater ratio of surface area to body mass and
absorb heat more readily.10 Signs of dehydration in children
include dark urine, small urine volume, muscle cramps, reduced
sweating, increased heart rate, headaches, and nausea. Specific
recommendations for fluid consumption are as follows:
• Child and adolescent athletes should
aim to replenish lost hydration stores during and after an event.
This can be done by weighing the athlete before and after an
event and replacing fluids lost (16 to 24 ounces for every pound
lost).7
• For activities lasting less than 60
minutes, select water for hydration.
• For activities lasting more than 60
minutes, select sports beverages for hydration, electrolytes,
and energy from carbohydrate. Select a beverage that provides
6% to 8% carbohydrate.
• Lastly, be aware that children do not
instinctively drink enough fluids to replace lost stores and
thirst does not always indicate when the body is in need of
more fluids.
Overcoming Nutritional Obstacles
While young athletes rely on their parents and health professionals
for advice, they are extremely susceptible to peer and media
influence and the plethora of misinformation that exists in
the sports nutrition world.8 As a result, obstacles to improving
the nutritional status and consequent performance of the young
athlete abound.
Kelly White, MS, RD, LD, a sports nutrition
and wellness dietitian in Starkville, Miss., notes that young
athletes often struggle with inadequate nutrition-based knowledge,
lack of healthy food options, and making the “right”
food choices. She suggests that athletes and their parents plan
ahead and pack lunches and fueling snacks. Good choices include
whole grain granola bars and sandwiches, fresh fruit and vegetables,
water, and Gatorade. White suggests that RDs become familiar
with the food items offered in school cafeterias and vending
machines so athletes will have a better idea of what to select.
Taking into account all the obstacles and elevated
nutritional needs that young athletes face, the RD mentioned
at the beginning of this article approaches the nutritional
status of her young client not with an air of condescension
but concern. She knows that he made the right choice by asking
her for assistance with his diet and performance. As a nutrition
professional, she realizes it is her job to help this young
athlete understand that to meet the demands of his sport and
the physiological needs of his developing body, it is critical
that he not deprive himself of macronutrients and micronutrients.
Thus, her first goal is to provide simple tips to improve his
day-to-day, game-to-game intake. Her final goal is to impress
upon him that it is never to early or too late to make nutrition
a top priority.
— Pamela M. Nisevich, MS, RD, LD,
is a consultant for Nutrition for the Long Run in Dayton, Ohio.
She specializes in writing, counseling, and speaking on sports
nutrition, weight management, and wellness. She is also a pediatric
clinical dietitian at Dayton Children’s Medical Center
and the director of The Body Shop, a weight management program
for overweight and obese children.
References
1. Brenner JS, American Academy of Pediatrics Council on Sports
Medicine and Fitness. Overuse injuries, overtraining, and burnout
in child and adolescent athletes. Pediatrics.
2007;119:1242-1245.
2. Croll JK, Neumark-Sztainer D, Story M, et
al. Adolescents involved in weight-related and power team sports
have better eating patterns and nutrient intakes than non-sport-involved
adolescents. J Am Diet Assoc. 2006;106:709-717.
3. Kern M. Dietary intake of adolescent athletes
and nonathletes. J Am Diet Assoc.
2006;106:717-718.
4. Thompson J, Manore M. Nutrition:
An Applied Approach. San Francisco: Benjamin Cummings;
2006.
5. Dietary Reference Intakes (DRIs): Recommended
Intakes for Individuals, Vitamins. Food Nutrition Board, Institute
of Medicine, National Academies, 2004. Available here.
Accessed December 31, 2007.
6. Sports Cardiovascular and Wellness Nutritionists,
Dunford M. Sports Nutrition: a Practice Manual for Professionals,
4th edition. Chicago, Ill: American Dietetic Association;
2006.
7. Spear BA. Nutrition management of the child
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Dietetics, 2nd edition. Chicago, Ill: American Dietetic
Association; 2003.
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Int J Sport Nutr. 1998;8(2):160-174
9. Montfort-Steiger V, Williams CA. Carbohydrate
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