More and more young athletes are seeking
personal fitness trainers for specialized workouts. As part of their training,
we strive to help these young people become stronger and better able to
withstand the rigors of sports competition. But physical training is only one
part of the equation: young athletes also need to learn why proper nutrition is
vital to optimizing their sports performance.
Nutrient needs are higher during adolescence than at any other
time in the life cycle (Croll et al. 2006). Even kids not engaged in sports
need the proper mix of calories, carbohydrates, healthy fats and protein. Among
young athletes, many are deficient in some of the key nutrients that should be
fueling their workouts.
Although it is outside your scope of practice as a fitness
professional to make specific dietary recommendations, you can educate young
athletes about sound nutrition choices that will help them win—both on and off
How Nutrition Affects Kids’ Performance
While proper nutrition is important for
all athletes, it is of particular concern for young, growing bodies that
compete in sports. IDEA contributing editor Jenna A. Bell-Wilson, PhD, RD, is a
certified specialist in sports dietetics who is based in Arlington,
Massachusetts. She says that an inadequate diet can result in a young athlete
getting insufficient fuel for workouts; having deficiencies that can lead to
illness or fatigue; suffering a decrement in bone growth and maintenance; and
not achieving proper muscle growth. According to Bell-Wilson, nutrient
deficiencies will negatively affect the youngster’s growth and his or her
ability to compete in a chosen sport.
Maintaining the appropriate balance between energy and protein
intake is critical for the growth and development of young athletes. Despite
the recent public attention given to the benefits of healthy eating, many young
athletes remain undernourished (and undereducated!). Self-reported dietary
intakes often reveal that an increasing number of children have energy,
carbohydrate and certain micronutrient intakes below the recommended daily
levels. In particular, athletes in sports that focus on body composition and
appearance (e.g., gymnastics and distance running) are often deficient in
several key nutrients (Kern 2006).
Common Nutrient Deficiencies
in which young athletes are most often deficient are carbohydrates, calcium,
folate and iron (Kern 2006; Thompson 1998).
A deficiency in carbohydrates leads to inadequate glycogen stores
and premature fatigue, both of which compromise performance and force the body
to rely on an alternative source of fuel. Glucose is essential to body functioning
during exercise. If glucose from carbohydrate is not available for use as fuel
during physical activity, the body will instead use protein (muscle) stores for
energy. However, the body would much rather use carbohydrate or fat for fuel.
Proper intake of calcium is needed to support bone growth,
increase bone mass and aid in nerve impulses and muscle contraction (Thompson
& Manore 2006). Inadequate calcium intake can lead to decreased bone mass,
which can increase the risk for stress fractures and other bone-related
Both vitamin B6
and folate are critical components of energy metabolism and blood health
(Thompson & Manore 2006). Both these nutrients are vital for amino acid
metabolism (think “the building blocks of proteins”). A deficiency in vitamin
B6 and folate can lead to fatigue, muscle soreness, apathy and loss of
cognitive function for an athlete.
While iron is vital for oxygen-carrying capacity, it is also a
major player in the energy metabolism of carbohydrates, protein and fats. This
is why young athletes who are deficient in iron (i.e., have iron-deficiency
anemia) may experience fatigue, compromised immune function and impaired
cognitive reasoning during exercise. Iron intake is especially critical for
prepubertal and menstruating female athletes.
Although iron deficiency is a worldwide problem, there is such a
thing as too much iron.
Young athletes who take iron supplements can build up toxic levels of this
mineral. That’s why iron supplement recom┬¡┬¡mendations should always come from a
physician or a registered dietitian (RD).
Fluid & Macronutrient Needs
dietary advice to young athletes is beyond your scope of practice, but you can
promote healthful eating behaviors and energy-rich foods that are in accordance
with recommendations established by nutrition professionals. Here are some
guidelines for young athletes that are culled from recently published
Maintaining the proper fluid balance is
critical for this population. In addition to the risk of causing a heat-related
illness, dehydration can lead to fatigue during exercise. Altered fluid status
can be a bigger risk for kids than for adult athletes for two reasons: (1)
children experience greater heat stress and heat accumulation during exercise;
and (2) children have a greater ratio of surface area to body mass and absorb
heat more readily than do adults (Petrie, Stover & Horswill 2004).
Signs of dehydration in children include, but are not limited to,
- dark urine
- small volume of urine
- muscle cramps
- reduced sweating
- increased heart rate
Child and adolescent athletes should replenish lost hydration
stores during and after a competition or a heavy workout. Weighing an athlete
before and after an exercise bout allows you to gauge how much fluid needs
replacing; the general rule of thumb is 16-24 ounces of liquid for every pound
lost (Nevin-Folino 2003). Be aware that children do not instinctively drink
enough fluids to replace lost stores, and thirst does not always indicate when
the body needs more fluids.
During activities lasting less than 60 minutes, water is all that
is needed to hydrate young athletes. However, during longer activities, sports
beverages that provide 6%-8% carbohydrate will help rehydrate and replenish
electrolyte stores in young athletes. It helps that kids like the flavoring of
sports beverages, which means they will drink more of them without prodding
carbohydrates are the preferred fuel for athletic performance, approximately
55% of a young athlete’s total daily calories should come from
carbohydrate (Nevin-Folino 2003). Carbo┬¡hydrate needs are based on body weight
and intensity of activity. The American Dietetic Association (ADA) has set the
following daily recommendations for young athletes (Nevin-Folino 2003):
- 3-5 grams (g) carbohydrates per kilogram
(carb/kg) for very light intensity training
- 5-8 g carb/kg for moderate or heavy training
- 8-9 g carb/kg for pre-event loading (24-48
- 1.7 g carb/kg for postevent refueling (within 2-3
part of a young athlete’s diet, protein is responsible for building,
maintaining and repairing muscle and other body tissue (Nevin-Folino 2003). It
should be noted that inadequate caloric intake will cause a protein imbalance
even if the athlete consumes the recommended daily allowance (RDA) of protein
(Thompson 1998). Young athletes need to consume enough calories each day to
maintain body weight and keep protein stores in balance.
While it has been suggested that adult athletes may need more
protein per pound of body weight than adults who are not athletes, additional
protein needs have not been specifically evaluated for younger athletes.
However, the ADA has issued the following daily recommendations (Nevin-Folino
- Athletes who have just begun a training program
require 1.0-1.5 g/kg of protein.
- Athletes who participate in endurance sports
require 1.2-1.4 g/kg.
- Vegetarian and vegan athletes should be
counseled to ensure that adequate intake or protein is consumed from plant
- Athletes need to consume sufficient calories
each day to maintain protein balance.
A word of caution: consuming an overabundance of protein can lead
to dehydration, weight gain and calcium loss. It is critical that young
athletes monitor their daily protein intake, because this population is already
at risk for calcium deficiency.
Fat is an
essential fuel for young athletes who engage in light- to moderate-intensity
exercise or in endurance events. Although carbohydrates are the preferred fuel
for adult athletes, healthy fats may be a better choice for children who engage
in sports (Montfort-Steiger & Williams 2007). This could be due to the
higher rate at which fat oxidizes in the young body; the faster the fat is
broken down, the quicker it can be used as fuel for exercise (Montfort-Steiger
& Williams 2007). Keep in mind, however, that kids who compete are usually
trying to build muscle mass and may not want to add any fat to their diet.
Teach them that healthy fats are a far better choice than butter, animal fat or
Below are some easy-to-follow guidelines for young athletes on
daily consumption of fats:
- It is important that young athletes obtain an
average of 20%-30% of their calories from fat; clients can achieve this even
with low-fat foods (but not nonfat)
- Young athletes should aim to significantly
lower the amount of saturated and trans fat in their diet.
- The best choices for young athletes are healthy
fats from plant oils (e.g., canola or olive oil); these clients should limit
their intake of unhealthy saturated fats found in fried and processed
Kids Will Be Kids
are often grossly misinformed about sports nutrition practices and very easily
influenced by outsiders, especially their peers. They also rely heavily on the
Internet and other media for information (Thompson 1998). Another obstacle that
young athletes face is finding the time to fuel their bodies properly. With the rigors
of school, work, practice and competition, time and access to quality nutrition
are often limited.
While some athletes need only a few dietary tweaks, others
require great care to improve their nutrition and subsequent performance.
That’s when it is best to employ the help of an RD who is an expert in sports
dietetics or sports nutrition. Look for an RD who is credentialed as a
certified specialist in sports dietetics (CSSD). You can find a local sports
dietitian through the ADA’s practice group, SCAN, at
As a fitness professional, you can and should help young athletes
understand the role that proper nutrition plays in sports performance. Kids
need to know exactly why it is essential that they fuel their bodies with the
nutrients and fluids that will help them succeed in their chosen sports. It is
critical that all athletes—young and old—make nutrition a top priority if they
want to win at sports and life.
SIDEBAR: Adequate Intakes of Commonly Deficient Micronutrients
The following recommendations for children and adolescents are in accordance with those set by the Institute of Medicine National Academies Food and Nutrition Board (2004):
Nisevich, MS, RD, LD, is a clinical dietitian at Dayton Children’s Medical
Center in Ohio, where she specializes in pediatric clinical nutrition. She is
the founder and owner of Nutrition for the Long Run, a counseling firm that
focuses on sports nutrition and weight management for athletes of all ages.
Dunford, M. 2006.
Sports Nutrition: A Practice Manual for Professionals (4th
ed.). Sports Cardiovascular and
Wellness Nutritionists. Chicago: American Dietetic Association.
Food and Nutrition Board.
2002/2005. Dietary Reference Intakes for energy, carbohydrate, fiber, fat,
fatty acids, cholesterol, protein, amino acids. Washington, DC: The National
Academies Press. www.nap.edu;
retrieved Dec. 31, 2007.
Food and Nutrition Board.
2004. Dietary Reference Intakes (DRIs): Recommended intakes for individuals,
vitamins. www.iom.edu/Object.File/Master/21/372/0.pdf; retrieved Dec. 31, 2007.
Kern, M. 2006. Dietary intake
of adolescent athletes and nonathletes.Journal
of the American Dietetic Association, 106, 717-19.
Montfort-Steiger, V., &
Williams, C.A. 2007. Carbohydrate intake considerations for young athletes. Journal of Sports Science and Medicine,
Nevin-Folino, N. 2003. Pediatric Manual of Clinical Dietetics
(2nd ed.). The Pediatric Nutrition Practice Group. Chicago: American Dietetic
Petrie, H.J., Stover, E.A.,
& Horswill, C.A. 2004. Nutritional concerns for the child and adolescent
competitor. Nutrition, 20, 620-31.
Thompson, J.L. 1998. Energy
balance in young athletes.International
Journal of Sport Nutrition, 8160-74.
Thompson, J., & Manore, M.
2006.Nutrition: An Applied
Approach, My Pyramid Edition. San Francisco: Benjamin Cummings.
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