Pediatric Exercise Physiology
Applications for the Teacher and Coach
Why is information important?
 Teachers and coaches work with individuals between
ages of 5 and 18 years of age
 Children and adolescents compete in sports
 Advise on potential benefits
 Advise on potential hazards
 Dispel inaccurate myths
 We must understand the impact of exercise on the
physiological aspects of growth and development.
What we do know!
 As children’s size increases, so do almost all of their
functional capacities:
Strength
Motor abilities
Cardiovascular and Respiratory function
Aerobic and Anaerobic capacities
Understanding how these capacities develop and how we can
use this knowledge is the goal.
How do we define the state of a
child’s or adolescent’s maturity?
 Chronological age
 Skeletal age
 Stage of sexual maturation
Puberty
 Sexual maturation
Important to identify because normal growth patterns
and responses to exercise training are substantially
different in children than in adolescents.
MarkersWomen- menarche
Men- ten fold increase in testosterone
Both- dramatic increase in ht. and wt.
Does exercise training
affect growth or body size?
 Exercise or physical training has no effect on height, body
build or biological maturation.
 Exercise and PT has the following positive effects on
children and adolescents:
↑ CR fitness, stronger muscles and bones
↓cardiovascular disease risks and obesity
Body Composition
 Although at puberty boys develop more lean body
mass than girls, girls stay the same or slightly increase
fat mass
 Physically active children and adolescents have lower
body fat % and more fat-free wt. than inactive peers.
 Enforced inappropriate wt. or body comp. standards
can lead to disorder eating and dangerous methods
of wt. loss
Implications
 Weight class sports should be matched for age as well as
body weight.
 Because girls gain fat mass at puberty girls aerobic fitness
declines (if looking at V0₂)
 Energy needs for growth in children complicate the issue of
wt. loss in growing children. Medical supervision may be
needed.
 Children greatly benefit from PA in prevention of obesity
(prevention is the key!)
Regarding Bone mass
in Children and Adolescents
 Young bone is more responsive to osteogenic stimuli.
 Evidence indicates that physical activity during
growth (particular running and jumping activities or
multi-joint exercises) if preformed progressively can
significantly increase bone mass.
 Achieving peak bone mass as an adolescent will
contribute to maintaining more bone mass during
later decades of life where bone mass is diminished.
Vulnerability to Injury
 Overuse and traumatic injury can cause injury to the growth
plate of bones.
 Excessive throwing, or repetitive micro- trauma can cause
premature closing of growth plate and retard normal bone
growth.
How much training is optimal?
Aerobic Fitness
Considerations
 Smaller heart, total blood volume= smaller stoke volume
and lower cardiac output
 Heart rate response to a given sub max work is higher than
and adults
 Max H.R. of children is higher
Implication for activities such as cycling at Max: performance
is limited because of this reduced capacity deliver O₂
VO₂
 Normally expressed relative to body weight
V0₂ doesn’t reflect the significant gains in endurance performance
that are noted with maturation and training.
Body surface area is now considered a better means of reducing
the effect of body size instead of body weight
 Events such as distance running, children’s performance is far
inferior to adults. (smaller hearts, ↓ stroke volume
 Endurance training yields improvements that are 1/3 those of
adults.
 Children exert more energy compared to adults in wt. bearing
activities for the same relative intensity of work compared to
adults.
Endurance performance and
economy of movement
 Children are less economical runners
Higher metabolic rates
Greater ventilatory equivalents
Disadvantageous stride rates to stride lengths
Implications regarding aerobic
performance
Children are working relatively harder for the same absolute
intensity.
children under 14 years not train or run more than a 10k
Ages 12 and younger – 2 mile on flat is appropriate (Micheli, 1981)
Most studies reviewed by Rowland indicate improvement of 7-26% in
VO₂ Max
Adult ACSM standards of training can be used for children. Training
effect is the same.
Use the Borg Scale of perceived exertion to monitor intensity.
Anaerobic Performance
 Anaerobic capacity is lower than adults as measured by
power output (Wingate test).
Lower muscle glycogen (energy source).
Lower lactate concentrations at max work rates. (they tend to rely on fat
oxidation for fuel)
Children differ in hormones response and reflect higher stress response to
exercise.
Implications: Activities of high intensity lasting
15 sec. to 2 min. will be limited compared to
adults.
Training program should be age/size group specific.
Training will improve anaerobic capacity.
Strength in Children
 Prepubescent strength gains occur in the absence of
changes in muscle size.
 Children are able to get stronger because of growth and:
 Improvements in neural mechanisms
 Learned motor skill coordination
 Increased motor unit activation
Strength in Adolescents
 Strength gains at puberty are a result of growth, increasing
body weight and muscle mass.
 Boys experience greater strength because of the anabolic
effects of higher levels of circulating testosterone.
 Boys can gain greater mass and strength than women
Potential Hazards with
Resistance Training
 Acute musculoskeletal injuries
Epiphyseal fractures- injury to growth plate at the
end of long bones
Risks involve premature closure of growth plate
 Chronic musculoskeletal injuries
 Repeated micro-trauma due to overuse
Include stress fractures, cartilage damage
Implications of Strength Differences
 Children can gain significant strength if proper
training and safety precautions are taken:
Limit wt. to not more than a 10 RM.
1 RM should be avoided.
Proper technique should be taught with
no load.
All major muscle groups should be included especially core
muscles.
Exercises using own body weight are
appropriate for children.
The Young Nervous System
 As children grow they develop better balance,
coordination and agility as their nervous system matures
 Myelination of muscle fibers is important for the
conduction of nervous signals.
 Fast reaction time, skilled movement and fine motor
control cannot occur before nerve fibers are completely
myelinated.
 This continues well beyond puberty.
 Development of strength is also dependent on
myelination.
Implications
 Children are not capable of fine motor skill
development.
 Skills will take a long time to refine.
 Gross motor movement (large muscle) should be the
emphasis. (positioning and understanding strategy
can be the focus).
Heat Stress in Children
 Children:
have a lower capacity to lose body heat
through sweating.
Produce more body heat per mass unit than adults
A child has a greater ratio of body surface area to mass.
Children’s bodies rely on convection and radiation more than
adults. This ratio is advantageous unless the environment
temp. is higher than skin temp.
Acclimation rates of children are slower than adults.
Implications
 Children should take frequent breaks while exercising in the
hot temperatures and high humidity.
 Activities lasting more than 15 minutes should be reduced
 Shade should be provided
 Frequent breaks for water and electrolytes is imperative.
Thirst mechanism is not sensitive enough to replace fluid
when needed.
 Protection from sun is a must.
 Allow more time for children a adolescents to acclimate to
new climates.
Cold Exposure in Children
 Because of the larger ratio of surface area to mass,
children lose more heat through conduction placing
them at more risk for hypothermia
 Implication: Due to greater risks children should dress
in more clothing layers than the typical adult.
 Children may not realize they are at risk for frostbite.
Exercise Induced Asthma
 A condition brought on by faster breathing when
exercising that causes constriction of airways making
breathing difficult.
 13% of population have it, many athletes
 Symptoms: coughing, tight chest, wheezing, fatigue,
shortness of breath
What to do about EIA
 Identify symptoms: coughing, difficulty breathing
fatigue, not being able to perform
 Make sure they use the preventive inhaler 15 minutes
before class (albuterol-broncodialator)
 Try to avoid triggers: pollen, cold temp. pollution, cold
and allergy.
 Use intermittent warm up, wear a mask or scarf in
cold.
 Know what kids have this condition and work with
parents.
Rhabdomyolysis
A life threatening condition that can lead to kidney
failure and death
 Resulting from too much and too intense exercise
 Excessive muscle breakdown causing enzymes and
myoblobin to be released in the blood stream
 Kidneys try to filter out the muscle components but
kidney failure could result.
 Rare occurrence but documented cases exist in high
school and college
 Risk factors- drugs, severe exertion, heat stroke
 Symptoms- dark urine, weakness, fatigue
Conclusions
 Children are not just smaller versions of adults.
 Children and adolescents don’t follow the same rates
of change (early and late biologic maturers).
 They have many physical developmental differences
that must be considered in planning activities and
especially when training for sports.
 Much about the exercising child is not yet know so err
on the side of being conservative.
Bibliography
 Rowland, Thomas, W., Children's Exercise Physiology,
(2005). Human Kinetics, Champaign IL.
 Kenney, W., Wilmore, J, Costill, D., 2012, Physiology of
Sport and Exercise, 5th ed., 2012, Human Kinetics,
Champaign, IL.
 Powers, S. and Howley, E. Exercise Physiology, 2009,
McGraw –Hill, New York, NY.