Growth, Development, and Exercise in Children and Adolescents Chapter 18

Learning Objectives Compare and contrast growth, development, and maturation. Define infancy, childhood, and adolescence. Discuss the basic changes that occur at puberty. Describe age-related changes for, and the effects of training on, absolute and relative maximal oxygen consumption, anaerobic capabilities, and muscle strength.

Working with Children and Adolescents Physical educators, teachers, and coaches are often called on to give advice about benefits and hazards of exercise for youngsters. Exercise professionals need to know about the areas of growth and development and the effects of exercise on young competitors.

Growth, Development, and Maturation Growth: An increase in the size of the body as a whole or the size of particular body parts Development: Biological vs. behavioral Maturation: The tempo and timing of progress toward a mature biological state

Infancy and Childhood Infancy:  The first year of life  Rapid growth in body functions and physical characteristics Childhood:  The time between the first birthday and puberty  Steady growth and maturation  Rapid growth in motor development

Adolescence Defined by the adolescent growth spurt and onset of puberty Age ranges:  8–19 years for females  10–22 years for males Variability in maturation rates Dramatic differences in strength, sports skills, and performance

Onset of Puberty and Exercise It’s important to be able to recognize onset of puberty:  Normal growth patterns and response to exercise training are different for children and for adolescents. Coaches and physical educators should have different expectations for training programs depending on levels of maturation.

Signs of Puberty Beginnings of puberty are marked by:  In females: development of breasts and pubic hair, beginning of menarche  In males: circulating levels of testosterone Peak height/weight velocity: A way to identify growth spurts by examining changes in height or weight as a function of age.

Peak Height Velocity— 13 Years for Females and 14 Years for Males

Peak Weight Velocity— 12–13 Years for Females and 14 Years for Males

Height (a) and Body Weight (b) Throughout Childhood and Adolescence

What Effect Does Exercise Have on Normal Growth and Development? Participating in athletics does not accelerate or decelerate growth and maturation. Athletic training has no effect on height, body build, or biological maturation.

Changes in Fat-Free Weight (a), Fat Weight (b), and Percent Body Fat (c) in Childhood and Adolescence

What Effect Does Physical Activity Have on Body Composition? Results in lower levels of percent body fat and fat weight and increases fat-free weight Can improve athletic performance by developing sport-specific body composition Can decrease health risks associated with obesity

Health-Related Benefits of Exercise for Children and Adolescents Positive effects on cardiovascular disease risk factors and obesity Higher levels of cardiorespiratory fitness Stronger muscles and bones Reduced levels of anxiety and depression Positive effects on academic performance and self-esteem

Exercise and Aerobic Fitness Increase in VO 2 max is a function of growth in lungs, circulatory system, and musculature. Increases throughout childhood, then changes in adolescence.

Absolute VO 2 max Increases in Males but Plateaus in Females

Maximal VO 2 max, Relative to Body Weight, for Both Genders

Your Perspective When you were in high school, did you ever have to lose weight quickly in order to compete in a sport? If so, what did you do to lose the weight? What would your advice be to a younger brother or sister who is trying to make weight for a wrestling match or gymnastics competition?

Long-Distance Running for Children Potential hazards:  Heel cord injuries and shin splints  Epiphyseal growth plate injuries  Chronic joint trauma  Thermal intolerance  Psychological problems from unrealistic goals Distances:  Children under 14 should not train or compete at distances greater than 10 km.

Exercise and Anaerobic Fitness Children have a lower capacity for performing anaerobic exercise than adolescents or adults. As children develop, their capacity in anaerobic sports/activities increases.

Absolute Mean and Peak Power from the Wingate Anaerobic Test Absolute Mean Power Absolute Peak Power

Effect of Anaerobic Training Children and adolescents respond well to anaerobic training. Factors to consider when planning an anaerobic training program:  Program should closely mimic the intended sporting activity  Protocol should include repetitions that tax the appropriate system

Strength in Children and Adolescents Both genders increase in strength across age, with males just a bit stronger than females throughout childhood. At 13 to 14 years of age, males begin to increase at a greater rate than females—  Increase in body weight and muscle mass as well as strength  Probably reflects effect of circulating testosterone and neural maturation

Resistance Training for Children and Adolescents Conventional wisdom doubting the wisdom of resistance training for children is wrong. Results in increased strength in prepubescent children.  Greater than those attributable to normal growth/development.

Other Potential Benefits of Resistance Training Improved flexibility Favorable changes in blood lipid profiles Enhanced bone and connective tissue development Favorable changes in body composition Reduced musculoskeletal injuries during sports Improved motor skills Increased muscular endurance Positive psychological effects

Clinical Application Resistance Training for Young Populations Some risks with resistance training and competitive weight lifting for young people  188,000 reported injuries between 1978 and 1998 (plus more unreported ones) However, benefits outweigh the potential risks—especially in supervised training programs

Potential Hazards Associated with Resistance Training Acute musculoskeletal injuries:  Damage to the epiphyseal growth plate Chronic musculoskeletal injuries

Recommendations for a Resistance Training Program From the American Academy of Pediatrics: Follow proper resistance techniques and safety precautions Avoid power lifting and body building until child has reached physical and skeletal maturity Educate athletes about performance-enhancing substances Consider issues of diseases/disorders, warm-ups and cool-downs, fluid and nutrition, proper technique and supervision, etc.

Weight Training Progression for Children

Your Perspective What kind of exercise program would you design for a 10-year-old boy who has not previously engaged in regular physical activity or competition? For a 10-year-old girl?

Where to Learn More Physical fitness and activity in schools:  pediatrics;105/5/ pediatrics;105/5/1156 American Academy of Pediatrics:  Strength training for children and adolescents:  m m

NASPE Guidelines— E6 Explain the concept of optimal weight for athletic performance and acknowledge the dangers of excessive weight loss and excessive training.  Imagine you are talking to a wrestling coach who is encouraging his wrestlers to fast or to use such techniques as rubber suits, steam rooms, and diuretics in order to lose weight. What do you say about the long-term dangers of this behavior?  What could you do to help a school district or state governing body adopt new legislation regarding this practice?