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Age and Sex Considerations in Sport and Exercise

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Phases of Growth and Development

Infancy: first year of life

Childhood: age 1 to puberty

Puberty: development of secondary sex characteristics; sexual reproduction becomes possible

Adolescence: puberty to completion of growth and development

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Changes With Age in the Rateof Increase in Height (cm/yr)

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Height and Weight

• The rate of growth is slower throughout childhood until a marked increase occurs near puberty

• Full height is typically achieved at age 16 in girls and 18 in boys

• Growth in weight follows the same trend as height, with the peak rate of weight increase occurring at age 12.5 in girls and 14.5 in boys

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Muscle Growth

• Muscle development rate peaks at puberty in boys corresponding with a ~10-fold increase in testosterone

• In girls, skeletal muscle mass increases from 25% of body weight at birth

• Muscle development is slower in girls

• Muscle development primarily results from hypertrophy of existing fibers

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Growth and Fat Storage• Fat cells form and fat deposition starts in fetal development

• Fat is stored by increasing the size and number of fat cells

• Fat storage depends on

• At birth, 10-12% of total body weight is fat

• At maturity, fat content averages 15% of total body weight in males and 25% in females

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Changes in Percent Fat, Fat Mass, and Fat-Free Mass for Females and Males From Birth to 20 Years of Age

Reprinted, by permission, from R.M. Malina, C. Bouchard, and O. Bar-Or, 2004, Growth, maturation, and physical activity, 2nd ed. (Champaign, IL: Human Kinetics), 114.

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Strength

• Improves as muscle mass increases

• Peak strength occurs at

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Children have smaller hearts and blood volume

Maximal Exercise• Maximal heart rate is higher in children than adults (MHR = 220 – age)• Lower maximal cardiac output in children• Oxygen delivery limits performance in children

Lung Function• Lung volumes increase until physical maturity, primarily because of

increasing body size

.

Cardiovascular and Respiratory Function

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Physiological Adaptations to TrainingBody composition changes with training in children and adolescents are

similar to those seen in adults

With both resistance and aerobic training, boys and girls will:

Endurance performance improves with aerobic training in preadolescents

A child’s anaerobic capacity increases with anaerobic training

.

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Sport Performance

• Records in running, swimming, cycling, and weightlifting indicate that we are in our physical and physiological prime in our 20s and early 30s

• Most athletic performances decline steadily because of decrements in endurance and strength

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Change With Age in Men’s and Women’s World Records for (a) 100 mand (b) 10 km Runs

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Introduction: Sex Differencesin Athletic Performance

Things to consider:

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Body Size and Composition

• Puberty in girls: follicle stimulating hormone (FSH) and luteinizing hormone (LH) cause estrogen production from the ovaries

– Causes pelvis broadening

– Breast development

– Increased bone growth

• Puberty in boys: FSH and LH cause testosterone production from the testes

– Stimulates EPO production from the kidneys

Until puberty, girls and boys do not differ significantly in most measurements of body size and composition

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Changes in Blood Concentrations of Testosterone and Estrogen From Birth to Adulthood

Reprinted, by permission, from R.M. Malina, C. Bouchard, and O. Bar-Or, 2004, Growth, maturation, and physical activity, 2nd ed. (Champaign, IL: Human Kinetics), 414.

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Range of VO2max for Female and Male Nonathletes and for Female and Male Elite Athletes

Data from L. Hermansen and K.L. Andersen, 1965, "Aerobic work capacity in young Norwegian men and women," Journal of Applied Physiology 20: 425-431.

.

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Training and Body Composition in Women

• With either cardiorespiratory endurance training or resistance training, both men and women:

• Magnitude of changes in body composition are more related to energy expenditure than participant’s sex

• Density of bones increases with weight-bearing exercise

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Strength Training

• Women have less muscle mass

• Similar to men, women gain considerable strength through strength training

• Strength gains are usually not accompanied by a large increase in muscle bulk

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Sport Performance

Sex differences are more pronounced in events where high levels of upper body strength are required (e.g., shot put)

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Women’s and Men’s World Records in Six Running Events Between 1960 and 2006

(continued)

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Eating Disorders

• Eating disorders: a group of disorders that must meet specific criteria established by the American Psychiatric Association– Anorexia nervosa– Bulimia nervosa

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Anorexia Nervosa

• Distorted body image

• Intense fear of fatness or gaining weight

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Bulimia Nervosa

• A feeling of lack of control during binges

• Purging behavior, which can include self-induced vomiting, laxative use, and/or diuretic use

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3 Categories of High-Risk Sportsfor Disordered Eating

1. Appearance sports: diving, figure skating, gymnastics, bodybuilding, and ballet

2. Endurance sports: distance running and swimming

3. Weight-classification sports: horse racing (jockeys), boxing, and wrestling

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Exercise Physiology in schools

How is all of this stuff relevant??

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The Obesity Crisis

• Discourage forms of comparison between kids

• Encourage personal comparisons

• Psychological/ motivational factors

• Increase chances of success in all students– Pedometers– Strength

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Develop muscle strength

• Number of muscle fibres is fixed at birth

• Increases in strength more likely than size

• Active muscles = greater increase

• Doesn’t mean lifting weights!

• Means weight bearing exercise- running, aerobics

• And resistance exercise using body weight- push ups, sit ups, jumping etc

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Heart rate•Decrease in RHR with increased fitness same as in adults

•This activity allows kids to track the change in their hear rate, and you can explain what is happening as this occurs

•Left ventricle increases ability to pump blood around to the muscles

•Therefore it doesn’t have to pump as often to get the blood to go around

•So a decrease in RHR is a direct representation of your heart getting stronger!

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Fitness Testing?

• Focus on individual comparison and improvement

• Gain a holistic understanding of fitness

• Experience feeling of improving fitness

• Needs to be done correctly

– Self Esteem

– Ensure privacy- secret!

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ACHPER

• Growth: Height and Weight, with Body Mass Index (BMI) calculated by the computer program.

• Cardiorespiratory Endurance: Multi-Stage Fitness Test and 1.6 km run/walk.

• Muscular Strength and Endurance: The Curl-up and the Basketball Throw.

• Muscle and Joint Flexibility: The Sit and Reach Tests and Shoulder Stretch.

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Programs

• Kids should be active for an hour a day

• Map out all school and after school activities to see if you are getting enough

• Suggest FUN stuff that counts as activity!

• Incentive programs