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Age and Sex Considerations in Sport and Exercise 1 EDU2EXP Exercise & Performance 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 2 EDU2EXP Exercise & Performance Changes With Age in the Rate of Increase in Height (cm/yr) 3 EDU2EXP Exercise & Performance 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 4 EDU2EXP Exercise & Performance 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 5 EDU2EXP Exercise & Performance 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 6 EDU2EXP Exercise & Performance 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. EDU2EXP Exercise & Performance 7 Strength • Improves as muscle mass increases • Peak strength occurs at 8 EDU2EXP Exercise & Performance Cardiovascular and Respiratory Function 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 9 EDU2EXP Exercise & Performance Physiological Adaptations to Training Body 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 10 EDU2EXP Exercise & Performance 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 11 EDU2EXP Exercise & Performance Change With Age in Men’s and Women’s World Records for (a) 100 m and (b) 10 km Runs 12 EDU2EXP Exercise & Performance Introduction: Sex Differences in Athletic Performance Things to consider: 13 EDU2EXP Exercise & Performance 14 EDU2EXP Exercise & Performance Body Size and Composition Until puberty, girls and boys do not differ significantly in most measurements of 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 15 EDU2EXP Exercise & Performance 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. EDU2EXP Exercise & Performance 16 . 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. EDU2EXP Exercise & Performance 17 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 18 EDU2EXP Exercise & Performance 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 19 EDU2EXP Exercise & Performance Sport Performance Sex differences are more pronounced in events where high levels of upper body strength are required (e.g., shot put) 20 EDU2EXP Exercise & Performance Women’s and Men’s World Records in Six Running Events Between 1960 and 2006 (continued) 21 EDU2EXP Exercise & Performance Eating Disorders • Eating disorders: a group of disorders that must meet specific criteria established by the American Psychiatric Association – Anorexia nervosa – Bulimia nervosa 22 EDU2EXP Exercise & Performance Anorexia Nervosa • Distorted body image • Intense fear of fatness or gaining weight 23 EDU2EXP Exercise & Performance Bulimia Nervosa • A feeling of lack of control during binges • Purging behavior, which can include self-induced vomiting, laxative use, and/or diuretic use 24 EDU2EXP Exercise & Performance 3 Categories of High-Risk Sports for Disordered Eating 1. 2. 3. Appearance sports: diving, figure skating, gymnastics, bodybuilding, and ballet Endurance sports: distance running and swimming Weight-classification sports: horse racing (jockeys), boxing, and wrestling 25 EDU2EXP Exercise & Performance 26 EDU2EXP Exercise & Performance Exercise Physiology in schools How is all of this stuff relevant?? 27 EDU2EXP Exercise & Performance The Obesity Crisis • Discourage forms of comparison between kids • Encourage personal comparisons • Psychological/ motivational factors • Increase chances of success in all students – Pedometers – Strength 28 EDU2EXP Exercise & Performance 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 29 EDU2EXP Exercise & Performance 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 30 getting stronger! EDU2EXP Exercise & Performance 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! 31 EDU2EXP Exercise & Performance ACHPER • Growth: Height and Weight, with Body Mass Index (BMI) calculated by the computer program. • Cardiorespiratory Endurance: MultiStage 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. 32 EDU2EXP Exercise & Performance 33 EDU2EXP Exercise & Performance 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 34 EDU2EXP Exercise & Performance