HKR 2300 Lecture 12: Growth & Development of Cardiorespiratory Endurance, Strength, and Flexibility PDF

HKR 2300 Growth & Development Fall, 2024 Lecture 12 – Development of Cardiorespiratory Endurance Development of Strength & Flexibility Weight Status, Fitness, and Motor Competence  Key Points for Lecture 11...

HKR 2300 Growth & Development Fall, 2024 Lecture 12 – Development of Cardiorespiratory Endurance Development of Strength & Flexibility Weight Status, Fitness, and Motor Competence  Key Points for Lecture 11 Piaget’s stages Declarative v procedural v strategic Expert-novice differences Boys v girls Processing speed Today’s Constraint  Development of Cardiorespiratory Endurance  Cardiorespiratory (CR) Endurance Ability to sustain vigorous activity through efficient delivery of oxygen to muscles Many activities demand exertion CR systems are related to endurance level Relates to the heart, lungs, and vascular system The worldwide trend is toward reduced fitness A high percentage of children in Western societies have risk factors for heart disease 1. Heart Rate (HR): Concepts Number of heart beats each minute (bpm) HR changes through the lifespan as a function of growth, maturation, and aging Maximal HR declines with age (0.8 bpm/yr) 220 minus age HR Work and HR Linear relationship Workload  1. HR: Lifespan Fetal HR Children’s HR Rapid and irregular 1 year: 80-100 bpm 125-175 bpm HR will continue to decrease until Birth HR adolescence 120-140 bpm Periods of Adolescents’”HR bradycardia (slow Males: 57-60 bpm heart beat) Females: 62-63 bpm HR < 60 bpm Take your pulse; how “normal” are you?  1. HR: Training Endurance training decreases resting HR (Carter, Banister, & Blaber; 2003) Due to reduced sympathetic activity to the heart Restrains heart from getting too excited Endurance training improves HR during exercise  2. Stroke Volume (SV): Concepts Amount of blood the SV affected by: Size of heart Contractile force of the heart Vascular resistance to blood flow Venous return (how quickly blood returns to heart)  2. SV: Lifespan SV is lower in children due Steady and progressive increase in SV through the lifespan Birth: Adolescence: 40 mL/beat Adult: 70-90 mL/beat  2. SV: Training Exercise can increase SV Males (during exercise) Untrained: 100-120 mL/beat Trained: 150-170mL/beat Females (during exercise) Untrained: 80-100 mL/beat Trained: 100-120 mL/beat Why the difference between sexes?  3. Cardiac Output (CO): Concepts Amount of blood CO = HR x SV Number of times the Amount of blood ejected heart beats in one minutewith each heart beat Resting CO? Approximately  3. CO: Lifespan CO is low at early ages because of low SV CO increases through adolescence and into adulthood CO declines with age as HR and SV decline Approximately 1% decline per year after age 25  3. CO: Training Is CO directly affected by training? Increases in CO are indirectly affected by improvements in HR and SV  4. VO2max: Concepts : Largest amount of O2 a human can process Best measure of physical work capacity (ability to do work without fatigue) VO max for children ~ 50 mL/kg/min 2 Must account for weight to compare across sexes (heavier people use more O2)  4. VO2max: Lifespan Gradual decline in VO max for pubescent 2 females Decline in large muscle development Many girls become less active In general, decline in VO max across life 2 Approximately 1% loss per year Increasing physical activity stalls this decline 4. VO2max: Lifespan  4. VO2max: Training Estimated improvements of 5-15% for adults Claim to be limited by genetics Intervals 30 to 180 seconds Rest Repeat  5. Anaerobic Fitness: Concepts Anaerobic means without O2 Exercise periods from 10s to 120/180s : Rate at which a person’s body can meet the demand for short-term, intense activity : Maximum O2 deficit body can tolerate Anaerobic fitness related to: Body size Metabolizing fuel sources Mobilizing energy sources 5. Anaerobic Fitness: Example  5. Anaerobic Fitness: Lifespan Children have less anaerobic fitness than adults Less Mature children have better anaerobic fitness Regardless of body size Related to efficiency of metabolizing and mobilizing energy Muscle mass and energy sources increase w/ age  5. Anaerobic Fitness: Lifespan Anaerobic performance stabilizes once adult body size attained Any improvements In older adulthood, loss of muscle mass and Type II muscle fibers results in declining anaerobic performance Sex differences result of muscle mass 5. Anaerobic Fitness: Training For youth, anaerobic power increases with training When For older adults, undertaking high-intensity endurance training improves anaerobic capacity Resistance training is valuable for anaerobic fitness  6. Aerobic Fitness: Concepts Aerobic means with O2 Exercise periods from 2-3 minutes onward : Rate at which long-term O2 demand is met : Total energy available for prolonged activity Related mostly to VO2max Amount of O2 body consumes during aerobic work Linked to lean muscle mass  6. Aerobic Fitness: Lifespan Children have: With growth & Smaller SV and CO maturation: (hypokinetic Heart size increases circulation) Higher HR to So do SV & CO compensate for Hemoglobin hypokinetic concentration circulation increases Lower concentrations O2 extraction ability of hemoglobin increases (protein in blood that Ability to sustain carries O2) Inability to exercise exercise increases VO as2max long increases linearly from 4 years to late adolescence in boys, but only until age 12/13 for girls  6. Aerobic Fitness: Training Early studies showed equivocal results Small improvements in preadolescents Significant improvements after puberty Recent studies show training with sufficient intensity improves aerobic performance and capacity Trigger hypothesis (Katch, 1983) Hormones associated with Should PE classes spend time on aerobic exercise?  Cardiovascular Structure & Function Changes occur in structure and function in adulthood: Loss of elasticity in cardiac muscle Thickening of left ventricle Fibrotic changes in valves Loss of elasticity in major blood vessels Maximum achievable heart rate with exercise declines Stroke volume in some older adults declines Cardiac output declines  Cardiovascular Structure & Function Implications What middle and older adult lifestyles maintain cardiorespiratory endurance? What lifestyles are detrimental to cardiorespiratory endurance? How might school teachers educate children about these effects while they are still young?  Development of Strength & Flexibility  Strength: Concepts The ability to exert force Minimum strength is required for movement E.g., Toddler standing vs. walking vs. running More mature children tend to be stronger Endocrinology Maturity = more hormones, which impact muscle fibers Neurology Maturity = more coordination, activation, etc…  Strength: Concepts Static : Muscle force exerted against an immovable object Isometric: Exertion of force without limb movement Dynamic : Muscle force exerted against a moveable object Isotonic: Exertion of force against constant resistance Isokinetic (3:45): Exertion of force at a constant velocity  Strength: Lifespan Muscle growth follows a sigmoid pattern Increases largely due to muscle fiber diameter Neurological factors also improve strength (maturity matters) Myelination of nerve fibers More rapid firing of nerves Improved muscle coordination Simultaneously contracting and relaxing different muscles CNS ability to fully activate muscles Sex differences in strength are minimal until puberty  Strength: Lifespan Boys’ peak strength velocity occurs approximately one year after peak height velocity and 3-4 months after peak weight velocity Around 14.5-15 years Tend to outgrow their strength just prior to puberty (might explain adolescent awkwardness) Girls’ peak strength velocity occurs during same year as peak height velocity and peak weight velocity Usually between 12 and 13 years Strength: Lifespan  Strength: Lifespan Strength generally declines gradually after 30 Muscle mass declines in the average older adult Loss of strength may be greater than loss of muscle mass (possibly due to changes in fiber types, nervous system, vascular system) Muscular coordination factors might be involved in declining strength Influenced by exercise and activity levels  Strength: Boys vs. Girls Pre-pubescent boys are generally 10% stronger than girls Post-puberty strength differences are larger Total body strength in females is 63% of males Upper-body strength in females is 50% of males Lower-body strength in females is 70-80% of males  Strength: Training Sadres et al., 2001 2 year, twice weekly training program for boys Only one minor injury; healthy bone development Children’s strength improves with weight training Believed to be increase in neurological coordination Small increases in muscle mass 2x/wk; 60% of max rep; 1 set; 8-10 reps Children’s skills improved in: Broad jump, vertical jump, running speed, agility Strength: Training  Flexibility: Concepts Moving joints through a full range of motion Joint specific Flexibility leads to better sport and motor performance Decreased flexibility associated with injury Flexibility examples: Extreme flexibility Flexibility coach  Flexibility: Concepts Girls are more flexible than boys Due to acceptability of exercises? Participation in activities stressing flexibility? E.g., Dance, gymnastics Physica l Sociocultural  Flexibility: Lifespan Infants are very flexible, but declines start in childhood Early loss of elasticity in joints, tendons, and ligaments How does this happen? Sedentary lifestyle; activities that challenge one type of flexibility Adults lose flexibility, especially in little used joints and after 50 y/o  Flexibility: Training Training can assist flexibility Maintain flexibility for those with full range of motion Improve flexibility for those with limited range of motion Types of training? Yoga Stretching Pilates Dance Weight Status, Fitness, and Motor Competence  Body Composition Proportion of body’s lean and adipose tissues Weight (kg)/height2 (m) Not directly determined by weight E.g., Body builder versus obese person Overweight = BMI > 25 Obese = BMI > 30  Importance of Body Composition Body composition Determines appearance Affects self-concept Related to working capacity Excess fat: Adds to workload Limits range of motion Increases risk of disease  Model of Constraints Structural Body composition leads to success in executing motor skills Functional Obese individuals can have decreased self-esteem & motivation Environmental sociocultural Diet and exercise  Body Fat % A good body fat % for: Males 8-15% Females 15-20% Why would it be beneficial for females to have a higher body fat percentage? Breast feeding Only EXCESS body fat is detrimental  Genetics & Body Composition Basal metabolic rate The amount of energy needed to sustain the body’s vital functions in the waking state Higher basal metabolic rate = more caloric output Thermogenesis The production of heat in the body Higher thermogenesis (heat) = more caloric output Thyroid disorder Regulates metabolism Accounts for less than 1% of childhood obesity  Environment & Body Composition This is the most important factor for body composition Caloric intake (diet) should match caloric output (exercise) Easy formula, not always easy to follow 99% of obese children intake more calories than they output  Development of Body Composition Adipose tissue Major increases in first 6 months of life and start of adolescence In girls, increases continue through adolescence In boys, gains stop shortly into adolescence Lean tissue Rapid growth in infants Steady growth in childhood Rapid growth in adolescence More dramatic growth in adolescent boys  Body Composition: Lifespan Obese children tend to be obese adults Obesity tends to be stable throughout adulthood Highlights importance of maintaining healthy diet, exercise, and weight throughout youth  Obesity By Country (%) 1 Cook Islands 50.8 21 Lebanon 31.9 41 St. Lucia 26.9 2 Palau 47.6 22 Barbados 31.3 42 South Africa 26.8 3 Nauru 45.6 23 Trinidad & Tobago 31.1 43 Czech Republic 26.8 4 Samoa 43.4 24 Oman 30.9 44 Panama 26.8 5 Tonga 43.3 25 Antigua 30.9 45 Uruguay 26.7 6 Niue 43.2 26 Jordan 30.5 46 Malta 26.6 Marshall 7 Islands 42.8 27 Andorra 29.5 47 Argentina 26.3 8 Qatar 42.3 28 Turkey 29.5 48 Seychelles 26.3 9 Kiribati 40.6 29 New Zealand 29.2 49 Grenada 26.2 10 Tuvalu 40.3 30 Egypt 28.9 50 Iran 26.1 11 Kuwait 39.7 31 Australia 28.6 51 Suriname 26.1 12 United Arab Em 37.2 32 St. Kitts & Nevis 28.3 52 Lithuania 25.9 13 Micronesia 37.2 33 Mexico 28.1 53 Dominica 25.8 14 Fiji 36.4 34 United Kingdom 28.1 54 Slovakia 25.7 15 Bahamas 36.2 35 Canada 28.0 55 Ireland 25.6 Papua New 16 Vanuatu 35.4 36 Guinea 27.9 56 Israel 25.3 17 Bahrain 35.1 37 Chile 27.8 57 Cuba 25.2 18 Saudi Arabia 34.7 38 Solomon Islands 27.7 58 Poland 25.2 19 United States 33.7 39 Jamaica 27.2 59 Slovenia 25.1 20 Libya 33.1 40 Tunisia 27.1 185 Japan 3.3  Bottom Line Obesity is an environmental factor Youth (and adults) need healthier diets Youth (and adults) need more exercise  Key Points for Lecture 12 Cardiorespiratory endurance HR, SV, CO, VO2max, anaerobic, aerobic Strength 3 types of contractions Flexibility Body composition  Upcoming Schedule Quiz #4 due Dec 1 Class Dec 2? Final Exam on Dec 12 9am-11am PE-2001 Details to be posted on the Announcements board Questions mainly from Lectures #7-12 Some cumulative content