Exercise Physiology Chapter 6

Exercise Physiology Chapter 6 - Physiological Capacity and...

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Unformatted text preview: Physiological Capacity and Physiological Capacity and Performance Across the Lifespan Metabolic differences between Metabolic children & adults 1. 2. 3. 4. Lower glycogen stores Lower ATP stores Fewer glycolytic enzymes Fewer mitochondrial enzymes Why? LESS MUSCLE MASS! Cardiovascular differences between children & adults 1. 1. 2. 1. 2. Higher HR Lower stroke volume Lower cardiac output More blood flow to working muscles Less hemoglobin in blood 2 1. a­v O difference is about equal Respiratory differences between children & adults 1. 2. 1. Higher minute ventilation Higher respiratory muscle fatigue Smaller lung volumes Why? Children are smaller people. Thermoregulatory differences between children & adults 1. 1. 1. Greater metabolic heat during exercise. Later onset of increased sweat production at higher relative workloads. Less responsive thirst mechanism. 1. Differences in VO2max: Increases until age 16­18 in males & until age 12­14 in females VO2max is higher in boys than girls after age 9. 2max Female VO =85­90% of males before puberty & 70% of males after puberty Aerobic Exercise Capacity in Aerobic Exercise Capacity in Children Changes in VO2max are due to changes in size & body composition Aerobic Training in Children Aerobic Training in Children What endurance training adaptations do we observe in children? – Decreased resting HR – Increased Sv+ Q (cardiac output) – Increase in VO2max (5­25%) – Increased lactate threshold Aerobic performance increased more than VO2max. How is this possible? Anaerobic Exercise Capacity in Anaerobic Exercise Capacity in Children Children have a lower anaerobic capacity than adults even when adjusted for lean body mass. How is this possible? ­ Lower glycogen stores ­ Lower glycolytic enzyme activity ­ Lower buffering capacity They recover faster than adults after intense bouts of physical activity. How is this possible? Oxygen doesn’t have to travel as far Anaerobic Exercise Capacity in Children Anaerobic capacity rises during childhood & adolescence – between ages 9­15 Anaerobic capacity peaks after puberty & into early adulthood: ­ 14­16 in females ­ At least 20 in males Muscular Strength in Children Muscular Strength in Children There is a linear relationship between strength and age until age 13­14 in males & 14­16 in females. After puberty muscular strength is related to: 1. Body mass – weight 2. Body composition – % mass vs. muscle vs. bone 3. Testosterone – male sex hormone is a steroid hormone 4. Maturation of neural pathways Strength Training in Children Strength Training in Children Should children strength train? Recommendations for strength training and children: • Supervision when lifting weights above their heads and/or using free weights • Emphasis should be on form & technique, not competition • 30 minute sessions!! Decreases in Exercise Capacity Decreases in Exercise Capacity During Aging Aerobic & Anaerobic capacities decrease with age. What factors cause this decline? • Cardiac output (Q) • Aerobic power (VO2max) • Muscle mass • Muscular strength Aerobic capacity decreaes about 1% per year. HRmax decreases about 1 beat/year. SVmax decreases, though it can be well maintained with training. Qmax decrease Aerobic Power (VO2max) Aerobic Power (VO With aerobic training… ­VO2max can increase – Increased mitochondrial and capillary density → great oxidative capacity and O2 extraction Muscular Strength Muscular Strength Why is it important for adults to maintain muscular strength? ­posture ­balance ­coordination ­daily activities How does muscular strength How does muscular strength change as we age? decrease by 2­4% per year Between 20­80yrs. we lose 40% of our muscle mass. – Gradual decline between 30­50 yrs. – Accelerated decline after 50 yrs. What causes these changes? • inactivity • Muscle atrophy –decrease in muscle size • Neural input Exercise Prescription for Older Exercise Prescription for Older Adults The goal of program design for older adults is to improve or maintain: 1) 1) 2) 1) 1) 2) 3) Functional capacity Muscular strength Muscular endurance Quality of life Flexibility Coordination Balance Gender Differences in Aerobic Gender Differences in Aerobic Exercise Capacity Differences in performance can’t be explained by difference in VO2max alone. – 40% difference in absolute VO2max – 20% difference in relative VO2max – 10% difference when adjusted for lean body mass Lean body mass – body mass minus fat mass Gender Differences in Aerobic Gender Differences in Aerobic Exercise Capacity What can account for the difference in VO2max between males and females when adjusted for lean body mass? • RBC count • Hemoglobin • Heart size • Lung capacity ADAPTIONS ARE TO AEROBIC TRAINING ARE SIMILAR BETWEEN MALES AND FEMALES ALTHOUGH THE MAGNITUDE IS GREATER IN MALES! Total work and power output is greater in males than females Differences still remain when adjusted for lean body mass. Causes of differences? – Body composition – Limb length (males have larger and longer limbs) ADAPTIONS ARE TO ANAEROBIC TRAINING ARE SIMILAR BETWEEN MALES AND FEMALES ALTHOUGH THE MAGNITUDE IS GREATER IN MALES! Gender Differences in Anaerobic Gender Differences in Anaerobic Capacity Physiological difference in Effect on performance females Smaller bodies ie: shorter limbs Less lean muscle mass in relation to fat mass Gender Differences in Sport Gender Differences in Sport Performance Lower muscular strength and power Lower oxidative capacity → lower VO2max (aerobic power); fewer Type II fibers lower anaerobic power Lower force production → lower muscular power & strength Lower stroke volume → lower cardiac output →lower VO2max Less O2 carrying capacity → lower a­v O2 diff → lower VO2max Lower sweating rate during exercise Smaller muscle fiber diameter Smaller heart Lower hemoglobin Greater reliance on circulatory adjustments than sweating for thermoregulation TABLE 12.2 YOU NEED TO KNOW THIS TABLE! ...
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This note was uploaded on 02/18/2011 for the course MVS 340 taught by Professor Horowitz during the Winter '11 term at University of Michigan.

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