Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 9 Human Energy Expenditure During Rest and Physical Activity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Energy Expenditure at Rest Basal metabolic rate (BMR) –Energy to maintain vital functions in awake state Resting metabolic rate (RMR) –Energy to maintain vital functions plus digestion –Measured 3 – 4 hours following a meal

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Metabolism at Rest Resting energy metabolism varies in proportion to the body’s surface area Allometric scaling is used to –Establish a relationship between body size and a variable such as Muscular strength Aerobic capacity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Effects of Regular Exercise Resistance training increases BMR by increasing FFM. Endurance training increases BMR without increasing FFM. Exercise can offset the age-related decline in BMR.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition “Normalcy” of BMR Values Compares a person’s measured BMR with “standard metabolic rates” based on age and gender

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Estimating Resting Daily Energy Expenditure RDEE = BMR × m 2 Contribution of diverse tissues –Muscle is more active than fat mass. –The brain has a high metabolic rate. –During exercise, muscle metabolism may increase nearly 100 times.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Factors that Affect Energy Expenditure Physical activity –Largest variable in daily energy expenditure Diet-induced thermogenesis (DIT) –Obligatory thermogenesis –Facultative thermogenesis

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Factors that Affect Energy Expenditure Climate –Hot or cold environments increase energy expenditure. Pregnancy –Increases BMR due to added weight gained during pregnancy

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Energy Expenditure in Physical Activity Classification of physical activities by energy expenditure –Intensity –Duration Physical activity ratio (PAR) –Determined by ratio of energy required in relation to BMR Light work = 1 – 3 × BMR Heavy work = 6 – 8 × BMR Maximal work = > 9 × BMR

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition The MET MET = metabolic equivalent –1 MET = 3.5 mL × kg −1 × min −1 –Exercise intensity described relative to resting rate –Used to guide or prescribe exercise intensity

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Daily Rates of Average Energy Expenditure The average U.S. adult spends 75% of the day in activities requiring light energy expenditure. In the United States, 300,000 deaths per year result from physical inactivity and poor eating habits.

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Energy Cost of Household, Industrial, and Recreational Activities Effect of body mass –Weight-bearing exercise –Weight-supported exercise

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Heart Rate to Estimate Energy Expenditure Heart rate and oxygen consumption –Linear relationship exists –Linearity is not identical for everyone Other factors altering heart rate –Temperature– Humidity –Food intake– Body position –Muscle groups worked– Emotions –Static v. dynamic work

Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition