chapter 9
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Chapter 9. Human Energy Expenditure During Rest and Physical Activity. 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 - PowerPoint PPT PresentationTRANSCRIPT
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 × m2
• 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