Human Energy Expenditure during Rest & Physical Activity: Chapter 9

Understand the components of TDEE and what percentages make up each section

What three factors impact total daily energy expenditure?

1. Resting metabolic rate (60-75%)

- Fat free body mass

- Gender

- Thyroid hormones

- Protein turnover

2. Energy expended during physical activity and recovery (15-30%)

- Work and exercise

3. Thermic effect of feeding (10%)

- Obligatory

- Facultative

Define metabolism, BMR, and RMR

Metabolism

Involves all chemical reactions within the body that encompass synthesis (anabolism) and breakdown (catabolism)

Basal Metabolic Rate (BMR)

- Minimum level of energy to sustain vital functions in the waking state

- Reflects the body's total heat production

- Knowledge of BMR establishes the energy baseline to develop weight control strategies through food restriction, regular physical activity or combination of both

Resting Metabolic Rate (RMR)

- Always slightly higher than BMR

- Often used as a substitute and is used interchangeably with BMR

- Influences: body size, health/fitness, muscle mass, hormones, body temperature

- This measurement looks at more pieces of the puzzle then basal metabolic rate

BMR and RMR can both be used to measure

the sum of metabolic processes required to sustain normal regulatory balance and body functions during the resting state

BMR and RMR both can account for ____ to _____ % of TDEE

60-75%

BMR can be measured by

STRICT laboratory conditions, fasting state for 12-18hrs, no physical activity 2hrs prior to assessment, rest supine for 30min before testing

RMR can be measured by

3-4hrs after a light meal without prior physical activity

Explain the metabolic size concept

Surface area law

- Fundamental relationship between heat production and body size

- Resting energy expenditure varied in proportion to the body's surface area

- BMR and RMR vary in proportion to the square of body surface area per hour (kcal/m2/h)

List the differences of metabolic rates with change of body composition, gender, age, and physical activity

Changes in body composition can explain the ____ to ____% per decade BMR reduction observed in adults

2-3%

Females exhibit an average ____ to ____% lower BMR than males of same age

5-10%

As aging occurs what happens to BMR?

It decreases

There is a strong relationship between BMR and

fat free mass

What effect does regular physical activity have on BMR?

Offsets decreases in BMR and RMR that occur with aging

Understand how to estimate resting daily energy expenditure

How do you estimate resting daily energy expenditure (RDEE)?

- Usually expressed in kcal/h or kcal/d

- Can be estimated from BMR and surface area

- Can also be estimated from fat free mass (FFM)

Explain the absolute and relative energy needs of various organs and tissues

What organs consume about the same total quality of oxygen even though one is much smaller?

- Brain and skeletal muscle

For children, _____ metabolism represents nearly 50% of total resting energy expenditure

Brain

Which organ has the most oxygen consumption?

Liver

Which organ has the least oxygen consumption?

Heart

What other factors effect total daily energy expenditure?

1. Thermic effect of feeding/diet-induced thermogenesis

2. Thermic effect of physical activity

3. Climate

4. Pregnancy

Distinguish between obligatory and facultative thermogenesis

Food consumption increases energy metabolism, _____% of TDEE

10%

Obligatory thermogenesis

- Energy required to digest, absorb, and assimilate food nutrients

- Eating a meal high in protein vs. high in fat

Facultative thermogenesis

- Activation of sympathetic nervous system and its stimulating influence on metabolism

- Reaches maximum within 1hr following a meal

Overweight individuals often have a _______ thermogenic response that contributes to

- Blunted

- Excess body fat accumulation

Eating a nutrient rich breakfast does what to metabolism?

Increases resting metabolism by 10%

Diet induced thermogenesis (DIT) of _______ and ______ exceeds lipids DIT

- Proteins

- Carbohydrates

For most individuals, it seems reasonable to encourage ______ after eating to possibly augment

- Moderate physical activity

- a diet-induced increase in caloric expenditure for weight control

RMR of people in tropical environments is normally _____ to ____ % higher than those living in temperate area

5 to 20%

Exercising in hot weather causes about a ___% higher O2 consumption

5%

Cold environments _____ energy metabolism during rest and exercise

Increase

Added energy costs of weight-bearing locomotion during pregnancy results primarily from

- Additional weight transported

- Fetal tissue

Increased body mass raises

energy expenditure

With weight-supported exercises such as cycling, the influence of body mass on energy cost _____

decreases

Expressing energy costs per kg or body mass reduces energy cost differences between individuals regardless of

race, age, gender and body mass

For overweight persons, weight-bearing exercise generates

a considerable caloric expenditure

A heavier person will expend more total calories than a lighter person for an equivalent exercise because

the activity mainly requires the transport of body mass, which requires more energy

Understand how to classify physical activities based on energy expenditure

How does physical activity effect TDEE?

It accounts for 15-30% of TDEE

Regular physical activity stimulates....

resting metabolism

Regular endurance and resistance exercise does what to metabolism?

Offsets the decrease in resting metabolism that usually accompanies aging

Each 1lb gain in FFM increases RMR by

22 kcal/d

Classification of physical activities by energy expenditure

1. Classifying strenuousness of physical tasks

2. Physical activity ratio

Classifying strenuousness of physical tasks

- Intensity (how hard you perform; based on % VO2max RPE scale)

- Duration (how long you perform activity)

Physical activity ratio (PAR)

Classifies work as the ratio of energy required for a task to the resting energy requirement

- Light work: Up to 3x the resting oxygen consumption

- Heavy work: 6-8x the resting oxygen consumption

- Maximal work: 9x or more above the resting oxygen consumption

Explain MET and understand the ranking of certain activities

What is MET?

Metabolic equivalent

- Multiples of RMR

1 MET equals the resting oxygen consumption

- 250mL/min for men

- 200mL/min for women, absolute values

To consider variations in body size how would you express METs

- METs in VO2 per unit of body mass

1 MET =

3.5 ml/kg/min

- relative = more accurate

For example, exercising at 2 METs requires how much resting metabolism

twice

List the average rate of energy expenditure for men and women

What is the average energy expenditure for an average man?

2900kcal/d

What is the average energy expenditure for an average woman?

2200kcal/d

Most people spend nearly _____% of their day in light energy expenditure activities

75%

Understand the influence of body mass on exercise and VO2

For an individual, HR and VO2max relate linearly over the range of exercise intensities to about _____ % of max

80%

Exercise HR can provide an estimate of

VO2max and energy expenditure during aerobic exercise

Using HR to measure VO2max an only be validated for

general large muscle activities

What are the faults of using exercise HR to measure VO2max?

- Environmental temperature

- Emotions

- Food intake

- Body positions

- Musculature

- Continuous vs. discontinuous mode

- Static or dynamic movements