Energy Costs of Physical Activity

Question 0

Direct Calorimetry requires that…

Answer 0

requires that the person performs an activity within a specially constructed chamber
chamber is insulated and has water flowing through its walls

Question 1

Direct Calorimetry

Answer 1

considered the gold standard, but difficult to do

Question 2

Direct Calorimetry chamber

Answer 2

water flowing through walls of the chamber is warmed by the heat given off by the subject
chamber is insulated and has water flowing through its walls
–by knowing the V of water flowing through the chamber per minute and the change in water temp from entry to exit, calorimetry is determined…

Question 3

It takes 1 kcal…

Answer 3

to raise the temperature of 1 L of water 1deg C

Question 4

additional heat producing adjustments for direct calorimetry

Answer 4

subject loses additional heat though evaporation of water from skin and respiratory passages

equipment utilized produces heat

Question 5

indirect calorimetry

Answer 5

estimates energy by measuring O2 consumption

uses certain constants for converting liters of O2 consumption to calories expended

Question 6

Constants Derived From Bomb Calorimeter

Answer 6

1g CHO = 4.0 kcal
1g of FAT = 9.0 kcal
1g of PROTEIN = 4.0 kcal

Question 7

energy density of CHO

Answer 7

4.0 kcal

Question 8

energy density of fat

Answer 8

9.0 kcal

Question 9

energy density of protein

Answer 9

4.0 kcal

Question 10

caloric equivalent of O2

Answer 10

the number of calories of energy produced when 1L of O2 is consumed

Question 11

CHO vs FAT

Answer 11

CHO gives 6% more energy / LO2 than Fat (5 kcal/L vs 4.7 kcal/L)
fat gives more than 2x the energy per gram than CHO (9 kcal vs 4 kcal)

Question 12

Respiratory Quotient (RQ)

Answer 12

the ratio of CO2 produced to O2 consumed at the cell

Volume CO2 produced / Volume O2 consumed

Question 13

Respiratory Exchange Ratio (RER)

Answer 13

RQ measured by conventional gas exchange procedure

used to indicate fuel use (CHO vs fat) during exercise

Question 14

caloric equivalent of 1L O2 for CHO

Answer 14

5.0 kcal

Question 15

caloric equivalent of 1L O2 for FAT

Answer 15

4.7 kcal

Question 16

caloric equivalent of 1L O2 for PROTEIN

Answer 16

4.5 kcal

Question 17

RQ for CHO

Answer 17

1.0

Question 18

RQ for FAT

Answer 18

0.7

Question 19

RQ for PROTEIN

Answer 19

0.8

Question 20

types of indirect calorimetry

Answer 20

closed-circuit spirometry

open-circuit spirometry

Question 21

closed-circuit spirometry

Answer 21

subject breaths 100% O2 from a spirometer and the exhaled air passes through a chemical that absorbs the CO2
over time, the O2 in the spirometer decreases, giving a measure of the O2 consumption in ml/min
Because the CO2 is absorbed, R can’t be calculated and caloric equivalent of 4.82 kcal/L is used to indicate a mixture of CHO, fat, and protein producing the energy

Question 22

R used for Closed-circuit spirometry? why?

Answer 22

4.82 kcal/L O2
because the CO2 is absorbed, R can’t be calculated
represents a mixture of CHO, fat, and protein used to produce energy

Question 23

What is the old system of indirect calorimetry?

Answer 23

Closed-circuit spirometry

Question 24

What is the most common technique for indirect calorimetry? (currently)

Answer 24

open-circuit spirometry

Question 25

Open-circuit spirometry

Answer 25

O2 is calculated by subtracting O2 exhaled from O2 inhaled (O2 inhaled - O2 exhaled) CO2 is calculated by: CO2 inhaled - CO2 exhaled Allows for calculation of R and determination of which fuel (CHO and fat) is primary energy source

Question 26

Which indirect calorimetry allows for the calculation of R?

Answer 26

open-circuit spirometry

Question 27

Caloric equivalent of 1 L of O2 in calculation of energy expenditure

Answer 27

5.0 kcal/ L is typically used to convert O2 uptake to kcal | per ACSM guidelines

Question 28

expressing energy expenditure

Answer 28

the energy requirement for an activity is calculated from the subject's steady-state O2 consumption (VO2) measured during an activity

Question 29

5 most common ways to express energy expenditure

Answer 29

1. VO2 (L/min) 2. Kcal/min 3. VO2 (mL/kg*min) 4. METs 5. kcal/kg*hr

Question 30

VO2 (L/min) | "Volume of O2 in L/min"

Answer 30

the calculation of O2 uptake yields a value expressed in L of O2 per minute ABSOLUTE this does not account for body mass, so is not good for comparing individuals

Question 31

Kcal/min

Answer 31

The caloric equivalent of 1 L O2 ranges from 4.7 kcal/L for fat to 5.0 kcal/L for CHO 5.0 kcal.L IS USED TO CONVERT THE O2 UPTAKE TO KCAL/L Energy expenditure is calculated by multiplying the kcal expended per min (kcal/L) by the duration of the activity in minutes

Question 32

VO2 (ml/kg*min | "Volume of O2 in ml/kg*min"

Answer 32

this expression allows you to compare values for people of different body sizes calculated by taking the O2 uptake expressed in L/min multiplied by 1000 and divided by the subjects body weight in kg

Question 33

METs

Answer 33

metabolic equivalent is a term used to describe resting metabolism 1 MET = 3.5 ml/kg*min Activities are expressed in terms of multiples of the MET unit

Question 34

1 MET =

Answer 34

3.5 mL/kg*min

Question 35

Kcal/kg*hr

Answer 35

you can use the MET value to calculate this | convert the MET value back to the number of mL/kg*min and multiply by 60min/hr

Question 36

Who prefers METs? Who prefers mL/kg*min

Answer 36

Doctors prefer to talk in terms of METs. exercise professionals prefer to express in terms of ml/kg*min

Question 37

Equations for estimating the energy cost of activities

Answer 37

In mid 1970s, ACSM identified some simple equations to estimate the steady-state energy requirements associated with common modes of activities used in GXTs EQUATIONS PROVIDE ESTIMATES OF ENERGY COSTS WITH STD DEVIATIONS OF ~7-9%

Question 38

Standard deviation of equations for estimating energy costs

Answer 38

7-9%

Question 39

Additional error when using ACSM equations can happen when... (3 examples)

Answer 39

1. when the equations are used to estimate maximal aerobic power and the increments between the stages are too large 2. When the person tested is somewhat unfit 3. when the person is "diseased" (i.e. cardiac patients)

Question 40

when the ACSM equations used to estimate maximal aerobic power have increments between stages that are too long...

Answer 40

equations overestimate actual measured O2 uptake O2 uptake cant keep pace with the stage of the test ex. jumping from 3.2mph to 6.0mph in consecutive stages

Question 41

when the person being tested is somewhat unfit, ACSM equations...

Answer 41

equations overestimate the actual measured O2 uptake O2 uptake cant keep pace with the stage of the test this is probably because tests were developed in fit individuals

Question 42

when the person is "diseased" ACSM equations...

Answer 42

ex. cardiac disease equations overestimate the actual measured O2 uptake The GXT is too aggressive The O2 uptake can't keep pace with the stage of the test

Question 43

Gross (Total) O2 consumption =

Answer 43

Net O2 consumption + Resting O2 consumption

Question 44

Net O2 consumption vs. Resting O2 consumption

Answer 44

``` Net = O2 consumed to complete an activity Resting = baseline measure = 3.5 ml/kg*min ```

Question 45

Resting O2 consumption =

Answer 45

3.5 ml/kg*min | 1 MET

Question 46

Net O2 cost of the activity - components

Answer 46

Includes horizontal and vertical components of work | ex. treadmill, accounting for speed and grade of incline

Question 47

Note for GXT

Answer 47

Subjects must follow instructions (don't hold on to the treadmill railing, maintain pedal cadence) work instruments MUST BE CALIBRATED so the settings are known to be correct

Question 48

WALKING EQUATION

Answer 48

- - used for walking speeds between 1.9 and 3.7 mph and the client must be walking - -eliminate vertical component if walking on flat surface or 0% incline VO2 ml/kg*min = 3.5+ 2.68 (speed in mph) + 0.48 (speed in mph)(%grade)

Question 49

TREADMILL RUNNING EQUATION

Answer 49

--used for jogging speeds greater than 3.7mph VO2 ml/kg*min = 3.5+ 5.36(speed in mph) + 0.24(speed in mph)(%grade)

Question 50

OUTDOOR RUNNING EQUATION

Answer 50

--if you don't have a steady grade or if it is unknown, eliminate the vertical component of the equation VO2 mL/kg*min= 3.5+ 5.36(speed in mph) + 0.48(speed in mph)(%grade)

Question 51

LEG ERGOMETRY EQUATION

Answer 51

ACSM equation comes out (is reported in) ml/min, while the simplified equation reports it in mL/kg*min workload or power is in the units kg*m/min (ACSM refers to these units as kgm/m (min)) Vo2 ml/kg*min= 3.5+ 2(workload)/BW

Question 52

Workload for arm and leg ergometry equations

Answer 52

ACSM refers to the units as kgm/m The power depends on how fast the flywheel is moving against the set amount of resistance Resistance generally reported in kg (technically should be N) Speed of the flywheel depends on how fast the subject is pedaling and on the gearing used to drive the flywheel

Question 53

Monarch bike

Answer 53

flywheel moves 6 m per revolution

Question 54

Proper unit for expressing workload vs ACSM expression for ergometry (leg and arm) equations

Answer 54

proper unit is watts ACSM expresses in kgm/m ACSM conversion is 1 watt = 6 kgm/m

Question 55

watt conversion

Answer 55

1 watt = 6 kgm/min | technically 6.12

Question 56

ARM ERGOMETRY EQUATION

Answer 56

ACSM equation reported in ml/min, while simplified equation is reported in mL/kg*min VO2 mL/kg*min= 3.5+ 3(workload)/BW workload = (resistance setting)(flywheel setting per revolution)(rpm)