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Unformatted text preview: Importance of Metabolic Calculations Metabolic Calculations
Calculations
Chapter 5 and Appendix D Metabolic Topics
Work,
Work, Energy, Power as they relate to
calorimetry
Expressions
Expressions of oxygen uptake
Concept of the MET
Metabolic
Metabolic calculations
Case
Case studies It
It is imperative that the exercise physiologist is
able to interpret test results and estimate energy
expenditure.
di
Optimizing
Optimizing exercise protocols.
Exercise
Exercise prescription.
Weight
Weight loss. Work and Energy
Work
Work  Application of force through distance
Work
Work = Force x distance (i.e.kg x m)
(i.
Force
Force is constant W = 70 kg x 0.75 meters
52. kg•
52.5 kg•m or 515 Joules Energy
Energy – capacity to perform work
1 kcal = 4,186 J
CHO
CHO = 5.05 kcal • LO2
Fat
Fat = 4.74 kcal • LO2 Each L of O2 consumed
= 5 kcal 1 Power (on different modes)
• Power – Amount of work per unit time
• Bike
• work/time (I.e. kgm/min; Watt)
• 1 W = 6 kgm•min1
• Note = For cycle ergometry you must account for
• kg
• distance the flywheel moves the kg with one turn
• rev•min1
• I.e. Monarch = 6 m • rev 1
• Power = (2 kg x 6 m • rev 1 x 60 rev•min1)
= 720 kgm•min1 or
W Power (on different modes)
• Power – Amount of work per unit time
• Step –
• step height (m)
• 4 cycle steps / minute (f)
• Treadmill
• Speed (m/min)
• Grade (% grade – use decimal) Energy Expenditure
Understanding
Understanding energy expenditure is important
for weight loss, work tasks, exercise
prescription, etc.
Calorie
Calorie  basic unit of measure of energy
expenditure
Direct
Direct and Indirect Calorimetry can be used to
estimate energy expenditure Calorimetry
Direct Calorimetry
Calorimetry Metabolic Chamber
(enclosed)
Slide 8 Indirect Calorimetry
Calorimetry Closed or Open Circuit
Spirometry Indirect Calorimetry,
Slide 11, Slide 10 2 Calorimetry
Calorimetry Indirect Calorimetry Calorimetry
Calorimetry 3 Indirect Calorimetry: Variables Obtained
Oxygen
Oxygen consumption and carbon dioxide production
(VO2, VCO2)
Respiratory
Respiratory exchange ratio (RER or R)Noninvasive
Noninvasive method to estimate the relative contribution of
fat and CHO to energy metabolism
RQ
RQ during steady state conditions VCO
VCO2/VO2 Need a link
In
In research and in practice, we use information
obtained from opencircuit spirometry to give
openus estimates of energy expenditure, aerobic
power and fuel utilization
power, and fuel utilization.
For
For example, we can use oxygen consumption
measures to help us determine caloric
expenditure during exercise. Calorie/
Calorie/ energy expenditure
i.e.
i.e. 1 liter of VO2 = ~ 5 kcals For example:
How
How many calories are you burning
if you exercise in a step class using
an 8 inch bench?
If we need to know the oxygen
If we need to know the oxygen
consumption
consumption (workload) for
someone exercising at 6 mph at 5%
grade…..
If
If we need to figure out, how long it
will take an individual to loose a
certain amount of weight…. 4 Expressions for O2 uptake (VO2)
We
We will be using metabolic calculations to
calculate oxgyen consumption and calories
Oxygen
Oxygen consumption in humans can be
expressed in two different forms
expressed in two different forms
Absolute (L·
Absolute – (L·min1 or ml·min1): Can be used in a
or ml·
form that will yield rate of energy expenditure
(1
(1 L of O2 = 5 kcal) (ml•kg
(ml•kg1•min1): Relative
Relative –
used to compare
individuals of different body size and to better
quantify aerobic fitness level MATH AND UNITS ??
Make
Make sure that you have your answer is in the
right units.
Make
Make sure your answer units make physiological
sense
Make
Make sure your answer units agree with the
problem (i.e. apples = apples NOT apples =
oranges)
Make
Make sure you cancel out units correctly
i.e.
i.e. 3 L/K X 5 K/ P = 15 L/Ps Expressions for O2 uptake (VO2)
Absolute (L·
Absolute – (L·min1 or ml·min1): Can be
or ml·
UNITS ! UNITS ! yield rate!of
used in a form that will UNITS
energy expenditure good for converting
energy expenditure ; good for converting
oxygen
oxygen consumption into calories
(1
(1 L of O2 = 5 kcal) Relative (ml•kg
Relative – (ml•kg1•min1): used to
compare individuals of different body size
and to better quantify aerobic fitness level Example
5 apple/oranges X 6 orange/ bananas = ???
apple/oranges 30
30 apple / bananas ÷ 6 oranges = ??? 5 apple/ banana/ oranges
apple/ Expressions
Expressions of units
a/
a/ b/ c is the same as a•b1•c1 5 MET METs Clinically,
Clinically, the MET or “Metabolic equivalent”
is used to express energy expenditure and to
prescribe
prescribe exercise in clinical settings.
1 MET = 3.5 ml•kg1•min1
MET
ml•
For
For example
80
80 kg man working at 2.5 L•min1
2,500 mL•min 80kg
2,500 mL•min1 / 80kg = 31.25 ml•kg1•min1
ml•
31.25 ml•
31.25 ml•kg1•min1 / 3.5 = 8.9 METs Met Calc warming up
Man
Man weighing 200 lbs has pk O2 uptake = 4.0 L•min1
What
What is his relative oxygen consumption?
How
How many METs is this? A woman weighing 155 lbs has VO2 pk = 32.1 ml•kg1 • min1
woman
ml•
What
What is her absolute oxygen uptake?
How
How many METs is this? What
What is the difference between indirect and direct
calorimetry?
calorimetry? 6 Practice with O2 calculations
Man
Man weighing 176 lbs has pk O2 uptake = 4.4 L•min1
What
What is his relative oxygen consumption?
How
How many METs is this? A woman weighing 140 lbs has VO2 pk = 36.7 ml•kg1 • min1
140 lb
VO
36
What
What is her absolute oxygen uptake?
How
How many METs is this?
How
How many METs would 70% of her peak capacity be
equivalent to?
How
How many calories per minute is she burning at her peak?
How
How many calories per minute is she burning at 70%? ACSM Metabolic Calculations
Can
Can estimate energy expenditure if you have
Vertical
Vertical component
Horizontal
Horizontal component
Resting
Resting component Useful
Useful conversions (Memorize)
(Memorize)
Always
Always convert lb to kg (lb/2.2)
Centimeters = in x 2.54
Convert
Convert speed from mph to m/min (mi/h X 26.8)
1Watt
1Watt = 6 kgm•min1
kgm•min
Remember
Remember equivalents
Watts
Watts to kgm •min1
kcals
kcals (3,500 kcals = 1 lb of fat gain or loss)
1 L O2 = 5 kcals For
For weight loss purposes, always account for resting metabolic rate, weekly
physical activity and energy expenditure, and food intake Estimation of Energy Expenditure
We
We can estimate energy expenditure through
American
American College of Sports MedicineSM Metabolic
Equations
Special
Special considerations for these equations
Need to assure that person is at steady state in order to use
th
equations
There
There is a variance in prediction
Need
Need to consider environmental considerations
No railNo railholding and make sure equipment is calibrated
Gross
Gross Vs. Net O2 cost Metabolic Calculations – (see also page 216)
Walking
Walking (S=Speed; G=Grade) VO (0.1•
VO2 = (0.1• S) + (1.8 • S • G) + 3.5 Treadmill
Treadmill and Outdoor Running
VO (0.2•
VO2 = (0.2• S) + (0.9 • S • G) + 3.5 Leg Ergometry (watch the units here)
th
VO
VO2 = (10.8 • W • M1) + 7 OR
VO ((kgm
VO2 = ((kgm • min1) • 2) + (3.5 • W) Arm
Arm Ergometry
VO
VO2 = (18 • W • M1) + 3.5 Stepping
Stepping
VO (0.2•
VO2 = (0.2• F) + (1.33 • 1.8 • H • f) + 3.5 7 Break it down – Walking equation oxygen
consumption
(ml/kg/min) VO [(0.1•
VO2 = [(0.1• S)] + [(1.8 • S • G)] + 3.5
Horizontal component –
i.e. oxygen cost of
Speed (units are
Speed (units are
carrying
m/min)
m/min)
body in horizontal
body in horizontal
direction over distance
Vertical component – i.e.
(units are ml/kg/m)
oxygen cost of carrying
body in vertically(units are
ml/kg/m) grade Resting oxygen
consumption
(ml/kg/min) Useful calculation tips to live by Practice Calculation (from pg 311) Write
Write down all known’s and do any necessary
conversions first.
Calculate
Calculate each component separately, then
complete the calculation
complete the calculation A 71yearold man weighing 180 lb walks on a
71yearmotormotordriven treadmill at 3.5 mph and a 15%
grade. I.e.
I.e. vertical, horizontal, resting Make
Make sure your answer agrees with the
question in numerical and unit form (always
(always What is the oxygen consumption
What is the oxygen consumption
What
What is the MET level
How
How many calories is he burning at this level? provide units!!!) 8 More Practice Calculations
A client weighs 155 lbs was determined to
client
have a VO2 pk of 45 ml/kg/min.
What
What is his oxygen consumption in absolute terms?
In
In METs?
How many kcals
How many kcals/min is he expending?
is he expending A 23yearold woman weighing 150 lb jogs
23yearon a motordriven treadmill at 5.8 mph and
motora 0% grade.
What
What is the oxygen consumption?
What
What is her MET level?
How
How many kcals/min is she expending?
kcals/min …and Even More Practice
Calculations  bonus
A cardiac patient has just entered your cardiac
cardiac
rehabilitation program and has an exercise
prescription to exercise 40 minutes at 6 METs,
4 days per week and the client weight 210 lbs.
Calculate
Calculate the following
Treadmill
Treadmill grade for a speed of 2.5 mph
Step
Step rate for a 4 inch bench
Resistance
Resistance for a monarch bike at 50 rpm
Total
Total caloric expenditure for each workout session 9 ...
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 Fall '11
 Dr.JenniferBlevinsMcNaughton

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