1. Metabolic Calculations - Purpose
Estimate energy expenditure during steady state exercise

2. Importance of Metabolic Calculations
It is imperative that the exercise physiologist is able to interpret test results and estimate energy expenditure.
Optimizing exercise protocols.
Exercise prescription.
Weight loss.

3. Metabolic Calculations (S=Speed in m/min; G= % Grade)
MODE Horizonal Vertical Rest
Walking VO2 = (0.1• S) (1.8 • S • G)
Running VO2 = (0.2• S) (0.9 • S • G)
Cycle VO = 1.8 (work rate)
Body Weight (kgs)
Arm VO = 3 (Work Rate)
Stepping VO2 = (0.2• f) (1.33 • 1.8 • h • f)
CARRY OUT EACH STEP TO 2 DECIMAL PLACES
Monark Cycle Work Rate: Resistance X Revs/min x 6m/rev
Monark Arm Work Rate: Resistance X Revs/min x 2.4m/rev

4. 1L= 1000 mL
1kg= 2.2 lbs
1mph= 26.8 mmin-1
1 MET = 3.5 mLkg-1min-1
1 W= 6 kgmmin-1
1 in = m=2.54 cm
Pace: min/mile to mph = 60/time
Ex: 7.5 min/mile / 60 min/hr = 8mph
Kcal/min = METS * 3.5 * BW
200
1L O2min-1 = 5 kcalmin-1
1 lb of fat= 3500kcal

5. Metabolic Calculations (S=Speed; G=Grade)
Walking (most accurate from mph)
VO2 = (0.1• S) + (1.8 • S • G) + 3.5
Treadmill and Outdoor Running (for speeds > 5 mph)
VO2 = (0.2• S) + (0.9 • S • G) + 3.5
Leg Ergometry
VO2 = 1.8 (work rate)/(BM)
Arm Ergometry
VO2 = 3 (Work Rate)/(BM) + 3.5
Stepping
VO2 = (0.2• F) + (1.33 • 1.8 • H • f) + 3.5
CARRY OUT EACH STEP TO 2 DECIMAL PLACES

6. Assumptions and Limitations
Measured VO2 is highly reproducible at a given steady state workload. Failure to achieve steady state is an overestimation of VO2.
Accuracy of equations is unaffected by most environmental conditions such as heat and cold.
However, variables that change mechanical efficiency (gait abnormalities, wind, snow or sand) result in a loss of accuracy.
Assumption that ergometers are calibrated and no holding on to hand rails occur during on treadmill.

7. Met Calc - Key Points
Estimates oxygen requirement (VO2) for various workloads
Linear relationship
Some variability (S.E.E. ­ 7%)
assumptions
S.E.E. ­ 7%

8. Met Calc - Key Points (con’t)
“Steady State” or submax exercise:
O2 cost = O2 uptake
“Maximal” Exercise
O2 cost > O2 uptake
Anaerobic
Component =
Predicted
VO2max
VO2max
O2 Requirement
Max Exer
you cannot predict maximal
Workload

9. Met Calc - General Principle
Mechanical
Workload
Metabolic
Equivalent
Meters.min-1
kgm.min-1
VO2
METs
kcals.min-1
We estimate one value based on
knowledge of the other

10. Metabolic Units Gross vs. NET All equations give Gross VO2 values.
For weight loss use the NET VO2 vales.
NET: Gross – resting value
VO2 NET : 40 ml/kg/min – 3.5 ml/kg/min = 36.5 ml/kg/min OR
: METS – 1 MET = 10.4 METS

11. Metabolic Calculations (S=Speed in m/min; G= % Grade)
MODE Horizonal Vertical Rest
Walking VO2 = (0.1• S) (1.8 • S • G)
Running VO2 = (0.2• S) (0.9 • S • G)
Cycle VO = 1.8 (work rate)
Body Weight
Arm VO = 3 (Work Rate)
Stepping VO2 = (0.2• f) (1.33 • 1.8 • h • f)
CARRY OUT EACH STEP TO 2 DECIMAL PLACES
Monark Cycle Work Rate: Resistance X Revs/min x 6m/rev
Monark Arm Work Rate: Resistance X Revs/min x 2.4m/rev

12. ACSM Walking Equation Speeds ­ 50-100 m/min; 1.9-3.7 mph
(1 mph = 26.8 m/min)
“Relative” VO2 unit (ml/kg/min; ml.kg-1.min -1)
VO2 walking = Horizontal Walking (HW) + Vertical Climb (VC) + Resting
VO2 walking = Speed (m/min) x % grade x Speed (m/min) x

13. ACSM Walking Equation Example: VO2 for walking @ 3.0 mph at 5% grade
Convert 3.0 mph to m/min
3.0 x = 80.4 m/min
VO2 walking = Horizontal Component + Vertical Component Resting
VO2 walking = Speed (m/min) x % grade x Speed (m/min) x
VO2 = x x .05 x
VO2 =
VO2 = ml.kg-1.min-1
VO2 = ml.kg-1.min-1 / 3.5 = 5.4 METS

14. ACSM Running Equation
Speeds > 134 m/min; > 5.0 mph (1 mph = 26.8 m/min)
VO2 for running at 6.0 mph at a 5% grade
Convert 6.0 mph to m/min
6.0 x = m/min
VO2 running = Horizontal Component + Vertical Component Resting
VO2 running = Speed (m/min) x % grade x Speed (m/min) x
VO2 running = x x x
VO2 running =
VO2 running = 42.9 ml/kg/min
VO2 running = 42.9 ml/kg/min / 3.5 = METS

15. ACSM Leg Cycling Equation
Loads kgm/min; watts
Work Rate = kg x meters/rev x RPM
Use 6 meters/revolution for the Monark Ergometer
Add resting twice : 1 for resting and 1 for unloaded
Q: What is the VO2 for a 90 kg subject pedaling at 2.0 kgs at 60 rpms
Work Rate: 2.0 kg x 6 m/rev x 60 rpms = 720 kgm
VO2 Cycling = 1.8 x WR BW
VO2 Cycling = 1.8 x
90 kgs
VO2 Cycling =
VO2 Cycling = ml/kg/min or 6.1 METS

16. ACSM Arm Cycling Equation
Loads 150 to 750 kgm/min; watts
3.0 = ml.min-1 per kpm/min ( from leg cycling)
Only 1 resting component (3.5)
Monark™ Rehab Trainer: 2.4 meter/rev
Work Rate: kg x 2.4 meters/rev x rpm
Q: What is the VO2 of a 100 kg person who uses a Monark arm ergometer at 3 kg at 50 rpms.
Work Rate: 3 kg x 2.4 meters/rev x 50 revs/min = 360 kgm
VO2 arm= 3 x WR ml.kg-1.min-1 BW
VO2 arm= 3 x ml.kg-1.min-1 = 14.3 ml/kg/min
100

17. ACSM Stepping Equation
VO2stepping = 0.2 x f x 1.8 x h x f + 3.5
VO2 varies with Step height & rate
“Relative” VO2 unit (ml.kg-1.min-1)
VO2 (ml.kg-1.min- 1 ) = Horizontal + Vertical + Resting
Horizontal = steps/min x 0.2
Vertical = step ht x steps/min x x 1.8
Down cycle ­ 0.33 VO2 of the up cycle (add this in by multiplying by “1.33”)
1.8 is the constant for vertical work
Step height is entered in meters
1 in = m=2.54 cm

18. ACSM Stepping Equation
Q: What is the VO2 for a 55 kg woman who is stepping on a 12” bench at 30 steps per minute
Calculate step height in meters
12” x = 0.31 meters
VO2stepping = 0.2 x f x 1.8 x h x f
VO2stepping = 0.2 x x 1.8 x 0.31 x
VO2stepping =
VO2stepping = ml/kg.min
VO2stepping = /3.5 = 9.1 METS
Question: What is the kcal expenditure (kcal.min-1) for this 55 kg person exercising at the above VO2 or METS? This person exercises at this rate 3 times per week for 30 minutes each session.
How long will it take this person to lose 10 pounds exercising at this rate?

19. Kcal conversion example
Q: What is the kcal expenditure (kcal.min-1) for a 55 kg person exercising at an oxygen uptake of 9.1 METs? This person exercises at this rate 3 times per week for 30 minutes each session. How long will it take this person to lose 10 pounds exercising at this rate?
kcal.min-1 = METs x x BW (kg)
200
kcal.min-1 = 8.1 x x 55 (Why did we use 8.1 METS?) (For weight loss use the NET)
kcal.min-1 = 7.8
1 pound of fat = 3,500 kcals pounds = 35,000 kcals
Answer: 35,000 kcals = 4, minutes
7.8 kcals/min
4, minutes = weeks
90 minutes/week