Section 11: Metabolic Prediction Equations

Revisited

HPHE 4450

Dr. Cheatham

Outline

• What are prediction equations?

• How are they useful?

• Walking, running, cycling equations

• Determining calorie expenditure

Prediction equations allow us to predict the

oxygen uptake (VO2) of a person for a given

exercise session.

Used for a various types of exercise

Cycling, walking, running, stepping

We are using ACSM prediction equations

What Are Prediction Equations

Allows us to predict VO2

Allows us to determine the exercise

intensity that will elicit a known VO2.

Can estimate calorie expenditure

Uses of Prediction Equations

Review of Workload on Cycle

Workload is measured in:

kg • m • min-1 or Watts

Two factors can be adjusted:

Resistance on the flywheel (kg or kp)

Rate (RPM’s)

kg•m•min-1

= kg (6m/rev rev/min)

Conversion: 6 kg•m•min-1

= 1 Watt

Tom is pedalling at 60 RPM’s with a resistance of 2.5 kp.

What is the workload is kgm/min and Watts?

Kgm/min = 2.5 (6m/rev 60 rev/min)

Workload = 900 kgm/min

Watts = 900 kgm/min 1 Watt

6 kgm/min

Workload = 150 Watts

Example Problem

ACSM Prediction Equations

VO2 is mL/kg/min (Relative)

VO2 = ((1.8 Workrate) / BM) + 7.0

ACSM Cycle Ergometry Equation

VO2 = (0.1 S) + (1.8 S G) + 3.5

Speed (m/min)

Speed (m/min)

Constant Constant

Constant

% Grade (decimal)

VO2 is mL/kg/min (Relative)

m/min = mph 26.82

ACSM Walking Prediction Equation

Used for speeds 1.9 to 3.7 mph

VO2 is mL/kg/min (Relative)

m/min = mph 26.82

ACSM Running Prediction Equation

VO2 = (0.2 S) + (0.9 S G) + 3.5

Speed (m/min)

Speed (m/min)

Constant Constant

Constant

% Grade (decimal)

Used for speeds > 5.0 mph

Predicting VO2 of a given exercise

session.

We’ve done this one.

Practical Application

Determining the proper exercise

intensity to elicit a given VO2

Joe has a VO2max of 55 ml/kg/min and weighs

75 kg. What do we set the bike at so that he is

exercising at 70% of his VO2max?

Example

Solution

•Determine 70% of VO2max

•Solve prediction equation for kgm/min

•Pick an RPM and solve for resistance

(workload equation)

Practical Application

VO2 has to be in LO2/min

Getting from mLO2/kg/min to LO2/min Multiply VO2 in mLO2/kg/min by bodyweight and divide

by 1000 Ex: 40 mLO2/kg/min 60kg = 2400 mLO2/min

2400 mLO2/min 1000 = 2.400 LO2/min

Energy Expended Kcal = VO2 (LO2/min) * RER kcal Equiv. * minutes

Remember, if we don’t know RER kcal Equiv. then we use the value of 1 LO2/min = 5 kcal/min

Determining Energy Expenditure

Determining Energy Expenditure

Practical Application

Determining caloric expenditure for

an exercise session?

Example One

Bill, who weighs 83 kg, exercises on a cycle ergometer for 30

minutes at an resistance setting of 3.0 kg and 60 rpm. What

is his predicted total caloric expenditure for the exercise bout?

•Determine kgm/min and then determine predicted VO2.

•Multiply predicted VO2 (LO2/min) by 5 to get kcal/min

•Multiply kcal/min by 30 minutes to get total caloric expenditure

Solution