Learning Module 3:
Measuring Metabolic Rate
Clark J Cotton
Measuring Metabolic Rate
Metabolic Rate: the sum of all energetic
processes occuring in the body.
Measuring Metabolic Rate
Metabolic Rate: the sum of all energetic
processes occuring in the body.
How do you measure metabolic rate?
Measuring Metabolic Rate
Metabolic Rate: the sum of all energetic
processes occuring in the body.
How do you measure metabolic rate?
– Direct Calorimetry
Measuring Metabolic Rate
Metabolic Rate: the sum of all energetic
processes occuring in the body.
How do you measure metabolic rate?
– Direct Calorimetry
– Mass Balance
Measuring Metabolic Rate
Metabolic Rate: the sum of all energetic
processes occuring in the body.
How do you measure metabolic rate?
– Direct Calorimetry
– Mass Balance
– Oxygen Consumption
What’s Oxygen Got to do with It?
•
Oxygen is the basic reducing
compound used to convert sugar to
carbon dioxide, releasing energy
for our bodies and producing
carbon dioxide.
•
Depending on level of activity,
almost all of our metabolism is
dependent on oxygen.
6 O2 + C6H12O6
6 CO2 + 6 H2O
Measuring Metabolic Rate
•
Materials: 1 empty milk jug, plastic
tubing, 500ml beaker, permanent
markers.
•
Gradually fill up milk jug in 500ml
increments, mark each addition.
•
Flip jug upside down in tub of water
and insert plastic tube.
•
If you breath in through your nose,
and out through your mouth you
can calculate the amount of air you
breath.
Tidal Volumes
•
Tidal volume is the volume of air you inhale and then exhale with each breath.
Vital Capacity
•
Vital Capacity is the maximum amount of air that you can inhale and exhale.
Dead Space
•
Dead space volume is the volume of air that does not participate in gas
exchange because of airway volume. Dead space volume (ml) = body weight
(kg) * 2.2
Total Lung Capacity
•
Total lung capacity is equal to the vital capacity + the dead space.
Measuring Metabolic Rate
•
If you know the number of breaths
you take per minute, and the
average volume of air per breath,
you can calculate the total volume
of air you’re breathing per hour.
Example:
15 breaths / minute
500ml air / breath
450 L air / hour
•
Assuming that the air you breath
contains 21% oxygen, and the air
you exhale contains 17% oxygen,
you can calculate your total
oxygen consumption per hour.
(.21*450) – (.17*450) = 18 L O2 per hour
Possibilities with Metabolic Rate Measurements
Effects of:
• Age
• Exercise
• Size
• Temperature
• Time of Day
Possibilities with Metabolic Rate Measurements
Effects of:
• Age
• Exercise
• Size
• Temperature
• Time of Day
Possibilities with Metabolic Rate Measurements
Effects of:
• Age
• Exercise
• Size
• Temperature
• Time of Day
Possibilities with Metabolic Rate Measurements
Effects of:
• Age
• Exercise
• Size
• Temperature
• Time of Day
Possibilities with Metabolic Rate Measurements
Effects of:
• Age
• Exercise
• Size
• Temperature
• Time of Day