2. Methods of Measuring
Body’s Heat Production
Two methods
Direct calorimetry
Indirect calorimetry
• Closed-circuit spirometry
• Open-circuit spirometry
3. Measurement of heat actually
produced by the body which is
confined in a sealed chamber or
calorimeter.
DIRECT CALORIMETRY
4.
5. Measures how much
CO2, is produced
and how much O2, is
consumed at
both rest and during
aerobic exercise.
INDIRECT CALORIMETRY
6. This enables us to
find out the main
energy source (fat
or carbohydrate)
being used during
exercise.
INDIRECT CALORIMETRY
7. The accuracy of the test
is very reliable as it
gives a precise
calculation of your vo2
and vo2 max.
INDIRECT CALORIMETRY
(VO₂ max is the maximum rate of oxygen consumption
attainable during physical exertion.)
8. WHY WOULD THAT BE IMPORTANT?
We all need oxygen for metabolism to
work because it depends so heavily on
it. In order to determine how much
energy our metabolism requires, we
can monitor the amount of oxygen we
take in.
10. OPEN-CIRCUIT SPIROMETRY
The open-circuit method provides a relatively
simple way to measure oxygen consumption.
A subject inhales ambient air with a constant
composition of 20.93% oxygen, 0.03%
carbon dioxide, and 79.04% nitrogen
(including a small quantity of inert gases).
11. the amount of air breathed over a
specific period of time and the
characteristics of expired air—provides
a useful technique to measure oxygen
consumption to estimate energy use.
12. Three common indirect calorimetry
procedures measure oxygen
consumption during physical
activity:
1.Portable spirometry
2.Bag technique
3.Computerized instrumentation
14. PORTABLE
SPIROMETRY
Carrying the portable spirometer allows considerable freedom of movement in
physical activities as diverse as mountain climbing, downhill skiing, sailing, golf, and
common household activities
15. BAG
TECHNIQUE
AIR IS COLLECTED IN A
LARGE BAG (DOUGLAS BAG).
SMALL SAMPLE FOR GAS
CONCENTRATION
16. COMPUTERIZED
INSTRUMENTATION
• A DEVICE TO CONTINUOUSLY COLLECT
SAMPLES OF THE SUBJECT'S EXHALED AIR,
• A FLOW-MEASURING GADGET TO TRACK
THE AMOUNT OF AIR BREATHED,
• THE COMPOSITION OF THE EXPIRED GAS
COMBINATION USING OXYGEN AND
CARBON DIOXIDE ANALYZERS.
18. FOOD
RESPIRATORY QUOTIENT
O2 ENERGY CO2
REACTANTS PRODUCTS
ENZYMES
C₆H₁₂O₆ + 6O₂
RQ= volume of CO2 (produced)
volume of O2 (consumed)
ENERGY+ 6CO2 + 6H₂O
RQ= 6CO2
6O2
= 1
C₁₆H₃₂O₂ + 23 O₂ ENERGY + 16CO2 + 16H₂O
RQ= 23CO2
16O2
= 0.7
Editor's Notes
Energy expenditure Is the measurement of the amount of energy a person uses over a given period of time for any physical functions.
Direct calorimetry measures heat production in an appropriately insulated calorimeter.
Indirect calorimetry infers energy expenditure from oxygen consumption and carbon dioxide production, using either closed-circuit spirometry or open-circuit spirometry.
direct calorimetry is the gold standard for figuring out the amount of calories that we and we expend.
our body uses ATP. ATP is the energy system by which allow us to live. when enzymes act on the ATP molecule they end up releasing heat so that heat release is indicative of ATP use so that said we can measure the amount of heat that is released from our body and then we can estimate the amount of calories through the unit of calories we can then estimate how much energy we use.
For example, you are inside the chamber which is closed off is well insulated as the water around it and then that water
that absorbs through the walls of that chamber the heat that we release, there's the controlled amount of oxygen
that goes in and controlled amount of co2 that comes out so we're able to measure and calculate exactly the variables
This machine here, we'll be measuring how much CO2 has been produced and how much oxygen has been consumed through the machine
they measure the amount of oxygen that you consume in the amount of co2 that you then release.
vo2 Exchange tells us the amount of oxygen and co2 that we end up consuming or
interchanging now why would that be important well the reason why we measure that is because our metabolism is highly dependent on oxygen we have to have oxygen for metabolism function in every single one of ourselves so that said what we can do is measure the amount of oxygen that we intake and then that will correlate strongly with the amount of energy that our metabolism has to go through
vo2 Exchange tells us the amount of oxygen and co2 that we end up consuming or interchanging.
Now why would that be important? well the reason why we measure that is because our metabolism is highly dependent on oxygen we have to have oxygen for metabolism function in every single one of ourselves so that said what we can do is measure the amount of oxygen that we intake and then that will correlate strongly with the amount of energy that our metabolism has to go through.
The subject breathes 100% oxygen from a prefilled container (spirometer). The equipment is a closed system because the subject rebreathes only the gas in the spirometer. A canister of potassium hydroxide (soda lime) placed in the breathing circuit absorbs the carbon dioxide in the exhaled air. A drum attached to the spirometer revolves at a known speed to record the oxygen removed (oxygen consumed) from changes in the system’s total volume.
the volume of air breathed during a specified time and the composition of expired air—provides a practical way tomeasure oxygen consumption and infer energy expenditure.
gas concentration” alone typically refers to how much of a gas (either in mass or in molecules) is present at a certain time and at a certain location.
The subject inspires ambient air through a two-way breathing valve, while expired air exits through a gas meter. The meter measures the total expired air volume and simultaneously collects a small gas sample for later analysis of oxygen and carbon dioxide content. These values determine oxygen consumption and energy expenditure for the measurement period.
rides a stationary bicycle ergometer, wearing headgear attached to a two-way, high-velocity, low resistance breathing valve. He breathes ambient air through one side of the valve and expels it through the other side. The expired air then passes into either large plastic or canvas Douglas bags (named for distinguished British respiratory physiologist Claude G. Douglas [1882–1963]) or rubber meteorological balloons or directly through a gas meter that continually measures expired air volume. The meter draws off an aliquot sample of expired air for subsequent analysis of O2 and CO2 composition.
The computer performs metabolic calculations based on electronic signals it receives from the instruments. A printed or graphic display of the data appears throughout the measurement period. More-advanced systems include automated blood pressure, heart rate, and temperature monitors, including preset instructions to regulate speed, duration, and exercise intensity with a treadmill, bicycle ergometer, stepper, rower, swim flume, or other exercise apparatus.
so to begin with we consume food because food is the source of energy it is fuel for our body so this food it combines with the oxygen because we breathe, we take in oxygen and we give out carbon dioxide
so this food it combines with oxygen to produce energy and during this process of producing energy there is carbon dioxide liberated, there are also other wastes that are excreted out. So this is nothing but a chemical reaction.
because these are the Reactants and these are the products
food reacts with oxygen through oxidation and it produces energy that is utilized for our daily life activities and also during our exercise giving out carbon dioxide
with the help of enzymes so the food that we eat, consists of macronutrients which are nothing but carbohydrates fats and proteins so the food macronutrients it combines with oxygen through the process of oxidation which is a chemical reaction and energy is produced giving out carbon dioxide now we consume carbohydrates fats and proteins now this production of energy is continuous even when we are at rest and even when we are exercising the need increases because energy we require more during our exercise.
so when you're using glucose as a source of fuel glucose chemical formula is .................. you're using glucose which is a carbohydrate as the source of fuel to produce energy and this combines with oxygen because of your breathing it's an oxidation process and this gives energy giving off six molecules of carbon dioxide and six molecules of water so this is nothing but the biochemical reaction taking place in the human body when we use glucose as the source of fuel.
so now coming back to the respiratory quotient which is rq.
now let us understand the rq value of fats. Palmitate fatty acid like I mentioned fats can be used as a source of fuel palmitate which is a fatty acid when it oxidizes then it produces energy and there are 16 molecules of carbon dioxide liberated with 16 molecules of water so now the rq value is carbon dioxide liberated to the amount of oxygen which is 0.7, so the rq value of fat is 0.7
