021308
BSL PRO Lesson H29:
Basal Metabolic Rate
Overview
INDIRECT MEASUREMENT OF METABOLIC RATE
Richard Pflanzer, Ph.D., Associate Professor
Indiana University School of Medicine / Purdue University School of Science
The human body’s oxidation of organic food such as carbohydrate, fat, or protein, produces carbon dioxide and water,
and releases chemical and thermal energy:
Food + O2 ® CO2 + H2O + Energy (chemical & thermal)
The chemical energy is used by the body’s cells to generate adenosine triphosphate (ATP), a compound containing highenergy bonds which the cell may later break to release energy and perform work, such as secretion, contraction, or
membrane transport. The thermal energy (heat) is used to maintain a relatively stable, optimum internal body
temperature.
Metabolic rate is the amount of energy released per unit of time. It can be determined by using a whole-body calorimeter
to measure the amount of heat given off by the body (direct calorimetry), or it can be determined by measuring the volume
of oxygen consumed by the body during a brief time period (indirect calorimetry).
The amount of heat (measured in kilocalories) released during the oxidation of a food is directly proportional to the energy
content of the food and directly proportional to the volume of oxygen required for complete oxidation. For example, the
complete oxidation of one mole of glucose (in a calorimeter) requires 134.4 liters of O2 (6 moles x 22.4 liters/mole = 134.4
liters of O2) and yields 673 kcal of energy:
C6H12O6 + 6O2 ® 6CO2 + 6H2O + 673 kcal
Thus, the complete oxidation of one mole of glucose yields 5.01 kcal per liter of O2 consumed. This value is called the
caloric equivalent of glucose. The caloric equivalent of other foods are 5.06 kcal/liter O2 for starches, 4.70 kcal/liter O2 for
fats, and 4.6 kcal/liter O2 for protein.
The human body is continually oxidizing a mixture of carbohydrate, protein, and fat rather than using any single food as
the sole source of energy. Based on an average utilization of all three foods, the average release of energy (in terms of
oxygen consumed) is 4.825 kcal per liter of O2 consumed. Metabolic rates under varying conditions may, therefore, be
measured by determining oxygen consumption in liters per hour and multiplying by the caloric equivalent of 4.825 kcal per
liter of oxygen consumed.
Basal metabolic rate (BMR) refers to body metabolism as measured under a set of standard basal conditions designed to
minimize the effects of as many influencing factors as possible. Basal conditions are as follows:
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BSL PRO Lesson H29
BIOPAC Systems, Inc.
1. The subject must ingest no food for at least 12 hours prior to the test.
2. The subject must be mentally and physically relaxed.
3. The subject's core body temperature must be normal.
Room temperature must be comfortable (65°F - 80°F).
Objectives
1. To obtain Basal Metabolic Rate (BMR) values from a subject
2. To compare this rate to standardized rate.
3. To measure post-exercise metabolic rate and compare it to BMR.
Equipment
•
•
•
•
•
•
•
BIOPAC Acquisition Unit (MP30 or MP35)
BIOPAC Gas Analysis System: O2 only (GASSYS2-EA or -EB)
BIOPAC Air Flow Transducer [Medium Flow Pneumotach] (SS11LA)
BIOPAC Calibration Syringe (AFT26 or AFT6)
BIOPAC Face Mask w/ T valve (AFT25)
BIOPAC Smooth Bore Tubing-35mm (2 x AFT7)
BIOPAC Flexible Coupler 22 mm OD/35 mm ID (2 x AFT11E)
---OR---
•
•
•
•
•
•
•
•
BIOPAC 22mm Non-Rebreathing T-valve (AFT22)
BIOPAC Flexible Coupler 22 mm OD/35 mm ID (2 x AFT11E)
BIOPAC Rigid Coupler 22 mm OD/22 mm OD (2 x AFT11C)
BIOPAC Smooth Bore Tubing-35mm (2 x AFT7)
BIOPAC Disposable Nose clip (AFT3)
BIOPAC Disposable Mouthpiece (AFT2)
BIOPAC Disposable Bacterial Filter (AFT1)
Tripod (Recommended)
The following measures are also required:
•
•
•
Ambient temperature in deg C
Ambient barometric pressure in mmHg
Pressure of water vapor at ambient temperature = 22.4 mmHg
Setup
Hardware
1. The Gas-System2 module is supplied with a 12 V DC @ 1 amp wall adapter. Plug the adapter into the main
power supply and insert the adapter plug into the DC Input on front of the Gas-System2 module.
2. Flip up the power switch on the Gas-System2 to turn it "ON."
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BIOPAC Systems, Inc.
BSL PRO Lesson H29
o
The unit should warm up for at least ten minutes before calibration, so it is suggested that you turn it
on now and then complete setup.
3. Plug the transducers into the MP3X as follows: (CO2 line is not needed for this experiment).
Transducer
MP3X CH #
SS11LA
CH1
O2 line (from the Gas-System2) CH2
4. Turn the MP3X unit on (assuming the AC100A power adapter has already been connected).
5. Setup the equipment.
NOTE: The ideal setup includes the AFT25 Face Mask, which allows for more natural and relaxed breathing and
will provide better data. If the Face Mask is available, follow Preferred Setup; otherwise use Secondary Setup.
Preferred Setup
Air Flow Accessory
Connects to
Secondary Setup
Air Flow Accessory
Connects to
AFT1 filter
SS11LA transducer,
on"Inlet" side
AFT1 filter
SS11LA transducer, on
the "Inlet" side
SS11LA transducer
AFT11E flexible coupler
SS11LA transducer
AFT11E flexible coupler
AFT11E flexible coupler AFT7 tubing
AFT11E flexible coupler
AFT7 tubing
AFT7 tubing
AFT25 face mask
AFT7 tubing
AFT11E flexible coupler
AFT25 face mask
AFT7 tubing
AFT11E flexible coupler
AFT11C rigid coupler
AFT7 tubing
GASSYS2 “Inlet” (back)
AFT11C rigid coupler
AFT21 non-rebreathing
T-valve
AFT21 non-rebreathing
T-valve
AFT11C rigid coupler
AFT11C rigid coupler
AFT11E flexible coupler
AFT11E flexible coupler
AFT7 tubing
AFT7 tubing
GASSYS2 Inlet (back)
NOTE: Attaching the SS11LA airflow transducer to a
tripod will greatly increase accuracy of experiment.
Software
1. Launch the BSL PRO software on the host computer.
•
The program should create a new "Untitled1" window.
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BSL PRO Lesson H29
BIOPAC Systems, Inc.
2. Open the BMR Template by choosing File > Open > choose Files of type: Graph Template (*GTL) > File
3.
name: "h29.gtl"
• The template will establish the required settings.
• This particular setup will provide a reading that, at any point in time, indicates the absolute volume of
oxygen consumed in the last 60 seconds. Units are liters because it is a volume measure, not a flow rate.
Save As the desired file name.
Calibration
Notes
• The Gas-System2 sensors are factory calibrated prior to shipping. The O2 sensor is a zirconia solid electrolyte
with a 0.1-25% sensing range and an estimated 5-year lifetime. It runs hot, which helps to burn off humidity.
Suggested warm-up time is ten minutes. The CO2 sensor is not connected for this lesson.
• In the calculation channel formulas, the following assumed values were used for gas concentrations in normal
atmosphere (chamber flooded with ambient air):
CO2 = 0.04%
N2 = 79.03%
02 = 20.93%
• Gas Calibration is not required, but can be performed using the small line inlet on the back panel of the GasSystem2 module. If you introduce calibration gases into the chamber, adjust the calculation channel expressions
for the real gas values.
• If you perform a gas calibration, use the following ranges:
Flow (inspired): calibrate within the range of 0 to 13 liters/sec
O2 concentration: calibrate in range of 21% to 16% O2
Calibration is a three-step procedure, as outlined below:
A. Calibrate Flow transducer.
B. Calibrate O2 channel (CH2).
C. Normalize moist gas to volume occupied by dry gas at 0 deg C, 760mm.
Flow
1.
2.
3.
4.
5.
6.
7.
8.
Select MP3X > Setup Channels.
Click the wrench icon for CH1.
Click the Scaling button.
Airflow Transducer should be on tripod or held upright.
Click the Cal1 button.
Subtract "3000" from the Cal1 Value and enter the result in Cal2 Value (Cal2 Input Value should be 3000 less
than Cal1 Input Value).
Confirm Cal1 Scale Value= 0 and Cal2 Scale Value=10.
Click OK.
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BSL PRO Lesson H29
BIOPAC Systems, Inc.
O2
1. Gas System Chamber should be flooded with ambient are prior to O2 calibration.
2.
• Press calibration syringe into Face Mask airway and pump 10-15 times.
• If using mouthpiece, unplug the mouthpiece and plug syringe and pump 10-15 times.
• Now you are ready to calibrate.
Click the wrench icon for CH2.
4.
5.
6.
7.
Click the Cal2 button.
Enter "20.93" into the Cal2 Scale Value.
Confirm both Cal1 Input Value= 0 and Cal1 Scale Value=0.
Click OK.
Gas Normalization
Normalize moist gas to volume occupied by dry gas at 0 deg C, 760mm
1. Find the normalization factor.
2. Click the wrench icon for C3 Vis (STPD).
3. Enter the normalization factor in the formula: C1*(normalization factor)
•
Be sure to enter the value as 0.x, with the leading decimal.
4. Click OK.
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BSL PRO Lesson H29
BIOPAC Systems, Inc.
Optional: Interval
Only required if you change the time interval from the template, which is set for a 60-second interval.
1. Click the wrench icon for C2.
2. Calculate the Samples entry as follows:
3.
4.
Integration Samples = Time Interval x Sample rate
(Template setting: Integration Samples = 60 sec x 100 samples/sec = 6000 samples)
Enter the new Samples value.
Click OK.
Recording
This lesson records absolute volume of O2 in 60-second intervals. Units are "liters" because this provides a
volume measure, not a flow rate. If you change the time interval, you must adjust the Integrate formula.
Hints for minimizing measurement error:
1. Ensure that the connections among the various pieces of equipment are fairly tight to prevent contamination via
room air.
2. Try to start the recording immediately after a full exhale. This will prevent receiving results with an O2 inspiration
value less than that of the total expiration value (although the averaging will minimize the inaccuracies that this
would cause).
3. It's very important that any extraneous volumes are minimized between the subject and the T-valve. Additional
volumes affect the effective expired gas concentration levels.
4. The tubing must be connected to the SS11LA on the unlabeled side (that does NOT say "Inlet").
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BIOPAC Systems, Inc.
BSL PRO Lesson H29
Segment 1: BMR
NOTE: Results will not be 100% accurate unless the following conditions are met:
•
•
•
•
1.
2.
3.
4.
5.
6.
Subject must ingest no food for at least 12 hours prior to the test.
The subject must be mentally and physically relaxed.
The subject's core body temperature must be normal.
Room temperature must be comfortable (65°F - 80°F).
Subject must be seated in a comfortable, relaxed position.
Have the subject put on AFT25 Face Mask and start breathing normally.
If using the mouthpiece, have subject put on nose clip.
Press the START button in the PRO software.
Have the subject breathe normally for at least six (6) minutes.
• Subject must breathe long enough to ensure that the mixing tank has been filled, thereby enabling it to
average those breaths.
Press the STOP button in the PRO software.
Optional Segments:
Post-exercise Metabolic Rate
1.
2.
3.
4.
5.
6.
Subject should perform five minutes of medium-to-strenuous exercise (i.e. running in place).
After exercise period, allow subject to rest in a comfortable inclined position, as in BMR test, for 7-8 minutes.
Flush the Gas System Chamber with ambient air using calibration syringe.
Press the START button in the PRO software.
Have the subject breathe normally for at least six (6) minutes.
Press the STOP button in the PRO software.
Notes
To save recorded data, choose File menu > Save As… > file type: BSL PRO files
(*.ACQ) File name: (Enter Name) > Save button
To erase all recorded data (make sure you have saved it first), and begin from Time 0,
choose: MP30 menu > Setup Acquisition > Click "Reset"
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BIOPAC Systems, Inc.
BSL PRO Lesson H29
Analysis
The BMR template will display channels as follows:
Channel
Displays
Measure
CH 1
Air Flow
Area
CH 2
O2E (expired O2)
Mean
CH 44 (C5)
VO2 (STPD)
Mean
1. Take a mean measurement of VO2 waveform. This will give you a value of mean Liters of O2 consumed per
2.
minute.
In order to calculate BMR, you will also need to know Body Surface Area in square meters.. Use the following
formula to calculate Body Surface Area:
Body Surface Area (m2) = ( [Height (cm) x Weight (kg) ]/ 3600 )½
Click here to review the BSA Adult Nomograph (based on the formula of DuBois and DuBpois, 1916)
3. Use VO2 and Body Surface Area in the following equation to calculate metabolic rate, or click here to use the
BMR Calculator (requires Microsoft Excel; if your browser does not open the calculator, click here to download
the BMR Calculator file for Windows or Mac).
Metabolic Rate =
2
(kcal/m /hr)
(VO2)(60)(4.825 kcal/l)
2
Body Surface Area (m )
4. Use the BMR Calculator to establish predicted BMR and calculate % deviation from predicted rate.
5. If doing post-exercise metabolic rate, use the BMR Calculator to calculate % increase over BMR.
APPENDIX
GRAPH TEMPLATE SETTINGS
Click here to open a PDF of the graph template file settings. The BSL PRO Graph Template file automatically establishes
the settings shown in the table.
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Page 8 of 10
BIOPAC Systems, Inc.
BSL PRO Lesson H29
Normalization Factors
The following table lists the factors required to reduce volume of moist gas to volume occupied by dry gas at 0 deg. C,
760mm. OBR is an abbreviation for observed barometric reading, uncorrected for temperature. Fahrenheit values are
roughly converted and rounded from Celsius values as TF=(9/5*TC)+32ºF.
Important!
All factors are 0.x, with x being the value from the table. Be sure to include the leading decimal
when you complete your calculation.
ºC
15
16
17
18
19
20
21
22
23
24
25
26
27
28
ºF
59
61
63
64
66
68
69
72
73
75
77
79
81
OBR
700
855
851
847
842
838
834
829
825
821
816
812
807
802
702
857
853
849
845
840
836
832
827
823
818
814
809
805
800
795
790
785
780
704
860
856
852
847
843
839
834
830
825
821
816
812
807
802
797
792
787
783
706
862
858
854
840
845
841
837
832
828
823
819
814
810
804
800
795
790
785
708
865
861
856
852
848
843
839
834
830
825
821
816
812
807
802
797
792
787
710
867
863
859
855
850
846
842
837
833
828
824
819
814
809
804
799
795
790
712
870
866
861
857
853
848
844
839
836
830
826
821
817
812
807
802
797
793
714
872
868
864
859
855
851
846
842
837
833
828
824
819
814
809
804
799
794
716
875
871
866
862
858
853
849
844
840
835
831
826
822
816
812
807
802
797
718
877
873
869
864
860
856
851
847
842
838
833
828
824
819
814
809
804
799
720
880
876
871
867
863
858
854
849
845
840
836
831
826
821
816
812
807
802
722
882
878
874
869
865
861
856
852
847
843
838
833
829
824
819
814
809
804
724
885
880
866
872
867
863
858
854
849
845
840
835
831
826
821
816
811
806
726
887
883
879
874
870
866
861
856
852
847
843
838
833
829
824
818
813
808
728
890
886
881
877
872
868
863
859
854
850
845
840
836
831
826
821
816
811
730
892
888
884
879
875
871
866
861
857
852
847
843
838
833
828
823
818
813
732
895
890
886
882
877
873
868
864
859
854
850
845
840
836
831
825
820
815
734
897
893
889
884
880
875
871
866
862
857
852
847
843
838
833
828
823
818
736
900
895
891
887
882
878
873
869
864
859
855
850
845
840
835
830
825
820
738
902
898
894
889
885
880
876
871
866
862
857
852
848
843
838
833
828
822
740
905
900
896
892
887
883
878
874
869
864
860
855
850
845
840
835
830
825
742
907
903
898
894
890
885
881
876
871
867
862
857
852
847
842
837
832
827
744
910
906
901
897
892
888
883
878
874
869
864
859
855
850
845
840
834
829
746
912
908
903
899
895
890
886
881
876
872
867
862
857
852
847
842
837
832
82
797
29
84
793
30
86
788
31
88
783
32
90
778
748
915
910
906
901
897
892
888
883
879
874
869
864
860
854
850
845
839
834
750
917
913
908
904
900
895
890
886
881
876
872
867
862
857
852
847
842
837
752
920
915
911
906
902
897
893
888
883
879
874
869
864
859
854
849
844
839
754
922
918
913
909
904
900
895
891
886
881
876
872
867
862
857
852
846
841
756
925
920
916
911
907
902
898
893
888
883
879
874
869
864
859
854
849
844
ºF
59
61
63
64
66
68
69
72
73
75
77
79
81
82
84
86
88
90
ºC
15
16
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17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
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BIOPAC Systems, Inc.
BSL PRO Lesson H29
ºF
59
61
ºC
15
16
17
18
19
20
21
22
23
24
25
26
27
758
927
923
918
914
909
905
900
896
891
886
881
876
872
866
861
856
851
846
760
930
925
921
916
912
907
902
898
893
888
883
879
874
869
864
859
854
848
762
932
928
923
919
914
910
905
900
896
891
886
881
876
871
866
861
856
851
764
936
930
926
921
916
912
907
903
898
893
888
884
879
874
869
864
858
853
766
937
933
928
924
919
915
910
905
900
896
891
886
881
876
871
866
861
855
768
940
935
931
926
922
917
912
908
903
898
893
888
883
878
873
868
863
858
770
942
938
933
928
924
919
915
910
905
901
896
891
886
881
876
871
865
860
772
945
940
936
931
926
922
917
912
908
903
898
893
888
883
878
873
868
862
774
947
943
938
933
929
924
920
915
910
905
901
896
891
886
880
875
870
865
776
950
945
941
936
931
927
922
917
912
908
903
898
893
888
883
878
872
867
778
952
948
943
938
934
929
924
920
915
910
905
900
895
890
885
880
875
869
780
955
950
945
941
936
932
927
922
917
912
908
903
898
892
887
882
877
872
ºF
59
61
63
64
66
68
69
72
73
75
77
79
81
82
84
86
88
90
ºC
15
16
63
17
64
18
66
19
68
20
69
21
72
22
73
23
75
24
77
25
79
26
81
27
82
28
28
84
29
29
86
30
30
88
90
31
32
31
32
From Peters and Van Slyke, Quantitative Clinical Chemistry, vol. 11. (Methods) Baltimore: Williams and Wilkins, 1932, reprinted 1956.
Definitions
These abbreviations are used in the discussion and calculation channel Expression formulas for VO2 and BMR:
BMR
Basal Metabolic Rate
ATP
Concentration of gas at ambient temperature and pressure
CO2
Carbon dioxide
Est. concentration ambient environment: 0.04%
CO2e = Carbon Dioxide fractional concentration in expired air
Fi
Inspired air flow (ATP)
N2
Nitrogen
N2e = Nitrogen fractional concentration in expired air
N2e = 100 – (CO2e + O2e)
O2
Oxygen
Est. concentration in ambient air: 20.93%
O2e = Oxygen fractional concentration in expired air
Est. concentration in expired breath: 16% oxygen
Pb
Ambient barometric pressure (e.g. 745 mmHg)
PH20
Ambient pressure of water vapor (e.g. 22.4 mmHG)
STPD
Concentration of gas at standard temperature and pressure, dry
Ta
Ambient temperature (e.g. 24 deg. C)
VO2
Volume of oxygen consumed (STPD) per 60-sec interval
Real-time oxygen consumption
VO2 = (Vies/100)*(20.93-O2e)
Vi
Inspired air volume (ATP) per 60-sec interval
Vi = Integrate (Fi) over 60 seconds. The number of samples is equal to the time interval x sample rate
(template is 60 sec. x 100 samples/sec = 6000 samples). Select "Average over samples."
Vies
Inspired/Expired air volume (STPD) per 60-sec interval
Vies = Vi * (0.874)
In this experiment, inspired air volume is assumed to be equal to expired air volume.
Note: If you change the time interval from 60 seconds, you must adjust the Vi formula.
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