EE: Application of RQ (2005)

Citation:

Peronnet F, Massicotte D. Table of nonprotein respiratory quotient: An update. Can J Sport Sci. 1991;16(1):23-29

 
Study Design:
Narrative Review
Class:
R - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • The table of nonprotein RQ that is currently universally used is the one proposed in 1901 and modified in 1912. Biochemical data on which the computations were made have been improved over the past decades; some inconsistencies can be found in the derivations of the values; therefore nonprotein RQ table should be slightly revised.
Inclusion Criteria:
  • Criteria for article inclusion not described.
Exclusion Criteria:
  • Criteria for article exclusion not described.
Description of Study Protocol:
  • Search procedures: Were based on historical tables printed.
  • Was study quality assessed? Study calculations were assessed and refuted.
  • Populations: that the calculations were made were considering healthy adults.
Data Collection Summary:

Outcome(s) and other measures

  • Why type of information was abstracted from articles? Biochemical and physical data
  • How was it combined? Data was not combined.
  • What analytic methods were used? Atomic weights of carbon, hydrogen, and oxygen.
    Oxidation of glucose and fatty acid.
Description of Actual Data Sample:
  • # 18 articles included
  • # of articles identified not addressed.

The earliest study was in German and printed in 1901 by Zuntz N, Schumburg H. Studien Zu Einter Physiologie des Marches. Who proposed the table of nonprotein RQ (and was cited by Williams, Richie, & Lusk in 1912 following a study of metabolism in a dog who ingested large quantities of meat).

The revised table by Lusk was corrected in 1924 in a paper titled, “Animal calorimetry. Analysis of the oxidation of mixtures of carbohydrates and fat. A correction.” There are 3 animal studies cited.

Current biochemical and physical data is based on studies reporting the average fatty acid composition of triacylglycerols from human adipose tissue. There are 5 primary research publications.

Eight textbooks representing the fields of physics, chemistry, nutrition, exercise physiology, and metabolism are used.

Summary of Results:

Table of Lusk (1924) 

Basic biochemical data required to generate a table of nonprotein RQ are:

  1. Eqn of oxidation of glucose & representative fatty acid(s)
  2. Energy potentials of glucose and representative fatty acid(s)
  3. Volumes occupied by one mole of O2 and CO2 involved in the oxidation reaction under standard conditions (STPD). From these basic data, the volumes of O2 and CO2 involved in the oxidation rxn, RQ, & energy equivalent of oxygen can be computed for any given mixture of glucose & fatty acid substrates.

Energy combustion of fat

  • Unable to trace consistency of Lusk table derivations: i.e., according to reference citations in original article, the energy equivalent of oxygen should have been either 4.946 kcal/l (STPD) or 5.030 kcal/l and NOT the 5.047 kcal/l (STPD) times 2.0182=9.457 kcal/g as computed by Zuntz and not explicitly written in Lusk’s 1928 paper. However, in the 1928 Table by Lusk, the energy value of fat was 9.384 for olive oil; 9.372/g for animal tissue fat, or 9.179 kcal/g for butter.
  • Finally the quantity of CO2/gram lard is mistaken; The RQ should have been 1.4289/2.0182=0.708 and not 0.707.

Current Biochemical and Physical Data

Based on implicit model of human triacylglycerol stores [or palmytoleyl-steroyl-oleoylglycerol (Frayn) or tripalmitorylglycerol by Ferrannini)], the weight average foumula is 272.4051 gram/mole.

The current model takes into account:

  • 13 fatty acids represent 99% of fatty acids found in human triacylglycerols and are the respective average abundance
  • 5 of 13 fatty acids in human triacylglycerols are known and represent 71.69% of the fatty acid stores. On the basis of this data, the energy potential is 9.7460 kcal/g.

Corrections to volume of gas that CO2 and O2 occupy:

  • 1 mole O2 occupies 22.3858 STPD
  • 1 mole CO2 occupies 22.2966 STPD

RQ of complete oxidation of a fatty acid =0.7036

  • Energy equiv O2=4.851 kcal/L STPD

Energy combustion of glucose

The RQ associated with the oxidation of glucose is 0.9960.

  • Issues arise in the different values used for the energy potential of glucose.
  • Ferrannini (1988): 673 kcal/m
  • Lehninger (1981): 686 kcal/mole
  • Weast (1989): 669.94 kcal/m

The current report uses 696.90 kcal/mole or 3.8683 kcal/g. Thus the RQ is 0.9960

Computation of the Table  

  • For the extreme values of the RQ (0.7036 and 0.9960), the corresponding % of energy provided from glucose or fatty acid oxidation and the energy equivalent of oxygen are taken directly from balanced equations.
  • For a given RQ between these two extremes, the values in the table cannot be easily interpolated because the relationships between the RQ and the % energy provided from glucose and fat oxidation, and the energy equivalent of oxygen are not linear.

Table of Nonprotein Respiratory Quotient (RQ)

Percentages of energy from
RQ Glucose Fatty Acids

0.7036

0.00

100.0

0.7050

0.50

99.5

0.7100

2.30

97.7

0.7150

4.20

95.8

0.7200

6.00

91.0

0.7250

7.80

92.2

0.7300

9.60

90.4

0.7350

11.40

88.6

0.7400

13.20

86.8

0.7450

15.00

85.0

0.7500

16.80

83.2

0.7550

18.60

81.4

0.7600

20.40

79.6

0.7650

22.10

77.9

0.7700

23.96

76.1

0.7750

25.70

74.3

0.7800

27.40

72.6

0.7850

29.20

70.8

0.7900

31.00

69.0

0.7950

32.70

67.3

0.8000

34.50

65.5

0.8050

36.20

63.8

0.8100

38.00

62.0

0.8150

39.70

60.3

0.8200

41.40

58.6

0.8250

43.20

56.8

0.8300

44.90

55.1

0.8350

46.60

53.4

0.8400

48.30

51.7

0.8450

50.00

50.0

0.8500

51.70

48.3

0.8550

53.40

46.6

0.8600

55.10

44.9

0.8650

56.80

43.2

0.8700

58.50

41.5

0.8750

60.20

39.8

0.8800

61.90

38.1

0.8850

63.60

36.4

0.8900

65.30

34.7

0.8950

66.90

33.1

0.9000

68.60

31.4

0.9050

70.30

29.7

0.9100

71.90

28.1

0.9150

73.60

26.4

0.9200

75.30

24.7

0.9250

7.69

23.1

0.9300

78.60

21.4

0.9350

80.20

19.8

0.9400

81.80

18.2

0.9450

83.50

16.5

0.9500

85.10

14.9

0.9550

86.70

13.3

0.9600

88.40

11.6

0.9650

90.00

10.0

0.9700

91.60

8.4

0.9750

93.20

6.8

0.9800

94.80

5.2

0.9850

96.40

3.6

0.9900

98.00

2.0

0.9950

99.60

0.4

0.9960

100.00

0.0

  • Source: Peronnet F, Massicotte D. Table of nonprotein Respiratory Quotient: An update. Can J Sport Sci. 1991;16(1):23-29.
Author Conclusion:

As stated by the author in body of report 

“Obviously, the differences between the Lusk table (corrected) and the proposed table are small and considered insignificant in the context of indirect respiratory calorimetry which may often entail large errors of measurement.

On the other hand, there is no apparent reason to continue using a table that contains systematic inconsistencies when it is as easy to use a table that is more consistent and in better accordance with biochemical and physical data currently accepted.

“Although the error is not great, yet it is worthy to note and of record (Lusk, 1924)”
Funding Source:
University/Hospital: Universite de Montreal (Canada)
Reviewer Comments:
  • The strengths are that the authors provide a simple, yet thorough, physics and biochemistry description of how the Lusk nonprotein RQ table was developed.
  • Calculations are accurate
  • Weakness is that authors reference development of nonprotein RQ using animal data; also note the paper was published in 1991 so is over 10 years old.
  • The findings are generalizable to healthy adults.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
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  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
2. Was the selection of study subjects/patients free from bias? No
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
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  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
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  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
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  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
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  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
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  7.5. Was the measurement of effect at an appropriate level of precision? N/A
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  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
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  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A