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EE: Room Conditions (2013)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To examine whether the conventional range of thermal comfort was appropriate enough to determine definite BMR.


 

Inclusion Criteria:
  • Understand and give written consent
  • Apparently healthy via present and past health questionnaire, blood pressure, body temperature and heart rate.
Exclusion Criteria:

Refusal to consent.

 

Description of Study Protocol:

Recruitment

Subjects were students of the School of Health Sciences, University of Tokyo who had experience of measuring oxygen consumption in an undergraduate course.

Design

TIme series.

Statistical Analysis

  • Two-way or three-way ANOVA used to test effects of room temperature, season of measurements and time course
  • Two-way ANOVA to examine the effects of temperature conditions (room and outdoor temperatures) and of time course
  • Three-way ANOVA (room temperature, 20o and 25o; season, summer and winter; time course, four or seven measurements) was used to assess the independent effects of room and outdoor temperatures on RMR
  • A post-hoc Tukey test was used to determine specific mean differences.

 

 

 


 

Data Collection Summary:

Timing of Measurements

  • RMR measures were completed in a laboratory room at the lower limits of thermal comfort zone (20oC) in winter season (December 1986 and in January 1989 to March 1989) and in the summer season (July 1987 to August 1987 and in July 1988 to August 1998)
  • Initial RMR was taken 10, 20, 30 and 40 minutes after wakening (four initial RMR measures were taken)
  • The subject then walked outdoors at a normal pace for 10 minutes and the outdoor temperature was recorded
  • The individual came indoors, rested 15 minutes and RMR were measured every 15 minutes from 75 to 120 minutes (i.e., three post-walk measurements)
  • Following post-absorptive measures, the individuals were fed breakfast (700kcal per 14% protein; 17% fat; 69% CHO). The post-prandial measures were taken every 15 minutes during first hour, then every 30 minutes  from 175 to 310 minutes). 
  • Three to seven days later, the study was repeated at upper limits of thermal comfort zone (25) in both seasons.

Dependent Variables

  • Measured REE [(VO2, L per minute), VCO2 (L per minute; ml per kg per minute), RQ, ventilation (L per minute)]. After awakening and post-prandial:
    • IC type: Face mask attached to a Douglas bag
    • Equipment of Calibration: Yes
    • Coefficient of variation using standard gases: Yes or No
    • Rest before measure (state length of time rested if available): Yes, overnight
    • Measurement length: Five minutes
    • Steady state: Five minutes of stabilization; tests for subjects heart rate to check state of repose
    • Fasting length: 14 hours
    • Exercise restrictions XX hour prior to test? Yes
    • Room temp: Varied 20oC and 25oC
    • Number of measures within the measurement period: One measure taken four times
    • Were some measures eliminated? No
    • Were a set of measurements averaged? No
    • Coefficient of variation in subjects measures? Not reported
    • Training of measurer? Not specified
    • Subject training of measuring process? Yes
    • Monitored heart rate? Yes
    • Body temperature? Yes
    • Medications administered? No
    • Height measured? Yes
    • Weight measured? Yes
    • Fat-free mass measured? Yes, by triceps skinfolds

Independent Variables

  • “Thermoneutral environment” : 20oC and 25oC as the lower and upper limits of temperature for the conventional BMR determination
  • Season: Winter or summer.

 


 

Description of Actual Data Sample:
  • Attrition (final N): N= 23 healthy males
  • Age: 20 to 29 years (mean 24.6±2.2)
  • Ethnicity: Japanese.

Anthropometrics

  Mean ±SD     Range
Weight, kg 64.7±7.6 51.2 to 81.2
Height, cm 170.5±4.9 159.8 to 181.8

Fat-free body mass, kg

 55.5±6.0 45.2 to 67.8
Fat, percent 14.1±2.9 9.3 to 20.6

There was no substantial weight gain or loss in any subject between separate occasions of measurements (P>0.05).

Location

University of Tokyo, Japan.

Summary of Results:

There were no statistical differences in outdoor temperatures between the two measurements at room temperatures at the same season. 

Indirect Calorimetry Results  

Pooled Data for Initial, Post-walk (Excluding the First Measure) and Post-prandial RMRs

 

  Initial RMR RMR, kcal per minute ±SE
Winter measures 20oC 1.025±0.082
  25oC 0.943±0.077
Summer measure 20oC 0.967±0.071
  25oC 0.969±0.059

Initial RMRs measured at room temperature of 20oC in winter were 6% to 9% greater than other initial RMR measures.

Pooled Data for Initial, Post-walk (Excluding the First Measure) and Post-prandial RMRs

 

 

Post-walk RMR (25 Minutes After Walk and Excluding the First Measure)

 RMR, kcal per minute ±SE
Winter measures 20oC                        1.090±0.075
  25oC                      1.013±0.075
Summer measure 20oC             1.032±0.064
  25oC 1.032±0.061

Post-walk RMRs measured at room temperature of 20 C in winter were 6% to 7% greater than other post-walk RMR measures.

Post-prandial RMR

Winter Measures 20oC 1.292±0.134
  25oC 1.193±0.089
Summer Measure 20oC 1.199±0.095
  25oC 1.197±0.097

Post-prandial RMRs measured at room temperature of 20oC in winter were 8% greater than other post-prandial RMR measures.

Summary

  • RMRs have an increasing tendency during the initial RMR measure in any season or temperature
  • Except for the first post-walk group mean RMR measured 25 minutes after the walk, mean RMR appears to be stabilized
  • The post-prandial mean RMRs showed a slight increase with time
  • The winter season RMR measured at 20oC were higher than the measures at 25oC winter season, 20oC  and 25oC summer season
  • A two-way ANOVA indicated both temperature condition and time course were statistically significant; i.e., RMRs at 20oC in winter were significantly greater by 6% to 9% than those at 25oC in the same season. These differences were commonly observed in the initial, post-absorptive and post-prandial RMRs.
  • Interaction between temperature condition and time course was not statistically significant throughout the other three measurement periods
  • According to three-way ANOVA, the effects of room temperature, season and time course were statistically significant. The effects of room temperature and of season on RMRs were independent of time course and interacted with each other. These results suggest that 20oC room temperature is not sufficient to determine definite RMR. At the lower room temperature, outdoor temperature is a possible factor that can affect RMRs. By contrast, RMRs at 25oC are minimally affected by outdoor temperature.
  • Results of Tukey’s range test indicated RMR measured at 20oC in winter was significantly greater than on the other three occasions (25oC winter, 20oC  and 25oC in summer) at any time of measurement.
Author Conclusion:
  • In our study, a total of four separate occasions of RMR determination under different room temperatures and outdoor temperatures indicate that RMRs determined at 20oC in winter are significantly greater by 6% to 9% than those determined at 25oC in winter, and those at 20oC and 25oC in summer
  • Our observations performed in winter indicated that there were significant differences in post-prandial RMRs for about two hours following breakfast. There is an elevation of post-prandial RMRs at the lower temperature. This important finding in the present investigation was that the differences in the RMRs between temperatures at 20oC and 24oC were observed only in measures performed in winter. No differences were observed in summer between the two levels of room temperature in any determination.
  • In our study, subjects came to the laboratory on foot or vehicles early morning on the day of the measure
  • Room temperature of 20oC is not enough to determine a constant fasting and post-prandial RMR
  • A three-way ANOVA of the present study indicates that the interaction effect on RMR between room temperature and season (outdoor temperature) is statistically significant, suggesting that both room temperature and outdoor temperature affect RMRs
  • Particularly important conditions, to which less attention has been paid, are those of clothing, outdoor temperature, room temperature and humidity.
Funding Source:
Government: Japanese Ministry of Education Science and Culture
University/Hospital: Universtiy of Tokyo
Reviewer Comments:

[Not used in Conclusion Statement Grade due to concerns regarding research design (i.e., baseline RMR may have been associated with non-shivering RMR increases before temperature changes)]

Strengths

  • Repeat measures and full description of outdoor and indoor temperatures
  • Complete description of IC measure
  • Appropriate statistics.

Generalizability/Weaknesses

  • Generalizable to lean, young adult Asian males
  • Study biases include self-selection bias due to volunteering; subjects were students who had taken a calorimetry course taught by the researcher, making them more motivated than the general public
  • An intervening variable not measured in subjects and limits generalizability is habitual diet; a 700kcal diet that only includes 17% fat is not typical of an American 700kcal diet; thus post-prandial RMR effects may be different 
  • These are important variables on REE measurement accuracy; steady state was defined but did not establish VO2 and VCO2 steady state conditions.
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
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  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? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
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? ???
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
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) Yes
  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? No
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  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? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? ???
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? Yes
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? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  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? Yes
  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? Yes
  10.2. Was the study free from apparent conflict of interest? Yes