EAL

EE: Rest Period Duration (2013)

Citation:

Turley KR, McBride PJ, Wilmore JH. Resting metabolic rate measured after subjects spent the night at home vs. at a clinic. Am J Clin Nutr. 1993; 58 (2): 141-144.

PubMed ID: 8338039

Study Design:

Randomized Crossover Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

To determine whether there is a difference in RMR values between subjects who spend the evening in a clinical setting and subjects who spend the evening before measurements at home.

Inclusion Criteria:

Understand and give written consent
Healthy volunteers.

Exclusion Criteria:

Refusal to consent
Not meeting inclusion criteria.

Steady state: For the three clinical and three home measures, a VO₂ within ±25mL per minute was applied.

Description of Study Protocol:

Recruitment

Procedures not described

Design Randomized crossover trial

Blinding used

Not applicable

Intervention

Not applicable

Statistical Analysis

The average VO₂ for each RMR test was used in the statistical analysis
Analysis of variance using a repeated-measure, two-witin design with a Student's T-test applied to determine significance was used to analyze mean VO₂, V_E, RER, HR and energy expenditure (in kJ per hour, kJ· kg body weight^-1· h^-1, and kJ· kg FFM^-1· h^-1.

Data Collection Summary:

Timing of measurements

Six randomized RMR measurements: Three measurements were made after subjects slept the evening before the measurements in their home (H1, H2, H3) and three after they slept in a clinical setting (C1, C2, C3)
All six of each subject's RMR measurements were conducted within a four-week time period.

Dependent variables

Difference in RMR measurements (VO₂, V_E, kJ per hour, RER)
- IC type: metabolic cart-model 2900
- Equipment of Calibration: Yes
- Coefficient of variation using standard gases: Yes
- Rest before measure (state length of time rested if available): Yes, equal to seven hours of sleep
- Measurement length: 30 minutes
- Room temp: 22
- Steady state? YES, stringent; Used a criterion of repeated measurements of VO₂ within ±25mL per minute was applied; If this standard was not met subjects were asked to return for an additional RMR measurement under those same conditions; N=4 subjects failed to meet the std within their six tests
- Fasting length: 12 hours
- Exercise restrictions XX hours prior to test? Yes, 24 hours
- Room temperature: 22 C
- Number of measures within the measurement period: Not specified
- Were some measures eliminated? Yes; if VO₂ data point that was not within ±30mL per minute of the mean VO₂ for that trial was discarded to eliminate any erroneous values
- Were a set of measurements averaged? Yes
- Coefficient of variation in subjects measures? YES, stringent; Used a criterion of repeated measurements of VO₂ within ±25mL per minute was applied; If this standard was not met subjects were asked to return for an additional RMR measurement under those same conditions; N=4 subjects failed to meet the std within their six tests
- Training of measurer? Yes
- Subject training of measuring process? Yes
- Dietary: Standardize the meal each night before the measurement
- Clinical: HR.

Independent variables

Home measurements (H) vs. Clinic measurements (C)
- Home measurements: Measurement made after subject spent previous night at home and drove to laboratory
- Clinic measurements: Measurement made after subjects spent previous night at the clinic.

Description of Actual Data Sample:

Initial N: Not given
Final N: N=10
- Four males
- Six females
Age: Mean=26.1 years
Ethnicity: Not specified
Other relevant demographics: None reported
Anthropometrics:

	Mean±SD
Height, cm	170.9±9.6
VO₂ Max, mL/kg per minute	53.2±8.2
Fat, percent	14.6±3.4
Weight (1) Night before first RMR	66.4±15.6
Weight (2) (Weight after third RMR)	66.6±15.4
Weight (3) (Weight after sixth RMR)	66.6±15.4

Location: University of Texas at Austin.

Summary of Results:

There were no significant differences (P<0.05) in oxygen consumption (VO₂, mL per minute), RMR, or respiratory exchange ratio (RER) between any of the six RMR measurements, or between the mean values for the three home trials vs. the three clinical trials (i.e., 4.4kJ per minute ±0.83 (1.05kcal per minute ±0.20) vs. 4.4kJ per minute ±0.92 (1.05kcal per minute ±0.22)
There were no significant differences in RMR measurements whether expresses as kJ per minute, kJ/kg body weight/height or kJ/g fat-free mass per hour (P<0.05)
The mean VO₂ values for the six trials were highly intercorrelated with a mean correlation of r=0.95 (P<0.01) and values ranging from r=0.90 to 0.97
There was a correlation of r=0.99 (SEE=2.1) when FFM was compared with RMR, expressed as VO₂ in liters per minute.

Author Conclusion:

“RMR measured after the subjects transported themselves to the testing facility the morning of the RMR measurement was not different from RMR measured when the subjects spent the night in the facility where the RMR was measured.”

“Having subjects spend the night in a clinical setting is expensive, requires special facilities, and requires a more substantial amount of time for both the researcher and the subject than does RMR measurements conducted when the subjects transport themselves to the testing site the morning of the assessment. Therefore, it is recommended that the following criteria be met before RMR is measured:

No formal exercise for the 24-hour period immediately before the RMR measurement begins
A 12-hour fasting before testing, with the measurement made in the early morning
Repeated measurements with defined limits of acceptable test (e.g., VO₂±25mL per minute)
HR monitoring for the eight- to 10-hour period before measurement
Rest with the face mask or ventilated hood in place for 30 minutes before the actual measurement period begins.”

Funding Source:

Government:

NIH

Reviewer Comments:

Strengths

Detailed measurement protocol with heart rate monitoring that increases subject compliance with pre-measurement conditions.

Generalizability/Weaknesses

Results are limited to healthy adults. Whether or not the same recommendations still hold true in ill patients are not known
Small gender representation
RMR measures taken in a semi-recumbent position; unable to determine if applied to supine position.
Questionable validity of indirect calorimeter

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?		???
	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)	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.)	Yes
	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?		???
	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%.)	???
	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?	N/A
	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?		???
	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?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	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?	Yes
	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?	Yes
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