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EE: Physical Activity (2013-2014)

Citation:

Frankenfield DC, Coleman A. Recovery to resting metabolic state after walking. J Am Diet Assoc. 2009; 109: 1,914-1,916.

PubMed ID: 19857634
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To determine the mean and individual time required to recover to a resting state after a walk of 300 meters. 
Inclusion Criteria:
  • Ambulatory
  • 18 years of age or older
  • Able to tolerate an overnight fast
  • Provided written informed consent.
Exclusion Criteria:
Not described.
Description of Study Protocol:

Recruitment

  • Volunteers were recruited by posting flyers within the institution (a hospital and medical school) and by referral from weight management clinics
  • Time period of recruitment was January 2007 to November 2008
  • Participants were not compensated.

Design

Randomized controlled trial. In a random manner, some participants were studied in reverse order to account for the potential effect of measurement sequence on the results (i.e., the participant walked first, then was measured for 30 minutes, the canopy removed for a minute, then replaced and the resting measurement was conducted for 30 minutes; in this configuration, the post-walk measurement also served as the 30-minute rest period).

Blinding Used

Implied with measurements.

Intervention

Each participant’s metabolic rate was measured with indirect calorimetry for 30 minutes after a 30-minute rest. The participant then walked 300 meters on a measured course, and metabolic rate was measured again for 30 minutes. Recovery to rest was considered to have occurred when the measured metabolic rate returned to a level of less than 6% above the resting measurement.

Statistical Analysis

  • The mean of each five-minute block of metabolic rate in the post-walk period was compared with mean resting metabolic rate using one-way analysis of variance and Dunnett's method for comparison of multiple means (family error rate 0.25 based on 95% confidence intervals)
  • The pre-walk resting metabolic rate and post-walk metabolic rate were tested for normality using the Anderson-Darling test statistic with a significance level of 0.05
  • X2 was used to analyze categorical data and correlation methods were used to determine whether there was a relation between any of the variables and the length of time to re-establish resting conditions in the post-walk phase
  • Minitab Release 14.2 was used for all data analysis.
Data Collection Summary:

Timing of Measurements

  • All measurements made on the day of testing
  • Time period of recruitment was January 2007 to November 2008.

Dependent Variables

  • Energy expenditure was measured using a Sensormedics Deltatrac Metabolic Monitor. Warm-up and calibration instructions from the manufacturer were followed. The indirect calorimetry methodology followed the evidence-based procedure described by the EAL. A 30-minute measurement period was used in all cases. The first five minutes of data were recorded but were not used to compute resting metabolic rate. The coefficient of variation for oxygen consumption and carbon dioxide production for the
    remaining 25 minutes had to be 10% or less. If this threshold was not met, a smaller five-minute segment was accepted if coefficients of variation were within 5% and the participant was observed to be quiet and unmoving. The discard and coefficient rules were not applied to the post-walk measurement. During the test, the researcher used a subjective 10-point scale to record the degree to which the subject remained still during the measurement (one completely still, 10 sustained movement of arms or legs).
  • Pre-study requirements included a 12-hour overnight fast (water was allowed); avoidance of vigorous physical activity over the same time; and no caffeine, ethanol, or nicotine after awakening on the morning of the test. Participants spent the night in their homes. Normal activities of dressing, bathing, driving to the hospital, and walking from their vehicle to the test site were allowed.
  • The mean resting metabolic rate of the pre-walk period was used as the baseline against which post-walk comparisons were made. The 30 minutes of post-walk data were divided into five-minute segments.

Independent Variables

  • Measurement was divided into four phases:
    • 30-minute rest in a supine position without moving
    • Indirect calorimetry measurement using a ventilated hood system for 30 minutes
    • 300-meter walk conducted indoors, climate-controlled on a flat surface observed and timed by the investigator
    • Repeat indirect calorimetry immediately after completing the walk. 
  • Recovery to rest was considered to have occurred when the measured metabolic rate returned to a level of less than 6% above the resting measurement.

Control Variables

  • Habitual exercise status was recorded
    • One: Fewer than three times per week
    • Two: Three to five times per week
    • Three: More than five times per week.
  • Height and weight were measured upon arrival to the testing site.
Description of Actual Data Sample:
  • Initial N: 40 subjects
  • Attrition (final N): 40 (75% female, 25% male)
  • Age: Mean age 41±13 years (range, 18 to 70 years)
  • Other relevant demographics: Exercise frequency of fewer than three times per week was more common in obese participants than in non-obese participants (71% vs. 38%, X2=4.3, P=0.037)
  • Anthropometrics: 40% were obese (BMI more than 30kg/m2)
  • Location: Pennsylvania.
Summary of Results:

Key Findings

  • Analysis of variance indicated that after a 300-meter walk, resting level of metabolic rate was achieved by the 10th minute of rest. However, it took 20 minutes for 95% of all participants to meet the 6% threshold (the remaining 5% who did not reach the threshold were observed to be moving during the measurement).
  • The time it took to walk the 300 meters was longer for the obese (250±25 seconds) than the non-obese participants (225±23 seconds) (P=0.007)
  • Walk time was not correlated with exercise frequency (R=-0.23, P=0.172)
  • Recovery time was not associated with walk time (R=0.107, P=0.524) or with exercise frequency (R=0.047, P=0.769)
  • The mean pre-walk metabolic rate measured during the discard period was not statistically significantly different from the remaining 25-minute resting period (1,713kcal±357kcal per day vs. 1,613kcal+317kcal per day, P=0.190). This was a mean difference of 6%, but individual differences were as high as 249kcal, which was 13% more than the resting value.
  • The discard period exceeded 10% of the resting value in 22% of individuals.
  • Analysis of variance indicated that metabolic rate in the first five minutes after walking was significantly higher than resting metabolic rate, but in each subsequent period metabolic rate was not significantly different from resting
  • On the other hand, on an individual basis, it took 15 minutes for 93% of the subjects to return
    to rest, and 20 minutes for 95% of the subjects to return to rest. One subject had not returned to rest by
    30 minutes. The two subjects that did not return to rest within 20 minutes were observed to be moving during the post-walk measurement period despite instruction not to do so. Recovery time was directly correlated with the degree of movement recorded subjectively by the researcher at the time of the study (R=0.49, P=0.001).
Author Conclusion:
Resting conditions can be restored after 20 minutes if the patient does not move. This amount is the upper range suggested by the ADA expert panel on indirect calorimetry, and this finding should pinpoint and improve the strength of the conclusion of that group. The standard practice of discarding the first five minutes of measurement is confirmed in this study. The discard period should be in addition to the 20-minute rest recovery.

 
Funding Source:
Other: No Funding Disclosed
Reviewer Comments:
  • The main limitation of this study is the 6% threshold used for defining recovery to rest. The literature offers no clear direction for setting such a threshold.
  • Another potential limitation in the data is the fact that elderly people are under-represented. Only three people who were at least 60 years old were measured and the oldest person measured was 70 years old.
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? ???
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? Yes
  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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  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? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
  3. Were study groups comparable? N/A
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? 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
  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
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? 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
  5.4. 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
  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. 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
  6.1. 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
  6.2. 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
  6.3. 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
  6.4. 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? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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
  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? Yes
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  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
  7.2. 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
  7.3. 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? Yes
  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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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
  8.5. 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
  8.6. 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? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
  9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes