PDM: Metabolic Syndrome (2013)

Citation:

Yassine HN, Marchetti CM, Krishnan RK, Vrobel TR, Gonzalez F, Kirwan JP. Effects on exercise and caloric restriction on insulin resistance and cardiometabolic risk factors in older obese adults: A randomized clinical trial. J Gerontol A Biol Sci Med Sci. 2009; 64: 90-95.

PubMed ID: 19164269
 
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 examine the effect of exercise alone or exercise combined with moderate caloric restriction on major cardiovascular disease risk factors, notably the criterion that defines the metabolic syndrome. To test if the combined intervention has an added benefit over exercise alone in older obese men and women.

Inclusion Criteria:

Older participants who were:

  • Weight stable (less than 2kg weight change in the previous six months)
  • Sedentary (less than 20 minutes of exercise twice per week)
  • Obese (BMI 30 to 40kg/m2)
  • Not taking blood pressure or diabetes medications
  • Women were post-menopausal for more than one year and had not been on hormone replacement therapy for at least one year prior to enrollment.
Exclusion Criteria:
  • Evidence of overt type 1 diabetes mellitus or treated type 2 diabetes mellitus
  • Acute or chronic disease (cardiovascular, cerebrovascular, liver, renal, hematological, thyroid or cancer)
  • Smoking
  • Medications affecting metabolism.
Description of Study Protocol:

Recruitment

Did not state how participants were recruited.

Design

Randomized clinical trial. Participants randomly assigned to exercise alone or exercise combined with a 500kcal reduction in energy intake. Intervention lasted 12 weeks. 

Blinding Used

Implied with measurements.

Intervention

  • Exercise alone: 50 to 60 minutes per day, five days per week for 12 weeks. Exercise consisted of walking on a treadmill and pedaling a cycle ergometer, with more than 75% of their effort spend on the treadmill. Initial sessions performed at between 60% to 65% maximum heart rate and gradually increased to 80% to 85% maximum heart rate.
  • Exercise and calorie restriction: Same exercise regimen and calorie reduction of 500kcal per day. Energy intake estimated using the Harris Benedict equation and activity factor of 1.3.

Statistical Analysis

  • Student's T-test used to evaluate baseline differences between groups
  • Two-way time-by-group repeated measures analysis of variance was used to assess changes in variables from baseline to end of intervention
  • Relationship between the dependent and independent variables was based on univariate correlation analysis using the differences before and after the intervention
  • Multiple regression analysis used to evaluate the independent effects of fitness and insulin sensitivity on measured risk factors.
Data Collection Summary:

Timing of Measurements

Baseline and after intervention (after 12 weeks).

Dependent Variables

  • Body weight was measured once each week to monitor compliance
  • Measures of insulin sensitivity: Euglycemic hyperinsulinemic clamps and an oral glucose tolerance test, fasting glucose, fasting insulin
  • Body composition: Hydrostatic weighing to determine body density. Computed axial tomography used to measure the distribution of cross-sectional abdominal fat depots (total abdominal, visceral and subcutaneous)
  • Waist circumference
  • Lipid profiles
  • Blood pressure
  • Aerobic fitness: VO2max.

Independent Variables

  • Exercise alone or combined with 500kcal reduction
  • Participants completed two three-day food records before the intervention and again during weeks one, three, six, nine and 12 to assess compliance to caloric intake.
Description of Actual Data Sample:
  • Initial N: 24 participants (nine males, 15 females)
  • Attrition (final N): 24 participants
  • Age: 65.5±5.0 years
  • Anthropometrics: No between-group differences as baseline for exercise capacity, caloric intake, body composition, blood pressure, insulin resistance or lipids
  • Location: Cleveland, OH.
Summary of Results:

Key Findings

 Variables

Exercise Group (N=12) 

Pre-intervention

Exercise Group 

Post-intervention

 Exercise + Calorie Restriction (N=12)

Pre-intervention

Exercise + Calorie Restriction 

Post-intervention 

Significant Within Group P-value  Significant Between-group P-value 
Weight (kg)  99.7±15.7  95.9±14.6  94.9±16.5  88.0±14.5  <0.001  0.02 
BMI (kg/m2)  35.3±5.8 34.0±5.8  33.7±4.7  31.3±4.3  <0.001  0.01 
Fat mass (kg)  41.6±11.3  37.1±11.4  37.6±9.8  31.6±8.7  <0.001   
Waist circumference (cm) 118.3±12.7  112.7±11.9  113.6±12.7  107.1±11.7  <0.001   
Visceral fat (cm2) 192.3±104.3  158.4±87.0  236.8±71.6  197.0±73.6  <0.001   
Subcutaneous fat (cm2 383.4±106.4  347.8±94.2  426.7±121.7  360.4±130.3  <0.001  0.03 
Systolic blood pressure (mm Hg 135.6±11.2  121.1±11.2  134.2±11.6  119.7±8.1  <0.001   
Diastolic blood pressure (mm Hg)  81.6±11.2  71.6±9.6  81.3±4.1  72.2±5.1  <0.001   
Fasting insulin (pmol per L) 107.9±48.8  84.6±26.5  108.4±30.8  79.2±20.8  <0.001   
Glucose disposal rate (mg per kg, FFM per minute)  5.0±1.9  6.4±1.8  4.2±1.8  6.6±2.9  <0.001   
Glucose infusion rate (mg per kg, FFM per minute)  2.2±0.9  3.1±1.3  1.5±0.7  2.6±1.2  <0.001   
Oral glucose tolerance test (OGTT 28.0±30.3  16.5±19.2  29.4±15.9  16.7±18.7  <0.001   
Triglycerides (mg per dL) 169.2±62.5  134.1±37.5  171.1±52.6  117.0±48.2  <0.001   
Cholesterol (mg per dL)  180.7±37.2  161.7±32.6  181.2±24.0  157.1±27.6  <0.001   
VO2max (L per minute)  2.0±0.5  2.3±0.6  2.0±0.5  2.2±0.5  <0.001   

Other Findings

  • Participants in the exercise and calorie restriction group consumed fewer calories (1,303±210kcal per day) than those in the exercise group (2,141±1,338kcal per day) (P<0.05)
  • From the criteria that make up the metabolic syndrome, systolic blood pressure and glucose correlated with visceral fat, HDLs correlated with aerobic capacity and waist circumference correlated with body weight and subcutaneous fat
  • The best predictor of change in insulin resistance was the change in body weight and visceral fat.
Author Conclusion:

Exercise alone is an effective non-pharmacological treatment strategy for insulin resistance, metabolic syndrome and cardiovascular disease risk factors in older obese adults. The addition of a diet-based weight loss program to the exercise intervention did not lead to greater improvements in older obese adults.

Funding Source:
Government: National Institutes of Health
Not-for-profit
Diabetes Association of Greater Cleveland
Other non-profit:
Reviewer Comments:
  • Small sample size and recruitment methods not described.
  • Did not mention ethnicity.
  • Although obese, participants were relatively healthy to begin with (not on blood pressure or diabetes medications, cholesterol within normal range, fasting glucose normal at baseline, and so on).
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? ???
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  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? ???
3. Were study groups comparable? ???
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) 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? ???
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  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? 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? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  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? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? ???
  6.6. Were extra or unplanned treatments described? ???
  6.6. Were extra or unplanned treatments described? ???
  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? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  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