EAL

PDM: Metabolic Syndrome (2013)

Citation:

Pescatello LS, Blanchard BE, Van Heest JL, Maresh CM, Gordish-Dressman H, Thompson PD. The metabolic syndrome and the immediate antihypertensive effects of aerobic exercise: a randomized control design. BMC Cardiovasc Disord. 2008; 8: 12.

PubMed ID: 18544158

Study Design:

Randomized Controlled Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

POSITIVE: See Quality Criteria Checklist below.

Research Purpose:

To examine the influence of the metabolic syndrome on the blood pressure response following a session of low (light, 40% peak oxygen consumption, VO₂ peak) and moderate (moderate, 60% VO₂ peak) intensity, aerobic exercise among men with pre- to Stage I hypertension.

Inclusion Criteria:

Pre- to Stage 1 hypertension (systolic BP 130 or more and less than 160mm Hg and diastolic BP (DBP) 85 or more and less than 100mm Hg)
Based upon the National Cholesterol Education Program criteria, 39.1% of these men presented with metabolic syndrome
Physically inactive
No physical limitations that would prevent exercise and did not smoke
Provided written informed consent.

Exclusion Criteria:

SBP 160mm Hg or more
DBP 100mm Hg or more
Symptomatic atherosclerosis
CVD
Diabetes mellitus
Asthma
Thyroid dysfunction
Pancreatitis
Acute illness
Anti-depressant medication use.

Description of Study Protocol:

Recruitment

Subjects were men who volunteered for the study.

Design

Randomized controlled trial.

Blinding Used

Implied with measurements.

Intervention

Subjects consumed a standard meal and two hours later completed one of three randomized experiments separated by 48 hours
The experiments were a non-exercise control session of seated rest and two cycle bouts:
- Light (40% VO₂peak)
- Moderate (60% VO₂peak).

Statistical Analysis

Three by two-way repeated measures ANCOVA with HOMA as a covariate determined if BP, insulin and glucose differed over time among experimental conditions (non-exercise control, light, moderate) among men without and with metabolic syndrome
Significant interaction effects were found between BP and men without metabolic syndrome
In order to determine between group differences, two by two-way repeated measures ANCOVA determined if BP, insulin and glucose differed over time among exercise (light or moderate) and non-exercise control among men without and with metabolic syndrome
Multi-variate regression analyses were performed to examine what factors correlated with the BP change from baseline following exercise compared to non-exercise control over nine hours
All statistical analyses were done with the Statistical Package for Social Sciences Base for Windows with P<0.05 established as the level of statistical significance.

Data Collection Summary:

Timing of Measurements

Subjects completed three 40-minute experiments in random order on three separate days that were at least 48 hours apart to avoid acute exercise effects on BP.

Dependent Variables

Blood pressure response:
- BP was measured by auscultation during the experiments and over the course of nine hours after the experiments and over the course of nine hours after the experiments using the Accutracker II automatic non-invasive ambulatory BP monitor
- The average attachment time was 12:30 p.m. and the monitor was worn until waking the next morning
- The monitor was programmed to record BP and heart rate every 20 minutes
- BP and heart rate were taken three times an hour until 11:00 p.m.
- Subjects left the laboratory with instructions to proceed with their typical activities not to participate in formal exercise for the remainder of the day, to leave their arm still when the monitor was recording and to return the monitor the following day
Fasting blood samples were drawn into EDTA tubes for insulin, glucose and lipid-lipoprotein determinations
Blood samples were also obtained two hours after the standard meal for glucose and insulin determinations at the end of the baseline period at 30 minutes of each 40-minute experiment and at 15 and 45 minutes after the experimental sessions while subjects were still in the laboratory but prior to attachment to the ambulatory BP monitor
Body weights were obtained prior to the graded cardiopulmonary exercise test and of the three experiments to ensure weight maintenance.

Independent Variables

Subjects consumed a standard meal and two hours later completed one of three randomized experiments
The three experiments consisted of two exercise bouts on a cycle ergometer at 40% VO₂ peak and 60% VO₂ peak for 30 minutes and a 40-minute non-exercise control session of seated rest.

Description of Actual Data Sample:

Initial N: 46 men, 18 with metabolic syndrome, 28 without metabolic syndrome
Attrition (final N): 46 men
Age: Mean age 44.3±1.3 years
Ethnicity: Caucasian
Anthropometrics: Mean body mass index (kg/m²) 29.5±0.7
Location: Connecticut.

Summary of Results:

Key Findings

Weight was maintained throughout the experiments
Glucose levels decreased from baseline after exercise compared to non-exercise control during all experiments among men without and with metabolic syndrome (P< 0.05)
However, there was no significant difference in the glucose response from baseline during exercise compared to non-exercise control between groups
Systolic blood pressure (SBP) was reduced 8mm Hg (P<0.05) and diastolic BP (DBP) 5mm Hg (P=0.052) after light compared to non-exercise control over nine hours among men without vs. men with metabolic syndrome
BP was not different after moderate vs. non-exercise control between metabolic syndrome groups (P≥0.05)
The post-exercise blood pressure response from baseline was not significantly different after low and moderate intensity exercise vs. the non-exercise control among men with metabolic syndrome
The factors accounting for 17% of the SBP response after light were baseline SBP (B= -0.351, R²=0.123, P=0.020), metabolic syndrome (B=0.277, R²=0.077, P=0.069) and HOMA (B=-0.124, R²=0.015, P=0.424)
Metabolic syndrome (R²=0.096, P=0.036) was the only significant correlation of the DBP response after light.

Author Conclusion:

Men without metabolic syndrome appear to respond more favorably to the immediate anti-hypertensive effects of lower intensity, aerobic exercise than men with metabolic syndrome. Considering the public health burden of hypertension and metabolic syndrome and the importance of exercise in their prevention, treatment and control, results from such studies could yield important new knowledge for the personalization of exercise prescriptions among those with hypertension and metabolic syndrome.

Funding Source:

University/Hospital:

Department of Kinesiology, University of Connecticut, Storrs, CT

Reviewer Comments:

Limitations

Post-prandial plasma insulin and glucose assessments were measured only in the laboratory and not under ambulatory conditions in an attempt to minimize experimental intrusions that could affect the BP measurements and for reasons of subject convenience.

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?		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
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
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?	Yes
	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?		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
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	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
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	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
	5.4.	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?	N/A
	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?	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
	6.8.	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
	7.1.	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?	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
	7.7.	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)?	No
	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