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MNT: Weight Management (2015)

Citation:

Nagashima J, Musha H, Takada H, Takagi K, Mochida T, Yoshihisa T, Imagawa Y, Matsumoto N, Ishige N, Fujimaki R, Nakajima H, Murayama M. Three-month exercise and weight loss program improves heart rate recovery in obese persons along with cardiopulmonary function. Journal of Cardiology. 2010; 56: 79-84.

PubMed ID: 20378312
 
Study Design:
Before-After Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To investigate whether heart rate recovery after exercise was mainly improved by better cardiopulmonary function or by alteration of the metabolic profile.

Inclusion Criteria:
  • Obese persons without a history of stroke, cardiovascular events or use of medications
  • BMI above 25kg/m2 or percent body fat greater than 25% for men and 30% for women.
Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Recruitment methods are not described. The full quota of program was 30 individuals and the program was held twice per year.

Design

Before-and-after study.

Blinding Used

Implied with measurements.

Intervention

  • The weight loss program included two hours of group exercise per week and individual dietary instruction by a qualified dietitian every week
  • All subjects were instructed by a dietitian to reduce their daily intake to 25kcal per kg of IBW, and daily calorie intake was calculated from a questionnaire based on the DRI for Japanese (2005)
  • The weekly exercise program was 60 minutes of group aerobics and four strength-training exercises (abdominal crunch, prone arm leg extension, push ups and squats) with three sets of 30 repetitions of each exercise being done under a trainer's supervision
  • All subjects were advised to perform 30 minutes of walking at least five times per week.

Statistical Analysis

  • All parameters were compared between before and after the weight loss program by using paired T-tests
  • Correlations of heart rate recovery with each parameter were examined by univariate and multivariate regression analysis.
Data Collection Summary:

Timing of Measurements

Clinical assessment was done before and after the three-month program.

Dependent Variables

  • Body weight and percentage of body fat examined through body composition analyzer
  • BMI was calculated
  • Subcutaneous fat area and visceral fat area were measured manually by tracing on magnetic resonance images
  • Fasting blood levels of HDL-cholesterol, LDL-cholesterol, triglycerides, glucose, insulin, leptin and HbA1c were measured through standard laboratory methods
  • Homeostasis model assessment of insulin resistance was performed by using Matthew's equation
  • Symptom-limited maximal graded exercise testing was done on an electronic bicycle ergometer using a ramp protocol
  • Electrocardiograms were recorded
  • Systolic blood pressure and diastolic blood pressures measured before, during and after exercise testing.

Independent Variables

The weight loss program included two hours of group exercise per week and individual dietary instruction by a qualified dietitian every week.
Description of Actual Data Sample:
  • Initial N: N=130 obese subjects
  • Attrition (final N):  N=125 obese subjects (14 males, 111 females); five dropped out due to orthopedic problems
  • Age: Aged 22 years to 71 years; mean age 53.1±11.4 years
  • Ethnicity: Assumed Japanese
  • Location: Japan.

 

Summary of Results:

Key Findings

  • Heart rate recovery was significantly faster after the program (35.61±12.83 to 45.34±13.6 beats per minute, P<0.0001)
  • The change in heart rate recovery was significantly correlated with the changes in body weight, BMI, percent body fat, waist circumference, hip circumference, resting heart rate, peak exercise heart rate, exercise time, maximal workload and physical working capacity divided by body weight (PWC75%HRmax/weight), subcutaneous fat area, visceral fat area, LDL-cholesterol and leptin (all P<0.05)
  • Multivariate analysis showed that the change in heart rate recovery was significantly correlated with the changes in resting heart rate, peak exercise heart rate and PWC75%HRmax/weight (all P<0.05).

Physical and Biochemical Characteristics of the Subjects Before and After the Program
 

Variables Before After P-Value
Weight (kg) 70.9±11.4 66.0±10.9 P<0.05
BMI (kg/m2) 28.3±3.5 26.3±3.4 P<0.05
Fat percentage 38.0±6.2 34.0±6.6 P<0.05
Waist circumference (cm) 99.2±9.0 93.2±9.3 P<0.05
Hip circumference (cm) 101.0±6.5 97.5±6.0 P<0.05
Systolic blood pressure (mm Hg) 133.5±20.5 124.0±19.2 P<0.05
Diastolic blood pressure (mm Hg) 82.5±13.0 75.8±12.6 P<0.05
Resting heart rate (beats per minute) 85.6±14.7 76.3±13.1 P<0.05
Peak exercise heart rate (beats per minute) 149.0±16.9 150.0±16.0 NS
Exercise time (minutes) 7.2±1.8 7.9±1.7 P<0.05
Maximal workload (W) 127.7±34.6 139.5±36.1 P<0.05
PWC75%HRmax/weight (W per kg) 1.2±0.4 1.5±0.4 P<0.05
Heart rate recovery at two minutes 37.4±12.8 46.3±13.5 P<0.05
Subcutaneous fat area (cm2) 310.6±85.3 255.7±83.4 P<0.05
Visceral fat area (cm2) 123.7±51.9 94.5±46.4 P<0.05
HDL-cholesterol (mg per dL) 53.4±11.5 52.9±10.8 NS
LDL-cholesterol (mg per dL) 129.2±27.7 114.1±24.6 P<0.05
Triglycerides (mg per dL) 130.4±82.2 93.3±55.9 P<0.05
Fasting glucose (mg per dL) 104.9±15.1 98.0±9.4 P<0.05
Fasting insulin (mcgU per ml) 10.8±7.8 7.4±5.7 P<0.05
HbA1C (percentage) 5.4±0.5 5.2±0.3 P<0.05
Leptin (ng per ml) 14.4±6.9 7.3±4.3 P<0.05
Insulin resistance (HOMA-IR) 14.4±6.9 1.8±1.5 P<0.05

 

 

Author Conclusion:

Our data demonstrate that heart rate recovery can be improved in obese subjects by a three-month exercise and weight loss program. Improvement in cardiopulmonary function by exercise seems to be the main contributor to improvement in heart rate recovery.

Funding Source:
Other: no information provided
Reviewer Comments:
  • Recruitment methods were not described. The program was offered twice a year; all subjects not completing the program concurrently
  • Authors note the following limitations:
    • Relatively small number of subjects
    • Lack of evaluation of other adipose tissue-related factors
    • Used PWC75%HRmax/weight as the marker of cardiopulmonary function and a substitute for peak VO2 because of limited time available for testing
    • No control group; it is therefore not possible to decide whether the observed changes were attributable to the program or were natural changes.
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? 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
  3.3. 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? 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? 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
  5.1. 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
  5.3. 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? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  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? 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? ???
  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? ???
  7.7. Were the measurements conducted consistently across groups? N/A
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)? ???
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? ???