DM: Physical Activity (2007)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine whether improvements in glycemic control and body composition, resulting from 6 months of supervised high-intensity progressive resistance training, could be maintained after an additional 6 months of home-based resistance training.
Inclusion Criteria:
  • subjects completed 6-month participation in a study conducted immediately previous to this study (Dunstan et al, 2002).  The original study had these inclusion criteria:
    • diagnosis of type 2 diabetes > 6 months duration with HbA1c of 7-10 %
    • BMI>27 and < or equal to 40
    • sedentary (less than 150 minutes of brisk walking or moderate exercise per week and less than 60 minutes of vigorous exercise per week)
    • not taking insulin
    • non-smoker
Exclusion Criteria:
  • from previous study
    • ischemic disease
    • uncontrolled hypertension
    • systemic diseases
    • advanced diabetic retinopathy or neuropathy
    • severe orthopedic, cardiovascular, or respiratory conditions that would preclude participation in an exercise program or with a medical condition listed as an absolute contraindication for exercise according to the American College of Sports Medicine.
Description of Study Protocol:

Recruitment: subjects who completed a previous study (Dunstan et al, 2002) were followed for an additional 6 months


  • two-phase 12-month randomized controlled trial with repeated measurements at 3-month intervals
  • Two phases:

    • Phase 1 (gymnasium-based)
      • 6 months of supervised training, reported in Dunstan et al 2002
    • Phase 2 (home-based)
      • additional 6 months of training in the home setting  

Blinding used (if applicable):  not applicable

Intervention (if applicable)

Phase 2 intervention

  • after 6 months of supervised training in the gym, each participant was provided with individualized instructions, training, and equipment to perform resistance training (RT) or light flexibility training (WL)
  • RT subjects performed their home-based routine at the gym during the last 4 weeks of Phase 1.
  • RT plan was designed for 3 sets of 8-10 repetitions with the goal to exercise at an intensity corresponding to 60-80% of the current one-repetition maximum (1RM)
  • the WL group member were given wall charts showing stretching exercises and asked to do the exercises at home
  • participants were telephoned weekly for he first 4 weeks and every 2 weeks after that to monitor compliance, answer questions, and provide individualized feedback

  • subjects were not asked to continue with the healthy eating plan during this phase

Statistical Analysis

  • independent Student's t-tests used for between-group comparisons at baseline
  • net between-group differences were calculated by subtracting the within-group changes from baseline for the WL group from the within-group changes for the RT group for each time point.
  • time, group, and interaction effects during the 12-month period were examined using pooled time series regression analysis for longitudinal data with random effects models.
  • fasting plasma insulin levels and HOMA values were log tansformed to yield a normal distribution before parametric analysis
Data Collection Summary:

Timing of Measurements every 3 months

Dependent Variables

  • HbA1c, plasma glucose, serum insulin, insulin sensitivity (HOMA)
  • height, weight, waist circumference
  • habitual physical activity, 1RM
  • total body fat and LBM assessed by dual-energy X-ray absorptiometery

Independent Variables

  • home-based resistance training
  • participants were asked to complete exercise diaries and were required to report to the gym once each month so that technique and progress could be monitored

Control Variables


Description of Actual Data Sample:

Initial N: 21 men and 15 women; total 36

Attrition (final N): 33; 2 lost from RT group and 1 from WL group

Age: 60-80 years

Ethnicity: not specified

Other relevant demographics

Anthropometrics no significant differences between groups

Location: Australia


Summary of Results:


  • The groups began Phase 2 with statistically significant differences in HbA1c, with the lower values in the RT group. 
  • At 9 and 12 months both groups had significant increases in HbA1c (P<0.05) from 6 months.
  • At 9 and 12 months the difference in HbA1c between groups was no longer significant.


RT Group

9-month change from baseline

WL  group

9-month change from baseline

Net difference (95% CI)

RT Group 12-month change from baseline WT group 12-month change from baseline Net difference (95% CI)

Fasting Plasma Glucose, mmol/l



-0.1(-1.7 to 1.5)

0.3±2.2  -0.5±2.1  0.8(-0.8 to 2.4) 

Fasting serum insulin, pmol/l



18.1(-16.0 to 52.1) 

-0.1±46.8  -19.3±50.1*   19.2(-16.3 to 54.7)

insulin sensitivity (HOMA), %



-4.7(-8.9 to -0.5) 

0.04±5.5  5.4±6.5*   -5.4(-9.8 to -1.0)
waist circumference, cm  -6.9±4.7* -6.1±4.3*  -0.8(-4.1 to 2.5)  -3.4±4.7* -2.0±4.3  -1.4(-4.8 to 1.8) 
upper body muscle strength, kg  26.3±22.8* -2.5±19.1  28.8(12.0-45.2)**  26.4±22.8*  -0.2±19.1  26.6(9.6-42.9)** 
lower body muscle strength, kg  7.1±6.1* 0.7±5.4  6.4(2.1-10.6)**  4.9±6.4*  -0.1±5.4  5.0(0.5-9.3)** 
energy expenditure, kcal/day  -65±195 -187±244*   122(-38 to 281)  -132±195* -192±244*  60(-99 to 220) 
total energy intake, kcal/day  -208±573 -166±399  -42(-426 to 329) -262±532§   -229±401§  -33(-389 to 342)

 Net difference refers to the within-group change from baseline in the RT group minus the within-group change from baseline in the WL group.

*P< 0.05 for within-group differences from baseline

**P< 0.05 for between-group differences from baseline

§ significant from baseline

Other Findings

Body weight at 12 months remained significantly lower than baseline for both groups.

The significant between-group difference in lean body mass observed after the gym-based training tended to be maintained through home-based training (group-by-time interaction; P=0.08) 

The between-group difference in body weight at 6 months were maintained at 9 and 12 months.

Both groups experienced a significant decrease in adherence during home-based training (P<0.05)

Author Conclusion:

The home-based resistance training maintenance program was well tolerated by older adults with type 2 diabetes but did not maintain improvements in glycemic control seen after supervised resistance training.

Home-based training was effective for maintaining improvements in muscle strength and LBM.

The apparent ineffectiveness of home-based training to maintain improvements in glycemic control was most likely due to a reduction in adherence  and exercise training volume and intensity during the home-based training.

Funding Source:
Reviewer Comments:
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) No
  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? 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? 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? N/A
  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? No
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