DM: Physical Activity (2007)
- 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
- 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.
Recruitment: subjects who completed a previous study (Dunstan et al, 2002) were followed for an additional 6 months
Design
- two-phase 12-month randomized controlled trial with repeated measurements at 3-month intervals
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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
- Phase 1 (gymnasium-based)
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
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
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
HbA1c
- 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.
Variables |
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 |
-0.8±2.2 |
-0.7±2.1 |
-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 |
1.6±45.6 |
-16.5±47.2* |
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), % |
-0.6±5.4 |
4.0±6.1* |
-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)
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.
Quality Criteria Checklist: Primary Research
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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 | |