EAL

DM: Physical Activity (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine the effect of high-intensity progressive resistance training combined with moderate weight loss on glycemic control and body composition in older patients with type 2 diabetes.

Inclusion Criteria:

age 60-80
treated 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:

ischemic disease
uncontrolled hypertension
systemic diseases
advanced diabetic neuropathy or retinopathy
severe orthopedic, cardiovascular or respiratory conditions that would preclude praticipation 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 were recruited from the International Diabetes Institute and by a media campaign.

Design 6-month RCT with subjects randomly assigned to either a high-intensity progressive resistance training plus moderate weight loss group (RT & WL) or a moderate weight loss group plus control program (flexibility exercises) (WL).

Blinding used (if applicable): subjects not blinded to treatment

Intervention (if applicable)

4-week baseline period
- healthy eating plan: 30% fat
- designed to elicit weight loss of 0.25 kg/wk
intervention period
- healthy eating plan continued
- exercise intervention
  - subjects attended exercise laboratory on 3 non-consecutive days per week
  - routine included 45 minutes of high-intensity resistance training (dynamic exercise involving concentric and eccentric contractions).
  - resistance was set at 50-60% of 1-RM for 2 weeks and then goal was to increase to 75-85%. 1-RM defined as the maximum amount of resistance that could be moved through the full range of motion of an exercise for no more than one repetition.
  - exercises used free weights and multiple station weight machine and included: bench press, leg extension, upright row, lateral pull-down, standing leg curl, dumbbell seated shoulded press, dumbbell seated biceps curl, dumbbell tripep kickback, and abdominal curls; 3 sets of 8-10 repetitions. 1-RM testing repeated every 12 weeks to establish new baselines
  - control exercise program (WL) was designed not to change muscle strength or cardiovascular fitness and involved 30 minutes of static stretching

Statistical Analysis

Independent t tests were used to assess between-group comparisons at baseline. Net differences at 3 and 6 months were calculated by subtracting the within-group changes from baseline for the WL group from the within-group changes for the RT & WL group. Time, group and interaction effects were examined using a two-way ANOVA or ANCOVA with repeated measures on one factor (time). Fasting plasma insulin levels were log transformed to yield a normal distribution before parametric analysis.

Data Collection Summary:

Timing of Measurements: 0, 3, and 6 months

Dependent Variables

body mass, using SECA electronic scale
waist circumference
fat mass, and lean body mass measured by dual-energy, X-ray absorptiometry using a DPX-L densitometer
muscle strength, according to 1-RM
blood pressure
energy expenditure
fasting plasma glucose
HbA1c
fasting plasma glucose, fasting plasma insulin, and insulin sensitivity (HOMA)
serum lipids

Independent Variables

nutrient intake, from 2 3-day food records obtained at 3 and 6 months and analyzed using Foodworks nutrient analysis software program
dietary compliance assessed through interviews with dietitian every 2 weeks
habitual physical activity was estimated using a 7-day physical activity recall questionnaire; the resistance training of the RT & WL group was not included

Control Variables

Description of Actual Data Sample:

Initial N: 36

Attrition (final N): 29; 84% of RT & WL group and 76% of WL group completed the study

Age: 67.6±5.2 years

Ethnicity: not specified

Other relevant demographics:

Anthropometrics: no difference in groups on baseline characteristics

Location: Australia

Summary of Results:

Adherence to the exercise sessions averaged 88% for the RT & WL group and 85% for the WL group.

6-month change from baseline in all outcomes

Variables	RT & WL Group	WL Group (control)	Net Difference (95% CI)
Fasting Plasma glucose, mmol/l	-1.4±2.7	-0.6±2.4	-0.8 (-2.8 to 1.2)
Fasting serum insulin, pmol/l	10.5±46.3	-4.7±27.2	15.2(-14.7 to 45.1)
Insulin sensitivity, HOMA (%)	0.03±5.2	0.8±6.5	-0.8(-5.2 to 3.7)
HbA1c, %	-1.2±1.0*	-0.4±0.8	-0.8 (-1.5 to -0.1)*
total cholesterol, mmol/l	-0.09±0.8	-0.5±0.8	0.4 (-0.3 to 1.1)
HDL, mmol/l	0.06±0.1	0.07±0.2	-0.01(-0.1 to 0.1)
LDL, mmol/l	-0.06±0.7	-0.5±0.9	0.4 (-0.2 to 1.0)
triglycerides, mmol/l	-0.2±0.7	-0.08±0.6	-0.1 (-0.7 to 0.4)
Body mass, kg	-2.5±2.9	-3.1±2.1	0.6 (-1.3 to 2.6)
waist circumference, cm	-6.9±5.7*	-6.7±6.1*	-0.2 (-4.8 to4.2)
Fat mass, kg	-2.4±2.8*	-2.1±2.5*	0.3(-2.4 to 1.8)
LBM, kg	0.5±1.2	-0.4±1.0	0.9(0.05-1.8)⁺⁺
upper body muscle strength, % change	43.2±34.2*	1.5±17.7	41.7 (14.4 to 69.0)⁺⁺
lower body muscle strength, % change	33.0±21.7*	5.0±16.9	28.0(9.1 to 46.9)⁺⁺
systolic blood pressure, mmHg	-6.7±10.0**	-2.5±15.8	-4.2 (-14.1 to 69.0)
diastolic blood pressure, mmHg	-4.4±6.9**	-0.9±10.1	-3.5 (-10.0 to 3.0)
energy expenditure, kcal/day	-97±204	-55±253	-42 (-216 to 131)
total energy intake, kcal/day	-281±418**	-391±251*	110 (-193 to 413)

*P<0.01

**P< 0.05 within-group differences from baseline

⁺⁺P<0.05 between-group difference from baseline

Other Findings

Author Conclusion:

The results of this study demonstrate that a 6-month supervised high-intensity resistance training program was safe and well tolerated by older patients with type 2 diabetes.

When compared with moderate weight loss, resistance training was more effective for improving HbA1c than moderate weight loss without resistance training and this observation could not be explained by differences in body weight, waist circumference and fat mass changes during the intervention.

The addition of resistance training conributed to the preservation of LBM durinng moderate weight loss.

These findings provide strong support for the recommendation of this form of exercise in the management of glycemic control of older patients with type 2 diabetes.

Funding Source:

Reviewer Comments:

The method of randomization was not noted.

The overall dropout rate was 19% but intent-to-treat analysis was not performed, so the results cannot be generalized to those unable to complete the program.

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?	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?	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