EAL

DM: Physical Activity (2007)

Citation:

Study Design:

Class:

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Quality Rating:

Research Purpose:

The purpose of this study was to determine the ability of high intensity, low-volume progressive resistance training (PRT) to improve glycemic control and other metabolic abnormalities in a population of Latino older adults with poor glycemic control and no personal history of regular exercise.

Inclusion Criteria:

>55 years of age with type 2 diabetes of at least 3 years duration
diabetes diagnosis confirmed by a fasting plasma glucose of >7.0 mmol/L or use of diabetic medications

Exclusion Criteria:

myocardial infarction within the past 6 months
presence of any unstable chronic condition (including dementia, alcoholism, dialysis, retinal hemorrhage or detachment)
current participation in resistance training

Description of Study Protocol:

Recruitment Not specified

Design 16 week randomized controlled trial

Blinding used (if applicable) Not specified

Intervention (if applicable) Three times per week, subjects participated in a progressive resistance training (PRT) intervention for a 16 week period. Each intervention lasted 45 minutes, and consisted of a 5 minute warm up (6 chair stands and a 1 minute brisk walk), 35 minutes of PRT using pneumatic resistance training machines (chest and leg press, upper back, knee extension and flexion), and a 5 minute cool down (flexibilty and stretching exercises). The PRT intervention was designed to provide progressive increases in intensity with periodic weeks of reduced intensity.

The control group continued only with their usual care, and received phone calls every other week.

Statistical Analysis Baseline comparisons were assessed by independent sample t test or chi square as appropriate. ANCOVA was used to measure the effect of PRT on the absolute change in glycemic, metabolic, and other physiological variables after controlling for other factors. Group differences were assessed by the chi square test.

Data Collection Summary:

Timing of Measurements

Baseline and at 16 weeks post-intervention

Dependent Variables

Plasma glycosylated hemoglobin (HbA1c - GlycTest II Assay; Pierce Chemical; Rockford, IL)
Muscle glycogen stores (Hexokinase enzymatic and spectrophotometric analysis; Sigma; St. Louis, MO)
Plasma glucose (Hexokinase enzymatic method; Sigma)
Serum Cholesterol/Triglycerides (Cobra Mira Analyzer; Roche; Montclair NJ)
Body weight/height
Body composition (DEXA)
Waist Circumference
Physical Activity (Physical Activity Scale for the Elderly)
Muscle Strength (1RM for each exercise)
Dietary Intake (Modified FFQ)

Independent Variables

Progressive resistance training (PRT) intervention for a 16 week period or control group

Control Variables

Description of Actual Data Sample:

Initial N: 62 (40 females, 22 males)

Attrition (final N): 60, 29 in intervention group, 31 in control group

Age: 66±1 years (control group); 66±1 years (intervention group)

Ethnicity: Latino

Other relevant demographics: Insulin use: 17% in intervention group; 48% in control group; P=0.05

Anthropometrics: No significant differences in anthropometrics between groups

Location: Boston, MA

Summary of Results:

Biochemical and clinical parameters

Dependent Variable	PRT Group	Control Group	P-value for absolute change
HbA1c (%)
Baseline	8.7 ± 0.3	8.4 ± 0.3
Final	7.6 ± 0.2	8.3 ± 0.5	0.01
Muscle glycogen stores (mmol glucose/kg muscle)
Baseline	60.3 ± 3.9	61.4 ± 7.7
Final	79.1 ± 5.0	47.2 ± 6.7	0.04
Fasting plasma glucose (mmol/L)
Baseline	8.8 ± 0.5	9.7 ± 0.7
Final	7.9 ± 0.4	8.9 ± 0.7	0.34
Serum triglyceride concentrations (mmol/L)
Baseline (median)	1.52	1.45
Baseline (range)	0.56-6.60	0.35-5.27
Final (median)	1.31	1.56	0.08
Final (range)	0.43-3.59	0.32-4.77
Total cholesterol (mmol/L)
Baseline	4.97 ± 0.18	4.73 ± 0.18
Final	4.81 ± 0.16	4.70 ± 0.18	0.59
HDL cholesterol (mmol/L)
Baseline	1.18 ± 0.05	1.23 ± 0.07
Final	1.25 ± 0.06	1.24 ± 0.07	0.46
LDL cholesterol (mmol/L)
Baseline	2.94 ± 0.18	2.71 ± 0.15
Final	2.70 ± 0.13	3.05 ± 0.15	0.13
Systolic blood pressure (mmHg)
Baseline	145.2 ± 3.6	142.7 ± 4.1
Final	135.5 ± 3.3	150.4 ± 3.9	0.05
Diastolic blood pressure (mmHg)
Baseline	72.6 ± 1.1	71.1 ± 2.1
Final	69.2 ± 1.2	70.8 ± 1.4	0.52
Heart rate (beats/min)
Baseline	71 ± 3	72 ± 2
Final	72 ± 1	71 ± 3	0.74

Body composition and physical activity parameters

Dependent variable	PRT group	Control group	P-value for absolute change
Body weight (kg)
Baseline	79.3 ± 3.2	78.6 ± 3.1
Final	79.5 ± 3.3	79.4 ± 2.9	0.89
Whole body lean tissue mass (kg)
Baseline	44.3 ± 1.7	44.9 ± 1.9
Final	45.5 ± 1.9	44.8 ± 1.7	0.04
Arm lean tissue mass (kg)
Baseline	4.0 ± 4.2	4.1 ± 0.2
Final	4.4 ± 0.3	4.1 ± 0.2	0.08
Trunk lean tissue mass (kg)
Baseline	21.9 ± 0.8	22.3 ± 0.9
Final	22.4 ± 0.8	22.5 ± 0.9	0.08
Leg lean tissue mass (kg)
Baseline	12.9 ± 0.6	12.7 ± 0.6
Final	13.1 ± 0.6	12.8 ± 0.5	0.07
Whole body fat mass (kg)
Baseline	35.0 ± 2.2	33.7 ± 2.4
Final	34.0 2.3	34.6 ± 2.2	0.26
Arm fat mass (kg)
Baseline	4.6 ± 0.4	4.5 ± 0.4
Final	4.7 ± 0.4	4.6 ± 0.3	0.69
Trunk fat mass (kg)
Baseline	18.8 ± 1.1	18.2 ± 1.3
Final	18.1 ± 1.2	19.0 ± 1.1	0.01
Leg fat mass (kg)
Baseline	10.6 ± 0.8	9.4 ± 0.7
Final	10.8 ± 0.9	9.4 ± 0.7	0.41
Waist circumference (cm)
Baseline	99.7 ± 2.3	100.1 ± 2.6
Final	97.5 ± 2.3	102.0 ± 2.2	0.07
Leisure physical activity score
Baseline	8.4 ± 1.9	12.8 ± 2.9
Final	28.3 ± 0.9	7.2 ± 2.8	0.001
Household physical activity score
Baseline	37.2 ± 4.8	32.4 ± 4.5
Final	56.6 ± 5.8	26.2 ± 4.1	0.001

Author Conclusion:

This study demonstrates for the first time that high intensity PRT is effective in the maangement of diabetes in this high-risk population of Latino older adults with poor glycemic control.

Appropriately prescribed and supervised high intensity resistance training proved both feasibile and effective among high-risk older adults with type 2 diabetes, resulting in improved glycemic and metabolic control.

Funding Source:

Reviewer Comments:

All subject characteristics were similar with the exception of insulin use. The authors state that the improvements seen in glycemic control with the intervention were independent of insulin use, suggesting that resistance training may be beneficial as an adjunct to standard care in this population.

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?	???
	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?		No
	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.)	???
	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?	N/A
	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