PDM: Prediabetes (2013)
Black LE, Swan PD, Alvar BA. Effects of intensity and volume on insulin sensitivity during acute bouts of resistance training. J Strength Cond Res. 2010; 24(4): 1,109-1,116.PubMed ID: 20093961
To measure the acute effects of two different resistance exercise intensities (moderate vs. high) under two different volumes (single set or multiple set) on 24-hour insulin sensitivity in individuals with impaired fasting glucose.
- Impaired fasting glucose (100 to 125mg per dL)
- Little to no strength training experience.
- Fasting blood glucose less than 100g per dL or greater than 125mg per dL
- History of smoking, cardiovascular disease, renal or liver disease
- Taking hypoglycemic or hypertensive medication
- Any conditions that would be contraindicated for exercise.
Participants were recruited from the Phoenix metropolitan area.
Participants were used as their own controls in a randomized, 2 x 2 factorial analysis of variance (ANOVA) crossover design.
Implied with measurements.
- The participants had two orientation days and four exercise testing days over a total of four to five weeks
- Two different resistance exercise intensities (moderate, 65% one repetition maximum [1RM] vs. high, 85% 1RM) under two different volumes (single set or multiple set)
- On each exercise testing day, after blood samples were drawn, participants consumed a pre-exercise meal of a bagel and 6oz of orange juice 20 minutes before the resistance exercise portion of the session
- Participants performed one of four randomly selected resistance exercise protocols each testing day lasting between 30 and 55 minutes
- 24 hours after the exercise session, participants returned for a second fasting blood draw.
Normality of variables was assessed by the Shapiro-Wilkes test. Differences of pre-exercise insulin sensitivity were compared with 24-hour post-exercise within subjects and between treatments using a 2 x 2 factorial ANOVA. Statistical analyses were performed using SPSS 15.0 for Windows (Chicago, IL).
Timing of Measurements
Participants participated in a maximum of two exercise sessions per week for consecutive weeks until all four protocols had been completed. A minimum washout of 72 hours was used between test days to prevent a carryover effect from previous testing. All resistance exercise sessions were conducted in a climate-controlled setting in a weightlifting laboratory.
- Anthropometrics: Height (cm) and weight (kg) were determined at baseline to calculate body mass index (BMI), weight was taken on a calibrated digital scale and height was measured using a wall-mounted stadiometer
- Body composition assessment: Fat mass, lean mass and body density were measured using whole body air displacement
- Blood glucose and insulin sensitivity: Venous blood samples were taken from antecubital vein in the morning between 6 a.m. and 9 a.m., insulin sensitivity was calculated from the homeostasis model of assessment HOMA-IR.
Two different resistance exercise intensities (moderate, 65% one repetition maximum [1RM] vs. high, 85% 1RM) under two different volumes (single set or multiple set).
- Initial N: 17 (12 males and five females)
- Attrition (final N): 15
- Age: 18 to 45 years old
- Anthropometrics: No differences in age or body mass index were found between sexes at baseline
- Location: Phoenix, AZ.
- There were no significant differences in baseline fasting glucose levels between males and females across each of the four exercise protocols (P=0.804)
- All of the exercise protocols improved subsequent insulin sensitivity (P=0.002) and glucose (P=0.001)
- There was significantly greater decrease in glucose (P=0.021) 24 hours after multiple set bouts
- High intensity showed significant decreases in insulin sensitivity as compared with moderate intensity protocols (P=0.046)
- High intensity protocols resulted in greater effect sizes for insulin sensitivity (0.83 multiple set, 0.53 single set) as compared with moderate intensity protocols
- The high intensity, multiple set bout yielded the greatest treatment effect in both fasting glucose (0.61) and insulin sensitivity (0.83)
- Overall, single set protocols were less effective than multiple set protocols in lowering fasting blood glucose.
The authors concluded the data suggest a dose-response relationship between volume and intensity on insulin sensitivity and fasting blood glucose.
|University/Hospital:||Arizona State University, Chandler-Gilbert Community College|
- Small sample size
- Sample was not well described.
Quality Criteria Checklist: Primary Research
|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|
|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?||Yes|
|2.2.||Were criteria applied equally to all study groups?||Yes|
|2.3.||Were health, demographics, and other characteristics of subjects described?||???|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||???|
|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)||Yes|
|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?||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?||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?||Yes|
|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)?||Yes|
|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?||Yes|
|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|