The objective of this meta-analysis is to summarize the effect of exercise intervention on flow-mediated dilatation (FMD) in overweight and obese adults. We searched four electronic databases (PubMed/Medline, Scopus, and CINAHL) through June 2016 for relevant studies pertaining to the effectiveness of exercise intervention on FMD. Seventeen of the 91 studies identified met the inclusion criteria. Comprehensive Meta-Analysis software (version 3) was used to compute the standardized mean difference effect size (ES) and 95% CI using a random effects model. We calculated 34 ESs. We found that exercise intervention had medium and positive effects on FMD, with an overall ES of 0.522 (95% CI = 0.257, 0.786). Heterogeneity of ESs was observed (
Obesity, a chronic metabolic disorder, is strongly associated with morbidity and mortality as well as a reduced life expectancy [
The vascular endothelium, which is a single layer of cells lining the interior surface of blood vessels, plays a key role in vasomotor regulation mainly through the nitric oxide- (NO-) dependent signaling pathways [
Endothelial dysfunction is commonly evaluated by flow-mediated dilatation (FMD) in human studies. The FMD is a noninvasive clinical tool that measures shear stress-mediated vasodilatory response and depends on NO bioavailability [
Although a recent meta-analysis demonstrated the beneficial effect of exercise training on FMD in both obese and nonobese adults [
To address the inconclusive findings, we conducted a meta-analysis to quantitatively evaluate the relationship between exercise training and EF in overweight and obese adults. We compared the effects of different characteristics of exercise interventions and participants’ demographics on FMD.
Source of data was identified by keyword searched from four electronic databases: the PubMed/Medline, Scopus, and CINAHL. The keywords used to identify the relevant studies were “obesity”, “overweight”, “exercise”, “training”, “flow mediated dilatation”, “flow mediated dilation”, and “FMD”. Additional potential sources were identified by hand search using personal databases and a reference list of published studies.
The studies were included in the review if sufficient information was reported that allowed us to compute the standardized mean difference of FMD. Specific inclusion criteria for eligible studies were the study (1) included the value of relative FMD; (2) included exercise intervention at least 7 days; (3) considered only overweight and/or obese adults; and (4) is written in English language and published in peer-reviewed journals through June 2016. Furthermore, studies were excluded if they were purposefully designed for examining the effects of weight loss medication, antiandrogens, fertility treatments, glucocorticoids, or oral contraceptives.
The two authors (YS, SJ) independently coded the identified studies using extraction sheets. The characteristics of the studies were coded for descriptive purposes and moderator analyses. Based on the procedures recommended by Lipsey and Wilson (2005), the outcome and moderator variables were extracted. The effect size (ES) of outcome variable, FMD, was computed using (a) before and after mean difference from intervention groups divided by pooled standard deviation (SD) and (b) mean difference between intervention and control groups divided by pooled SD. Also, moderator variables which may affect overall ES of FMD were coded as follows: body weight change, diet intervention, exercise duration/type/intensity, comorbidity, and baseline Body Mass Index (BMI). Exercise intensity and type were classified as low, moderate, and high intensity using the definition of the American College of Sports Medicine [
All coded data were crosschecked with authors for establishing consistency, and discrepancies were resolved by discussion. Figure
Flowchart for selection of studies.
The methodological quality of selected studies was assessed using the Physiotherapy Evidence Database (PEDro) scale [
All analyses were run in Comprehensive Meta-Analysis version-3 software with a significance level of 0.05. Because we assumed that the variety of research designs with study characteristics might affect the true ES from one study to another, a random effects model was used to estimate the overall ES and 95% confidence intervals (CIs). The measure of ES used for the present study is the standardized mean difference, Cohen’s
Figure
The funnel plot examination showed that the publication bias had little influence on our result. The studies included in the present meta-analysis were symmetrically distributed around the mean ES. The Duval and Tweedie’s trim and fill method also predicted no missing study to this meta-analysis. However, the regression intercept (3.37) from Egger’s test results was statistically significant (
The characteristics of these studies are shown in Table
Baseline characteristics of the included studies.
Author and year | County | Subject characteristics of treatment group | Subject characteristics of control group | Smoker | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sample size | Gender | Age | Health status | BMI |
|
Sample size | Gender | Age | Health status | BMI |
|
|||
Ades et al. (2011) a [ |
USA | 23 | Both | 66 | Coronary heart disease | 32 | −8 | Not included | ||||||
Ades et al. (2011) b [ |
USA | 15 | Both | 62 | Coronary heart disease | 33 | −2 | Not included | ||||||
Baynard et al. (2009) a [ |
USA | 10 | Both | 52 | Metabolic syndrome | 34 | 0 | Not included | ||||||
Baynard et al. (2009) b [ |
USA | 10 | Both | 52 | Metabolic syndrome | 34 | 0 | Not included | ||||||
Baynard et al. (2009) c [ |
USA | 11 | Both | 53 | Healthy | 33 | 0 | Not included | ||||||
Baynard et al. (2009) d [ |
USA | 11 | Both | 53 | Healthy | 33 | 0 | Not included | ||||||
Bhutani et al. (2013) a [ |
USA | 18 | Both | 45 | Healthy | 35 | −6 | 25 | Both | 42 | Healthy | 35 | −3 | Not included |
Bhutani et al. (2013) b [ |
USA | 24 | Both | 42 | Healthy | 35 | −1 | 16 | Both | 49 | Healthy | 35 | 0 | Not included |
Blumenthal et al. (2010) [ |
USA | 49 | Both | 52 | HTN | 34 | −9 | 46 | Both | 52 | HTN | 33 | 0 | Included |
Choo et al. (2014) a [ |
South of Korea | 39 | Female | 42 | Healthy | 29 | −2 | Included | ||||||
Choo et al. (2014) b [ |
South of Korea | 39 | Female | 42 | Healthy | 29 | −2 | Included | ||||||
Choo et al. (2014) c [ |
South of Korea | 39 | Female | 42 | Healthy | 29 | −2 | Included | ||||||
Choo et al. (2014) d [ |
South of Korea | 26 | Female | 46 | Healthy | 28 | −2 | Included | ||||||
Choo et al. (2014) e [ |
South of Korea | 26 | Female | 46 | Healthy | 28 | −2 | Included | ||||||
Choo et al. (2014) f [ |
South of Korea | 26 | Female | 46 | Healthy | 28 | −1 | Included | ||||||
Choo et al. (2014) g [ |
South of Korea | 27 | Female | 42 | Healthy | 29 | −1 | Included | ||||||
Choo et al. (2014) h [ |
South of Korea | 27 | Female | 42 | Healthy | 29 | −1 | Included | ||||||
Choo et al. (2014) i [ |
South of Korea | 27 | Female | 42 | Healthy | 29 | −1 | Included | ||||||
Cotie et al. (2014) [ |
Canada | 20 | Female | 30 | Healthy | 32 | −6 | NR | ||||||
Davison et al. (2008) a [ |
Australia | 13 | Both | 45 | Healthy | 34 | 1 | 11 | Both | 44 | Healthy | 35 | 2 | |
Davison et al. (2008) b [ |
Australia | 13 | Both | 46 | Healthy | 33 | 1 | 12 | Both | 45 | Healthy | 33 | −2 | |
Fayh et al. (2013) [ |
Brazil | 17 | Both | 31 | Healthy | 35 | −4 | 18 | Both | 32 | Healthy | 35 | −5 | Not included |
Franklin et al. (2015) [ |
USA | 10 | Female | 30 | Healthy | 34 | −1 | 8 | Female | 31 | Healthy | 32 | 0 | Not included |
Hamdy et al. (2003) [ |
USA | 24 | Both | 49 | Insulin resistance syndrome | 37 | −7 | Not included | ||||||
Kwon et al. (2011) a [ |
South of Korea | 13 | Female | 56 | Type 2 diabetes | 27 | −2 | 15 | Female | 59 | Type 2 Diabetes | 27 | −1 | NR |
Kwon et al. (2011) b [ |
South of Korea | 12 | Female | 56 | Type 2 diabetes | 27 | −1 | 15 | Female | 59 | Type 2 Diabetes | 27 | −1 | NR |
Olson et al. (2006) [ |
USA | 15 | Female | 38 | Healthy | 28 | 2 | 15 | Female | 38 | Healthy | 28 | 0 | Not included |
Pugh et al. (2014) [ |
UK | 13 | Both | 50 | Nonalcoholic fatty liver disease | 30 | −2 | 8 | Both | 47 | Healthy | 30 | −1 | |
Robinson et al. (2016) [ |
USA | 10 | Both | 34 | Healthy | 32 | −3 | 9 | Both | 28 | 33 | 0 | Not included | |
Swift et al. (2012) a [ |
USA | 68 | Female | 57 | Elevated BP | 32 | −1 | 23 | Female | 57 | Elevated BP | 32 | −1 | |
Swift et al. (2012) b [ |
USA | 32 | Female | 56 | Elevated BP | 33 | −1 | 23 | Female | 57 | Elevated BP | 32 | −1 | |
Swift et al. (2012) c [ |
USA | 32 | Female | 56 | Elevated BP | 31 | −1 | 23 | Female | 57 | Elevated BP | 32 | −1 | |
Vinet et al. (2011) [ |
France | 10 | Male | 51 | Healthy | 33 | −2 | Not included | ||||||
Wycherley et al. (2008) [ |
Australia | 13 | Both | 52 | Type 2 diabetes | 34 | −8 | 16 | Both | 53 | Type 2 Diabetes | 35 | −9 |
Characteristics of intervention of the included studies.
Author and year | Exercise intervention | Additional diet intervention | ||||
---|---|---|---|---|---|---|
Type | Duration (weeks) | Frequency of sessions (per week) | Duration of session (min) | Intensity | ||
Ades et al. (2011) a [ |
Aerobic | 16 | 1–3 | 40–60 | Low (high-caloric-expenditure) | Yes |
Ades et al. (2011) b [ |
Aerobic | 16 | 1–3 | 25–40 | Higher (lower-caloric-expenditure) | Yes |
Baynard et al. (2009) a [ |
Aerobic | 10 days | 6 | 60 | 70–75% of VO2 peak | No |
Baynard et al. (2009) b [ |
Aerobic | 10 days | 6 | 60 | 70–75% of VO2 peak | No |
Baynard et al. (2009) c [ |
Aerobic | 10 days | 6 | 60 | 70–75% of VO2 peak | No |
Baynard et al. (2009) d [ |
Aerobic | 10 days | 6 | 60 | 70–75% of VO2 peak | No |
Bhutani et al. (2013) a [ |
Aerobic | 12 | 3 | 24–40 | 60–75% of HRmax | Yes |
Bhutani et al. (2013) b [ |
Aerobic | 12 | 3 | 24–40 | 60–75% of HRmax | No |
Blumenthal et al. (2010) [ |
Aerobic | 16 | 3 | 45 | 70–85% of HRR | Yes |
Choo et al. (2014) a [ |
Aerobic | 12 | 3 | 60 | 50–70% of HRR | Yes |
Choo et al. (2014) b [ |
Aerobic | 24 | 3 | 60 | 50–70% of HRR | Yes |
Choo et al. (2014) c [ |
Aerobic | 38 | 3 | 60 | 50–70% of HRR | Yes |
Choo et al. (2014) d [ |
Resistance | 12 | 3 | 60 | 40–60% of MS | Yes |
Choo et al. (2014) e [ |
Resistance | 24 | 3 | 60 | 40–60% of MS | Yes |
Choo et al. (2014) f [ |
Resistance | 38 | 3 | 60 | 40–60% of MS | Yes |
Choo et al. (2014) g [ |
Combined | 12 | 3 | 60 (30 + 30) | 50–70% of HRR |
Yes |
Choo et al. (2014) h [ |
Combined | 24 | 3 | 60 (30 + 30) | 50–70% of HRR |
Yes |
Choo et al. (2014) i [ |
Combined | 38 | 3 | 60 (30 + 30) | 50–70% of HRR |
Yes |
Cotie et al. (2014) [ |
Combined | 16 | 7 | Expend 250 kal/day | 70%/3 set 10 rep | Yes |
Davison et al. (2008) a [ |
Aerobic | 12 | At least 1 | 45 | 75% of HRmax | Yes |
Davison et al. (2008) b [ |
Aerobic | 12 | At least 1 | 45 | 75% of HRmax | Yes |
Fayh et al. (2013) [ |
Aerobic | 10 | 3 | 45 | 70% of HRmax | Yes |
Franklin et al. (2015) [ |
Circuit-based RT | 8 | 2 | 80–90% of 10 RM | No | |
Hamdy et al. (2003) [ |
Aerobic | 24 | 3 | 30 | 60–80% of HRmax | Yes |
Kwon et al. (2011) a [ |
Aerobic | 12 | 5 | 60 | Moderate (3.6–6 METs) | No |
Kwon et al. (2011) b [ |
Resistance | 12 | 5 | 60 | Bands provide 1.2–3.2 kg of resistance | No |
Olson et al. (2006) [ |
Resistance | 1 year | At least 2 | 3 sets 8–10 repetitions | No | |
Pugh et al. (2014) [ |
Aerobic | 12 | 5 | 45 | 60% of HRR | Yes |
Robinson et al. (2016) [ |
Aerobic | 8 | 3 | 30–45 | 75% of HRmax | No |
Swift et al. (2012) a [ |
Aerobic | 24 | 3-4 | Expend 4 kcal/kg | 50% of VO2 peak | No |
Swift et al. (2012) b [ |
Aerobic | 24 | 3-4 | Expend 8 kcal/kg | 50% of VO2 peak | No |
Swift et al. (2012) c [ |
Aerobic | 24 | 3-4 | Expend 12 kcal/kg | 50% of VO2 peak | No |
Vinet et al. (2011) [ |
Aerobic | 8 | 3 | 45 | LIPOXmaxHR |
No |
Wycherley et al. (2008) [ |
Aerobic | 12 | 4-5 | 50–60 | 60–80% of HRmax | Yes |
FMD protocol and outcomes.
Author anB3:H25 | Timing of measurement | Placed cuff | Treatment group | Control group | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Preintervention | Postintervention | Preintervention | Postintervention | |||||||
mean | SD | mean | SD | mean | SD | mean | SD | |||
Ades et al. (2011) a [ |
Fast | Brachial artery | 2.9 | 3.6 | 6.5 | 3.5 | ||||
Ades et al. (2011) b [ |
Fast | Brachial artery | 3.6 | 4.1 | 4.9 | 3.8 | ||||
Baynard et al. (2009) a [ |
Overnight fast | Brachial artery | 8 | 1.5 | 7.5 | 1.2 | ||||
Baynard et al. (2009) b [ |
0.5–1 h ingestion | Brachial artery | 6 | 1.1 | 6.3 | 1.1 | ||||
Baynard et al. (2009) c [ |
Overnight fast | Brachial artery | 10.4 | 1.1 | 10.2 | 0.9 | ||||
Baynard et al. (2009) d [ |
0.5–1 h ingestion | Brachial artery | 9.8 | 0.8 | 8.5 | 0.8 | ||||
Bhutani et al. (2013) a [ |
NR | Brachial artery | 3.8 | 1.2 | 6.4 | 0.8 | 4.8 | 1.2 | 9.7 | 1.8 |
Bhutani et al. (2013) b [ |
NR | Brachial artery | 6.8 | 1.3 | 7.2 | 1.4 | 7 | 3.3 | 6.3 | 3 |
Blumenthal et al. (2010) [ |
Overnight fast | Brachial artery | 4 |
1 | 3.8 |
1 | ||||
Choo et al. (2014) a [ |
Overnight fast | Brachial artery | 11.28 | 3.5 | 11.55 | 3.8 | ||||
Choo et al. (2014) b [ |
Overnight fast | Brachial artery | 11.28 | 3.5 | 11.08 | 4.05 | ||||
Choo et al. (2014) c [ |
Overnight fast | Brachial artery | 11.28 | 3.5 | 10.7 | 3.75 | ||||
Choo et al. (2014) d [ |
Overnight fast | Brachial artery | 10.32 | 3.8 | 11.22 | 4.43 | ||||
Choo et al. (2014) e [ |
Overnight fast | Brachial artery | 10.32 | 3.8 | 10.89 | 4.33 | ||||
Choo et al. (2014) f [ |
Overnight fast | Brachial artery | 10.32 | 3.8 | 11.54 | 4.99 | ||||
Choo et al. (2014) g [ |
Overnight fast | Brachial artery | 11.02 | 3.49 | 11.1 | 3.4 | ||||
Choo et al. (2014) h [ |
Overnight fast | Brachial artery | 11.02 | 3.49 | 12.41 | 4.27 | ||||
Choo et al. (2014) i [ |
Overnight fast | Brachial artery | 11.02 | 3.49 | 11.3 | 4.04 | ||||
Cotie et al. (2014) [ |
NR | Brachial artery | 4 | 0.5 | 6.9 | 0.6 | ||||
Davison et al. (2008) a [ |
NR | Brachial artery | 5.37 | 0.68 | −0.4 |
0.77 |
3.65 | 1.4 | −0.3 |
0.53 |
Davison et al. (2008) b [ |
NR | Brachial artery | 4.05 | 0.51 | 1.5 |
0.68 |
4.12 | 0.75 | 1.8 |
0.89 |
Fayh et al. (2013) [ |
Overnight fast | Brachial artery | 8.1 | 3.6 | 10.7 | 3.6 | 9.9 | 3.4 | 10.1 | 5.8 |
Franklin et al. (2015) [ |
NR | Brachial artery | 9.5 | 1.6 | 9.8 | 1.6 | 8.4 | 3.5 | 8 | 3.3 |
Hamdy et al. (2003) [ |
NR | Brachial artery | 7.9 | 1 | 12.9 | 1.2 | ||||
Kwon et al. (2011) a [ |
10 h fast | Brachial artery | 4.3 | 1.6 | 6.4 | 1.9 | 4.7 | 1.9 | 4 | 1.9 |
Kwon et al. (2011) b [ |
10 h fast | Brachial artery | 4.9 | 2.5 | 5.6 | 2.8 | 4.7 | 1.9 | 4 | 1.9 |
Olson et al. (2006) [ |
Overnight fast | Brachial artery | 6.3 | 0.2 | 6.2 | 0.1 | 6.3 | 0.2 | 6 | 0.1 |
Pugh et al. (2014) [ |
NR | Brachial artery | 4.79 | 8.57 | (2.24–4.71) |
5.94 | 5.32 | (−1.72–1.46) |
||
3.47 |
−0.13 |
|||||||||
Robinson et al. (2016) [ |
NR | Brachial artery | 8.6 | 4.8 | 7.7 | 2.79 | 9.3 | 4.2 | 9.3 | 4.1 |
Swift et al. (2012) a [ |
Fast | Brachial artery | 4 | 2.6 | 1 |
(0.29–1.76) |
4.7 | 2.4 | −0.5 |
(−1.79–0.74) |
Swift et al. (2012) b [ |
Fast | Brachial artery | 4.4 | 2.4 | 1.5 |
(0.48–2.62) |
4.7 | 2.4 | −0.5 |
(−1.79–0.74) |
Swift et al. (2012) c [ |
Fast | Brachial artery | 3.7 | 2.6 | 1.2 |
(0.1–2.24) |
4.7 | 2.4 | −0.5 |
(−1.79–0.74) |
Vinet et al. (2011) [ |
Overnight fast | Brachial artery | 2.7 | 0.4 | 4.8 | 0.5 | ||||
Wycherley et al. (2008) [ |
Fast | Brachial artery | 4.2 | 1.2 | −0.52 |
1.06 |
2.5 | 0.9 | 0.03 |
0.26 |
Quality score by the PEDro scale was
Methodological scores by Physiotherapy Evidence Database (PEDro) scale.
Studies | PEDro criterion | Total score | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | ||
Ades et al. (2011) [ |
1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 9 |
Baynard et al. (2009) [ |
1 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 6 |
Bhutani et al. (2013) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 7 |
Blumenthal et al. (2010) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 8 |
Choo et al. (2014) [ |
1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 9 |
Cotie et al. (2014) [ |
0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 5 |
Davison et al. (2008) [ |
1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 9 |
Fayh et al. (2013) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 7 |
Franklin et al. (2015) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 8 |
Hamdy et al. (2003) [ |
1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 5 |
Kwon et al. (2011) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 8 |
Olson et al. (2006) [ |
1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 9 |
Pugh et al. (2014) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 7 |
Robinson et al. (2016) [ |
1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 5 |
Swift et al. (2012) [ |
1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 8 |
Vinet et al. (2011) [ |
1 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 5 |
Wycherley et al. (2008) [ |
1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 8 |
|
||||||||||||
|
16 | 12 | 12 | 17 | 3 | 0 | 4 | 9 | 17 | 16 | 17 |
The overall mean ES was 0.522 (95% CI = 0.257, 0.786) and statistically significant. This quantitative synthesis yielded a medium and positive ES using a random effect model. This indicates that exercise training is effective in improving FMD in overweight and obese adults. There was observed to be heterogeneous (
Forest plot illustrating effect of exercise intervention on FMD.
The moderator analyses were performed to examine the effect of body weight change, diet intervention, exercise modality, comorbidity, and baseline BMI. The results demonstrated that only comorbidity status explained the heterogeneity of ESs (
Subgroup analysis.
Moderator variable |
|
ES | 95% CI |
| |
---|---|---|---|---|---|
Lower | Upper | ||||
Body weight change | |||||
Increase | 7 | 0.10 | −0.50 | 0.70 | 2.545 |
0–2.9 kg loss | 19 | 0.61 | 0.26 | 0.97 | |
≥3 kg loss | 8 | 0.70 | 0.12 | 1.28 | |
Diet intervention | |||||
Yes | 20 | 0.51 | 0.18 | 0.85 | 0.008 |
No | 14 | 0.54 | 0.11 | 0.97 | |
Exercise duration | |||||
<12 weeks | 8 | 0.09 | −0.50 | 0.68 | 2.868 |
12–23 weeks | 15 | 0.61 | 0.20 | 1.02 | |
≥24 weeks | 11 | 0.71 | 0.24 | 1.18 | |
Exercise type | |||||
Resistance | 6 | 0.43 | −0.22 | 1.07 | 0.601 |
Aerobic | 24 | 0.52 | 0.18 | 0.85 | |
Combined | 4 | 0.82 | 0.01 | 1.62 | |
Exercise intensity | |||||
Low | 3 | 1.24 | 0.29 | 2.19 | 2.401 |
Moderate | 30 | 0.47 | 0.19 | 0.75 | |
High | 1 | 0.27 | −1.38 | 1.93 | |
Comorbidity | |||||
No | 21 | 0.26 | −0.06 | 0.58 | 6.392 |
Yes | 13 | 0.95 | 0.52 | 1.37 | |
Baseline BMI | |||||
25–29.9 | 12 | 0.31 | −0.11 | 0.73 | 1.647 |
30–34.9 | 19 | 0.67 | 0.30 | 1.04 | |
≥35 | 3 | 0.66 | −0.28 | 1.61 |
In this meta-analysis, we found 34 trials from 17 studies including 1,045 overweight and obese adults. The meta-analysis result showed that exercise training significantly improves vascular function as measured by FMD of the brachial artery. The studies were randomized controlled trials of control and noncontrol groups of Asian and Western adult populations. Endothelial dysfunction is inherent in overweight and obese adults, and exercise training is universally accepted to ameliorate the obesity-associated endothelial dysfunction in healthy adults [
Our results demonstrated that exercise has a moderate benefit on the improvement of FMD on overweight and obese adult populations in exercise intervention studies. When we probed moderators to examine the possible associations with ESs, we found that only comorbidity status influences the effectiveness of exercise intervention on EF. To our knowledge, we are the first to report this result. The finding could explain why exercise may not reverse the reduction of FMD attributable solely to obesity in isolation, whereas exercise may reverse the portion attributable to a comorbidity. While the explanation contrasts two previous meta-analyses [
The examination of mean ES and 95 CI of each subgroup showed that ES is above medium in the subgroups with weight loss whereas there is no significant benefit of exercise intervention in the weight gain group. Although the mechanism of the effects of weight loss on FMD in overweight and obese adults requires more elucidation, numerous studies confirm the positive effects of weight loss by exercise on FMD. The beneficial effect of weight reduction by lifestyle changes, such as exercise to improve vascular function in obese adults, is strongly supported in [
A study of the effect of surgically induced weight loss on FMD in hypertensive obese patients showed that bariatric surgery-induced weight loss improves blood pressure (BP), high-sensitivity C-reactive protein (hs-CRP), leptin, homeostasis model assessment (HOMA-IR), and abdominal fat, whereas FMD does not improve [
We also found a moderate to large beneficial effect of exercise in the longer-period intervention subgroup than with 12 weeks of exercise program, and no significant benefit in the group with less than 12 weeks of intervention. We suggest that at least 12 weeks of exercise intervention may improve FMD in overweight and obese adults. Although previous reviews hypothesized that a longer duration may increase efficacy and maintain the effect on EF from the exercise intervention [
As mentioned, exercise modality and intensity to improve EF remains controversial. For example, a meta-analysis of obese and nonobese adults showed that any type of exercise, including resistance, aerobic, and combined training improves EF [
Moderator analysis also demonstrated that adults with a BMI 30–34.9 (level 1 obesity) have large and medium to large beneficial effect from exercise, respectively, whereas adults without a comorbidity and BMI < 30 or ≥35 have no significant benefit from exercise. Previously, Joris et al. [
The effect of exercise on FMD may also depend on baseline BMI. Our result showed that only adults with level 1 obesity have a benefit from exercise training on FMD. A meta-analysis by Ashor et al., however, showed a greater effect of exercise on FMD in nonobese individuals than in obese individuals [
This study must be interpreted in the context of multiple limitations. First, the range in FMD levels in the studies is relatively small, and there is substantially less data for those with BMI > 35. Second, there were methodological limitations. FMD is well known for being operator and protocol dependent, and there was considerable variation in FMD data collection methodology [
In summary, our meta-analysis indicates that exercise training is able to improve EF in overweight and obese adults, and that the effect of exercise may depend on the different characteristics of exercise intervention and on participants’ demographics.
This study has been presented as the poster entitled, “Exercise and Vascular Function in Overweight and Obese Adults: A Meta-Analysis” at the American College of Sports Medicine’s (ACSM’s) 64th Annual Meeting and 8th World Congress on Exercise is Medicine in Denver, Colorado, USA, in 2017.
The authors declare that they have no conflicts of interest.