The effect of aerobic exercise training on endothelium-dependent dilation

The vascular endothelium is important for the regulation of blood pressure and blood flow, and impaired endothelial function is associated with increased risk of heart attack and stroke. Numerous studies have examined whether exercise training improves endothelium-dependent dilation, but the results have been inconclusive, with studies showing both improvement and no effect. Therefore, we undertook a systematic review of the literature and a meta-analysis to test the hypothesis that aerobic exercise training improves endothelium-dependent dilation in different subject populations. The Embase, Medline, Scopus, and Cochrane databases were searched using search phrases that included the terms “endothelium”, “nitric oxide”, “exercise training”, and “physical activity”. These search phrases returned 9,709 articles. Of these resultant articles, 832 titles were selected for abstract screening. Articles were rejected at this point if they did not mention aerobic exercise or clearly did not pertain to endothelium-dependent dilation. In addition, 41 more titles were selected for abstract screening after searching the references of selected reviews, resulting in 873 total abstracts. During abstract screening, papers were discarded if they lacked a control group, did not specifically measure endothelium-dependent dilation, or did not include aerobic exercise training. Following abstract screening, 331 papers remained that met all inclusion criteria. During our literature search, all population types were accepted. This included humans, animals, young, old, healthy, and those with pathologies such as diabetes, heart disease, stroke, hyperlipidemia, hypercholesterolemia, or hypertension. We intend to eventually address all of these different conditions. However, as this comprehensive population is too large for a single meta-analysis, we are presently aiming to determine the effects of training on endothelium-dependent dilation by applying meta-analysis to a single subgroup