Exercise Improves Vascular Function in Overweight Youth

Laurie Barclay, MD

August 13, 2015

Exercise training improves vascular function, as reflected in enhanced conduit artery flow-mediated dilation (FMD), in overweight and obese children, according to a systematic review and meta-analysis published online August 10 in Pediatrics.

"Impaired vascular function may contribute to increased cardiovascular disease risk, as atherosclerosis begins in childhood and endothelial dysfunction has been identified as an early event contributing to the development of atherosclerosis," write Katrin A. Dias, BExSS, from the School of Human Movement and Nutrition Sciences, The University of Queensland, St Lucia, Brisbane, Australia, and colleagues. "There is strong evidence that obese children and adolescents have lower arterial compliance and distensibility than their healthy matched controls, as well as depressed (2%) endothelium-dependent and -independent conduit artery vasodilator function."

The investigators note that conduit artery FMD is a noninvasive index of preclinical atherosclerosis, and that exercise may improve FMD in healthy persons as well as in those with cardiovascular disease.

The goals of this meta-analysis were to characterize the effect of an exercise intervention in overweight and obese children and adolescents on FMD and on cardiorespiratory fitness, measured by peak oxygen consumption (Vo 2peak).

With 219 study participants, there was a significantly greater improvement in FMD (mean difference, 1.54%; 95% confidence interval, 0.24 - 2.84; P < .05) and Vo 2peak (mean difference, 3.64 mL/kg/minute; 95% confidence interval, 1.57 - 5.70; P < .05) after an exercise training intervention than in control conditions.

"This meta-analysis indicates that exercise is able to induce improvements in FMD in overweight and obese children and adolescents," the authors write. "The magnitude of increase (∼1.5%) would be expected to restore diminished vascular function reported in this at-risk pediatric population. This review therefore supports the notion that exercise can be used as a therapy in pediatric obesity to reverse reduced vascular function, restoring FMD to levels comparable to those observed in normal-weight children and adolescents."

The authors searched PubMed, Medline, Embase, and Cinahl databases from inception to February 2015 to identify studies of overweight or obese children and/or adolescents. They used standardized data extraction forms for patient and intervention characteristics, control and comparator groups, and key outcomes, and they used a modified version of the Physiotherapy Evidence Base Database scale to evaluate procedural quality of the identified studies.

Limitations of the meta-analysis included small sample sizes, possible publication bias, and failure to include studies of vascular structure measured as arterial stiffness. FMD effect size varied among trials, which was not surprising in light of the diversity of exercise prescriptions, participant characteristics, and FMD measurement protocols. In addition, this meta-analysis could not identify the optimum exercise training protocol to maximize health benefits in obese children and adolescents.

"Considering the heterogeneity and small sample size of this analysis, further research is warranted to establish dose–response effects together with optimal exercise modality," the study authors conclude. "Extended postintervention follow-up will ascertain the long-term sustainability of exercise in the treatment of diminished vascular function."

St. Olav's Hospital, the Norwegian University of Science and Technology, and the Wesley St Andrew's Research Institute supported this study. The authors have disclosed no relevant financial relationships.

Pediatrics. Published online August 10, 2015. Abstract

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