Cardio revives blood vessel function when blood pressure runs high

The endothelium is the thin lining inside blood vessels, and how well it lets an artery widen in response to blood flow is a telling marker of vascular health. In people with high or borderline high blood pressure, that function is a natural target for improvement, because vessel behaviour sits upstream of many cardiovascular problems. Exercise is already a mainstay of blood pressure management, but the more specific question here is whether aerobic training improves endothelial function itself, and if so, what intensity and duration of training it takes to get that benefit.

The researchers systematically searched for randomised controlled trials testing aerobic exercise against control in hypertensive and prehypertensive patients, with flow-mediated dilation as the vessel-function outcome. Fifteen studies met their inclusion criteria. Results were combined using a random-effects model to calculate a weighted average difference between exercise and control groups. Beyond the headline pooled effect, the team examined how the training's intensity and duration, and the characteristics of the participants themselves, shaped the size of the improvement.

Aerobic exercise significantly improved flow-mediated dilation, with a pooled average improvement of 2.23 units over control, although the individual trials varied widely in the size of effect they reported. Training undertaken at moderate intensity was effective, vigorous intensity looked even better, and programmes lasting no less than 12 weeks were what it took. The benefit was not evenly spread: participants with better overall health, a younger age, a larger starting body mass index and a larger starting flow-mediated dilation tended to see bigger improvements.

This adds a vessel-level explanation to the well-established finding that aerobic exercise helps people with raised blood pressure, extending the evidence from the pressure reading itself to the function of the artery lining. The wide disagreement between trials means the precise size of the benefit remains uncertain, and the finding that healthier, younger participants gained more raises questions about who benefits least. How long the improvements last after training stops, and how aerobic work compares with other exercise types for this outcome, remain open.

For anyone whose blood pressure sits in the raised or borderline zone, this is a reason to think regular aerobic exercise is working on the blood vessels themselves, not just the number on the cuff. The pattern in the data suggests intensity and persistence both matter: moderate effort helped, vigorous effort helped more, and the programmes ran for at least 12 weeks. It is informational rather than a prescription, and the variation between trials means individual results will differ.