A runner in their forties has an echocardiogram — before a race, at a routine check-up or out of curiosity — and sees the words “dilation of the ascending aorta” in the report. What usually follows is an internet search: the term “aortic dilation” gets over 5,000 monthly searches on Yandex, Russia’s main search engine. The word “aneurysm” in the neighbouring articles is frightening. A fresh study from Poland and several earlier papers help clarify what counts as normal in a trained person.

The Polish study: runners versus their peers

Sacharczuk, Baszko and colleagues from Poznan University of Medical Sciences (European Journal of Applied Physiology, 2026) compared 42 recreational runners over 40 (at least 20 km a week for at least a year) with 27 peers who did no sport. None had cardiovascular disease, a bicuspid aortic valve or connective tissue disorders.

What they found:

The ascending aorta was wider in the runners: 3.25 versus 2.90 cm. After adjusting for age, sex and height, the difference was about 0.31 cm.
Nobody’s diameter reached 4.0 cm — all values were within the normal range.
Markers of collagen turnover (CTX-I, MMP-2), which could point to breakdown of the vessel wall, did not differ.
Left ventricular function was preserved, and the ankle-brachial index was higher in the runners — also within the normal range.

The authors’ conclusion: this is moderate remodelling of the aorta in response to exercise, not a sign of aortic disease.

What we know about elite athletes

This is consistent with a meta-analysis by Iskandar and Thompson (Circulation, 2013), although it measured the aortic root rather than the ascending segment. Its 23 studies included 5580 elite athletes. Their aortic root at the level of the sinuses of Valsalva was on average just 3.2 mm wider than in people without athletic training, and at the level of the annulus — 1.6 mm wider. The authors called the difference clinically insignificant and drew an important conclusion: marked aortic dilation in an athlete is more likely to signal disease than adaptation.

Does a dilated aorta keep growing

The most worrying question is whether things will get worse if you keep training. The Canadian group of Moulson and McKinney (JACC: Advances, 2025) followed 50 veteran athletes (mean age 60, about 45 years of sport, mostly running and cycling) for up to 10 years.

19 of the 50 (38%) already had dilation at baseline — 40 mm or more.
Their rate of growth was small: 0.2 mm per year at the sinuses and 0.5 mm per year in the ascending aorta. In athletes without dilation it was 0.1 and 0.3 mm per year. No statistically significant difference was found.
6 people (20%) from the group without dilation reached 40 mm during follow-up.
Nobody in the dilated group reached 50 mm.
High blood pressure was noticeably more common in those with a dilated aorta: 68% versus 32%.

One more recent detail: Italian cardiologists (American Journal of Cardiology, 2026) found no pathogenic genetic variants in endurance veterans whose aortic dilation was picked up at screening — in other words, typical “hereditary aortopathies” did not turn up in this group.

What not to believe too firmly here

The Polish study is a cross-sectional snapshot of 69 people. It shows that runners have a wider aorta, but it does not prove that running is what caused it, and it says nothing about what will happen in 10 years.

The Canadian sample is 50 people, analysed retrospectively from clinical echocardiograms. Scans were done on those who had a reason for one, which biases the sample. Usually there were only two scans about 5 years apart.

The 2013 meta-analysis is about elite athletes, not recreational runners over 40 with high blood pressure and extra weight.

The Italian genetic study is a brief report, and we don’t have detailed data on it.

Different segments of the aorta and different methods. The aortic root, the sinuses and the ascending segment are measured differently, and the result depends on the machine and the operator. A discrepancy of 2–3 mm between two scans is common.

How to apply this

This article does not replace a consultation with a cardiologist. Decisions about training with aortic changes are made by a doctor.

A difference of 2–3.5 mm compared with the “general population norm” is to be expected in a trained person. According to the research, it is physiological remodelling.
Values of 40 mm and above are a reason for follow-up with a cardiologist, not for panic. Usually a repeat scan is scheduled after a set interval to assess the rate of growth.
Check your blood pressure. Hypertension was twice as common in veterans with a dilated aorta. This is something you can influence.
Tell your doctor about any family history of aneurysms, aortic dissection or sudden death, and whether you have a bicuspid aortic valve. These people were not included in the studies, and their risks are different.
Discuss strength exercises involving straining with your doctor — maximal lifts with breath-holding cause a sharp rise in blood pressure.
Sudden severe chest or back pain is a reason to call an ambulance immediately, not to wait and see whether it “passes”.
Keep the bulk of your training in the easy zones. The zones generator will calculate the boundaries. For other heart changes in endurance athletes, see our pieces on atrial fibrillation and troponin after a marathon.

The bottom line

In the Polish study, the ascending aorta of recreational runners over 40 was on average 3–3.5 mm wider than in non-exercising peers, but nobody’s reached 4 cm.
A meta-analysis of 5580 elite athletes: a difference of just 1.6–3.2 mm. Marked dilation is more likely to signal disease than adaptation.
In veteran athletes with an aorta of 40 mm or more, it grew slowly — 0.2–0.5 mm per year, and none of them reached 50 mm.
In practice: values of 40 mm and above mean follow-up with a cardiologist, blood pressure control and attention to family history.

Sources: Sacharczuk W., Dankowski R., Tritt D., Szałek-Goralewska A., Kuciara M., Baszko A. “The ascending aorta and vascular profile in recreational masters runners: a cross-sectional study”. European Journal of Applied Physiology, 2026. DOI: 10.1007/s00421-026-06471-8 · Iskandar A., Thompson P.D. “A meta-analysis of aortic root size in elite athletes”. Circulation, 2013;127(7):791-798. DOI: 10.1161/CIRCULATIONAHA.112.000974 · Moulson N., Boroditsky N.D., Wiese J. et al. “Progression of ascending aortic dimensions in masters endurance athletes”. JACC: Advances, 2025;4(10 Pt 2):102163. DOI: 10.1016/j.jacadv.2025.102163 · Monda E., Caiazza M., Montuoro S. et al. “Lack of pathogenic variants in master endurance athletes with aortic dilatation identified with echocardiographic screening”. American Journal of Cardiology, 2026;275:41-43. DOI: 10.1016/j.amjcard.2026.07.008