Is marathon running good or bad for hearts? And whose? And how? Science doesn’t know yet.

Newspaper reporters just love lurking around medical conferences, or so it would seem. Not willing to wait for papers to come out in journals, peer-reviewed and edited over time, journalists are showing up incognito at ballrooms of large hotels, consulting schedules, jotting notes and taking names.

The thing is, though: just because some group of researchers gives a talk with a particular result, that doesn’t mean that result is true, or applicable, or important or generalizable. Sometimes it takes a while to figure out what’s going on; there’s often a period in which different studies yield conflicting results. That’s common in real science. It may take a while for a more accurate picture to come out.

And so it is with a recent study about the relationship between endurance sports and what’s called “vascular age” — something to do with stiffness of arteries, which is bad, and an indicator of greater risk for vascular disease. If that wasn’t helpful, maybe this graph will clear things up:

You might think that running marathons would be good for your arteries (I don’t know why; uh, why not?). Way back in January, a study came out saying just that.

According to a new study … researchers found that training for and completing a marathon, even at relatively low intensity levels, was associated with reversing age-related stiffening of the body’s main artery, the aorta, and helped to reduce blood pressure.

… researchers tracked 138 untrained and healthy first-time marathon runners over the course of a six-month period ahead of the 2016 and 2017 London marathons, including two weeks post-marathon….

The results found that for first-time long distance runners, training and completion of the marathon was associated with reductions in their blood pressure and aortic stiffening — which is when the arterial wall begin to fray due to stress.

Older, slower male marathons saw the most improvement. Researchers noted that while they only recruited healthy participants for the study, “those with hypertension and stiffer arteries might be expected to have an even greater cardiovascular response to exercise training.”

Well okay then. I’m happy for all those first-time marathoners. You go with your non-stiff arteries!

But wait– 5 months later, the news turned grim, at least for male marathon runners. According to another group of researchers, endurance sports like marathon running can increase vascular age by up to 10 years for men. But for women who ran marathons, their vascular age improved. Here are the deets, from a news article published this week:

Running marathons could age men by as much as a decade, research suggests... The study of males aged 40 and over who had taken part in at least 10 endurance events, found that their major arteries were far stiffer than would be expected for that age group.

However, the study of more than 300 regular athletes found the health of women who took part in endurance events improved. Female athletes had a vascular age around the same as their actual age and, by one particular measure, their vascular age was six years younger than their true age.

Scientists said the study… could not explain why the impacts of such events differed between men and women.

Okay, so some researchers gave a talk at a conference with some preliminary results that they can’t explain. Fair enough; this is legit practice at conferences. But I wouldn’t consider it news, much less important news, much much less worthy of the headline “Running marathons could age men over 40 by a decade”. Nope.

Sometimes, in fact most of the time, we need to wait for science to do more work and reach a solid consensus about what’s going on and why and for whom. this is one of those times.

While you’re waiting, it seems okay to rely on existing standard health advice, which is that exercise is good in many ways for us. More than that I shouldn’t say, lest some reporter is lurking around the corner…