My doctor told me to give up training for and running marathons by my mid 40s.

My doctor has never said anything like that to me. however, my body started to tell me to stop, by elevating my resting HR, lowering my HRV, making me irritable, raising my blood pressure. very few people can continue to train like that into their 40’s and beyond. it is really hard on your body. the only thing I can say is listen to your body. it took me years to figure out what was wrong with me until I took time off from running and felt so much better

Before you go quoting Alex Hutchinson, you first have to recognise and get past his innate bias.

He recently reported on a minimalist strength training routine recommendation from a study. In the article he also briefly acknowledged the dangers of overdoing a strength routine, as outlined by another piece of research. His overall analysis of that warning?…Meh. He clearly wasn’t too interested either way. It’s clear that Hutchinson only strength trains because he feels he has to.

However when O’Keefe and others came out with their warnings about too much cardio being a possible danger, Hutchinson, along with other running media types, couldn’t run fast enough to man the barricades and fend off this possible assault on their passion (and let’s not forget…livelihood…not much money to be made if no one is out their pushing the limits for race results, and instead only running 20 miles a week for health).

It’s clear where Hutchinson’s allegiances lie, and he will go out of his way to defend his passion and refute anything which might insinuate that running too much is not the best idea.

O'Keefe is a quack. You can't take his work seriously. Every time I've looked over one of his publications, he'll have ominous-sounding theories, slim data, and error bars massive enough to drive a truck through.

Attia's thesis is that to have a long healthspan and lifespam, you need to have elite v02 and elite strength. I think as long as you lift consistently and train smart, you can continue running marathons.

That your doctor follow Attia reflects well on your doctor. Attia was fantastic on Rogan's podcast.

Attiya is overconfident to the point to arrogance. He’s also sometimes wrong and reverses his strongly held convictions, which is a double edged sword. His standards are impossible for most normal people.

He thinks, among other things, everyone should be able to dead hang for at least two minutes and farmer-carry-walk their body weight for two minutes. Give me a break. I bet the majority of regular runners here can’t do it. He will change some of his standards in about 10 years when he starts slowly breaking down like all humans.

As for vo2max, all you need to do is to maintain a vo2max comfortably in the 20s till you die coz lower than that means your movement ability and quality of life will significantly degrade. That goal doesn’t necessarily require keeping it high for most of your life.

All that said, OP’s doctor isn’t wrong.

O’Keefe isn’t the only one with similar theories / conclusions. There are others.

Who would you trust on such issues? A cardiologist, or a running media type with an agenda to push?

What does O’Keefe and others gain from cautioning against too much cardio? Although the running media types who have tried to debunk his work and that of others, have a livelihood to look after.

I was going to post a similar comment. Past 45, running can be very hard on your body, and endocrine system (in my case). Being healthy should take priority over competition as you approach 50. I was doing marathons in my late 30s/early 40s.... until I couldn't. And rather than push through, I decided to reduce my running so I could continue to enjoy it.