Older than 40 endurance athletes, cardiac risk due to excessive training...link to paper within

Has TR podcast done anything on this? If so could someone direct to the podcast?

Cardiovascular Damage Resulting from Chronic Excessive Endurance Exercise - PMC.

I thought this paper was pretty interesting. Being over 40 myself and noticing my body does need more time to recover I’ve been struggling to figure out how do I improve while recovering. After discussion with a very well read friend of mine last night he mentioned no more than two high intensity days a week and carefully monitoring even Z2 rides due to possible adverse cardiac reconfiguration.

The paper linked above suggests something like 7 hrs a week. From the link above
“Avoid a daily routine of exhaustive strenuous exercise training for periods greater than one hour continuously. An ideal target might be not more than seven hours weekly of cumulative strenuous endurance ET.”
What does strenuous endurance training mean? Z3? Z4?

I’m thinking right now 2 VO2 workouts a week when next spring gets here and perhaps my longer ride each week which is 4-6hrs might replace a VO2 workout if it is indeed difficult at times. I suspect that a 90 or 120 min Z2 training ride isn’t considered “strenuous” but I"m not sure?

I’d love some insight, thought and discussion here.


This is something I am interested in too (recently turned 43). I think “longevity” experts recommend 1-2 hard (vo2) workouts per week and the rest “entrance”. Plus, strength, mobility and balance work. What constitutes hard and endurance is up for debate though. I’d love to hear others opinions on the matter.


This is very very interesting. I am following this closely. I wonder if there is a way on the fitness apps to see your “weekly avg” to indicate overall time and percentage. I think there would be wide variations in durations of intensity when considering both indicators. For example: 10% of a 6 hour training week isn’t that much. However, 10% of a 20 hour training block is a HUGE amount. of time difference at intensity. So, is it alright for the 6 hour/week athlete to do more percentage intensity because the overall load is lower?

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Great point. I know that intervals.icu will show you HR% of a workout by workout. It’s a great tool that I started using regularly this summer.


As someone that actually takes an mtor-inhibitor for longevity I’m pretty sure I’m probably most into longevity out of everyone here. You are probably right about the high intensity vo2max sessions that more than 2/week is suboptimal but just moving about like lower end z2 higher end z1 (in a 5 zone model) seems to be beneficial

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Leonard Zinn wrote a book about this:

When I hear the athlete stories, it’s usually those guys that have raced at a high level without stopping for 20-30+ years. With that in mind, I’m not going to personally worry about it.

I raced for 7 years in my 20s and then took a long break for that level of intensity. These days I do mostly aerobic workouts and occasional VO2 level work. I will do a build to be fit for the spring and do group rides and a few events but I’m not a burn the candle at both ends, A type, riding 15-20+ hours a week. Maybe I’m fooling myself but I think my risk is pretty low.


Have a listen to last weeks Inside Exercise podcast - no. 69 “Should Middle-aged Men Pull On Lycra” in which Dr Glenn McConell interviews sports cardiologist Assoc. Prof. Andre La Gerche.


I’m a participant in the VENTOUX study, it is gathering data over a couple of years into this sort of thing.

It involves an MRI on my heart, ECG, a ramp test and the implantation of a loop recorder into my chest. HR data is sent daily to the study.

Hopefully, it’ll be part of a body of knowledge helping to answer this.



Was going to post this link, awesome episode and quite reassuring

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I used to have heart palpitations regularly, especially at night, in my late 20s/early 30s. I got checked out and wore a 48-hour monitor and got an echocardiogram but nothing was seriously wrong they said. Once I got serious about structured training instead of just a “go hard all the time” attitude (which is basically a ton of sweet spot in the end) and started doing a polarized schedule, the heart palpitations are totally gone. I was doing like 15+ hours per week, with a few hard rides a week. Now I do the same or less hours and do only 2 high intensity workouts per week at most, often just one but it’s a really hard one. I keep endurance in the z2 or below based on HR (not power).

In the summer sometimes I’ll end up doing a few more hard days per week when the weather is nice and you just want to go go go but otherwise stick to the polarized plan of making hard days hard and easy days easy and <=2 hard days per week with recovery in between so I can do the next hard workout on target.

I feel better, happier, healthier, stronger and like I said the heart issue is gone.

Edit- obviously just my experience. If you experience any funny feelings you should get checked out. My PCP was happy to set me up with all the tests when I explained I was an endurance junkie.


So yes, there is a signal that high volumes of endurance activity may be harmful. A colleague of mine is the author of one of the references of this paper. The significance and how real this signal is are not clear.

For example:

If it is real, at what dose it may become a problem is not known with certainty. In addition, most of the data on this is mostly from running, rather than other endurance sports.

The lack of certainty on this topic means that there are a lot of individual factors that may come into play, and if you are concerned, you are best served by talking to someone who is familiar with both the medical literature on this topic and your own medical history.

However, I hope no one is under the impression that doing things like riding your bike for 24h straight is healthy for you.

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What is their definition of strenuous? I mean no one is “going to the well” every day. That’s just dumb.

That said… I bet there are more heart problems from people not exercising than exercising too much.


I reduced training to “medical recommended levels” and my health markers all turned for the worse. I returned to training for Ironman and turned them back.

I welcome more studies but it’s going to need to be clear and relevant, and moreover sign post a better way to health for me to change tracks.

  • what is a chronic marathoner?
  • paper seems to say not much more than “find a Goldilocks zone”
  • aren’t all meta-analyses going to argue to the middle by their nature?

This is a much more recent paper:


Right. When I looked into this in the past, the consensus was that you’re better off in the exercise bucket than the non-exercise bucket. No one wants to be that really healthy-looking person who drops dead though… or have to give up cycling because of a preventable heart condition that progressed too far. I think it was an episode of fast talk that interviewed a guy who keeled over while xc skiing in the colorado backcountry and was lucky that snowmobilers came by and found him.

I think it is interesting that Chloe Dygert had a cardiac ablation done in her mid-20s… although of course SVT can occur in anyone.

Many amateur athletes don’t know that they can’t “go to the well” every day though and need more knowledge around recovery - I used to be one of them.

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I see lots of recommendations to stick with maximum 2 HI workouts. During base not even 1 weekly. That’d be 1 each 10 workouts, not days. The rest is pretty much z2, and some SST sprinckled.

I’d be interesting in know the science behind TR’s recommendation, they look a bit intense for me.

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The “medical recommended levels” are such a low bar it’s absurd. Same when you’re pregnant! Some doctors still repeat the old advice of don’t get your heart rate above 140 during pregnancy!

But there’s probably a middle road between those and Ironman training lol.

We do know that some endurance athletes drop dead from heart conditions unexpectedly though so I think it’s worthwhile for people to get tested as I did (echocardiogram, 48-hour monitor, etc) if they have symptoms or concerns. It was about $1000 with my insurance and now I have peace of mind whenever I ride.


While this is true, lots of people who aren’t endurance athletes also drop dead unexpectedly. I’m not aiming this at you, but your quote kind of summarized what I feel is mostly just much ado about nothing. I think a lot of people over worry about things that are mostly out of our control.


So true!

For me, I was having so many palpitations… I’d ignored them for a couple of years but they were getting worse and I started to feel like any time I was doing a lot of training maybe I was ticking bomb so I didn’t know whether I should be doing what I was doing anymore and I decided it was time to get tested and be smarter about recovery. It made me faster in the end anyways.


I’ve ended up reaching the same conclusion.

I began road cycling in my later 30s, and by using HR monitors began noticing occasional arrhythmias during rides, and having got my eye in on what they felt like, off-bike also. I was looked at / monitored but nobody could find anything much wrong with me, but it made me really quite wary, and I paid attention, reading things like Leonard Zinn’s book, and wondering if I might turn out that way too :face_with_diagonal_mouth:.

I began paying even more attention to hydration, lightly supplementing with magnesium prior to rides, and tried to avoid doing very intense efforts on a given day unless I was well rested and recovered from prior days.

I registered with Crickles, a site run by a cycling cardiologist (I believe) in the UK, which links your Strava a/c to monitor your activities, making it easier to spot unusual cardiac episodes (eg. arrhythmia) during a ride.

In more recent years, and since doing the above - which may be a coincidence or not - I’ve experienced almost none of these episodes, and none that persisted. I still do all the sensible stuff, but I’m much less concerned now that I might have been on some slippery slope into enforced inactivity because of a very dodgy ticker. As you state, my impression is that the risks appear to be much greater if you really caned it on the endurance sport front for all of your adult life into/beyond middle age. I was a relatively late starter, never been obsessed, never done massive hours, and make an effort to rest and recover well. Hopefully this may serve me well.


But no hard science.

See the polarised is dead thread.

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