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Comment by polishdude20 | Hacker News Reader

I'm surprised an extra 30 mins per day of running for 6 weeks had enough of an impact to change the structure of the heart noticeably.

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Author here. I've been taking running seriously for 22 months, so maybe the past 6 weeks were just the last straw to trigger this arrhythmia. I also had covid at the end of July (very mild symptoms), which made me think there could be a link, but the tests seem to exclude any lingering inflammation or infection.

> the heart is designed for max availability over consistency, so when in doubt, it triggers a beat.

This is a great line, thanks! Going to share this with my distributed database reading group

I really enjoyed your article. I also get the occasional "missed beat"/palpitation. Mine only occur 0-3 times a day and have never been seen on a EKG. Nevertheless it was enough to trigger panic attacks in me and send me to the hospital with heart attack symptoms. Since then I've finally started taking medication for anxiety and no longer stay up all night thinking my hearts going to stop in my sleep so that's nice.
During that time though, nothing I read and nobody explained to me what keeps the heart beating despite all manner of possible failures. 10/10 was definitely worth the read.

The symptoms of a heart attack and a panic attack are annoyingly similar. Whereas people qualified to diagnose and treat one are generally nowhere near the people qualified for the other.

I get these missed beats occasionally, like a few times a year. Of course, they’re stress related for me. When I first got them, I also thought it was a heart attack and ended up in the hospital where they also ran a bunch of tests on me.

The wonderfully comical thing about mine is they’re stress related. So the first one happened, made me a little stressed because I thought something was wrong, which caused more of them, which made me even more worried, etc.

Can I ask what medicine are you taking right now? I have exactly the same problem as you, the thought that my healthy heart is going to stop any moment is crazy

Sorry if this is too much prying into your health, but what was the personal/medical verdict on whether to continue the running? You say that the symptoms disappear after a while without exercise, but if it’s benign will you keep it up?

I'm going to take it easy for a few weeks, just out of abundance of caution; just in case there's something else that got missed.

I'm not into any competitions or races. I run for health purposes only, so I'm okay losing some fitness. If the symptoms disappear, I'll certainly ramp up again. If they don't, I'll play it by ear :)

My understanding is that 35-50% of endurance athletes have what I have (including symptoms), and they continue to train without any harmful effects.

Thank you for sharing this! I'm into endurance cycling and had similar issues. I'm diagnosed with PVC as well and rely on medication to keep it from happening. I nearly fainted while driving a car, so it is not without "harmful effect".

In my case, the PVC disappears during exercise and comes back when I take a rest after exercising. I just wonder if you had any comparisons between rest vs. elevated heart rate scenarios. Now I'm super curious how elevated heart rate might change the clock rates for those nodes.

Mine is exactly like yours. During exercise it disappears. Then after about 5 minutes post-exercise, the symptoms become even more regular. I'd get 4-5 normal beats, and then a skipped beat. I managed to capture an ECG post-workout and it shows very clearly the regular PVCs: https://dvassallo.s3.us-west-2.amazonaws.com/twitter/F7yWouK...

From what I've read, when we're exercising (or sick or stressed) the heart rate gets overridden by the SNS (part of the autonomic nervous system). The SA node can only maintain resting heart rate, and once there's extra demands from the body, the SNS takes over (controlled by the brain, but involuntary).

It seems to be a good sign that PVCs disappear during exercise based on the studies I found.

I have the same problem. In my case PVCs at rest typically arose the next day after the workout. The only solution for me was to quit exercising for 1 month completely and letting the heart calm down at a max pulse rate of 100 during the day. It seems that the heart then shrinks a bit in size and the PVCs disappear. Then I started to work out slowly again and they didnt appear any more.

Could you share how you cope with all these findings and experiences, psychologically? I have anxiety that my heart is going to stop any moment (even after stress test came back ok), hope you can share your coping mechanism is any, thanks

Where did you get those numbers 35-50%?

https://www.revportcardiol.org/pt-electrocardiographic-evalu....

Crazy thought, could it be due to running specifically? Is there something about running, maybe the up and down motion that could be jarring to the heart? I wonder if there's less prevalence in say, rowers or cyclists .

To provide some anecdata. I started running again a few years ago (I'm late 30s now but used to run competitively when I was younger). Before I started, my Oura ring tracked resting heart rate while sleeping at an average of 55 bpm. After 2 years of doing an average of 60km a week (mostly aerobic work), my resting heart rate averages at 39 bpm. I guess the difference is because the heart chambers are now larger - the structure of the heart has significantly changed.

Only after a couple of weeks of running about 20km, did I start seeing my resting heart rate drop to the high 40s. After that, it gradually lowered over the next 18 months or so.

Furthermore, an article about a study back in 2008 [1]:

> At the end of the 90-day study period, both groups had significant overall increases in the size of their hearts. For endurance athletes, the left and right ventricles — the chambers that send blood into the aorta and to the lungs, respectively — expanded. In contrast, the heart muscle of the strength athletes tended to thicken, a phenomenon that appeared to be confined to the left ventricle. The most significant functional differences related to the relaxation of the heart muscle between beats — which increased in the endurance athletes but decreased in strength athletes, while still remaining within normal ranges.

> “We were quite surprised by both the magnitude of changes over a relatively short period and by how great the differences were between the two groups of athletes,” Baggish says. “The functional differences raise questions about the potential impact of long-term training, which should be followed up in future studies.”

[1] https://news.harvard.edu/gazette/story/2008/04/exercise-chan...

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