Yet another WSJ article, this time on cardiac dangers of extreme exercise. Apparently "exercise that is extreme in either volume or intensity may be associated with high levels of atherosclerosis in the coronary arteries."
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I've heard rumblings about this before. Velonews had an interesting, slightly long article about it a couple months ago. Given that I already have bad genetics for cardiac stuff, it scared me a bit. Based on the velonews article, seems like they understand that there is a correlation, but they don't seem to fully understand the cause of it.
I told my wife about the article, and she didn't tell me to stop swimming, so I'm in the clear for now.
Just read the article Mike linked to...
The studies that I've always read about use runners and cyclists as the test subjects. Anecdotal evidence to be sure, but I know for me, my heart rate tends to be much higher running, and when I would ride a bike, my heart rate would often be higher than what it is for me for a long pool workout, with the exception of IM days (which I have recently started incorporating back into my training a bit, scary, I know). I wonder if this higher heart rate has an effect on the findings of the study. I suspect they haven't performed the tests that thoroughly yet, but I haven't read any of the peer reviewed papers, only rehashes of said papers from other media sources.
Here's the thing. Marathon swimming is an extreme sport (I'm thinking more Channel level than 10k swims). If you don't understand this, you shouldn't be doing it.
Understanding this, you then need to decide if it's for you. If you don't, guess what, you shouldn't be doing it. Understanding this and integrating it and doing your best to minimise potential negative outcomes (euphemism for death or injury) is the core of every extreme sport.
I consider talking people out of doing a Channel swim a good result, because if I can do so, it means they weren't ready. Also I personally won't ever crew a Channel swim again for someone unless they've done an ECG regardless of age (barring experienced Channel swimmers).
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Before my Channel swim, I was worrying about this. I talked to my doctor about it because I know I'm prone to palpitations if I'm under stress and I was having a heck of lot of them in early 2014. (I don't find swimming stressful, I find it helpful.) The stress was probably due to my father being very ill at the time. She sent me for an ECG, an echocardiogram, a Halter test and an exercise tolerance test, (running, which sent my heart rate rocketing)......after which I had a consultation with a cardiac consultant, (and another ECG, as this is standard practice before going in to see the consultant). The consultant had a particular interest in endurance sports. My results were all within normal parameters, with isolated ventricular ectopics, and the echocardiography result showed, and I quote... "mild left atrial dilatation which we tend to see in well conditioned athletes". I had been told in a consultation with our local sports specialist doctor that some endurance athletes develop fibrosis over many years. There are many more studies to be found on the net. Here's a link to one. Apologies if it's been posted before. http://www.drjohnm.org/2011/03/cw-that-exercise-has-an-upper-limit-makes-perfect-sense/ Younger athletes and late starters tended to have less scarring. We had a bit of a laugh about me starting this lark at 51. The outcomes of my testing gave me peace of mind, even though I apologised for what I felt was a waste of valuable resources. They disagreed and were quite happy to do the tests.
I don't see myself aiming for the English Channel or such (except as a pipe dream); my goals, when I assess them realistically, are to stretch my limits a bit at a time. Longest distance so far is seven miles. Lowest temp without a wetsuit, 62 degrees. So instead of aiming for 20 miles, I'll aim for 8-10. If it turns out that's enough for me, fine. If this distance works and I feel more is possible--and desirable--I'll reassess. At 65, I'm mindful not so much that I should stop doing what I'm doing b/c of age but I do need to be aware that maintenance is all the more important and that I may at times need to adjust goals/ambitions based on where I am healthwise. But that's true at any age. I prefer to think in terms of what I can NOW do and shoot for, rather than allow pipe dreams to dictate what I aim for--and derive satisfaction with each step past a previous limit.