Long distance running and heart attack

Of all the questions we got from Dr Helen this one is about the most interesting.

It's a one line question by reader Richard who asks:

Does running damage the heart long term? I have in mind 6 miles per day average.

Richard, you asked an interesting question. Let us take a moment to remember the story of Pheidippides who collapsed and died after running 21 miles 1,470 yds from the plain of Marathon to the Agora of Athens in 490BC.

There is some truth that marathon runners who run more then three hours have a 1:50,000 chance of dying during the event or within 24hrs after the event. There is some evidence that severe exertion, like marathon running may cause rises in Troponin, an enzyme that measures heart muscle damage. This was shown in many clinical studies conducted by many investigators although there are dissenting studies.

Coming back to Richard, I don't think that 6 miles a day is quite the marathon, so there should be no risk of collapsing or heart muscle damage. Richard's troponin should not rise. However, if Richard falls in love with running and decides to take up the marathon then his risk is there.

The paradox is that we always encourage exercise to reduce heart disease and this is true. Now we know that severe exertion can be damaging to the heart. Therefore dear readers, always moderation in all things.