"I had a major stroke, I'm frankly lucky to be alive. I had been heavily overworking - mostly my own fault - in the year before that," he said.
"I'd had two minor strokes, it turned out, in that year - which I hadn't noticed - and then I did the terrible thing of believing what I read in the newspapers, because the newspapers were saying what we must all do is take very intensive exercise, in short bursts, and that's the way to health.
"Well I went onto a rowing machine and gave it everything I had, and had a strange feeling afterwards - a blinding headache, and flashes of light - served out the family meal, went to bed, woke up the next morning lying on the floor unable to move.
"And what I'd done, I'd torn the carotid artery, which takes blood into the brain, and had a stroke overnight - which basically wipes out a bit of your brain.
"In my case, luckily not my voice or memory or anything like that, but the whole left hand side of my body, which is why I'm still not able to walk fluently - I do a kind of elegant hobble is the best I can manage; my left arm isn't much good yet. I've got a lot of physio still to do."
Sports cardiologist Dr James OKeefe, from the Mid America Heart Institute, has carried out a number of studies on the impact exercise has on the body, and says that moderation is the key.
There is this growing movement toward longer and more intense exercise into middle age and the body simply doesnt recover as well," he said.
Exercise can cause damage to the heart, including causing premature ageing. The bottom line is that when you get to 40 you have to be more moderate about your exercise.
"When you overdo it you give up most of the longevity conferring benefits - if you are running marathons long term you won't live any longer than someone who is a coach potato.
Exercise is probably one of the single best things that you can do for your health, but if you overdose you start getting other affects that outweigh those benefits, and in extreme doses they even have fatal complications.
Read more from the original source:
Andrew Marr's stroke caused by intense exercise