This came up in the office today. I don't know that it happened while he was out jogging, but yes, he died of a heart attack. And there are rumours that Mr. Atkins, of the famed diet, was not exactly svelte at the time of his death, although these are unfounded as far as I know.

Of course, they're all just trailing after whoever it was that died after drinking Parisian water to demonstrate that it was potable (I'd have said W. C. Fields, except his water-related comment was "I never drink the stuff. fish fuck in it.")