New information has arrived since this story was posted -- apparently it wasn't a cardiac thing, as I'd thought when I posted my comment about Douglas Adams' death -- in this case, there was head trauma as a result of slipping while on a treadmill [1]:<p><i>The official said he left his room at about 4 p.m. to exercise, and family members went to look for him after he didn't return. He was found at about 6:30 p.m. in a resort gymnasium lying by a treadmill in a pool of blood, with a blow to the lower back of his head. He apparently had slipped on the treadmill and hit the machine, said the official, who spoke on condition of anonymity because the person was not authorized to speak to the press.<p>The official said Goldberg still had vital signs when he was discovered, but later died at a hospital in Nuevo Vallarta.<p>The official said the cause of death was severe head trauma and hypovolemic shock, or bleeding.</i><p>[1] <a href="http://www.sfgate.com/news/world/article/SurveyMonkey-CEO-died-of-head-trauma-in-exercise-6241399.php" rel="nofollow">http://www.sfgate.com/news/world/article/SurveyMonkey-CEO-di...</a>
Reminiscent of the untimely death of Douglas Adams [1] (author of "The Hitchhiker's Guide to the Galaxy", etc.) at 49, post-exercise:<p><i>Adams died of a heart attack on 11 May 2001, aged 49, after resting from his regular workout at a private gym in Montecito, California. He had unknowingly suffered a gradual narrowing of the coronary arteries, which led at that moment to a myocardial infarction and a fatal cardiac arrhythmia.</i><p>[1] <a href="https://en.wikipedia.org/wiki/Douglas_Adams#Death_and_legacy" rel="nofollow">https://en.wikipedia.org/wiki/Douglas_Adams#Death_and_legacy</a>