Originally Posted by
datlas
Rarely, you can get scar tissue in the heart but I believe this is really for ultra-distance activities. I see nothing wrong with 4 hours on the bike. Or even more. One of my former cycling friends was a commercial pilot and rode/rides lots and was not told to limit his riding.
Yeah you would know more than me on it, but the cases I've heard about that are people doing the truly stupid events like Leadville or Western States. It's not something I've heard of hitting any marathoners or Ironman sorts, even those who do a couple per year for years on end.