Inside the dangerous, deadly world of IronMan — and the ‘crazy’ intense competitors willing to risk it all just to to finish

It took 45 minutes of resuscitation to get Mark Allen’s heart going and save his life. The then-50-year-old was swimming in the open-water portion of a half-Ironman competition in Georgia, when he went into cardiac arrest. “I have no memory of what happened,” the Newark, Delaware, financial supervisor told The Post of the 2014 incident....