By all accounts, Paul Milligan was healthy. He ran marathons and triathlons, he was a cyclist, and he'd been doing CrossFit for the past decade. But after a few workouts left him surprisingly short of breath, he went to the doctor, who found major blockages in four arteries, necessitating a quadruple bypass. Scarier still, he had no symptoms at heart rates lower than 140 bpm. “The cardiologist told me if I had just been a jogger or cyclist and did not exercise at a CrossFit (workout) level of intensity … my five-year survival (prognosis) was less than 50 percent,” Milligan said.