Long-distance runner, motivational speaker, and yogurt salesman Dean Karnazes is a living legend in the running community. Among his many feats are marathons through Death Valley and the South Pole, an 80-hour treadmill session where he ran 350 miles without stopping, and the infamous Endurance 50—50 full marathons in 50 states over 50 consecutive days. His training and medical team, discovering that there was almost no scientific research into such a feat, decided to keep their own record of his health over the course of the event. That’s how they discovered something incredible: Dean Karnazes’ muscles are almost invulnerable to damage. The amount of creatine phosphokinase (an enzyme that heals muscle tissue and leads to soreness) in his bloodstream after the first week was less than a fifth of the amount of CPK present in an average runner after just one marathon. Also, while fooling around with his blood, they discovered that he just plain had more of it than most people, allowing him to stay hydrated and healthy for longer periods of time. After Karnazes finished the Endurance 50, his science team concluded that if he was kept properly hydrated and fed, he could literally run at around 7-10 MPH until he died of old age. That’s a man I’d like to buy a yogurt from!