You know the definition of “hardcore” in the endurance racing world has changed when No. 10 on the list is a comparatively “easy” marathon run, completed by some of the slower contenders, in five and a half hours — this following a 112-mile bike ride and 2.4-mile swim in choppy ocean waters. But consider the extreme competition on this list. In one race, you may find yourself hauling 32 pounds of pennies through a cold, rainy Vermont backwoods at 4 a.m. while memorizing Greek text. In another, you’ll run two marathons each day for 50 consecutive days, around the same course, over and over and over again. Given the choice, I’ll gladly pick the Ironman World Championship winding through scenic Kailua-Kona, Hawaii any day.