Even while the nation is getting fatter and unhealthier, more men are breaking 3:00 in US marathons now than in several decades, and more women are breaking 3:30 than ever before.

Last April’s Boston Marathon saw one of the most horrific moments in mass-participation sports. Bombs made out of pressure cookers exploded near the finish line, killing three people and injuring 264 others, with 14 requiring amputation. But not long before all that happened, something amazing took place, something that mostly escaped notice due to the bombings.