From Scientific American:
He was all red. Not just the crimson sweater with knitted reindeer crossing his belly, but his actual skin. It was cardinal dappled with violet, his nose a bulbous purple plum. In the pictures I’d seen of him in Sports Illustrated in the 1960s—when he’d won three Olympic gold medals in cross-country skiing—he was still white. But now, as an older man, his special blood had turned him red.
Mäntyranta, who passed away in late 2013, had a rare gene mutation that spurred his bone marrow to wildly overproduce red blood cells. Red cells convey oxygen to the muscles and the more you have, the better your endurance. That’s why some endurance athletes—most prominently Lance Armstrong—inject erythropoietin (EPO), the hormone that cues your bone marrow to produce red blood cells. Mäntyranta had about 50 percent more red blood cells than a normal man. If Armstrong had as many red blood cells as Mäntyranta, cycling rules would have barred him from even starting a race, unless he could prove it was a natural condition.
During his career, Mäntyranta was accused of doping after his high red blood cell count was discovered. Two decades after he retired Finnish scientists found his family’s mutation. A niece and nephew also had it; she was a world junior ski champion, he an Olympic gold medalist in the sport. None of the family members who didn’t have it were ski racers. Mäntyranta wasn’t doping, but you would never know that from his physiology. What does “a level playing field” mean for skiers who trained just as hard as Mäntyranta but were left behind him, gasping for air as he won the Olympic 15K race by 40 seconds, a margin never equaled at the Games before or since? Whereas Armstrong became a pariah for blood doping, Mäntyranta’s naturally doped …