I Ran Faster Because of My "Sports Gene"

Back when Eero Mäntyranta was the greatest endurance athlete in the world, there was nothing remarkable about his physical appearance.

Sure, in pictures I had collected of him from the 1960s, his slightly tan skin seemed more like something born of the Mediterranean coast than Arctic Finland's pine forest, but it was nothing to warrant a second look.

That's why I was startled by Mäntyranta's face when I stepped through the door of his home, in the tiny Arctic hamlet of Lankojärvi. Today, at age 75 and working as a reindeer farmer, his skin is closer to the hue of the red paint that comes from this region's iron-rich soil than to that of the snow. His daughter had told me on the drive up that his skin had changed, but I didn't quite expect this shade of cardinal, mottled in places with purple.

Mäntyranta's skin has progressively reddened because his body produces an overabundance of red blood cells. The condition was first discovered during a routine physical for the Finnish military when he was 18. The doctors initially worried that it might be dangerous, but Mäntyranta was perfectly healthy. In fact, he was more than that.

Almost as soon as he could walk, Mäntyranta could ski—it was, after all, the best way to get across the frozen lake to school—and as a seven-year-old he began to win local cross-country ski races. By age 11, Mäntyranta could polish off the competition in the entire municipality of Pello.

Still, he had no thoughts of athletic stardom. Not until, as a teenager, he found himself in dead-end work in postbellum Finland, cutting and hauling timber alongside men who had fled to the remote north to evade the law. Mäntyranta knew that the Finnish government was in the habit of giving promising young cross-country skiers cushy jobs as border patrol agents, so he started racing again.

His success was immediate, and at 22 he brought home a gold medal in the 4x10K relay from the 1960 Olympics in Squaw Valley, California.

At the 1964 Games in Innsbruck, Austria, Mäntyranta was peerless. He won the 30K race by over a minute and the 15K race by 40 seconds, a margin of victory never equaled at the Olympics before or since. Mäntyranta would compete in two more Olympics and win seven medals in all.

But his high red blood cell count—measured at up to 65 percent above an average man's—could no longer be ignored. Passed off for years as a medical oddity, in the midst of a world-beating athletic career it led to speculation that Mäntyranta was blood doping—artificially boosting the supply of red cells that carry oxygen to muscles. (As we now know, Tour de France riders famously injected synthetic versions of the hormone EPO, which spurs the body to produce more red cells.)

It was not until 20 years after his retirement from skiing that scientists pinpointed the truth, that Mäntyranta was naturally doped. Finnish geneticist Albert de la Chapelle found the single DNA letter swap in Mäntyranta's EPO receptor gene. The EPO receptor is like a lock that awaits the key—the EPO hormone. Once the key is in the lock, the receptor signals a bone marrow cell to start the process of creating a red blood cell.

In Mäntyranta's body, the braking mechanism that halts red cell creation was disabled, so production ran amok. Mäntyranta's niece, Elli, also has the gene mutation, and was world junior champion in the 3x5K relay in 1970 and '71. His nephew, Pertti, has it too, and won gold in the 4x10K relay at the 1976 Olympics.

"It's an advantage," says de la Chapelle. "There's no question."

I met Mäntyranta during the reporting of my book on the genetics of athleticism,The Sports Gene, for which I also had some of my own genes tested. I had been an 800-meter runner at Columbia University. I was paired up in training with a blue-chip recruit named Scott, who would enter every season in excellent shape, while I would start in dismal form. But once the hard training began, I would gain on Scott, rapidly, and surpass him. Teammates and coaches assured me that this was because I was just tougher than Scott. I had to be, they said, because he was so much more talented. And because he was not improving, he must just be a head case.

But Scott and I were doing the exact same workouts, stride for stride, day after day. Years later, I came across the most famous exercise genetics study in history, the Heritage Family Study. In Heritage, DNA was collected from 98 two-generation families who were put through five months of identical training on stationary bicycles. Amazingly, despite identical training, some exercisers did not improve their aerobic capacity—the amount of oxygen their bodies could use, and a powerful predictor of endurance—at all, while others improved more than 50 percent. And how much each subject improved had nothing to do with how good he or she was to start.

In a 2011 breakthrough, the researchers found 21 gene variants—slightly different versions of genes between people—that predicted changes in aerobic capacity. Heritage subjects who had at least 19 of the "favorable" versions of the genes improved their aerobic capacities three times as much as subjects who had fewer than 10.

When I had one of the Heritage scientists look at my genetic data, he informed me that I should be a "high responder" to endurance training. With the Heritage Family Study as my filter, I now believe that the narratives foisted upon Scott and me were nothing more than stories of convenience that obscured a tale of genes and gene/training interactions that was playing out hidden from sight.

Scott was like one of the Heritage subjects who started with a high aerobic baseline but barely improved, while I began with a low baseline and improved rapidly, and thus was granted the flattering side of the narrative.

I improved so significantly in college that I made the All-East team in the NCAA and was later presented with a dazzling wood and glass box known as the Gustave A. Jaeger Memorial Prize, given to a four-year Columbia athlete who "achieved significant athletic success in the face of unusual challenge and difficulty." My difficulty being that I just stunk at first. Certainly, I worked hard, but Scott did the same work.

As exercise genetics continues to progress, more people will have the chance to peer into their sports genes. How we choose to view the information, that's another matter entirely. I now credit much of the Jaeger Prize to my genes. Mäntyranta, though, cannot be convinced that his rare gene mutation was behind his success. Through his daughter's translation, he insisted it was his "determination and psyche."