Editor's note: This is adapted from David Epstein's new book "The Sports Gene: Inside the Science of Extraordinary Athletic Performance."
It was January 2002, my senior indoor track season at Columbia University. I was having a good start to the year, and on this particular day I was looking forward to testing myself against my training partner, Scott.
But in the final moments before our 800-meter race, Scott told me he wasn't going to finish — that he would run the first 600 meters and then drop out. It was a strange choice, but one I understood.
Two years earlier, when I was a college sophomore and he was a high school senior, I hosted Scott on his recruiting trip. I knew he was a hot prospect because one of our assistant coaches gave me the "be very, very nice to this kid" talk. In 1997, the year I took up track as a high school junior, Scott set a 14- to 15-year-old age group record for the 400 meters in his home county of Canada.
Not only did he appear talented, but he was competitive, smart and experienced. By contrast, I was a walk-on who had yet to make the varsity traveling team. Scott was already running a good five seconds faster in the half-mile than my two minutes flat.
Over the next two years, though, our fortunes changed. By my senior season, Scott was struggling mentally. His times weren't improving, and dropping out was a safety valve. If you stop at 600, no one can say you failed, again, to improve your 800 time. No one can say you have talent, but that you must be a head case because you're not getting faster.
I, meanwhile, had improved relatively rapidly. I came to track late in high school, so I was less experienced than my recruited training partners. And I was certainly no natural. Each fall, I would report to school having done the same prescribed light summer training as all the other half-milers. And yet, I would invariably be in worse shape than the rest of the guys. But when the arduous training began, I would catch up, quickly.
Coaches and teammates who saw me — a walk-on — gaining on a coveted recruit praised me for my toughness and work ethic. Our head coach even once used me in a pep talk about the power of hard work, saying that I appeared to have so little innate ability that he felt pity watching me race during my freshman year.
My coach was right: I was a hard worker. But he couldn't see the genes that were also driving this feel-good tale, the ones that made the hard work matter — that made my body respond to training more rapidly than many of my teammates.
This pattern plays out on every track in America — similar boys and girls experiencing spectacularly dissimilar results despite training similarly — and is now well known to scientists. In the most famous exercise genetics study ever conducted, the Heritage (Health, Risk Factors, Exercise Training and Genetics) Family Study, a consortium of five universities in the United States and Canada subjected 98 two-generation families to identical stationary-bicycle training regimens, three workouts per week of increasing intensity that would be strictly controlled in the lab.
The researchers collected DNA from all 481 participants and tracked their aerobic capacity — the amount of oxygen their bodies could use during exercise — a powerful predictor of endurance. After five months of training, the variation was astonishing, ranging from about 15 percent of participants who showed little or no aerobic capacity gain all the way up to 15 percent of participants who improved dramatically, increasing the amount of oxygen their bodies could use by 50 percent or more.
Amazingly, the improvement that any one person experienced had nothing to do with how good she was to start. In some cases, the poor got relatively poorer (people who started with a low aerobic capacity and improved little); in others, the oxygen rich got richer (people who started with higher aerobic capacity and improved rapidly); with all manner of variation between — exercisers with a high baseline aerobic capacity and little improvement and others with a meager starting aerobic capacity whose bodies transformed drastically.
But along the curve of improvement, families stuck together, and in 2011 the Heritage research group reported a breakthrough in exercise genetics. They identified 21 gene variants — slightly different versions of genes between people — that predict a substantial portion of an individual subject's aerobic improvement. Heritage subjects who had at least 19 of the "favorable" versions of the genes improved their aerobic capacity nearly three times as much as subjects who had fewer than 10. The fortunate few with the beneficial gene variants became known as "high responders."
Looking back at my time training with Scott, I believe that I was like a set of the Heritage subjects, a high responder to training who started with a low aerobic baseline. When I first started running track in high school, I had so much trouble keeping up on longer runs that I went to a pulmonologist who tested my breathing and found that I was only expelling about 60 percent as much air as my peers with each breath.
Despite my youth, one of the doctor's follow-up reports notes that my results were consistent with very early stage emphysema. When I'm in bad shape, I'm in really bad shape. As in, I get winded walking up stairs. But when I visited the pulmonologist in the winter, with serious training having just begun, I had been transformed into a young man with the power to exhale as forcefully as my peers. Though every member of my training group seemed to have a higher baseline aerobic capacity, we all responded to training to varying degrees.
In Scott's case, he would come into the season in good shape and improve slowly and modestly, making it easy to brand him as a big talent who didn't capitalize on his formidable gifts. When a story like that sets in, it can be devastating, as evidenced by his need to open the emergency pressure valve and drop out of our 800-meter race before it was finished.
I, on the other hand, was on the receiving end of a far more flattering story. I was the talentless duffer who was ready to chew through a crowbar if it meant another quarter-second off my time. Pain was nothing to me, and I was making the most of my meager gifts.
I envied Scott when we ran side by side in practice, stealing glances at his fluid stride. But I just had to be tougher than him, I thought, because I didn't have the talent. It was an idea that coaches and teammates reinforced, as they do on every track team.
I embraced the image of the hardened walk-on who squeezed drops of improvement out of a talent-dry rock of a body. Long before I had heard of Heritage or high and low responders, I would start each season with the same positive self-talk: "Don't worry, they'll all be in better shape, but you respond to training like it's rocket fuel."
When I reflect on it now, though, with the Heritage Family Study as my filter, I believe this story obscured a tale of genes and gene/training interactions, a tale that was playing out hidden from sight.
It's not that the tale I told myself was made up. I used to throw up after hard practices, stealing away to some secluded garbage bin — if I could make it in time — so that my teammates wouldn't see it.
It wasn't that I was wrong about myself. Rather, I was wrong about my training partner. One day during my senior year, while searching for a cloistered nook in which to puke, I spotted Scott, already retching. And again, and again. A few times, I even saw him dart from the track halfway through a workout to throw up and then come back and finish the intervals.
Turns out, he was tough as titanium screws. I wasn't gaining on him from the start to the finish of each season because I was outworking him. Late in my college career, in fact, he and I were doing the exact same workouts, stride for stride.
When one Heritage study scientist examined some of my genetic data, he indicated that I am likely an above-average responder to aerobic training. And I suspect, based on the kind of training that most benefited me in college, that I am an even greater responder to sprint-based workouts.
Just as for aerobic training, low and high responders have been documented in experiments that use training programs centered on explosive exercise. Because we are all genetically distinct, there is no one-size-fits-all training program. If you suspect that your training partner is responding better to a particular exercise plan, you might be right.
On that January day in 2002, with the weight of expectation lightened by his decision not to take the race seriously, Scott ultimately did finish, but I blew by him with 150 meters left to run 1:54 and beat him for the first time. It was 30 seconds faster than I had run as a high school junior.
Ultimately, Scott moved away from the 800, running it less and less as his career wore on, opting for and succeeding in other events. As for me, I continued to get faster. My substantial improvement landed me a dazzling wood and glass box known as the Gustave A. Jaeger Memorial Prize, given to a four-year Columbia varsity athlete who "achieved significant success in the face of unusual challenge and difficulty." Let's see someone with a high baseline aerobic capacity try to win that one.
This piece was adapted from David Epstein's new book "The Sports Gene: Inside the Science of Extraordinary Athletic Performance," in agreement with Current, an imprint of Penguin Random House.
© 2013 David Epstein