In the years following the sequencing of the human genome, sports scientists chose single genes that they guessed would affect athleticism and compared different versions of those genes in small groups of athletes and nonathletes. Unfortunately for that research, single genes often have tiny effects, so tiny as to remain undetectable in small studies. Even the genes for easily measured traits, like height, generally eluded detection because scientists had underestimated the complexity of genetics.
One of the innovative strokes of Bouchard and an international group of colleagues in follow-up work to HERITAGE was to let the genome tell the scientists which genes to study, as opposed to the scientists’ guessing genes beforehand. In an experiment separate from HERITAGE, the group put twenty-four sedentary young men through six weeks of cycling training. They then took samples of muscle tissue from the men before and after the training program and examined which genes were more or less “expressed”—in other words, their protein-creating activity was turned up or turned down. Differences in expression levels of twenty-nine genes distinguished the high from the low responders. That is, certain genes, though present in all subjects, were more or less active in highly trainable people compared with less trainable people. The gene expression signature held true when the researchers subsequently used it to predict the training responses of a separate group of young men who were already fit and who were put on a schedule of intense interval training. (Some of the human high-responder genes also predicted exercise adaptation in rats.) Importantly, the expression levels in the twenty-nine-gene set were unaltered by exercise, indicating that those genetic expression levels constitute a genuine personal signature, not the result of prior training.
It is still unknown whether the predictor genes that Bouchard and crew have identified are the important genes themselves or whether they are simply markers for broader networks of genes. Gene expression data suggests that hundreds of genes are involved in each person’s response to exercise, and that some, like the RUNX1 gene, are likely involved in changes in muscle tissue or in the formation of new blood vessels. Still others are found among genes that have helped organisms adapt to life in the oxygen-rich atmosphere of Earth that ocean bacteria started to create more than three billion years ago.
Because of the complexity of genetics, results should always be interpreted cautiously. Nonetheless, the HERITAGE findings are a stride toward understanding the genomic scaffolding of trainability, and independent work is bolstering the findings. In a separate study at the University of Miami, GEAR (Genetics Exercise and Research) researchers put 442 unrelated and ethnically diverse adults on identical cardio and weight training programs and found, just as in HERITAGE, that genes involved in the body’s immune and inflammation processes predict individual differences in aerobic trainability. Some of the same genes that emerged in HERITAGE also stood out in GEAR.
When I suggested to Tuomo Rankinen, one of the HERITAGE study scientists, that some people appear to be “aerobic time bombs” awaiting training, he laughed and suggested “trainability bombs” would be a better term. It is an idea that muddles the notion of innate talent as something that appears strictly prior to training. As to the other end of the trainability spectrum, an editorial in the Journal of Applied Physiology noted: “Unfortunately for the low responders in these studies, the predetermined (genetic) alphabet soup just may not spell ‘runner.’” There is a bright side, though, even for them.
The ultimate goal of the HERITAGE research was in line with the original promise of the Human Genome Project: to move toward personalized medicine. If doctors know how a patient responds to exercise, they can determine whether an exercise plan can usher in a desired health benefit, such as a drop in blood pressure or rise in cardiovascular power, or whether a particular low responder needs to be medicated. Fortunately, every single HERITAGE subject experienced health benefits from exercise. Even those who did not improve at all in aerobic capacity improved in some other health parameter, like blood pressure, cholesterol, or insulin sensitivity. (Then again, a small number of exercisers with two copies of a particular gene variant actually went in the wrong direction in terms of insulin sensitivity, suggesting that while physical activity moves most people away from becoming diabetic, it might actually move a small number of people closer.)
A spectrum of low to high responders appeared in every physical quality measured, and the research team is busy looking for genes that predict trainability for each trait. Already, genes that help account for an individual’s drop in blood pressure and heart rate with training have been identified. Variations of the CREB1 gene, which influences the heart’s pacing, were found to help predict the magnitude of the drop in a person’s heart rate as he or she became more fit.
A side effect of the HERITAGE findings was to identify genetic underpinnings, at least in that study sample, that tell the Doug Boyles from the Jim Ryuns. Not that Boyle was a slouch. In the mile time trial at the beginning of his senior year, he was third on the Wichita East team in 4:39. Ryun, meanwhile, cruised to a 4:06.
By that point, though, Ryun and Boyle, initially equally intimidated by the prospect of a five-mile run, were continents and oceans apart in terms of their skill levels. Ryun had already been to the Tokyo Olympics and was one of the best runners in the world. Besotted with the success he had dreamed of back when he was making Superman shakes, and bolstered by personal attention from his coach, Ryun made the most of a high responder’s body, pushing through 120-mile weeks and crushing workouts that are painful for most runners even to think about. Undoubtedly, Ryun’s single-minded dedication to running as fast as possible foisted him into the athletic pantheon. But that followed on his body’s extraordinary ability to respond to training.
One can only wonder where on the HERITAGE study spectrum the Ryun family would fall. When posed the question of whether other Ryun family members showed signs of being very responsive to endurance training, Ryun says: “That’s a good question. But I was the only person in my family who was athletic. Nobody else was interested.” What about his younger sister? “I don’t think she’s run at all,” he says. “She’s not very gifted in that area.” Then again, neither was big brother. Or so it seemed, before he started training.
This is a story that plays out on every track in America—similar boys and girls miraculously become less similar despite training similarly—albeit in far less dramatic fashion. In the absence of any biological explanation for these stories, we find other narratives to explain them, narratives that are not without consequences.
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The air in the Armory Track and Field Center at 168th Street in Manhattan is notoriously stale. It was January 2002, my senior indoor track season at Columbia University, and I was not going to miss that desiccated air. At night, after races at the Armory, scratching chest pains kept me awake. Why not just skip all the training and inhale iron filings if that was going to be the payoff? But I was having a good start to the season, and on this particular day I was looking forward to testing myself against my training partner, Scott.
A moment ago, we had been warming up together, but now I’d lost him. When Scott reappeared he told me he was only going to run the first 600 meters of the race and then drop out. It was a strange choice in the final moments before the race, 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. Despite the directive, I didn’t go out of my way. Scott specialized in the same event I did, the half-mile, or 800-meters. I was a walk-on who had yet to make the varsity traveling team and was less than enthused at the thought of recruiting a phenom who was two years my junior but already running a good five seconds faster in the half-mile than my two minutes flat.
In 1997, the year I took up track as a high school junior, Scot
t set a fourteen-to-fifteen-year-old age group record in his home county in Canada for the 400-meters. Not only did he appear to be talented, but he was competitive, smart, and experienced. Like other promising young runners in Canada, he had joined a club team that was more professional in its training than most U.S. high school teams. Scott just seemed like a natural. His mother had been the Canadian juvenile 100-meters champion in 1969, and she and Scott’s father were the female and male track and field MVPs for the University of Windsor in 1973–74.
So why had the natural suddenly decided, before the gun had even gone off, to drop out of the race at 600 meters? Scott was struggling mentally that season. His times weren’t improving, and planning to drop out was a safety valve that would release the pressure built up around him. If you drop out at 600, no one can say you failed, again, to improve your 800 time. No one can say that you have talent everyone else would kill for, but because you’re not getting faster you must be a head case.
I, meanwhile, had improved relatively rapidly. I came to track late in a high school career that included football, basketball, and baseball, so I was less experienced than my recruited training partners. But, looking back, I believe that I was like a set of the HERITAGE subjects, a high responder with a low baseline.
When I first started running track in high school, I had such 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 result was so low as to be 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.
Each fall during college I would report to school having done the same exact, prescribed light summer training that all the half-milers did. 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. When I visited the pulmonologist in the winter, the results showed that I was miraculously transformed into a young man with the power to exhale as forcefully as my peers. Low baseline, quick responder. Every member of my training group seemed to have a higher baseline aerobic capacity, but we all responded to training to varying degrees.
In Scott’s case, he would come into the season in relatively 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 Scott’s need to open the emergency pressure valve that day at the Armory.
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. It was true, of course. I used to throw up after most hard practices. I would steal away to some secluded garbage bin—if I could make it in time—so that my teammates wouldn’t see it.
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. When I reflect on it now, though, with the HERITAGE Family Study as my filter, I believe that the story was nothing more than a narrative that obscured a tale of genes and gene/training interactions, a tale that was playing out hidden from sight.
One day during my senior year, while searching for a cloistered nook in which to puke, I spotted Scott, already retching. And then it happened again. I saw him heaving his brains out over a trash can. 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 as 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 he and I were doing the exact same workouts, stride for stride. Perhaps I was gaining on him because I had a low baseline and a rapid training response. Long before I had ever even heard of HERITAGE or high and low “responders,” I would literally 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 one HERITAGE study scientist examined some of my genetic data, he indicated that I am likely an above-average responder to aerobic training. I also know that my blood pressure drops rapidly when I exercise. 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 based on explosive exercise. (If there is a lesson to be gleaned from this branch of exercise genetics, it’s that there is no one-size-fits-all training plan. If you suspect that you aren’t responding as well to a particular training stimulus as your training partner, you might be right. Rather than giving up, try something different.)
On that January day at the Armory, with the weight of expectation lightened by his decision not to take the race seriously, Scott ultimately decided to finish, but I blew by him with 150 meters left to run 1:54 and beat him for the first time. It was thirty 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 athletic success in the face of unusual challenge and difficulty.” Let’s see someone with a high baseline aerobic capacity try to win that one.
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Some people improve their endurance more rapidly than others. They are gifted with high trainability. Others are gifted with high baseline aerobic fitness. But how high can that baseline be? Or, the crucial question for sports: does anyone have elite-level aerobic endurance before training? It is a question that Norman Gledhill, a professor of kinesiology at York University in Toronto—who has administered the National Hockey League’s predraft combine—began to consider in the 1970s. Gledhill’s curiosity was ignited by a few cases in which a modicum of endurance seemed to precede training. The story of Nancy Tinari, a high school student at nearby George S. Henry Secondary School, was one that lodged firmly in Gledhill’s mind.
In 1975, Tinari showed up to gym class in cutoff jean shorts and battered canvas Keds and proceeded, with no prior training, to cruise two miles in the twelve-minute run test. “I didn’t think of myself as a jock,” Tinari says. “I wasn’t into equipment, or following training. I had no real interest in it.” Fortunately for her, the man holding the stopwatch that fall day, George S. Gluppe, had a lot of interest in it, and “was just smart enough to realize I had someone special on my hands,” he says. Gluppe pestered and prodded Tinari to start training. “You know, Nancy, you could be an Olympic runner,” he told her. She laughed. Ultimately, though, Tinari gave in and made good on those words.
As soon as she started training, she started winning. After high school, Tinari ran at York and then as a professional. In 1988, despite mustering a measly thirty to thirty-five miles a week of training because of injuries, she competed in the 10K at the Olympics in Seoul. To this day, Tinari holds the Canadian national record in the 15K.
Norm Gledhill never forgot the tale of the girl who was discovered in gym class and became York University’s greatest runner. He was often reminded of it through the 1980s and ’90s as he and his colleague Veronica Jamnik endurance tested thousands of subjects, from elderly women to elite cyclists and rowers. Now and then, they would find someone with a
VO2max that defied their sedentary existence.
In the late nineties, Gledhill and Jamnik, along with York researcher Marco Martino, set out to see whether they could identify and study such naturally fit folk. Part of their work was to administer fitness screenings to young men hoping to become Toronto firefighters. Over two years, the team gave VO2max tests to 1,900 young men.
Among them were six men with absolutely no history of training whatsoever who nonetheless had aerobic capacities on par with collegiate runners. The “naturally fit six,” as Australian physiologists Damian Farrow and Justin Kemp call them in their sports science book Why Dick Fosbury Flopped, had VO2max scores more than 50 percent higher than the average untrained young man, despite being inclined to couch-bound activities. When the York researchers examined their “hidden talents,” as they call them, they saw that the naturally fit men had a crucial gift, through no discipline or effort of their own: massive helpings of blood. They were endowed with blood volumes that could have been mistaken for those of endurance-trained athletes. “It’s the increased diastolic filling,” explains Gledhill, referring to the part of the heartbeat when the heart muscle relaxes to allow blood back in. “When you fill up the right side of the heart with more blood, then it pumps more blood into the left side, and the left side pumps it out into the body. The [return of blood to the heart] is enhanced because of the extra blood volume.”
An increase in blood volume is one of the telltale signs of a well-trained athlete. And, on occasion, a pro athlete has been caught doping with a blood volume loader in an effort to increase endurance. But not the naturally fit six; they just came out of the box that way, naturally doped.
The Sports Gene: Inside the Science of Extraordinary Athletic Performance Page 10