Can DNA Tests Tell You If You Have a Cycling Gene?
I probably didn’t need to take a DNA test to know that I’m a middling athlete, but there it was: On a sliding scale titled “Your Aerobic Potential,” an arrow pointed decisively at the word “low.”
Really? Low? I was hoping for at least “above average.” I like to think that I’m better than at least some people, like those flatlanders I blew past on the local climb yesterday. There had to have been some mistake. Or at least missing information.
As direct-to-consumer genetic testing grows in popularity-more than 14 million Americans have had their DNA analyzed by the two largest players, AncestryDNA and 23andMe-new tests are targeting amateur athletes. At last count, close to 40 companies offer some kind of gene testing for athletes, often packaged with training and nutrition advice based on the results. Prices start around $50 a pop.
I had signed up with one of the best-known providers, a UK-based startup called DNAFit, which offers a range of services, including an analysis of fitness-related genes, and one that looks at genes related to metabolism and diet. “We help you be the best you can be with unique genetic insights,” its website promised. A package had arrived in the mail containing a clear plastic tube and instructions to fill it with my saliva. A few weeks after I mailed my spit in, the report from DNAFit landed in my inbox.
“We’d say you’ve got kind of a low aerobic potential,” said Craig Pickering, a former British Olympic sprinter who is now DNAFit’s chief scientific officer. “You’re more likely to see small improvements and you’ll probably have to work much harder.”
I’m not the only one who learned something new about myself via genetic testing. Another rider I know, Phil, took a similar test, and it had reached a similar conclusion to mine. “Your genetic profile indicates you may not be as genetically well-suited to endurance sports as elite endurance athletes,” declared his report from coaching company Carmichael Training Systems.
Unlike me, Phil knew very well the results were laughably wrong. Phil-last name, Gaimon-was a pro for domestic and international road teams, including Cannondale-Drapac (now EF Education First-Drapac p/b Cannondale), for a decade, before leaving the pro peloton in 2016.
I started to wonder: Are genetic tests for athletes worthwhile? Can they help us train more intelligently? And how much of a role do genes play in determining talent? Is there a “bike gene?”
Seeking answers, I subjected myself to tests by four different companies. I also persuaded three current or former pro riders to be tested: Gaimon, retired German hardman Jens Voigt, and Taylor Phinney, an Olympian with Olympian parents.
If anyone has the “bike gene,” Gaimon probably does. For his first 19 years on Earth, he showed no signs of anything elite, much less athletic. But when he started riding a bike, he soared from the entry-level Category 5 up to near-elite Category 2 in six months. Within two years, he had a domestic pro contract with Jelly Belly and was soon riding in breakaways in the Tour of California. Not too long after that, he was racing in Europe. “I didn’t use the word ‘genes,’ but I sort of compare it to discovering a superpower,” he says.
A good number of us, it turns out, might be secret superheroes. In the 1990s, researchers at Louisiana’s Pennington Biomedical Research Center and four other institutions recruited about 750 sedentary people to ride exercise bikes three times a week for 20 weeks. When they measured the subjects’ VO2 max (maximal oxygen uptake) at the end of the study, they found something striking: Average oxygen-using capacity for the group had gone up with training, but there was an immense variation. Some had more than doubled their VO2 max, while others barely moved the needle.
Further investigation revealed that the key factor seemed to be heredity: Siblings and immediate relatives were much more likely to have improved by roughly the same amount. The HERITAGE Family study, as it was called, pointed to a major role of genetics in determining one’s VO2 max, as well as what sports scientists call “trainability,” or how strongly individuals respond to training. The authors estimated that up to 47 percent of an individual’s response to their training program was determined by genes.
The next question was obvious: Which genes?
The human genome consists of between 20,000 and 25,000 genes. The genetic tests I took do not sequence the entire genome, an elaborate endeavor that can cost around $1,000. Instead, they look for single nucleotide polymorphisms (SNPs), which are variations in a single DNA building block at a specific location on a given chromosome.
The variants we would look for are those that promote endurance and give us a high VO2 max, plus muscular power to let us wind up in a sprint, and the ability to recover from hard rides. But it turns out the genetics that underlie those traits are not so simple to identify.
One of the first sports-related genes to be discovered was called ACTN3, which popped up in a study of elite Australian sprinters circa 2003. It contributes to the development of fast-twitch muscle fibers. This “sprint gene” is now probably the most-famous and most-studied gene in sports.
Another early example was a gene called ACE, which helps regulate blood pressure. People with one variation of the ACE gene tend to have a higher maximum heart rate and greater
oxygen-carrying capacity, and tend to be better at endurance sports. A different version of ACE, studies suggested, supports strength and power.
The discovery of these “sports genes” launched the direct-to-consumer genetic testing business for athletic talent. When they first appeared in the mid-2000s, many of these tests were targeted at parents who wanted to know if their children would grow up playing football, winning medals as track sprinters, or running marathons.
Since then, the field has gotten more sophisticated-as have the products. My report from DNAFit was a sleek 15-page PDF that began with “Understanding Genetics” and continued on to the main dish: my “Power/Endurance” score, based on a complex algorithm weighting my results from 15 SNPs on genes relevant to athletic performance.
According to DNAFit, my physiology was 70.6 percent favorable to power-oriented sports like weightlifting, sprinting, and track cycling, but only 29.4 percent geared toward endurance pursuits such as long-distance running, mountain climbing, or road cycling. Hmm. I did win a Cat 5 track sprint that one time. But I hate weightlifting and have the skinny arms to prove it. I love long, steady climbs on the bike and hiking up mountains. I have gravitated toward these kinds of endurance activities since college-and now I find out that I’ve been a secret sprinter all along?
The point of the test was not to determine my athletic destiny, said DNAFit’s Pickering. Rather, it was to help me train more effectively. “What we’re interested in is matching people to the type of training that works best for them,” he said. “In the gym, you’re probably going to respond better to high-intensity resistance training.” Indeed, I was soon receiving emails prodding me to sign up for one of DNAFit’s training programs, like the 100-Day Muscle Builder, at about $62 per month.
But I still had one overarching question: Was any of this actually true?
My quasi-scientific experiment-to get actual pro cyclists tested, and to compare my results among different services for consistency-aimed to answer this question. It didn’t take much persuading to get Voigt, Phinney, or Gaimon on board.
“I’m curious, because I’ve been told I’m like a freak of genetics my whole life,” said Phinney when I reached him at his training base in Girona, Spain. The son of Olympic road race gold medalist Connie Carpenter Phinney and Tour de France stage winner Davis Phinney, he seemed to have been bred for cycling glory. And indeed, he competed in the 2008 Olympics in Beijing at the age of just 18, finishing 7th in the individual pursuit.
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Not surprisingly, DNAFit rated Phinney’s aerobic potential as “high,” and found that he was more or less equally balanced between power and endurance genes. Jens Voigt also scored well on endurance, which makes sense for a rider who seemed to be in every Tour de France breakaway ever and also set a world hour record (since broken) in 2014, at the age of 42.
But there was still Gaimon’s mystifying result from Carmichael Training Systems, which said he had “typical” endurance ability. This conflicts not only with his real-life result of making the ProTour, but also with his recorded VO2 max of 88.7, which is near the upper end of the testing range even for pro cyclists. (A fit amateur cyclist will likely have a VO2 max in the 40s or 50s.) “I think the [DNA] test is missing something,” Gaimon noted drily.
Things got even stranger when I submitted my own DNA to the three other services: Athletigen, Orig3n, and Carmichael Training Systems.
DNAFit and Carmichael both use a third-party provider called Helix to do the gene sequencing, then apply their own interpretation to the raw data. Orig3n does its own sequencing. And Athletigen accepts data from third-party platforms like 23andMe and AncestryDNA (I uploaded my data from 23andMe), and offers its own sequencing.
Not surprisingly, CTS and DNAFit agreed that my aerobic potential is nothing special-DNAFit rated it “low,” and CTS said it’s “normal.” Athletigen offered a little bit more hope. Things got brighter when I opened my report from Orig3n. It concluded that, contrary to my other results, I really was a genetically gifted endurance god. Strange. Were these companies looking at entirely different genes to draw their conclusions?
“They absolutely could be using different variants to test the same phenotype,” says Emily Spencer, a genetics research at the Scripps Research Institute in La Jolla, California, who has written critically about direct-to-consumer fitness genetic testing. “It doesn’t necessarily mean either is ‘wrong,’ just that neither is the complete story. ”
So what does the research community think of genetic tests? In 2015 an international group of two dozen leading sports scientists and geneticists published a joint paper that began with this sentence: “The general consensus among sport and exercise genetics researchers is that genetic tests have no role to play in talent identification or the individualised prescription of training to maximise performance.”
It’s not that they disagree with the premise that athletic ability is largely influenced by heredity. The problem is that the science behind the genes being tested for is far from settled. “Scientists who work in this area will tell you very clearly that you cannot use any of this genomic stuff as predictive,” says Timothy Lightfoot, a professor of genetics at Texas A&M University.
It all boils down to the complexity of genetics-and the complexity of athletic talent. There are a few obvious traits that depend on single genes, such as the “coffee
gene,” which impacts how quickly one metabolizes caffeine. For more complex traits, however, the picture is less clear. “A phenotype like exercise endurance is incredibly complicated,” says Lightfoot. “As is trainability, as is strength.”
Even if you did get your entire genome sequenced, for $1,000 or so, we simply have not uncovered all of the genes that play a role in athletic ability, much less figured out how they might interact. The handful of sports-
related genes that have been identified to date all have fairly
small individual effects on performance. Even ACTN3, the “sprinter gene,” has been found to confer just 1 to 1.5 percent of sprint speed performance among elite male athletes.
In the joint paper mentioned above, the authors wrote that both ACTN3 and ACE-the best-studied sports genes-have “zero” predictive value in determining athleticism. More importantly, genetics researchers say, we don’t even know which or how many genes are involved in the traits that contribute to sports performance. “They’re [genetic testing providers] trying to tell you what the puzzle depicts, based on one or two pieces,” David Epstein, author of The Sports Gene, tells me. “They don’t even know how many pieces there are in the puzzle.”
Even fairly simple traits turn out to be mindbogglingly complex. Take height, which is easy to measure, and highly inheritable-scientists believe that about 80 percent is genetically determined, if childhood malnutrition is not a factor. Still, a study of more than 250,000 subjects, published in 2014, found that at least 697 gene variants determined the eventual height of a growing child. Even those genes, the authors estimated, accounted for only about 20 percent of the variability in height.
In this light, the formula used by DNAFit, which it calls its Peak Performance Algorithm and is based on just 15 genes that are each given a weighted score, does seem rather flimsy.
Making Sense of Bill's Results
DNAFit
Cost: $120*
Genes tested: 15 core “sports genes,” plus a handful pertaining to nutrition and metabolism.
Surprise finding: I’m a sprinter, apparently
Caveat: Per the user consent agreement, Helix owns your data; you can’t download the file the way you can with 23andMe and other services.
*price include $40 sequencing by Helix.
Carmichael Training Systems
Cost: $60*
Genes tested: Not specified, but traits range from endurance to strength to caffeine metabolism to B vitamin levels.
Surprise finding: High bone density, contrary to family belief that we have brittle bones.
Caveat: The report covered general traits ranging from endurance to nutrition to bone density, but felt vague. A follow-up consultation with a CTS coach helped answer some questions but quickly turned into a sales pitch for coaching services.
*price include $40 sequencing by Helix.
Athletigen
Cost: $45 for Athletic report, and $50 for Nutrition report
Genes tested: Unknown. Uses 23andMe or AncestryDNA data.
Surprise finding: I should eat less chargrilled meat, due to low genetic levels of enzymes that remove toxins from the body.
Caveat: My report had conflicting conclusions about whether I was suited for endurance. On one page, I was; on the next, I seemed to have poor endurance.
Orig3n
Cost: $149 for fitness test, $149 for nutrition test
Genes tested: 27 genes pertaining to endurance, strength, metabolism, recovery, and injury risk.
Surprise finding: See below.
Caveat: My results from Orig3n differed drastically from the other services on more than a dozen different genes, suggesting that some sort of lab error had taken place. The accuracy of their testing has come under question before: A reporter from Gizmodo submitted a DNA sample from her dog, and got back training advice and analysis (but no recognition that it was dog DNA).
Speaking of height, let’s go back to Taylor Phinney. Even if he did inherit a monster engine from his parents, he also grew to be 6'5". He could train for years and never be able to haul his 180-plus-pound bulk over the Alps and the Pyrenees to win the Tour de France-although his size and power profile probably did help him finish eighth in last year’s Paris-Roubaix. So according to his test results, Phinney has a handful of favorable endurance genes, but he also has at least 697 other genes that made him grow so tall and muscular.
Either way, Phinney does not spend much time dwelling on his cycling pedigree. He has learned that natural talent only takes you so far. “I quickly found out when I turned professional that everybody in the World Tour is extremely talented,” he says, “but whether that talent is a physical gift or more of a mental gift depends on the person. In my experience, the mind trumps the body, every time.”
He cites fellow rider and friend Mark Cavendish, who is widely known for winning sprint stages almost at will. Cavendish, he points out, has been open about the fact that he wins races in spite of past test results that indicated a mediocre (for an elite athlete) physiology. “They were almost taking him off the team because his [VO2 max and lactate threshold] test scores were so low,” Phinney says. “But mentally he just knows that he’s the best, and he’s the fastest, and he’s going to win.”
He sees the same characteristic in his father, Davis Phinney, who was also a fast sprinter who won two Tour de France stages and over 300 other bike races in his career: “I don’t think that my dad physically was that talented either, at least as a cyclist. I think he had this really deep, strong, innate confidence.”
That confidence does not register on genetic tests; it’s nevertheless an important part of his athletic toolkit.
Clearly, Phinney would not have gotten anywhere close to where he did without a pretty stellar set of genes. We just don’t know what those are yet, exactly. And we may not anytime too soon-as Lightfoot explained, finding the genetic recipe for elite-level performance has been a relatively low priority in genetics research.
But maybe that’s okay. Circling back to my own results, when I first started riding more than 30 years ago, little did I know my aerobic potential was “low.” Maybe it was. I’m not ever going to be a pro-that’s been sorted. But that didn’t stop me from riding and racing all these years, and it won’t stop me from heading out onto my favorite local climb next spring, a 45-minute, switchbacked piece of singletrack called Jenni’s. And when I do, I will once again revel in the feeling that ride by ride, week by week, I’m getting better, stronger, and faster-regardless of my genetic makeup.
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