“Now thanks to the latest breakthroughs in genetic testing you can find out what type of exercises and sports you are genetically built for.”
So goes the promotional blurb for one of the many companies now offering Direct-to-Consumer (DCS) genetic testing for athletic performance. These companies typically promise that knowing more about your genes will help you personalize your training, take advantage of your inherent strengths and overcome your limitations. They even promise to show parents their children’s pre-determined aptitudes.
It’s temptingly easy; the tests will be mailed out to you, and all you need do is send back a swab of saliva.
There’s no doubt this will appeal to conscientious and competitively-minded parents keen to direct their children towards the sports they might excel at. Coaches and sports teams seeking a performance advantage over the competition might be interested. And anyone hoping to find out about their inner Usain Bolt or Katie Ledecky can’t help but be tempted.
So is it scientifically valid?
Sort of. We all carry the same 20,000 genes or so, but different people often carry different variations of those genes. The two gene variants have been most consistently related to athletic performance are ACE I/D and ACTN3 R577X, which have been associated with endurance and power-related performance respectively. (You could say there is a “talented” and “untalented” version of each variant.) Around 200 genes have been linked to athletic performance, so far, but experts say that none of them have been linked strongly enough to suggest they can be used to predict athletic success or reveal enough to direct people toward different sports.
A position paper published in the BMJ in 2015, signed by a group of experts in genomics, exercise, sport medicine, disease, injury and anti-doping, said: “The general consensus among sport and exercise genetics researchers is that genetic tests have no role to play in talent identification or the individualized prescription of training to maximize performance.”
The authors also point out that half of the companies that offer genetic screening for athletic performance don’t publicly state which genetic markers they screen for. “The reasons for such apparent secrecy are presumably commercial sensitivity in part, although it is tempting to conclude that failing to publicize the tests conducted is a tacit admission that the scientific evidence supporting the genetic variants chosen is weak.” In short, the information such tests provide is unlikely to be useful, and possibly misleading.
We do know, however, that genes can influence personality and even intelligence. The cognitive scientist, psychologist, linguist, and popular science author Steven Pinker has said that whatever we measure, “Identical twins (who share all their genes) are more similar than fraternal twins (who share half their genes that vary among people). Biological siblings (who share half those genes too) are more similar than adopted siblings (who share no more genes than do strangers). And identical twins separated at birth and raised in different adoptive homes (who share their genes but not their environments) are uncannily similar.”
But even he notes that while genetics is a fascinating area of research (which is conducted across populations rather than in individuals), much of what your personal genome currently reveals can be better found out though old-fashioned methods. If you want to know your cholesterol level, then get a cholesterol test. If you want to know whether you are good at math, take a math test. Similarly, if you want to find out how good you are at running, run a race!
Of course evolution hasn’t produced a level playing field. You don’t need to be a genetic scientist to know that height and body composition have a huge influence on athletic performance and what sports people are likely to be good at. These are highly heritable traits. It’s estimated that:
- 60 to 80 percent of the difference in height between individuals is determined by genetic factors (20 to 40 percent can be put down to environmental effects, particularly nutrition).
- Aerobic endurance has a heritability of about 50 percent.
- Muscular strength has a heritability factor of anywhere between 30 and 80 percent.
A study by British researchers in 2007, which looked at 700 pairs of twins, showed that 66 percent of the differences in our sporting abilities could be put down to genetic differences.
But it is not a simple relationship. Hundreds of genes are likely to be involved, or variations of genes, with many of them yet to be identified. And while scientists have learned a lot about the connection between genes and sporting talent in the last decade, they’d be the first to say they don’t know enough to use that information to predict sporting talent or to guide people in their choice of sports.
This much we all know; genes are part of the equation (one you can’t do that much about), but so are training, nutrition, psychology and technique. At this stage at least, it might be better to concentrate on those aspects of athletic performance you know you can really do something about.