The obvious answer or follow up question should be “beat him at what?” If the answer to this is a marathon then even the great man himself will probably concede a lot of people could beat him as long as you'd already left him way behind when you reached the last few hundred metres! Obviously though I am referring to the 100/200m at which he is currently the fastest person in the world ever, unless you are getting pedantic about this piece of anthropology.

So what is it that makes him so fast? Well there are lots of things at least some of which are genetic. It is the genetic portion of the article title that I want to discuss in this post. Recent advances in DNA analysis have revealed a number of genes that appear to have an influence on sporting performance. One of these genes (ACTN3 R577) codes for a protein called alpha-actinin-3. This protein is only found in fast twitch skeletal muscle fibres, the type of muscles needed for sprinting and other high speed/power activities.

Alpha-actinin-3 appears to have a structural role in the muscles as well as possibly being involved in the growth of more fast twitch muscle and also in the use of glycogen as a fuel source. For more detail on DNA transcription and protein production see here. The key point is that a variation in the code can lead to different versions of genes with knock on effects for the function of the proteins they code for. With ACTN3 R577 (imagine that as a twitter hashtag) the R allele will code for alpha-actinin-3 production whereas the X allele will not. So the 3 possible outcomes in each person are the RR genotype, RX genotype and XX genotype.

Several studies on elite vs non-elite athletes have shown a significantly higher prevalence of the protein (from the genotypes ACTN3 R577 RR or RX) compared to non-elite power/speed athletes and also compared to elite and non-elite endurance athletes (higher percentage of XX genotype). In fact during testing leading up to the 2012 Olympics in London none of the 100/200m Olympic qualifiers had the XX genotype! It has been estimated that for 100/200m running the ACTN3 gene accounts for just under 10% of overall performance, so if you don't have an R allele you are up against it if you want to be an elite speed athlete in most sports.

Overall I didn't write this blog to tell you that your DNA will stop you doing things though. The beauty of DNA analysis as it continues to progress is that you can use it to maximise your potential. If you have the R allele (along with some other genes, see more on ACE I/D for example) then not only are you more suited towards power/speed activities but your responses to training will be better with high intensity, shorter bouts of exercise with a low to moderate volume. Also you will be able to efficiently use glycogen in the muscles as an energy source. Even if you do want to do a marathon or similar endurance event you will still benefit from some higher intensity training like interval runs (eg 20x400m & 6x1000m) compared to the XX genotype who will do well on longer slower runs with higher mileage.

As for the XX genotype in power/speed activities yes you may struggle to be elite but you can still be damn good at anything if you train hard and smart. The point with the XX genotype is you will fatigue slower and be able to cope with a higher volume of training overall. Also you will burn fatty acids more efficiently as a fuel so you may want to consider shifting away from typical high carb diets to give your body the fuel it is built for using. For those who are serious about their sports performance DNA analysis is the future allowing you to plan a training and nutrition schedule that maximises your abilities for whatever goal you desire.


Published by Paul Hindle