Athletic success is the result of a combination of genes and training.
Your muscles and metabolism are very adaptive, and they respond to training by becoming stronger and better. They can only improve because training stimulates your body to produce enzymes and other proteins which are then used to make your metabolism more effective, and your muscles, bones and tendons stronger.
Even genes that code for the same protein can be slightly different between people. This is called polymorphism. They might therefore produce a slightly different protein, which does not matter in daily life but could make the difference between winning and losing during a race.
As your genes code for every protein your body makes, most scientists assume that the genetic profile you have inherited is at least partially responsible for the differences in athletic capabilities between people.
On the other hand, we all know that you have to train hard and have the right lifestyle to improve, and therefore training and healthy living are likely to influence the activity of your genes. The question therefore is: what is more important: your training or your genetic profile as you have inherited it?
Studies on families and twins
Researchers have compared strength and muscle power between family members and twins, but their results are controversial. Genetic influences could be found in all studies, but their importance was very different from one study to another. Moreover, some studies suggest that genetic influences become less important as you get older.
VO2 max, or the maximal amount of oxygen that you can burn to produce energy, is a popular measure of your maximal work rate. It varies considerably between individuals, and studies have shown that high values run in families. You can increase it by training, but the extent to which you can do so is also inherited, probably mainly from your mother’s side.
If you want to perform at the highest level, you cannot afford to lose time due to injuries. Studies have shown that Achilles, rotator cuff and anterior cruciate ligament injuries run in families, and two genes have been linked to a higher risk of getting injured.
The perfect genetic profile
Athletic performance is associated with many characteristics, such as muscle strength, size of your heart, tendon elasticity etc…, and therefore with a large number of genes. As yet, 23 polymorphisms have been associated with endurance performance. According to studies, the chances to have the perfect profile are very low, less than 1 in 20 million. You have to add to this the odds of having the perfect psychological profile. Psychology is very important in sports, but as yet we know very little about its genetics.
It is unlikely that somebody will ever inherit the perfect or even a near perfect profile, but the chance that exceptional talents will be born increases as the population grows. It is therefore likely that records will continue to be broken.
Do we really need it?
In 2009, Spanish researchers looked at the 7 most important genes known to be associated with fitness in 46 world-class endurance athletes and compared it with the same genes in non-athletic controls and in the general population. All the participants were Spanish.
On average the genetic profile of the top athletes was only slightly better than that of the other groups. None of the elites had the perfect genetic profile and only 3 of them had a favourable polymorphism for 6 of the 7 genes. A top-3 finisher of The Tour de France had a profile comparable with the average Spanish population. This is remarkable as The Tour de France is one of the hardest endurance events regularly undertaken by competitors. They concluded that anybody with an average profile could make it to the top.
The importance of the right training in the right environment at the right time
In his book “Bounce”, Matthew Syed argues that athletic success is only the result of many hours (at least 10.000) of deliberate practise and training during optimal periods of life and has nothing to do with inheritance. He agrees Erickson who suggests that intense exercise activates dormant genes that we all have.
Unfortunately, this does not correspond to what we experience in daily life: who has never been beaten by a “newbie”? We can all name athletes who have progressed to the top in a minimal amount of time. Some people improve much quicker than the average, while others can handle a larger training volume, or have almost spontaneously a better technique.
Nobody will ever contradict that many hours of hard training are a must, but ignoring all the good science about inherited genes is probably a mistake, just as ignoring the importance of training would be one. Nevertheless, Matthew Syed has thought-provoking arguments and his book is a “must read” for everybody who is interested in this subject.
It is likely that our genetic profile, training and the interactions contribute to our performances. We need more research, as we probably have not found all the genes yet. We might not even have discovered the most important ones.