During marathon history results have implied that there may be a genetic component involved in giving many nations their big champions.
The first United States great runners were Native Americans, specially from the Hopi Tribe, who understood running as a connection with their gods and ancestors. Among them we could talk of Lewis Tewanima, who placed ninth in the marathon during the 1908 Olympics and claimed silver in the 10000 metres during the Olympics four years later.
Athletes from Finland ruled in many distances from the 1912 Olympics until 1976. It was the time of “The Flying Finns”, a golden generation that started with Hannes Kolehmainen, who won four Olympic gold medals ranging from the 5000 metres to the marathon, and finished with Lasse Virén, who won another 4 Olympic gold medals, in the 5000 and 10000 metres in the 1972 and 1976 Olympics.
In the United States the running boom started during the 1970s, especially propelled by the victory of Frank Shorter in the 1972 Olympic marathon, and the victories of Alberto Salazar in Boston and New York in the early 1980s.
Besides the sporadic winning news of some Tarahamura Indians from Mexico in ultra-marathons, nowadays the international marathon scene seems ruled by athletes from East African countries, especially Kenia, Ethiopia, Eritrea and some others.
Therefore, genetics has been linked to elite international marathon performance. Trying to find these sport performance phenotypes, or in other words the genes involved in marathon success, has prompted a whole new area of genetic studies.
The main factors related to running performance are maximal oxygen uptake (VO2max), lactate threshold, running economy and oxygen uptake kinetics. It has been found that VO2max is heritable by 40-50%, confirming the importance of genetics in the performance. But obviously not everything is genetics, as there are other key factors involved, such as training.
A recent big meta-analysis has found a total of 14 different genes that could be associated with endurance performance:
PPARAGC1α, PPARAGC1β, NRF1, SIRT1, HIF1A, AQP1, AMPD1, BDKRB2, NFIA-AS2 and TSHR
They are mainly involved in ATP generation (the primary energy fuel of all living things), glucose and lipid metabolism, thermogenesis and muscle fibre type composition. They could contribute to an adequate body fluid balance and improvements in blood flow and oxygen delivery to exercising muscles.
Important for the collagen in the ligaments, that influence motion, it could improve the energetic cost of running and consequently the performance.
ACE, NOS3 and ADRB2
These genes codify the enzymes involved in cardiovascular function, contributing to blood pressure and vasodilation control. A variant of the ADRB2 has been associated with faster marathon times by improving blood delivery to muscles and a better recycling of lactate to produce energy.
All the studies included in the analysis have their own limitations, as sometimes they include athletes from the same ethnicity, different endurance sport disciplines, or a small sample size.
Other genes are linked to power-related sports. Every Olympic sprinter tested had a copy of a R allele in its ACTN3 gene. This allele is involved in the production of proteins used in fast-twitch muscle fibres, determinant in short running sprint distances.
Although we can see the results of these studies are far from determinant, the risk of gene manipulation is already a possibility. The transference of genes or genetically modified cells into an individual to enhance its athletic performance is called genetic doping. Anticipating this issue, the World Anti-Doping Agency (WADA) prohibited its use back in 2003, but how could it be tested? Nowadays there is not enough knowledge to test it or know if it has already happened.
As history has sadly proved us, if something can be done, it is done, no matter the consequences. We can be sure that genetic doping will happen, even with all the potential risks that could be associated: what would be the future effects on athlete’s health?
Despite gene doping potential is clear, genetic testing could also be useful to identify the most suitable runners among the young athletes. This tool would allow to optimise training and improve marathon running performance. Therefore, the increasing interest in this research area.
It is important to know that besides genetics there are other factors involved. Nobody will start running sub-2h marathons because his/her good genes are good. Training, diet and mental strength must be also considered. Additionally, there are more than 100 thousand genes in the human genome, all of them interacting among themselves and with the environment. Maybe is not a unique gene necessary to improve your running performance, but a combination of them.
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Thanks for reading.
Genes and Elite Marathon Running Performance: A Systematic Review.
Moir HJ, Kemp R, Folkerts D, Spendiff O, Pavlidis C, Opara E.
J Sports Sci Med. 2019 Aug 1;18(3):559-568.