After winning seven gold medals in Commonwealth Games, 41-year-old table tennis player Sharath Kamal left no stone unturned in his preparations for the 2024 Paris Olympics, which began on July 26. In March, he opted for genetic screening, an emerging science that is becoming popular among sportspersons. “Age is not on my side. I decided to eliminate all elements that could hinder my performance,” Kamal tells Down To Earth (DTE). The tests informed him of his food allergies and the minerals and vitamins his body needed. Kamal is not the only one to use these tests to boost performance. In 2017, the Board of Control for Cricket in India reportedly introduced genetic testing to help the Indian men’s cricket team improve speed, fat-burning, endurance, recovery time and muscle-building.
“These tests were introduced in India around 2011. Many players were individually getting these assessments done before,” says Ramji Srinivasan, former strength and conditioning coach of the national cricket team. Genetic tests, initially used for detecting diseases or predispositions, entered the sporting world in the late 1990s, when scientists began to gather evidence that genes influence various aspects of athletic performance, including endurance, flexibility and psychological traits.
Genetic tests read instructions stored in deoxyribonucleic acid (DNA), a two-metre-long molecule present in our cells. The code in our DNA maintains our bodies’ functions, determines our appearance and influences our likelihood of developing certain diseases. Genetic data consists of four letters or chemicals—Adenine, Guanine, Cytosine and Thymine—repeated in specific sequences. These sequences are read by cellular machinery to create amino acids, the building blocks of proteins. Genes dictate how individuals absorb, metabolise and expel nutrients, explaining why some do this differently than others.
Some athletes have won the genetic lottery, prompting scientists to probe the role of genes in athletic prowess. For example, Eero Antero Mäntyranta, a Finnish skier who participated in four Olympic Games in 1960s and won seven medals, had a red blood count 20 per cent higher than that of other athletes, even though his training regime was not different. In the 1990s, scientists discovered that 50 of 200 members of his family, including the Olympian, carried a rare mutation in a gene that increased the oxygen-carrying capacity of his red blood cells by 25-50 per cent and gave him a performance boost.
On average, 66 per cent of differences in athlete status can be explained by genetic factors, with the remaining shaped by environmental factors such as practice, nutrition, birthplace and the availability of medical and social support, as per a 2007 study published in the journal Twin Research and Human Genetics.
Scientists study genetic variants, which are differences that arise from mutations in specific DNA sequences. These mutations contribute to unique athletic characteristics and traits.
Fifty years after the structure of DNA was first decoded, former US President Bill Clinton and former British Prime Minister Tony Blair announced a significant scientific achievement in 2000: the initial sequencing of the human genome as part of the Human Genome Project, launched in October 1990.
Within 24 hours of this announcement, the information was made publicly available, allowing scientists worldwide to begin decoding the mysteries of human biology
In 1998, angiotensin-converting enzyme (ACE) gene, involved in the control of blood pressure and skeletal muscle function, first captured scientists’ attention. A 2002 study published in the journal Exercise and Sports Sciences Review strengthened this theory after finding that a variant of this gene, ACE-I, was linked to endurance performance, giving runners, rowers and mountaineers an edge over others. The study found another variant, ACE-D, associated with strength gain, essential for weightlifting.
Another gene linked to sports performance is alpha-actinin 3 (ACTN3). This gene produces the ACTN3 protein found in skeletal muscle tissue, particularly in type 2 or “fast-twitch” muscle fibres. These fibres are known for generating short, powerful movements. The gene has two variants: R577 and 577X. People possessing the latter carry a mutation that disables the production of the ACTN3 protein. A 2002 study published in the American Journal of Human Genetics found that 107 Australian sprint athletes who had competed in an international event had a lower frequency of the 577X variant. Endurance athletes, on the other hand, carried more of the 577X variant. These results have been replicated in players in Taiwan, Greece, Italy and Spain, according to a 2020 study in the Indian Journal of Orthopaedics.
Though ACE and ACTN3 are the most extensively studied genes linked to athletic performance, scientists have, so far, found links between 128 DNA markers and athlete status. Genetic testing has also helped athletes optimise their diet. Kamal, for instance, discovered he is lactose intolerant. These tests can also identify specific food allergies and recommend dietary adjustments to improve performance. “Specific genes have been mapped with nutritional information. They are quite accurate,” says Henry Chung, lecturer at the School of Sport, Rehabilitation and Exercise Sciences at the University of Essex, UK.
A gene-diet interaction affects body composition and circulating vitamin D levels, influencing athletic performance, injury risk, and post-training recovery. For example, individuals with low iron levels struggle with haemoglobin production, reducing the blood’s oxygen-carrying capacity. Three genes are associated with low iron status. A 2019 review published in the journal Frontiers in Nutrition identified 18 genetic variants that can modify the relationship between various dietary factors, such as caffeine, iron, and calcium, and performance. Research shows that genetic differences may increase or decrease tendon and ligament damage.
Four genetic variants have been linked to damage, response to injury and recovery time. The collagen type V alpha 1 gene helps in the formation of connective tissue in the musculoskeletal system. One variant of this gene, T allele, has been linked to the increased risk of injury, according to a 2018 study published in the journal Sports.
Studies have yet to settle the debate on why players in certain sports emerge from specific parts of the world. For example, Kenya has bagged 113 medals at the Olympics overall, primarily in track and field and boxing. Many scientists assume that genetic advantage is key to their performance. However, research has yet to identify a gene or combination of genes linked to their success. “Genetic makeup alone does not determine performance. It is a result of the gene-environment interaction,” says Amit Ghosh, professor, All India Institute of Medical Sciences, Bhubaneshwar.
Not long after the discovery of sports genes, commercial businesses began cropping up, offering direct-to-consumer tests. As early as 2001, Australia mandated that their boxers undergo genetic screening for the apolipoprotein 4 gene variant after a 1997 study published in the journal JAMA suggested that it could be linked with a higher risk of brain damage. The US and the UK, too, use this tool to screen injuries or adapt training programmes. In the following years, gene tests began to be used for scouting talent. In 2015, Uzbekistan’s National Olympic Committee tested people for 50 genes to identify future champion athletes. Three years later, in 2019, China’s Ministry of Science and Technology announced complete genome sequencing to identify athletes for the Olympic Winter Games 2022 that were held in Beijing.
So far, sports associations from five countries have used gene testing, according to a 2020 study in the Indian Journal of Orthopaedics. In India, Mapmygenome, a Hyderabad-based genomics company, launched its testing services for sports in 2013. “Initially, the product was only available for elite athletes, but now anyone looking to improve their health or fitness can opt for these tests,” says Anu Acharya, CEO of Mapmygenome. She adds that the company has seen increased demand from people over 40 preparing for marathons or parents keen on understanding their child’s ability in sports.
The company also works closely with sports academies. Before the Rio Olympics in 2016, the company collaborated with the Pullela Gopichand Badminton Academy in Hyderabad. The following year, players at the Academy had their genes screened to enable them to design a personalised diet regime. Others like badminton players Srikanth Kidambi and Pullela Gopichand, cricketer Divya Gnanananda and fitness trainer Diksha Chhabra are some of the known names who opted for these tests, according to the company.
Though these tests have become accurate in detecting genes, scientists have been critical of them, stating that the association between genes and sports performance is weak. A 2012 study published in the Indian Journal of Human Genetics examined the presence of the ACE gene in 147 athletes and 131 nonathletes and found no significant difference between the two groups.
Another 2011 study, published in the same journal, evaluating ACTN3 in India found no significant difference in the distribution of the gene between athletes and nonathletes. One reason why the studies offer contradictory results is that they have small sample sizes. In 2015, the International Federation of Sports Medicine in Italy, which has national sports medicine associations from five continents as members, observed that such tests by private companies should not be used for predicting sports performance and talent identification, and that the current level of genetic knowledge is being misrepresented for commercial purposes.
Cut to 2024, there are still gaps in the understanding of how genes interact with each other. The majority of studies so far have evaluated genes independently even though a lot of the genes interact with each other. “It is possible that an individual could have a gene that could be blocking the functioning of the ACTN3 gene. We need to study these interactions,” says Chung. Researchers worry that coaches and parents may base their decisions on these genetic tests, pushing children towards certain careers. Even Acharya strongly advocates against this. The entrepreneur has the ACTN3 gene but her daughters do not. “I have a constant discussion with my daughters about this. We should not use these tests to discriminate against people, but to improve performance,” she says. Srinivasan, who now runs a sports training centre, Sports Dynamix, in Chennai, says he stopped using genetic testing at his academy in 2015-16 after three years because of challenges in inferring data.
“I cannot find a good nutritionist or a person who can decipher the data and give it to me. We need experts who can help us with that,” he says. Other issues include the risk of invasion of an individual’s privacy. In 2005, professional basketball player Eddy Curry Jr was forced by the Chicago Bulls, an American professional basketball team, to get genetic testing to detect any predisposition to a rare heart condition. The test was added as a clause to Curry’s new long-term contract offer.
The sportsperson declined it, arguing that the test was violating his right to privacy.
Along with gene testing in the 2000s, biometrics, analytics and more recently, artificial intelligence (AI) have begun to make inroads into sports. “Earlier, the coach would measure the heart rates of athletes before training. The heart rate would tell if they are rested,” says Kannan Pugazhendi, founder-director of the Indian Institute of Sports Medicine, an educational institution in Chennai.
Now, sportspersons use wearables like watches, allowing coaches to monitor their heart rate and sleep pattern, which are essential for recovery and play a role in deciding the training routine. Companies are also increasingly turning to AI to find new gene variants that could be linked to sports performance. “The AI craze is huge now. Its use in this field picked up in 2023,” says Chung. Initially, companies used to manually scan studies linking genes with sports, or use softwares to do the job. AI scans the literature instantly, he adds.
The technology is also being used to help scout talent. India has embraced data analytics and AI to identify and groom athletes aged 8-19 years under the Khelo India Rising Talent Identification programme, launched in March 2024. The goal is to conduct 2 million assessments across the country throughout the year. Under the scheme, the Sports Authority of India (SAI) is using a proprietary AI algorithm to analyse data such as strength, endurance, flexibility, height, weight, and explosive strength, providing a percentile calculation for each sports discipline. “For example, if we see that children from a specific region have good explosive strength, we can predict that they could excel in sports that demand this parameter,” says Devesh Yadav, assistant director at SAI.
He adds that the tool will also help in talent transfer. “If we find that a child, for instance, would perform better in hockey than athletics, we can shift him or her accordingly,” he says. The children will be selected based on decisions made by coaches and AI. So far, SAI has completed 50,000 talent assessments. “We plan to declare the results in the next three months,” Yadav says. Srinivasan lauds this initiative but is cautious. “ We cannot just go by AI-generated numbers or a child’s fitness,” he says.
Pugazhendi says the world needs more studies by independent scientific bodies, with help from coaches, to better the science that has future potential.
This was first published in the 1-15 August, 2024 print edition of Down To Earth