Rainer Martini/LOOK-FOTO / Getty ImagesThe expression “genetic mutation” is often thought to be a red flag for risk of developing diseases or the direct cause of certain health problems. But most alterations in our genes are neutral or non-pathological. They are seen as polymorphisms, which are possible alternative forms (variants) that a gene can present. In more than 3,000 scientific papers published in the past 10 years, polymorphisms in 240 human genes that make up nearly 1% of the total for our species have been associated, at least once, with an issue that will be widely discussed at the Rio de Janeiro Olympics in August: athletic performance. Despite the number of publications, the potential influence of most of these genetic alterations on the actual practice of sports is still viewed as tenuous or difficult to prove. Some of these mutations, however, could be promising candidates for genetic markers that are the molecular signature of the DNA of potential champions. By cross-tabulating the information on polymorphisms found in four genes (ACTN3, ACE, AGT and BDKRB2), the team led by molecular biologist João Bosco Pesquero at the Federal University of São Paulo (Unifesp), coordinator of the Athletes of the Future project, has created the first Brazilian version of a genetic code that could indicate an athlete’s strongest point.
Roughly speaking, the molecular score indicates whether an athlete’s greatest physical advantage is stamina (a prerequisite for endurance contests), muscle strength/explosion (which generally translates into high speed in competitive terms), or an intermediate case between these two extremes. The goal of the Unifesp project is to build a database of genomic information specific to Brazilian athletes that could be useful in guiding the choice of physical activity best suited to each individual, besides helping to discover athletic talent at an early age and serving as a guide for improving an athlete’s training and performance. “I’ve always researched genetic alterations that cause loss of function, particularly diseases that affect muscles,” Pesquero explains. He recently presented some of his research findings at the March 2016 edition of the Research on Sports and Healthy Living workshop jointly organized by FAPESP and the Netherlands Organization for Scientific Research (NWO). “I decided to study the other side of the coin: mutations that cause an increase in function and create abilities that help athletic performance.”
Since 2009, the initiative has already collected DNA samples from approximately 1,000 Brazilian athletes and former athletes from various sports: Oscar and Hortência (basketball), Gustavo Kuerten (tennis), Aurélio Miguel (judo), and Joaquim Cruz (track and field). Genetic material was also collected from athletes who participate in team sports such as soccer and baseball, in addition to 13 teams from the 2013 Brazilian basketball league. Most of this material is still being analyzed, although researchers say that some results are illustrating the potential of the approach. One of the clearest examples of using the molecular index occurred during the 2012-2013 season of the NBB, Brazil’s new premier professional men’s basketball league, when the team training method was altered on the basis of genomic information.
During the first round of the championship, the Palmeiras team had lost 15 of its 17 games and was in last place. Faced with this desperate situation, the technical committee, under the direction of physical trainer Chiaretto Costa, a member of the Athletes of the Future team, decided to change the training plan for the second round. He implemented individualized training for each athlete based on the genetic profile obtained through Unifesp tests. The university team had already collected and analyzed the DNA of the players and had the results in hand. The strategy worked. Palmeiras won 10 of the 17 games in the second round and its athletes, who were always getting hurt, no longer got injured. The results of the work on the São Paulo research team were reported in an article published in May 2015 in the journal Medicine & Science in Sports & Exercise.
The logic behind the new genetically-driven training regimen was simple: don’t fight molecular biology; invest in the parameter on which a player receives the highest score on the DNA test. If the test pointed to the fact that the athlete had genes with mutations that gave him more muscle strength, that should be the aspect emphasized in his training. If one’s strong point were aerobic stamina, the main focus of the training would be to maintain endurance capacity. “The plan was just the opposite of what is usually put into practice on the teams,” says exercise physiologist Paulo Correia, at Unifesp, one of the Athletes of the Future researchers and former Olympic cyclist in Moscow (1980) and Los Angeles (1984). “Normally, teams try to increase a runner’s strength and build up endurance in strength athletes.” In other words, they try to improve the weak points rather than enhance the strong points.
There were some challenging moments for the researchers, such as when center Marcão, then 28, was often injured and had trouble on the court. Data on his four genes indicated that he had more stamina than strength, a problem for one who plays the key position near the basket, and has to fight for the ball with athletes who are tall and strong. The solution in this case was to reduce the amount of muscle strength training. If, for example, the athlete did ten 100-pound bench presses, which exercise the pectoral muscles, he would start using half the weight and increase the number of repetitions. This way, the technical staff focused on the athlete’s stamina and avoided exposing him to injuries from excess weight training. On the court, the player was also instructed to be more active and play more outside the lane. Thus, his opponents would tend to tire out before him and the Center could still be going strong late in the game. In the next season, the Athletes of the Future team repeated the experiment with another NBB team, this one from São José dos Campos, under the direction of physical trainer Adilson Doretto. The results were similar to those experienced with the Palmeiras team.
Gene for speed
Although several genetic markers have been associated with superior performance in certain sports, some researchers in the field are cautious with respect to what this correlation really means. “It’s always hard to replicate these studies,” says physician Masashi Tanaka of the Tokyo Metropolitan Geriatric Hospital, an expert on the link between genetic factors and athletic performance. The Japanese researcher is beginning a study in which he will sequence the entire genome of a small number of marathon runners from Kenya and Ethiopia, two African countries famous for their long-distance runners. “To have a larger sample in the studies, we need to also include amateur athletes along with elite athletes,” the physician says. Alun Williams, an expert in sports and the genetics of physical fitness at Manchester Metropolitan University (United Kingdom), shares this thinking. “Many findings that associate gene variants to sports performance are probably ‘false positives’ and hard to interpret,” says Williams. “These studies have not been reproduced by other research groups and were conducted using small samples of athletes, often combining data on athletes from different sports.”
For now, the gene deemed most reliable for determining whether an athlete has more strength or stamina is ACTN3, probably the gene most studied for this purpose. Pesquero’s team published an article in 2015 in Genetic Testing and molecular biomarkers, describing a new and simpler method to sequence ACTN3. Located on chromosome 11, ACTN3 is responsible for the production of alpha-actinin-3, a protein activated exclusively in fast twitch muscle fibers that retract at between 40 and 90 milliseconds. These fibers function without oxygen and generate the energy needed to drive physical actions that call for great strength or intensity for a maximum of two to three minutes. It is this fleeting mechanism that sustains extreme yet short-term movements like sprinting in a 100- or 200-meter race or lifting heavy weights over one’s head for a few seconds.
An alteration in a single nitrogen base causes this gene to manifest itself in two ways in humans: the “normal” version named R, which is functional and produces alpha-actinin 3; and the altered variant named X, in which such protein is not synthesized. Humans carry two copies of ACTN3. They can therefore be homozygous (RR or XX) or heterozygous (RX). Several international studies on elite athletes indicate that short distance runners, known as sprinters, tend to have at least one and sometimes two copies of R, or the functional variant of the gene. Most of the protein would improve the performance of athletes on tasks that rely on the fast twitch muscles. Long-distance runners, who need stamina, tend to be XX. The complete absence of the protein would cause the body to better adapt to long-duration exercises, which derive energy from oxygen consumption. The determination has resulted in ACTN3 being named, with the use of much hyperbole, the gene for speed.
Professor Sandra Lia do Amaral Cardoso at the Exercise Physiology Laboratory of São Paulo State University (Unesp), in Bauru, and her former doctoral student Thiago José Dionísio of the Federal University of São Carlos (UFSCar), analyzed the frequency of the ACTN3 gene variants found in 100 athletes among14- to 20-year-old youth league players from the São Paulo Soccer Club. Most of the athletes (57%) had the RX genotype, in which one copy of the gene was normal and the other presented the mutation. The other 29% were RR, having in theory more strength or explosive power, and 14% were XX, indicating a molecular profile closer to that of long-distance runners. The researchers observed that the players that had at least one copy of the R allele had better results on short- distance running and jumping tests while those with one X allele distinguished themselves on the issue of strength. “In the older players, this relationship was more apparent than in the younger ones,” says Cardoso, whose research was funded by FAPESP. The study, whose findings have only been shared at scientific conferences, also detected the association of a variant of the angiotensin-converting enzyme (ACE) gene, indicating better performance on the parameter for strength and explosive power. An extended version of the study conducted on 220 players from São Paulo is in its final phase of journal submission.
The process of using the genetic profile as a guide to finding the ideal sport for an individual appears mechanical and precise. Researchers know that this line of simplistic and deterministic thought cannot be sustained alone, though. “Genetics is very important, but we cannot forget the environmental and psychological factors that affect athletes,” says physician Victor Matsudo, scientific coordinator of the São Caetano do Sul Physical Aptitude Laboratory Study Center (CELAFISCS). “It would be ingenuous to think that you can find a champion just by looking for a gene or an enzyme.” Besides innate biology, other factors influence sports practice and performance: nutrition, amount and type of training, psychological and motivational aspects, public policies and local culture. Finally, as with a good number of diseases, the weight of the external aspects cannot be neglected and should be analyzed along with the molecular information. “But it is important to map the key genes for sports,” Pesquero says. “Sometimes, information about a single gene can be enough to produce noticeable effects.”
Pesquero cites the case of hypertension, a topic in many of his studies. Although it is commonly known to be a health problem linked to lifestyle and the action and interaction of various genes, in many cases, the medicines that keep blood pressure under control act on only one gene, ACE, which encodes the angiotensin-converting enzyme. Along with ACTN3, ACE is part of the genetic index composed of four molecular markers for sports adopted by the Athletes of the Future. The other two genes are angiotensinogen (AGT), (a protein encoding gene that is also important for regulating blood pressure) and bradykinin receptor-B2 (BDKRB2) (a vasodilator compound.)
It is not always possible to conduct genetic tests and alter the training routine of elite athletes. In these cases, it is more feasible to study people who engage in sports for pleasure or as a hobby. Since 2006, physical education Professor Ana Sierra has studied the cardiac reactions that occur in amateur marathon runners. She is completing her doctorate on the topic at the School of Physical Education and Sports at the University of São Paulo (EEFE-USP). Sierra recently introduced genetic analyses into her studies, thanks to collaboration with Pesquero’s team. In a study soon to be published, conducted using the DNA of 49 male marathon runners between the ages of 20 and 55, she found that certain individuals with mutations in the ACE gene and in another gene called BNP appear to recover more slowly after completing the 42-kilometer (km) race. “Cardiac fatigue from a marathon can last for up to 15 days,” Sierra says.
Another recent study by EEFE researchers involved 150 healthy men who underwent running tests at two constant speeds: 10 and 12 km/hour. The results surprised the authors of the study, published in July 2015 in the journal Annals of Human Biology. Individuals who had an RX profile for the ACTN3 gene, in theory less able than those with XX to withstand physical efforts that required endurance, stood out for having consumed significantly less energy in moving during the races. “On average, the energy expenditure of the heterozygous individuals with RX genotype was 7% less at 10 km/h and 9% less at 12 km/h when compared with the homozygous RR and XX individuals,” says Leonardo Pasqua, principal author of the study, conducted as part of his master’s thesis under the orientation of Professor Rômulo Cássio de Moraes Bertuzzi.
It is important to obtain genomic data on Brazilian athletes and the national population: the incidence of mutations that help in the practice of certain sports can vary widely according to a country’s ethnicities. The form of the ACTN3 gene that seems to confer better performance in tests of endurance is more common in Africans than in Caucasians for example. That is why there are more than a dozen international initiatives underway to genotype their athletes, especially in Europe, the United States and Asia. Pesquero is focusing on this work in Brazil while developing a new genetic index associated with sports, now using 16 rather than the current four genes. For this increased version of the molecular score, his team sequenced the genetic material of 69 elite Brazilian track stars. “We’re including genes linked to factors other than strength and endurance such as the question of motivation among athletes and the capacity for recovery from certain types of injury,” says the Unifesp molecular biologist. The gene responsible for making brain-derived neurotrophic factor (BNDF), a protein that helps stimulate the maintenance and growth of neurons, seems to have repercussions on athletes’ motivation for instance. The creatine kinase (CKM) gene, another gene under analysis, is important for the process of recovering from muscle injuries and inflammation. With his studies, the Athletes of the Future project is hoping to introduce the genetic arsenal in service of physical activities in initiatives that seek to mine sports talent among Brazil’s children and improve the level of health of all Brazilians through physical activity.
1. The relationship between physical performance and genetic polymorphism in soccer athletes (nº 2011/21586-8); Grant Mechanism Regular Research Grant; Principal Investigator Sandra Lia do Amaral Cardoso (Unesp); Investment R$139,420.00.
2. Analysis of polymorphisms in genes linked to muscle strength in elite Brazilian athletes (nº 2012/14056-5) Grant Mechanism Scholarships in Brazil – Master’s; Principal Investigator João Bosco Pesquero (Unifesp); Recipient Elton Dias da Silva; Investment R$45,194.00.
LIMA, G. H. 0. et al. Association between gene ACTN3 and basketball position in elite athletes of Brazilian League. Medicine & Science in Sports & Exercise. V. 47. No. 5s, p. 424. May 2015.
SCHADOCK I. et al. Simple method to genotype the ACTN3 r577x polymorphism. Genetic Testing and Molecular Biomarkers. V. 19, No. 5, p. 253-7. May 2015.
PASQUA, L. A. et al. The genetics of human running: ACTN3 polymorphism as an evolutionary tool improving the energy economy during locomotion. Annals of Human Biology. July 6, 2015.