Special Feature: The Science of Performance Genes
Everyone has DNA and every single cell in your body has an exact copy; a cellular fingerprint, individual to you. Genes tell the body how to build certain proteins which lead to eye colour, height, enzymes or even personality, therefore they possibly contribute to athletic ability and nutrition metabolism. The race is now on in the field of genomics to unravel genes, not only to personalise medicine, but also training and nutrition on the most individual level.
A Brave New World
When it comes to genes, “I believe we are really in the evidence creation phase and things are moving so quickly, sometimes too quickly, that evidence is lagging behind even for medical aspects. Technology is moving faster than our ability to create evidence.” says Dr. Paul Lacaze, Head of Public Health Genomics, Monash University. “We now know there is more than one gene involved in almost every outcome.
As the cost of technologies declined, we began to measure the whole genome. Instead of looking at genes we deem important, we now scan everything and find changes anywhere. Big studies called association studies can now look at 10,000 people with high-athletic ability and find genetic associations. The same applies to height, broccoli preference, or anything you could imagine. We know there are genetic components to sense of humour, depression or temper.” However, current understanding of genes is neither predictive nor precise.
“Take the BRCA gene mutation for breast cancer susceptibility, it increases your risk and you should do something clinically, however only a third of people who have breast cancer have this gene mutation,” Dr. Lacaze adds. “Trying to predict cancer or heart disease risk based on genetic variation, involves many genes,” says Nanci S. Guest, a dietitian and gene researcher with the University of Toronto who works with high-performance athletes.
“There are 700 genes associated with height outcome and only 10-12% have been discovered. However, we also know it only takes a single gene variation to produce blue versus brown eyes.”
The Perfect Athlete
“Predicting athletic genes is a real problem with countries testing children trying to predict the next Olympian, attempting to mould children from five years old. This could save time by not training a child in swimming if they are predisposed to martial arts,” Nanci notes.
“Potentially, we could predict lactate clearance or VO2max, power output or muscle building potential. However, there are numerous factors involved, including distance from a training centre, family income, or how was their first coach experience? Many things are involved in the path of making great athletes, genes are only one part.”
Dr. Lacaze agrees “Potentially, there is a higher likelihood of children of athletes becoming athletes," he said. "But is this due to witnessing their parents become athletes, or do they have genes predisposing them. It’s probably both.”
Dr. Michael Joyner, a Human Performance Expert at the Mayo Clinic, has a similar take. “The elites have already self-identified via competitive processes typically starting as teenagers," he said. "And as successful talent ID programs used in numerous countries show, performance based tests probably tell you more than genes. In cycling, it does not take rocket scientists to know the smaller, slighter riders are likely to be climbers and bigger riders potentially better time trialists.”
However, Nanci said “I can see the flipside, with five studies now showing genes for motivation to exercise. It’s possible athletes have higher pain thresholds and feel more motivated, but I still think people are jumping the gun by making big statements not shown in evidence.”
Dr. Nir Eynon and Professor David Bishop are currently recruiting for the Gene SMART Study at Victoria University, looking at performance genes. “We have researched the field for the last 20-25 years but prior to this there was a big study, the Heritage Study, starting to look at genes and performance”, says Dr. Eynon,“but I still don’t think we have enough evidence. Potentially, the only genes showing strong evidence are the alpha-actin-3 and the ACE gene.
However, these genes contribute less than 1% to the actual outcome.” Dr. Eynon explains why the performance field is very complicated, “You need many cases to prove your point and we don’t have many people running marathons in less than two hours 20 minutes,” or in the Tour de France.
“It minimizes the subjects and makes it hard to find associated genes. Currently, we are recruiting people to do four weeks of high-intensity training, including cyclists, and looking at their genes. We are seeing some people are gaining performance by 2-3% and others as much as 25%. This is where we believe genes are playing a part. The other really appealing thing however for genes, is injury risk. We did a big study looking at ligament injuries and genes, as we believe as a coach, you'd want to know what genes are predisposing specific players to injury, then manipulate their training or recovery to account for this.”
Although researchers are excited by future prospects, not all are as optimistic about its application.
“I think it’s a bit far fetched measuring genes of top athletes, then telling them how to train based on their genes versus the regime they’ve used already. You would probably find some top athletes have genes suggesting they shouldn’t be high-performing athletes. We have pretty good evidence that hard work, dedication, diet, and sleep give good marginal gains but this is not particularly sexy,” says Dr Lacaze.
“I’m not sure genes would tell experienced cyclists anything they or their coaches do not already know,” adds Dr. Joyner. “Over the years people have tried all sorts of subtle nuances and when you get beyond a few key principles it is really hard to say definitively what is best. Many serious recreational cyclists could improve by merely dropping a bit of weight, training more, and doing some hard 3-5 minute intervals and hard 30-60 minute rides regularly.
People spend big money on bikes but have pot-bellies! By and large, tried and true is still very current, especially for road cyclists. Plenty of mileage and some very high-intensity interval or hill efforts. If you think about it, the 1-hour record set by Eddy Merckx hardly budged until the aero bikes.”
“Though we are not currently using genes to tell people how to train, for nutrition it’s more black and white,” says Nanci.
“The evidence base is larger at this point. We know the variance in a gene is potentially going to change your body’s need for a nutrient or how fast it metabolises it, such as caffeine. For example, if you have an impaired ability to recycle vitamin C, you may need to get more vitamin C in your diet. If you have obesity risk genes, for example, exercise can override those, but currently, if you are born a poor recycler of vitamin C, you die that way, people need to understand this.
"The same applies to vitamin D or iron absorption. We are not trying to prove that iron deficiency is problematic, that evidence is available, we are trying to show that some athletes have lower absorption rates than others. Popular media says sugar makes you fat, carbs are bad, and for those who are sedentary they are likely to do okay on high-fat diets, but athletes are very different. Most athletes who are very competitive cannot do low-carb. I’ve had 40 athletes attempting low-carb and I told them it was not aligning with their genes, to let me switch it up and bear with it for two weeks. I see improvements in most cases.
"I even found myself through trial and error that on low-carb I gained weight before I even knew about genetic testing. Sure enough, my genetics fall in line with that. However, for folate, untested people won’t necessarily know if they are low or not. Iron, lactose, and gluten are great examples where people don’t recognise for years that they have a sensitivity. I had an athlete heading to the Rio Olympics whose genes showed low iron risk and we performed aggressive supplementation.
"Athletes don’t often have six months to add additional meat and lentils to their diet, this makes screening useful. We may see a 5% difference in performance through nutrigenomics and this is critical considering the milliseconds between winning or losing. At the London and Rio six hour cycling road race, the difference between the top 20 was less than 0.01%, so 5% could mean the difference between gold and 200th place. Recreationally someone who wants to set a personal best may want to know these things. We just don’t know what to do with gene training information but for nutrition a lot of it is actionable. Get more of this in your diet, get less of that.”
“We know genes are involved in metabolism,” says Dr. Lacaze
“So mutations can affect how you metabolise drugs and caffeine but it’s not a binary thing where one group can metabolise caffeine and one cannot, you have all shades; slow, medium and fast. Unless you are the very rare person with a mutation wiping out your caffeine metabolising ability, causing you to get ill drinking coffee, I would not change your lifestyle based on the current evidence. It’s likely you would already be aware of this anyhow through personal experience”.
For athletes, however, where marginal gains are critical, Nanci’s gene research shows promising evidence. “I have tonnes of data coming out on caffeine and it appears fast metabolisers have better endurance. It looks like half the athletic population is benefiting from caffeine and for some, there is a negative effect. I actually have 30 subjects who did worse when they took caffeine during cycling time trials.
"As a practitioner, if I’m working with a team, such as the 400 athletes in the Canadian national team, and there are athletes who respond better or worse to caffeine, I need to know. Using genes to monitor metabolism crosses into pharmacogenomics where we see that levels of a drug useful for one person can be fatal in another. Take breast cancer chemotherapy drugs where some women see no benefit at all. Imagine taking chemotherapy that is doing nothing but has all the side effects.” states Nanci.
“Gene doping is a reality, however, it is very dangerous,” states Dr. Eynon.
“You can do gene manipulation in mice, but once you do it in humans we don’t know what the consequences will be. Specific genes are not usually influencing only one specific thing in the body. For example, the ACE gene is expressed in muscle, the heart, the liver and in blood. So manipulating this gene in the muscle, you actually don’t know what the consequences will be in the blood, the heart or the liver. But, you know what, some people will do anything to stand on the podium.”
Dr. Lacaze sees the potential but as a public health initiative. “In theory you could take blood cells out, edit them genetically and then put those cells back in, hoping they’d be super functional. Such things are possible in the future. We need to remember however, these things will also make huge differences to people suffering blood, muscle or skeletal diseases by manipulating someone's cells, or putting new cells developed for such a disease into someone.”
As with any therapy, there is the potential such technology might be used for doping. “Anabolic steroids, diuretics, and beta-blockers prescribed to patients can make a huge difference to health, but these are also used for doping in sport,” adds Dr. Lacaze. “We assume genes will actually make a difference for top performers but I’m not actually convinced it will. Top performers will always find ways of optimizing their performance, training, routines, and diet that will have as much impact.”
Gene Testing Kits
“Recently there’s been concerning developments in the direct-to-consumer market with genetic testing products appearing that are completely unsubstantiated by evidence and border on the absurd,” says Dr Lacaze.
“These include products claiming specific testing for soccer prowess or wine preferences based on DNA. The fact that people can charge money, without providing evidence, in my opinion, is highly misleading and damaging. These products threaten to mislead and confuse paying customers, but they also undermine the integrity and quality of bona fide genetic tests. Things have gone too far now and need to be pulled back in line”.
Nanci believes similarly, “Direct to consumer tests are really the 'wild west' and buyers should check who is behind the test,” says Nanci. “You want to make sure they have research experience in the field. Genetics is so broad that even if someone has a degree, it still may not be in the type of genetics examining gene associations.”
Dr. Lacaze adds, “The regulation a company has to go through is not standardised yet. It’s similar to supplements. If you deliver exercise or nutrition information, it’s not considered medical and is not heavily regulated. However, when people have been surveyed for why they did genetic testing, the number one reason is for interest, then ancestry, then medical. This is fine but we need to make sure we deliver them quality information.”
Nanci agrees, “For caffeine metabolism, we know who is at risk and who is not regarding heart health and high blood pressure, and my research has looked at athletic performance but even this straightforward data is being misinterpreted. Slow metabolisers should limit to 200mg per day but I have seen gene testing companies suggest everyone can have four cups, which is not what the data shows.” Dr Lacaze sums up the area perfectly, “Although I support the democratisation of genetic information in our society, we must ensure some level of quality control. Paying customers should receive information supported by evidence, not snake oil.”
The Sporting Spirit
“If you went and trained with Usain Bolt, same environment, and training, you probably won’t run less than 10 seconds over 100 metres,” says Dr. Eynon.
“You can manipulate the environment up to a point, for example, if you trained for the marathon, had the best training, ate exactly as you should, and even lived in Kenya, I still don’t think you’d run less than two hours and 20 minutes. For someone to do this is rare. So something must be different. However, we must be careful how far we manipulate anything before we begin to take the sporting spirit out of sport.”