Sports Science Quarterly – Q4 2023

Every quarter we take a deep dive into the latest research in sports science. In this edition we look at the latest research on the current state of genetic testing in sport, talent detection, injuries in youth athletics, the effects of long haul travel, and more.

As always, the full Sports Science Quarterly is available exclusively to HMMR Plus Members. You can browse the past topics on our archive page. The first topic below is free to everyone, but sign up now to read about all the latest research. To get an idea of what Sports Science Quarterly is all about, the April 2016 edition is available in its entirety for free.

This Quarter’s Topics

Genes and elite sports performance – where are we now?

Quick Summary – Genetic testing within sport—as a means of training modification or for talent ID—is a hotly debated topic. Whilst we know our genetics play a substantial role in our athletic performance, we’re still some way away from being able to “predict” we will, or will not, become an elite athlete based on their DNA profile. Recent research in this area has made steps to bridge the gap between theory and practice, but we’re still left with a lack of utility to genetic testing in sport at this point in time.

In what now feels like a lifetime ago, I used to be quite a good athlete. Over the course of my career, I competed in five World Championships across two sports, and was selected for both a Summer and Winter Olympic Games. I was a very good junior athlete; within a year of starting track and field, and only doing one training session a week, I became National Under-15 100m Champion, running the second fastest 100m time by an Under-15 in British history. Two years later, in 2003, I came third at the World Under-18 Championships (running the second fastest Under-17 time in British history), and, in 2005, I won the European Under-20 Championships, running 10.22 seconds at age 18.

After that, I progressed slightly; in 2007, aged 20, I came 2nd at the European Indoor Championships over 60m, and ran a personal best of 6.55 seconds for the distance. Later that year, I made the semi-finals in the 100m at the World Championships, won a Bronze medal in the 4x100m relay at those same Championships, and ran my personal best over 100m of 10.14 seconds. After that, my career was blighted by issues; I suffered multiple hamstring injuries, had a bout of Unexplained Underperformance Syndrome (UUPS), and experienced a long-term back injury that resulted in back surgery in 2012 (I missed the London Olympic Games as a result) and my eventual retirement from competitive sport in 2014, aged 27.

After I retired, one of my friends from track and field got in contact. He was working for a sports technology start-up, specializing in genetic testing. Would I like to take a test, he wondered. I did, and I found the results very interesting. I have a number of genetic variants associated with an increased risk of sports injury and increased post-exercise recovery requirements. Was this the reason for my frequent and severe injuries, and my experience with UUPS? I also have the “sprint” version of ACTN3, a gene commonly found in elite speed-power athletes; was this the reason I was naturally fast? I found the results compelling, and eventually went on to work for the company as Head of Sports Science for almost 5 years, working with athletes and sports teams interested in using genetic testing to support their performance. Eventually, I focused on genetic testing for my doctoral thesis. Over the course of my research, I found that:

  • Genetic testing is not useful for talent identification. For example, if you take a group of five elite athletes, and compare their genetic profiles to over 500 non-athletes, you can’t discriminate between the two. Furthermore, for a variety of reasons, I believe that genetic testing will never be useful for talent ID, as the effect of any gene is so small that it is very hard to detect. So, whilst genes are crucial for elite performance, we can’t actually use that information effectively.
  • However, I do believe that genetic variation likely explains a decent amount of the variation we see in response to a training program, in terms of both strength and endurance improvements. I also believe that at least some of this variation can be predicted beforehand through genetic testing, but potentially not enough to be useful to elite athletes—at least yet.
  • Variation in genes can also explain variation in response to popular ergogenic aids, such as caffeine, and this information may well be useful to elite athletes and support staff.

When I left the field in 2019 to start working at a National Sporting Organisation, I had reasonably high hopes. There were a number of research groups focused on identifying some of the drivers of the inter-individual response to training, both in sport and also the military. I was convinced that, five years down the line, we would know a lot more about the role genetics play in performance, and be able to use that information.

I was, unfortunately, wrong. Back in 2016, there were 155 genetic markers linked to elite athlete status. Now, in 2023, there are 251, as highlighted in a recent review article on the topic from key researchers in this field. Of these 251, only 128 can be associated with elite athlete status (i.e., they increase your chance of becoming an elite athlete), with 41 related to endurance performance, 45 to power performance, and 42 to strength performance. Of these 128, only 22 show “promise”, defined in this paper as having the most replications (a cornerstone of good science is having results that are repeated across a variety of studies; this allows us to develop a consensus of effect), and have fewer negative or controversial findings. With the effects of any single gene being very low, and traits like elite athlete status being complex and multifactorial, for genetic information to be useful, we likely need substantially more genetic variants to be identified before we can use this information. As an example, height is the most well studied performance-related trait in terms of genes, with other 12,000 genetic variants so far found to be associated with differences in height between people. However, to identify all the genes associated with variation in height, we would need around 100 million people, all of the same ethnicity. It’s easy to see how this makes identifying sport-related genes difficult; there are not 100 million elite athletes in the world, and, even if they were, the results of the study would only be valid in the ethnicity of the subjects—making generalisability very difficult. This highlights the challenges in this area quite succinctly.

Despite these challenges, athletes and sports teams can still utilise genetic testing. In a study of mine from 2021, we surveyed 243 people (110 athletes and 133 support staff) to gauge their attitudes towards genetic testing. We found that around 10% of athletes and 11% of support staff had undertaken genetic testing, and more planned on utilising testing in the future. These results were similar to a 2018 study, which reported that 17% of athletes and 8% of support staff had utilised genetic testing.

As such, it’s clear that, whilst genetic testing is currently not at the level to provide much use to athletes and coaches, a decent amount of people in elite sport are still going to use it. This requires us to take a pragmatic position; if, despite the evidence, sports people are still going to utilise genetic testing, what can we do to ensure the decision to use such testing is sufficiently well informed, whilst also protecting the athletes? This is the topic of a recent paper, published in the journal Current Issues in Sports Science, titled “Talent Inclusion and genetic testing in sport: A practitioners guide”, authored by Alexander McAuley and colleagues.

In their paper, McAuley and his coauthors outline a perspective very similar to mine; whilst the scientific consensus is that there is no validity to genetic testing in elite sport, the reality is that athletes and sports teams do, and will continue to, utilise such technology. As such, it’s important to explore how genetic testing could be utilised in such a setting, ensuring that the athletes themselves are protected from any dangers. This includes an overview of what the authors consider to be genetic testing best practice guidelines for practitioners, to which we should all pay heed:

  • Autonomy – athletes should be able to refuse a genetic test, with no negative consequences for non-participation. Athletes should also be able to withdraw their consent at any time, and be able to request that their genetic data be destroyed.
  • Discrimination – the genetic data of athletes must not be used for any discriminatory purposes, including talent de-selection. This is unethical, and may also provide the basis for future litigation against the team/individual carrying out the test.
  • Anonymity – when undertaking a test, the athlete data should be at least pseudo-anonymous. In practice, this means that when a test is carried out, the samples sent to the laboratory do not contain any identifying details of the athlete.
  • Data storage – the storage of genetic information should be on a password protected, encrypted external driver or server.
  • Data sharing – genetic information should not be shared over unencrypted email.
  • Data ownership – it’s important to consider that genetic data is fully owned by each individual athlete (or their parent/guardian if under-18). If requested, the athlete should be provided with their genetic data in full.
  • Consent – all athletes should provide informed consent prior to collection of their genetic data. In addition, athletes should also have a cooling off period whereby they can further consider whether testing is suitable for them, and be able to subsequently withdraw their consent without penalty.
  • Transparency – athletes should be fully aware of how their genetic data will be used and made aware of which organisations have access to their genetic data.
  • Counselling – performance staff should not discuss the genetic data of athletes with the individual athlete; instead, they should discuss the findings at the aggregate level. Education – educational workshops for athlete, coaches, and support staff should be implemented, to ensure that the results can be understood in the contextually appropriate manner.
  • Minimum necessary principle – only genetic markers fully relevant to sporting traits should be explored, and disease-related genetic markers should only be investigated by health professionals.

Ultimately, I’m challenged by some of these recommendations, and, even if they are fully implemented, I don’t think they offer sufficient protections to athletes. Firstly, because genetic testing is primarily available through Direct-to-Consumer (DTC) testing companies, and there are no regulations around what genetic variants can, or cannot be, collect, nor is there a minimum threshold of evidence required for a given genetic variant—which, as outlined above, is important given the low number of replications in sports genetics studies. As such, an athlete may take two different tests from two different companies, and get two different results. Making informed decisions on the results provided is, therefore, very difficult – and this is especially true for non-specialists (e.g., athletes), or those who lack the time to adequately upskill in this area (e.g., performance support staff).

There are a host of other ethical issues which aren’t addressed by these guidelines. For example, many researchers within the field of ethics question whether anyone under-18 can truly provide informed consent, which makes testing on under-18s challenging—even if their parent/guardians provide consent on their behalf. In addition, the paper outlines the minimum necessary principle, with only the genetic markers relevant to sporting traits explored. Given the rapid advances in research in this field (e.g., 100 additional markers discovered between 2016 and 2023), there is the potential that athletes may require further genetic tests in the future, which further opens them up to risks associated with genetic data collection. Finally, if an athlete can request their whole genetic data (under the principle of autonomy), they could then upload this data to a variety of third-party websites which provide reports on aspects such as disease risk—many of which is unmodifiable, and requires expert consultation.

Nevertheless, this paper from McAuley and colleagues is a crucial one; it represents a highly pragmatic way to attempt to take theory to practice, in a way that protects all involved as best as possible. I’m still left with the feeling that, whilst there is a desire—as evidenced by the research—to utilise genetic testing and genetic information in sport, ultimately there is very little evidence, outside of some initial studies, exploring how such information may effectively support practitioners and athletes in their develop. As such, this is the next challenge for researchers in this field; can we move away from theory-based papers towards evidence-informed interventions? In doing so, we will be better able to utilise the recommendations from this paper to ensure athletes are adequately protected when undergoing genetic test—which will be an important step for the sporting field.

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