Running in our genes

Just like a manual for a car, a recipe for a dish or a map to a destination, our genetics are the blueprint for understanding what makes us who we are.

From height to hair type, IQ to eye colour — our genes inform all of our basic traits.

Found in every one of the more than 30 trillion cells of our body, a gene is a small section of DNA that gives specific instructions for a certain attribute.

In addition to influencing how we look, our genes have a significant role in whether we might be more or less likely to get certain diseases or conditions.

But do our genes influence what sports we will be good at or what type of exercise we are more likely to have a positive response to?

Are we predisposed to be runners?

Were we born to play rugby or become a swimmer?

Can we really be naturally strong?

Well, scientists from the Manchester Metropolitan University Institute of Sport say yes — sport can run in our genes. The researchers have discovered that there are variations in our genes that make us faster, stronger or give us greater endurance. And elite athletes often have a combination of genetic factors that help give them the edge.

Sport performance

“Runners with a certain version of one particular gene will be able to finish a marathon around three minutes faster than those who don’t have this type of gene,” explained Alun Williams, Professor of Sport and Exercise Genomics.

He’s been researching genetics and physical activity for 25 years. “Three minutes might not seem massive, but on an elite level, it is really significant.”

Prof Williams’ research has led to a range of discoveries, including how certain genes can impact an individual’s response to aerobic endurance training. He said: “What our research has confirmed is that genetics influences our VO2 max capabilities — which is the maximum amount of oxygen your body can utilise during exercise. And in fact, there are variations within several genes that seem to do this.

“We looked at the DNA samples of a variety of athletes to find this out, including rugby players and long-distance runners.”

Although, for the most part, every person has roughly the same genes, scientists explain that we all have different versions of those genes inherited from our parents. How our body functions or appears is dependent on which version we have of these genes.

Dr Georgina Stebbings, Reader in Sport and Exercise Physiology, explained more: “Genes contain instructions that tell our cells to make proteins, and these proteins perform different functions in our bodies.

“For example, there is a gene responsible for creating a protein within our fast-twitch skeletal muscle fibres called alpha-actinin-3 (ACTN3). This contributes to force transfer during fast, powerful movements such as sprinting.

“Approximately 18% of the population with predominantly European ancestry do not produce the ACTN3 protein within their fast muscle fibres due to possessing a particular variant of this gene, known as the XX genotype.”

Hans Degens, Professor of Muscle Physiology, has also studied the effects genetics has on sport and exercise performance — particularly how genes impact our muscles and strength. He explained: “We have found that genetic variations in 11 genes we selected for analysis account for up to a 4% difference in muscle fitness in young, healthy males.

“What this means is certain genetic variations — or genetic polymorphisms — can make muscles up to 4% stronger and resistant to fatigue.

“Specifically, eight polymorphisms of the 11 genes were associated with an increase in muscle function, and also things like muscle size, in these individuals.”

For professional sportsmen and sportswomen, genetics can make all the difference.

In fact, experts have found that many of those who have reached the elite level could well be considered more genetically gifted than your average person.

Prof Degens said: “We have found that those who compete professionally do have more of these favourable variants of certain genes.

“Now, it doesn’t mean that all power athletes have all of the polymorphisms related to being strong or related to power generation, but they have, on average, more of them than a normal person does.

“This would make sense as if you have more of these favourable genetics, you’re more likely to excel at these sports and activities at a young age.”

There are said to be around 14 million polymorphisms in the human genome. And though not all of those will be associated with physical performance, there are many that scientists have yet to discover or test.

With that in mind, what is the full potential of genetics in relation to sports performance? Prof Degens answered: “In our study, only a limited number of polymorphisms were analysed, and we found they had the potential to make up to a 4% difference in muscle strength.

“There are many, many more polymorphisms we could look at, and there are indications that genetics could make a difference of anything up to 50% — so as you can see, there is much that we still do not know.

“That being said, it would be almost impossible for an individual to possess all of the most favourable gene variants to be good at a specific thing. But there definitely could be more genetic variations also contributing to performance, boosting that advantage even further.”

Injury resistance

Prof Williams agrees that other genetic variants could contribute to overall sporting success, specifically genes that help make us more robust to injury.

“It’s more than just about what genes you have that make you perform better at certain sports,” he explained.

“It’s also things like the genetics of injury resistance, which, in turn, helps with performance.”

To explore this, the team at Manchester Met conducted a study that included the DNA of around 500 professional rugby players.

The study aimed to analyse whether genetic profile impacts a player when it comes to protecting them from injury. They looked at whether a genetic variant — or combination of genetic variants — was associated with reducing the risk or severity of injuries and if these were prevalent in rugby players.

Dr Stebbings explained more: “For somebody to reach the elite level in rugby, they would have been exposed to one of the highest levels of risk for soft tissue injury in professional sport, but likely had few injuries and associated training interruptions. This might suggest elite rugby players have inherited resistance against soft tissue injury.

“We identified that elite rugby players did indeed possess more of the injury-protective variants of several genes responsible for encoding proteins involved in soft tissue development than non-athletes.”

This research demonstrates that rugby players have likely achieved elite status due to inherited resistance to soft-tissue injury. The inherited resistance has enabled them to maximise their training due to fewer interruptions through injury despite exposure to a high-risk environment.

Concussion is another common injury in rugby, with approximately 80% of rugby players experiencing it at least once during their playing career.

A study by the team looked at the interaction between two particular genetic variants on the COMT and MAPT genes, which is more common in rugby players than non-athletes. The COMT gene is known to affect behavioural capacity following a concussion.

It could increase risk-taking and impulsivity, and the MAPT gene affects the repair of neural structures in the brain. De Stebbings revealed: “We concluded that this combination of genetic variants might affect stress resilience, behavioural traits, and alter risk and severity of concussion in these rugby players.”

General exercise

You often hear athletes referred to as “natural” or “born” to do something.

There is clearly some truth to that, as the team’s research shows how elite athletes have excelled thanks to their genetic advantages.

But what about those who are not considered to be genetically gifted at sports? How can what’s in our DNA help everyday people with exercise and being active?

Well, Prof Williams says understanding our genetics could help encourage more people to become active, as they would have a better insight into what type of exercise they’d be best at.

He explained: “Both in the UK and across the globe, we have a health problem regarding increasing levels of obesity and diseases that relate to that.

“One way to combat this issue is to increase physical activity.

“Due to genetics, individuals will respond to certain training programmes better than others.

“There are many different types of training — from aerobic or endurance training to resistance or strength training, and everything in between.

“Some people might not be good at one type of exercise or responding to training, but it doesn’t mean they’re not going to be able to respond or do well with another type of exercise.”

Dr Maxime Boidin, Senior Lecturer in Cardiac Rehabilitation, agrees with this theory. He has contributed to research demonstrating that individuals are predisposed to respond better to either aerobic or resistance-type exercise according to their genes.

Boidin explained how they tested the impacts of four weeks of both aerobic and resistance training and how the participants’ vascular function responded to it.

Alongside this, a separate study examined the training’s impact on participants’ VO2 max capability and muscle adaptation. He explained: “What we found was if an individual improves in their vascular function after aerobic training, it doesn’t mean that they will have the same improvement after the same bout of resistance training.

“Similar conclusions were made for muscle adaptation, where some participants were more likely to respond to one type of exercise than the other.”

And guess what the research found: the individuals possessed different gene variables.

“If you have one type of a certain gene, you’re more likely to respond better to aerobic exercise. But if you have another variant of that same gene, you’ll respond better to resistance training,” said Dr Boidin.

“Therefore, if people knew what genotype they had, they would know what type of exercise had more impact on them.”

Prof Williams added: “There is a role for genetics in helping to prescribe exercise to people that they will get the most benefit from.”

“If we knew more about genetics, it could not only be used as a method of talent identification in elite sport, but it can also help to encourage people to pursue the types of exercise they might be better at or benefit more from."

But to do that, Prof Williams explained that we first need a better understanding of genetics’ role in sport and exercise performance.

“There is so much more left to learn than has been discovered so far,” he said. “The scientific community, globally, needs to come together to share information so we can upscale our research.

“Because the more people are involved, the more sophisticated laboratory work we can do and the more confident we can be of our findings."