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Are elite cyclists born or bred?

James Witts
2 Jun 2017

Some say performance on the bike is about genes. Others say it’s about upbringing. Let’s examine the science

‘I have to thank my parents for giving me good genes, and also my father for teaching me what I call good intentions. He always told me whichever race you’re going to do, race as well as you can, then afterwards you can say, whether you won or not, that you gave your best.’ 

So said sprinter Marcel Kittel when Cyclist spoke to him a couple of years back. In one Germanic soundbite, Kittel managed to encapsulate the centuries-old ‘nature versus nurture’ debate.

Is Kittel’s performance, and that of his elite brethren, predominantly down to genetics, or the result of environmental factors such as training, nutrition and family set-up?

‘Genetic providence creates opportunities to become an elite athlete and contributes as much as 90% of how good you can be,’ says Ken Matheson, former coach at British Cycling. ‘Sadly, you can’t be whatever you want to be.’

Matheson’s viewpoint is nothing new. Charles Darwin’s cousin, Francis Galton, is regarded as the original geneticist. In his 1869 book Hereditary Genius, Galton proclaimed, ‘There’s a definite limit to the muscular powers of every man, which he cannot by any education or exertion overpass.’

Genotype meet phenotype

On a basic level you can see where Galton is coming from. Nairo Quintana stands only 1.67m tall and weighs 58kg. His featherweight stature means he can float up mountains, but it also means he lacks the muscle mass to contend for sprints that require a power output of 1,600 watts.

Someone like Lotto Soudal’s André Greipel, on the other hand, measures 1.84m and weighs 80kg. That natural load is detrimental on the climbs but pays off handsomely on the flats.

So that’s it, then? It’s all down to your genes?

‘Not quite,’ says exercise physiologist Ian Craig. ‘Genes – which lie in long strands of DNA called chromosomes – lay the foundations for many characteristics, but your phenotype is who you are as a person. It’s where your genes interact with the environment.

‘You might be the most genetically gifted person but be rubbish at sport because you grew up in a non-sporty family, “enjoyed” a bad diet and lacked sleep.’

In recent times, the nature-versus-nurture debate has intensified because of books such as David Epstein’s The Sports Gene and Malcolm Gladwell’s Outliers.

The latter proposed that the route to becoming an expert at almost anything is to log 10,000 hours of practice, starting when you’re young.

Epstein’s book, by contrast, suggests that not everyone can reach the top with sufficient practice, and that sporting success is often dictated by hereditary factors. 

‘For each gene there are two letters [alleles] associated with it,’ says Craig. ‘They’re called base pairs within the DNA helix, and they’re essentially one letter each from your mum and dad. These dictate your physical, biological and psychological characteristics.

‘I’ll give you an example: the ACE gene [angiotensin-converting enzyme] is involved in controlling blood pressure. For ACE, you inherit either an I or a D allele so the potential combinations are II, DD or ID.

‘For ACE, II’s been strongly linked with endurance capabilities. DD’s been linked with power. DI is a mix of the two.’

So if both your parents’ ACE gene comprised II alleles, your sole permutation is II, meaning you’d exhibit endurance tendencies. It’s why thoroughbreds go to stud – and why super-horse Frankel’s semen is worth £125,000 a pop. 

Runners and riders

Yet still uncertainty derives from a horse comprising 20-25,000 genes – a similar number to humans. According to Yannis Pitsiladis, professor of sport and exercise science at Brighton University, in a review
of 133 studies published during 1997-2012, only 59 genetic markers were associated with endurance and 20 with strength. 

‘Sporting performance is a complex phenotype,’ he says. ‘To become an elite athlete, a synergy of physiological, behavioural and environmental factors is required.’

Pitsiladis is an expert on the subject. His work has taken him to Kenya in search of the synergy between genetics and environment, and while conceding that the Kenyans possess good genes for endurance (naturally high EPO levels, for instance), he concludes that the dominance of Kenya, Ethiopia and Eritrea in long-distance running is ‘a socioeconomic phenomenon’.

His studies showed that 81% of 404 Kenyan professional runners had to run or walk a considerable distance to and from primary school as children, meaning Kenyan kids had 30% higher aerobic capacities than their contemporaries.

It’s a notion reinforced by Epstein. ‘How many successful Kenyan runners’ children have successful running careers?’ he says in The Sports Gene. ‘I tell you, almost none. That’s because their parents’ wealth meant they didn’t have to run to school.’

Thank your mother

Tamsin Lewis was one of Britain’s best long-course triathletes before her retirement in 2014. She won Ironman UK and finished second at the notorious Alpe d’Huez Triathlon.

Her dad is Colin Lewis, a former professional cyclist who won the British Road Race Championships twice in the 1960s and domestiqued for Tom Simpson at the 1967 Tour de France, passing Simpson his last drink before he died on Mont Ventoux. 

‘Our personalities are similar – we’re chaotic, obsessive and highly driven, and it’s clear I inherited his physical genes, too,’ she says.

‘I only took up triathlon in 2007 and hadn’t ridden much to that point. I had my VO2 max measured and it was around 68, which is good for someone who’s relatively untrained.’

There’s a genetic component here, if not directly from Colin. Mitochondria number and size potential is inherited from the maternal line. (Mitochondria are the powerhouses of cells and energy production, and are crucial for endurance performance.)

‘My maternal grandfather was a national runner and his father an international swimmer,’ Lewis says. 

Then there’s the case of Mathieu van der Poel. Still only 20, Van der Poel has already clocked up a long list of victories on the road and in cyclocross, including a silver medal at the Cyclocross World Championships earlier this year.

It’s a staggering record but one that’s not surprising. His father, Adri, won the Tour of Flanders and Liège-Bastogne-Liège, while Mathieu’s maternal grandfather is Raymond Poulidor, who won the 1964 Vuelta a Espana as well as finishing second five times at the Tour de France. 

Genetic and environmental providence played key roles for both Lewis and Van der Poel but, despite scientific progress, there are no apps, no wearable technology, to quantify how much either influenced their current level of performance. 

The outliers

There are anomalies. Those 10,000 hours of practice were nothing compared with what American footballer Todd Marinovich went through.

Marinovich’s father groomed him from birth to become a quarterback, inventing games like lifting the medicine ball onto the kitchen table while not long out of nappies and banning junk food.

Dubbed the ‘Test-tube Athlete’ by Sports Illustrated, Marinovich made the draft for the Los Angeles Raiders in the 1990s before a drug problem ended his career – perhaps unsurprising for a child who grew up too soon.

Genetic anomalies exist, too. Finnish skier Eero Mantyranta won two cross-country skiing gold medals at the 1964 Winter Olympics.

He followed a similar diet to his contemporaries, trained the same and wasn’t exposed to the marginal gains that populate elite sport in 2017.

But he had one clear advantage over his rivals: his oxygen-carrying haemoglobin levels measured 236g per litre of blood at their peak compared with a usual range of 140-180g/l. 

Research in 1993 focused on the Mantyranta family and observed that 29 of them, including Eero, all had a genetic mutation that affected the EPO receptor, meaning their bone marrow produced red blood cells without being stimulated by the hormone EPO. In short, he was naturally doped.

Genetics is a relatively new field but genes have been identified that influence how you tolerate pain, motivation, fat metabolism…

Despite that, current estimates put genetic variation in performance at around 30%. The rest is down to your environment.

As our knowledge of genetics grows, those figures will fluctuate but, as Tamsin Lewis says, ‘Hard work beats talent if talent doesn’t work hard.’

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