Chris Horner turned heads earlier this month when, at 41 years old (Masters 3 here in Australia!), he became the oldest rider ever to win a Grand Tour. And just last night Horner released all 39 of his Biological Passport test results in an attempt to dispel speculation that he could only have won the Vuelta a Espana by doping.

In light of the ongoing scepticism about Horner’s performance we spoke to Dr Andrew Betik, a research fellow in Victoria University’s Institute of Sport, Exercise and Active Living, to work out whether we should really be that surprised by a rider over 40 performing so well.

There’s a perception that elite cyclists (and indeed other sportspeople) reach their prime in their mid-to-late 20s after which they experience gradual but steady performance declines.

Most cyclists, it is commonly thought, aren’t up to the rigours of WorldTour cycling by the time they reach 35 and seeing anyone racing at the highest level beyond their 40th birthday is very rare. In fact, as far as we can tell, there are only two riders in the WorldTour this year that are over 40: Chris Horner and Jens Voigt.

The reality is that only minimal physiological declines occur before about 50 years of age, particularly when we’re talking about an athlete’s musculature. Any declines in athletic potential and performance that happen until that point are largely due to a drop in the athlete’s VO 2 max.

As a quick reminder, VO 2 max is the maximum capacity of an athlete’s body to transport and use oxygen during exercise, a quantity that’s normally measured in milliliters of oxygen per minute per kilogram of body mass. An average untrained male will have a VO 2 max of around 45ml/min/kg while the best cyclists on record have roughly double that.

Our VO 2 max is determined by a couple things:

– cardiac output, which is a function of how much blood your heart can pump per beat, and how many beats per minute your heart is capable of (maximum heartrate), and

– how much oxygen our muscles are able to extract from our blood and then use.

As we get older, our cardiac output drops. Our heart loses some of its strength and our maximum heartrate drops. This is the reason that simple estimations of maximum heartrate can be done (sort-of accurately) by subtracting your age from 220.

As Dr Andrew Betik told CyclingTips, that decline might well start as early as 30 years old but, importantly, “we don’t necessarily see a change of performance” as a result.

So if the physiological decline that happens by, say, 40 years old is only minimal, and if those declines don’t have a noticeable impact on performance, why don’t we see more 40-year-olds competing at the highest level of the sport?

There are, of course, many factors at play here. One of the most important might be the impact of high-intensity training on older athletes.

We know anecdotally that recovering from intense exercise becomes harder the older you get but there’s limited evidence to show exactly why that might be the case. Dr Betik offered a couple of suggestions.

“[It could be down to] immune function that’s able to go in and clean up the damage from a previous workout. There is also protein synthesis which definitely goes down with ageing. [This is] the ability to have a damaged protein, clean it up and put out a new protein.”

In order to stay at the highest level of the sport cyclists clearly need to be training hard and training often. If recovery from that training is getting harder and impacting the cyclist’s ability to train, then it’s no wonder that many cyclists say that their body has had enough when they announce their retirement.

But as Dr Betik told us, there’s far more to competing as an elite sportsperson than simple physiology alone.

“What stops a lot of guys from riding until their 40s is not physical, but mental. Fifteen years of riding five hours a day, six days a week, counting every calorie you eat, and being on the road all the time has its toll on people.”

For many riders (and elite athletes generally) it seems that when they reach 35 years old or so, the life of a professional sportsperson starts to lose its appeal. It gets harder to recover from training, they might have a young family they’re looking to spend more time with, or they might be looking to start building a post-cycling career.

All of which makes the efforts of Horner (and Jens Voigt, who has six children to look after) all the more impressive.

I asked Dr Betik whether he thought Horner’s win at the Vuelta rang alarm bells, given the American was five years older than the next-oldest Grand Tour winner, and eight years older than the next-oldest Vuelta winner.

“I think it’s absolutely realistic that Horner could have won it [clean]”, Dr Betik said. “I would suspect that his physiology and genetics … allow him to train the huge miles and huge

intensities that he was doing when he was 30.”

Dr Betik continued:

“We’re seeing more and more that there’s a genetic influence in everything: our predisposition to diabetes, to cancer, to elite [athletic] performance, even at a young age. So there’s no reason to think that there’s not some genetic component that allows this guy to tolerate the huge [training] volumes.”

It might be that 80 or 90% of professional cyclists start to see declines in performance and in their ability to recover as they reach, say 35 years old. But as with any type of exercise or training stimulus, there will be a percentage of people that decline slower with age than others and that can handle higher intensity efforts further into their career.

“It’s very possible that guys like [Horner], Jens Voigt, Stuart O’Grady etc are just part of the special 5% of people who are still motivated and can handle big training loads at those ages”, Dr Betik said.

So how long could someone like Horner continue to compete at the highest level? Well the American’s most immediate concern is the fact that he doesn’t have a contract for next season, given RadioShack-Leopard is about to become Trek and the team will be built around a focus on the Spring Classics.

But assuming Horner can find a team, he’s already said he’d like to keep racing for another two or three years, if he feels as good as he did at the Vuelta. And if he keeps winning races he’ll make himself pretty hard not to employ.

But to answer the question of “how long could he go on?”, it’s perhaps worth looking to this study published last year. In the study, the author put five-time Tour de France winner Miguel Indurain through his paces to see how ageing had affected his cycling performance in the 14 years since he retired.

While the study had a number of flaws — for a start it tried to make a statement about the effects of ageing in isolation when both ageing and a significantly reduced training load were involved — it showed that Indurain hasn’t lost much in the 14 years since his last race.

The 46-year-old’s maximum heartrate was still 191bpm (around 17bpm higher than you might expect for someone his age) and he was still able to put out an impressive amount of power. To quote the author of the study: “Indurain’s absolute maximal and submaximal oxygen uptake and power output still compare favorably with those exhibited by active professional cyclists.”

Could Indurain still be competitive at an elite level if he had the motivation to do so? Well, he’d probably need to lose the 12kg he’s put on since he retired, he’d need to significantly increase his training, and it’s highly unlikely we’d see him winning the Tour de France again, but there’s no reason to suspect that he couldn’t still be mixing it up in the bunch.

Or, to quote Dr Betik one final time:

“There’s lots of evidence that these guys aren’t necessarily done at 40. It’s just whether they choose to do it or not.”

***

Further reading:

– Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms

– Masters athletes: an analysis of running, swimming and cycling performance by age and gender

– Ageing and physical performance

– Ageing and cycling

– Determinants of VO 2 max decline with ageing