Why do so many top-level cyclists suffer from asthma – and are the drugs that they're taking enhancing their performance?

When it emerged in April that British pro Simon Yates had failed an in-competition test for the prohibited medication terbutaline, questions were asked about what the substance is and what effect it can have on riders and their performance.

According to his team, Yates is permitted to take the asthma medication under a Therapeutic Use Exemption (TUE), but an administrative error by a team doctor meant that this didn’t apply on the day he was tested at Paris-Nice.

TUEs and the medications they can be applied to are once again back in the headlines after medical records of some British athletes, including Sir Bradley Wiggins and Chris Froome, were hacked and published.

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To find out more about this drug and why so many cyclists apparently require inhalers, Cycling Weekly’s David Bradford spoke to Dr John Dickinson, head of the respiratory clinic at the University of Kent.

CW: Tell us about terbutaline

Dr John Dickinson: Terbutaline is a drug classified as a beta-2 agonist that athletes may use to treat asthma. There are lots of different types of beta-2 agonist available for medical use, but only four of them are allowed to be used by athletes: salmeterol, salbutamol, formoterol and terbutaline. The odd thing about Simon Yates’s case is that terbutaline is the only one of the four that requires a therapeutic use exemption (TUE). Partly for this reason, it is far less commonly used by athletes.

Why is it the only one for which a TUE is required?

This is because there are different ways you can take beta-2 agonists: inhaled form or orally in pill form. Salmeterol doesn’t have an oral form; when testing for salbutamol and formoterol, you can distinguish between an inhaled dose and an orally ingested dose – but you can’t with terbutaline.

What’s the maximum dosage?

With terbutaline, you have to submit a TUE to prove that you have asthma. The controversial part is that once you have your TUE you can use as much as you like. A doctor would normally prescribe a therapeutic dosage, which would not normally be performance-enhancing, but there is nothing from that point to stop the athlete taking larger doses.

Is it performance-enhancing?

There is evidence emerging that large doses of terbutaline in inhaled form may improve sprint and power performance, but there is no strong evidence to suggest they would improve endurance performance. From a performance-enhancement point of view, these drugs don’t improve lung function. They are called beta-2 agonists because they act directly on beta-2 adrenoreceptors in the muscle, which improves the strength and power produced in each muscle contraction. It works in a similar way to adrenaline. Essentially you’re getting better adaptations in sprinting and power performance. From an endurance point of view for a cyclist, there are not many gains to be had.

>>> Are asthma medicines unofficial PEDs?

Could legal doses enhance performance?

Possibly. The emerging evidence suggests that at the upper limits of WADA-permitted dosages, there is potential to improve sprint and power performance, even within the rules and possibly over the long term. But the dosages required are above therapeutic levels. An athlete would have to be either using the medication wrongly, contrary to advice, or in a deliberate attempt to enhance performance. For me, it’s still a grey area, and more research is needed.

How should this risk be managed?

You could bring down the limit, but then you could get into the risk of accidental positives. In 2009, every athlete in every sport had to apply for a TUE to use a beta-2 agonist inhaler. That had two effects: it massively improved the quality of care an athlete received around asthma problems, but it also caused a huge increase in administration. In my opinion, having the TUE requirement in place improves the quality of care for athletes.

Team Sky's Chris Froome is another well-known asthmatic and has raced under TUEs to allow him to take medication that would otherwise be banned

Team Sky’s Chris Froome is another well-known asthmatic and has raced under TUEs to allow him to take medication that would otherwise be banned (Watson)

What is the prevalence of asthma among elite sportspeople?

In terms of the research we have done, around 21 per cent of the British Olympic team were using an inhaler. It’s higher in sports with a high aerobic element such as cycling and swimming. Some reports suggest that around 40 per cent of British Olympic cyclists use an inhaler, and it’s similar in other sports that have a high ventilatory requirement.

Why such a high proportion?

Athletes are more susceptible to asthma than the general population. The reason is that when you’re exercising you’re breathing in larger volumes of air, which, if you are susceptible, increases the dose of potential triggers for an asthma response. In cycling, you increase the amount of dry air going into your airway; and out on the road there is air pollution as well. Therefore you are more likely to trigger an inflammatory response, which is likely to cause asthma symptoms. Athletes increase their exposure, so they increase the chances of developing the condition.

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Why are the rules more liberal for inhaled forms of these drugs?

The reason why the inhalers don’t produce the same effect as the oral form is because you inhale the drugs directly into your lungs, where they work directly on the beta-2 adrenoreceptors in the lungs. It would require a large dose in inhaled form to be absorbed into the bloodstream and get a global effect.

Watch: How does weight affect your climbing speed?

How large a dose?

One or two puffs is not going to go anywhere beyond the lungs. Using salbutamol, to get anywhere near a performance-enhancing effect, you would need to take 16 puffs in one go, and that’s the upper limit permitted by WADA. The downside of such doses is that they may increase heart rate and cause tremors, so the potential benefits in muscle function you may lose in terms of increased heart rate. If you wanted to cheat, there would be far more effective ways.

  • GP

    In general practice it is deemed bad practice for asthmatics to be requiring daily beta -2 agonists as it shows poor control and that they should be on better steroids and long acting beta -2 agonists. I would be interested to know what their spirometry shows and why they are not on better regimes. But obviously steroids cause other problems. Maybe we will only see if they are taking excessive doses if we check bone density? And other signs of steroid abuse.

  • On “may improve sprint and power performance, but there is no strong evidence to suggest they would improve endurance performance.”.

    There is clear evidence however it leans muscle – muscles contain proportionally more protein by mass after a regime of β-2 agonists. So, it’s not just about increasing power, it seems likely one could also use such substances to _reduce_ weight while retaining the same muscle mass. That would give substantial benefits in cycling in performance and in endurance over climbs.

  • NitroFan

    Closing links on day two of tour de yorkshire 2016

  • The Awakening


    Do you have a link or can remember the exact episode please, as it would be interesting to listen what Chris Boardman had to say on the matter? Thanks.

  • Shane in Wonderland

    Sir, that is a well written, interesting take on the whole enchilada. Great angle of attack and possibly a good finish to this conversation. I followed the thread because I can’t breathe for a flip, and found the whole episode very interesting.

  • TheOtherManWithNoName

    A story without a byline is a story that is more akin to propaganda, or at best a bunch of BS. On another level, it is simply not believable. If you remember Schumacher, the cyclist who had a note from his mother, a doctor, for asthma medication, who also had a long history of doping for other substances, as well, is the perfect example of a sport doing everything possible not to catch an athlete until he has enough rope to hang himself. This article smacks of rationalizing away one of the vestiges of deceit that cripples cycling in the minds of many. Combine the use of asthma medication by many athletes with the fact that some athletes probably profit more than others by its use, it is simply not a level playing field and should be banned. In the Yates case, the doctor forgets to get permission? Hmmm! If it was not for this, we wouldn’t even be discussing the subject, and the beat would just go on and on. All of this will just get swept under the rug, for sure. Pathetic.

  • Ciaran Carroll

    Ever heard of exercise enduced asthma?

  • Ciaran Carroll

    I agree. I had bad asthma as a kid but luckily I rarely need my inhaler anymore. The only time I need it is in the cold (5°c or lower) and when it is cold I always bring it with me.

  • Ciaran Carroll

    Salbutamol does widen your airways BUT only when you’re struggling to breathe. If you’re breathing fine then taking a puff or two will only raise your heart rate. Salbutamol does not raise VO2 max.

  • Will Wright

    they would have had a spirometry reversibility test. Also, its possible to take B2 agonist before the race began and it can prevent synptoms

  • NitroFan

    Chris Boardman summed the whole thing and the reasons why so many pros have inhalers perfectly in 30 secs in the ITV4 coverage of TDY closing links!

  • Bermudaalan

    I have been diagnosed with exercise induced asthma, cannot even go for a couple of miles low effort without an inhaler. Salbutamol does the trick. With that I can ride much harder without an attack, without it and I’m doubled up trying to catch my breath, impossible to ride. So don’t think that mild asthma is the norm, there are people with legit reasons to use this stuff. Just saying……

  • Gerry O’Flynn

    Then your doctor is doing you no favours what so ever by not testing you, and is being lazy for just prescribing on your say so, you could have a more serious problem which is hidden.

  • Gerry O’Flynn

    You are lucky then, cold air is medically recognised to be a major problem for people with asthma and COPD as the cold air affects the receptors and sacs in the lungs, if you had to take Salmeterol and Eklira in addition you would soon realise these effect, I can only assume your asthma is not severe, severe winds and high humidity also cause problems do a bit more research into it.

  • Gerry O’Flynn

    No it is not I have Puffer tests every 6 months blowing into a machine, 3 short quick outs, 3 long empty lungs and also same after inhaler and compared against figures for healthy lungs and my previous figures, if it is humid, windy or cold I can assure you I suffer greatly and grab my salbutomol . As far as athletes are concerned prevention is better than cure so take it before hand I do if I am going to do anything strenuous and this is recommend by my specialist.

  • Jay

    Can’t help but be real sceptical about the pros using this type of medicine and claiming they have asthma. I recall Chris Froome is also asthmatic. The huge amount of cardio demand cycling takes simply would have eradicated asthmatic symptoms. That’s why truly asthmatic people take up cardio sports like swimming and running to help them get rid of it.

  • dougphoto

    I have more breathing problems the colder it is. Whenever I workout and it’s below 8 degrees c, I cough often and can never fill my lungs. I was an XC race for many years and knew lots of XC skiers who had inhalers. I can for sure see inhalers being needed more in the cold.

  • Haribo

    Regarding ‘let the doctors decide’ I’m in agreement – so long as the doctors are independently appointed and do not have financial conflicts of interest. Allowing a team doctor, who is financially dependant on the team sponsor, to decide is not going to achieve what is required in terms of a clean sport.

  • Ian Carter

    Well said. There are many different forms and triggers of asthma. But I’m sure they know better than the head doctor in the respiratory clinic at the university of Kent…
    I’m sure the asthma sufferers would be laying into the UCI if they banned all inhalers, and then Froome had to abandon the tdf halfway up Ventoux because he was having an asthma attack but couldn’t use an inhaler without getting a doping ban!

  • Haribo

    It’s not really about the lung performance, though. The action on the beta-2 adrenoreceptors has the effect of increasing the strength and power of the muscle. If it’s inhaled, then that’s probably only going to affect the lungs, but if it’s taken orally, or injected, then it’s going to improve the performance of all the muscle groups (or those that it’s injected near/ into). The test can’t distinguish which. So having a therapeutic exception for the inhaler covers you for any other use ( or misuse) of terbutaline in other forms. Thats the problem with TUEs, they can be used as a ‘get out of jail free’ card for misuses of otherwise valid medications.

  • Mike Williams

    I agree…and why I doubt any of them have even my level of severity because it would kick in during their racing career.

  • Mike Williams

    There’s real asthma…and there’s convenient asthma. When was the last time one of these “asthmatics” needed treatment mid-race…of the 100’s of races and 100’s of cyclists has their been a case of one going back to the team car to use an inhaler (never mind abandoning)? Nothing has triggered an attack? If I had an attack mid-ride, I’d need to do something about it.

  • Mike Williams

    No doctor has ever observed one of my asthma “attacks”. I describe the symptoms, get a prescription.

  • Amanda

    Are you joking? Not all people with asthma experience the same triggers. Cold air is a common trigger, as are heat and humidity. Repeated exposure to cold air at a racing level exertion has been shown to damage the lungs, worsening asthma in those who are prone to it. I also don’t often experience attacks in the cold, but I have no trouble accepting that there are those who do. I know I am also not exerting myself at an elite level. There’s nothing to “buy”, Dr. Dickinson’s comments are all based in extensive research.

    I think often as a person with asthma it’s difficult to imagine what life is like without asthma, because you come to accept your disadvantage as normal. Your lung function is permanently compromised, whether or not you are suffering from an attack. For athletes competing at an elite level, what may seem like an extremely mild level of asthma can still dramatically reduce their performance compared to their non-asthmatic peers.

  • Neb

    OK. Unlike some of the amateur asthmatics on here, I actually have asthma. I also have NTM (non-tuberculous mycobacteria). I started with a collapsed lung aged 2-and-a-half, spending weeks in an oxygen tent, and have been on serious asthma medication ever since (somewhat more than 40 years). I presently take a strict regimen of drugs to control it; I also sometimes need oral prednisolone if the air quality gets really bad. Precisely because I take the maximum recommended dose of budesonide (prophylactic steroid), formeterol (long-acting beta-2-agonist) and montelukast (a different long-acting agonist), I don’t need to use my salbutamol (short-acting beta-2-agonist) while cycling. There are days, though, if the air quality is poor, where I will need to take salbutamol before a ride to get my airways opened up sufficiently. Unmedicated, I’d be dead or bedridden – my medicated peak flow (a measure of airway throughput) is around 650l/m; unmedicated or ill, it can fall to 150.

    The medication allows me to cycle around 10,000km a year and compete (badly) as a Cat3/4. All it does is bring my PEF somewhere near normal (a real athlete might have a peak flow of 800 or more) and let me keep a reasonable blood oxygen level (around 96). It certainly gives me no advantage over someone who’s healthy to begin with.

    So any athlete who actually has asthma has my sympathy; having been through the process of even asking about a TUE (for the Worlds in Denmark last year) I can tell you it’s a PITA and UKADA seriously need to improve their comms. If you don’t have asthma, none of the permitted medications are likely to do much for you, apart from wreck your skin and raise your heart rate. If your airways are already relaxed, they aren’t going to get any bigger…

  • Chris Williams

    Well said

  • Inge-Jarl Clausen

    There is a way remove the lung overload that can lead to Asthma symptoms. The method is called Vegetative training and have successfully removed Asthma and other breathing disturbances in Pro cycling, Iron Man and hobby cycling.

  • Rich Wake

    I can imagine that, LA is such a sprawl, and ringed by mountains to boot surprised any of you can breathe

  • tony365

    Thanks for the reasoning.

  • tony365

    They just don’t tell you this s**t man, Athletes are not healthy. there is nothing healthy about being an athlete, it kinda sucks, You do it because you have too, you starve you self, train 10 hours a day and fall over. and thats kiddo crap when I was, a junior fighter, my good friends that were wrestlers and cyclist were on all kinds of s**t, you name it was available. our hockey team our track team…. on and on, lots of Speed, lots of HGH

  • Shane in Wonderland

    The portion of the article regarding “high proportion” is weak and quite likely speculation. Maybe Asthma like symptoms is close to true. As for conspiracy or blatant concentrated efforts to cheat, not the issue. Asthma medicine helps you breathe better by dilating airways, in a highly conditioned athlete or person with debilitating lung problems. Let the doctors decide if a rider has health ailments. Let the governing bodies of sport decide if a rider races. Life is not a big conspiracy, this I agree.

  • Grégoire Denis

    Totally agree. In my case I had severe asthma when I was young and that is cycling that cured it ! I never use an inhaler anymore, even when I was racing !
    They use it because they think it it will make them faster (true or not), and that shows that these guys would use any other mean, as long they they are not caught, if they could. Just for killing this culture of cheating the TUEs should be prohibited.
    And the doctor to justify the “asthma” of the top athletes… “triggering” asthma when you climb superfast – that is just the body that tells you to slow down – that is insulting real asthmatic.

  • Hyun-ji Song

    I have asthma, and I ride with a pretty fast group and race. Honestly, if I do ride really hard, I do feel I need my inhaler, otherwise I start wheezing. Everyone has their own severity of Asthma.

  • What is wrong with half the people commenting? It makes me despair. Does anyone actually really think that their own anecdotal experience is more relevant? I know a guy who smoked until he was 102 doesn’t demonstrate that smoking is safe.

    Did anyone else actually read the article that suggested that it would be almost impossible to get any performance enhancement from this drug and also that there were sound reasons why the rate of asthma was higher in cyclists than the already crazily high rate in the general population.

    As for diagnosing asthma, people do a breathing test, they don’t just answer questions. Life is not one big conspiracy.

  • tony365

    HA! sorry, hard to tell sometimes without hearing the voice, Nice one. I had a Ford Fiesta ( not kidding ), and have asthma, Thankfully no Cancer.

    As you implied lets not get to carried away with this one, I don’t use an inhaler like I said before but have used Ephedra (in tea form when it was legal ) for my breathing issues and it was great now only the fake big Pharma stuff is legal instead of the plant based goodness. This is more than a doping issue and I understand both sides hear, not sure what to think about inhaler use in pro sports of any kind, seems pretty benign to me

  • Morten Reippuert Knudsen

    ditto. This rider is just a plain cheat…

  • Morten Reippuert Knudsen

    Me neither. Im astmatic too and i havent used my spray or felt the need while exersising for it for the last 15 years. When i was younger i tended to go too hard below zero degrees and could have a mild attack – i rarely brougth my mediaction with me and even if i had with me i would have to stop and wait it out. I serously doubt that an astmatic athlete can be competitive (mediacation or not). The 40% of elite athletes with astma medication are using it because they thik it will make the faster… (if it works is a whole other story), Remember De Luca or Petachi… does anyone really think those guys where astmatic?

  • Michael

    No, I’ve genuinely never had asthma, cancer or owned a ford fiesta.

  • Shane in Wonderland

    Myself having been born with Asthma and endured the medicines and treatments available since 1964 can confidently say all of your posts are correct. These Jokers are using drugs to enhance respiration unnaturally, not treat serious health concerns. Trust me when I say, “people who need inhaled Asthma medicines to get through the day do not ride at this level of sport”.

  • tony365

    Joking I assume?

  • Michael

    Well, I’ve never had asthma, cancer or owned a ford fiesta.

    Obviously all the people who have are making it up to get time off school because my experience completely defines everyone’s experience, right Mike?

  • tony365


  • Mike Williams

    The inhaler works like a charm…2 puffs and your fine. You might want to give it a try…here in Canada its like $10 for a 100 doses. I suspect they are using it to open their lungs (whether it is true is irrelevant if they believe it).

  • tony365

    Very True!

  • tony365

    Yeah the cold air one seams shaky to me too! Allergies and pollution do trigger it for me, but like I said in my comment below I don’t use one. Thought about it but we are moving to a place were it shouldn’t be as bad. Im very curious about this whole issue though.

  • Mike Williams

    P.S. it would be pretty easy to convince a doctor you have asthma…”I am having a bit trouble breathing” >> “Here is your TUE”. (In my case you can at least hear my lungs whistling.)

  • Mike Williams

    I am not buying this…I have asthma (albeit mild) and have prescriptions for Salbutamol. I have never ever had to use it outdoors or while exercising — my attacks seemed to be caused by indoor air pollutants. The excuse for exercise in cold air (typically used by XC-skiers who are worse offenders) doesn’t fly with me either as I fat bike all winter down to -30C and never have an issue.

  • tony365

    I think its a little different than that. Personally I haven’t used one but there are times when riding in Los Angeles and Portland in the summer, where I literally can’t breath and wish I had one, I can feel it on the first major incline I ride up and it sucks, I am a pretty good climber for an amateur and when then pollen count is high or there is a lot of Ozone in the air, 5 min climbs turn into 7 min climbs and I have to stop and head down the mountain, when the air is clear I can climb for an hour and feel awesome, If i was pro I would use one! Actually now that I have Healthcare, Thanks Barry! I can afford one now maybe I will make an appointment, you can have a asthma attack from allergies and pollution particularly when sports are involved, Lot of kids in the inner city hear in LA have it.

  • Stompin

    Well, it does get them up the hills quicker lol ;-P

  • Derek Biggerstaff

    Remember that time a rider had to abandon a race because he had an asthma attack? No, me neither. Lucky the drugs are 100% effective,eh?