Study finds paracetamol helps cyclists' endurance - but health and ethical questions arise

Earlier study said painkilling drug could shave 30 seconds off 10-mile time trial

by Simon_MacMichael   November 7, 2013  

London 2012 anti-doping lab (picture credit LOCOG)

A recent study suggests  paracetamol can help improve the performance of cyclists. The painkiller is not currently on the Prohibited List of the World Anti-Doping Agency (WADA) – but the academic who led the study says the agency should rethink its position. An earlier study found that taking the drug could shave 30 seconds off a 10-mile time trial.

Separately, concerns have been raised about people overdosing on paracetamol as a result of regular and excessive usage of the drug, plus the fact that in a sporting context it pushes ethical boundaries and may lead to athletes going on to take prohibited substances.

The study, carried out at the University of Kent, and published in September in the journal, Experimental Physiology, found that taking paracetamol, which also works as an anti-inflammatory, helped endurance by reducing pain and that physical exertion could be maintained on for longer in hot conditions.

It involved 11 men described as “recreationally active participants” participating in time-to-exhaustion trials on a stationary bike after taking either a placebo or paracetamol –known as acetaminophen in some countries – in temperatures of 30 degrees Celsius.

Findings that taking paracetamol improved the endurance ability of the riders who had taken it is an issue that anti-doping authorities need to address, said Dr Lex Mauger, who led the study at the University of Kent’s School of Sport and Exercise Sciences.

He urged that “consideration by the World Anti-Doping Agency (WADA) and local anti-doping authorities should be made about the use of non-steroidal anti-inflammatory drugs (NSAIDs) in sport – on both health and performance grounds. Secondly, the utility of paracetamol as a first-response drug to exertional heat illness should be investigated."

Dr Mauger added: "Whilst we have found that paracetamol improves the time someone can exercise in the heat, and that this occurs alongside a reduced body temperature, we did not measure the specific mechanisms by which this may have occurred. It is important now to try and isolate how paracetamol reduced participants' body temperature during exercise."

The earlier study, conducted by researchers at the University of Bedfordshire and published in the Journal of Applied Physiology in July 2009, analysed the performance of 13 competitive cyclists recruited from local clubs.

Following initial assessment, the participants returned to the laboratory on two separate occasions to ride a 10-mile time trial, using their own bikes on a RacerMate turbo trainer.

On each occasion they were given three capsules, either containing a placebo or paracetamol, which is known as acetaminophen in some countries and referred to by that name in the study. Total dosage was 1.5 grams on each occasion.

Besides the 30-second average improvement in time – 26 minutes 15 seconds with paracetamol compared to 26 minutes 45 seconds with the placebo – there was also a higher power output during the middle part of the time trial.

Although there was no reduction in perceived pain among those administered paracetamol, something that conflicted with researchers’ expectations, those participants did say that they found riding the time trial “easier” or “better.”

But experts have warned that if not taken as directed, paracetamol can lead to health problems including liver failure and even death through non-deliberate overdose, as well as potentially provoking severe allergic reaction.

A study led by Dr Kenneth Simpson, of Edinburgh University and the Scottish Liver Transplantation Unit in 2011, which analysed 663 patients admitted to Edinburgh Royal Infirmary for liver damage resulting from paracetamol warned of the danger of “staggered overdoses.”

That refers to patients where the hospital admission was not due to a deliberate overdose, but where instead the harm was done as a result of gradual build-up of using the drug more regularly and in greater dosage than directed.

In all, 141 of the patients analysed had taken a staggered overdose as they sought to combat the effects of conditions such as toothache or persistent headaches.

Dr Simpson said: “They haven’t taken the sort of one-off massive overdoses taken by people who try to commit suicide, but over time the damage builds up and the effect can be fatal.

“They are often taking paracetamol for pain and they don’t keep track of how much they’ve consumed over a few days.

“But on admission, these staggered overdose patients were more likely to have liver and brain problems, require kidney dialysis or help with breathing and were at greater risk of dying than people who had taken single overdoses.”

Earlier this year, a New Zealand cyclist with hopes of becoming a professional openly admitted using paracetamol during races – something that is entirely permitted under current anti-doping rules.

The rider, Alex McGregor, a 23-year-old who spent four years based in Belgium and was linekd to a US-based team until its sponsor got cold feet in the wake of the Lance Armstrong scandal last year, confessed “it’s not a good look” to be taking tablets prior to the start of a race.

"A lot of people think your taking it to work like a drug or enhance performance, but it doesn't really do that," said McGregor, quoted on

"I can see the effects of using paracetamol, for example, it stops . . . you don't feel the pain, as such. You don't feel that real heat.

"There's been times on a road race where I've found it really beneficial, like a cold, shitty day, where the legs are cold but hurting as well. You can feel the painkiller working, but you've got to have the dosage right, because when it wears off, you notice it.

"I'm looking into it with a sport scientist here in Dunedin," he added

The head of Drug Free Sport New Zealand, the national anti-doping authority, Graeme Steel, warned that even drugs that aren’t banned by WADA could give rise to concern.

He said: "Athletes begin on the road to doping by doing things that are technically permitted, but really are on the verge of unethical behaviour."

"It's something we would prefer athletes didn't do," he went on.

"We really have no jurisdiction over it in one sense, but one of the things that concerns us is that athletes begin on the road to doping by doing things that are technically permitted, but really are on the verge of unethical behaviour."

16 user comments

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Very interesting, although two very small sample sizes in this research. Wonder if the same could be said of Ibuprofen. Or booze - does wonders to block out my pain.

I'd say I'm a drug free cyclist but caffeine is at the heart of everything I do (on and off the bike!).

The Human Cyclist A blog. Try it, you might like it...

sm's picture

posted by sm [371 posts]
7th November 2013 - 20:21


Who knew? I've often dropped a couple before the Sunday morning ride as part of the hangover recovery, never did I suspect that this may actually help my performance.

posted by drfabulous0 [406 posts]
7th November 2013 - 22:36


It appears that these studies all took place indoors on static turbo trainers (obviously this makes it easier to standardise the test), where getting too hot is a real problem. Overheating in these kind of indoor tests is well known to significantly reduce one's effective power output even with the use of fans (see Bicycling Science by David Wilson, chapter 3 for details of how much). So while I don't find these claims about paracetamol use surprising, I'd bet the effect on real outdoors riding to be much much less significant or possibly insignificant.

Gasman Jim's picture

posted by Gasman Jim [114 posts]
8th November 2013 - 8:23


For what it is worth, as a cyclist with dodgy knees, the Sunday lunch break often gave me a problem getting back on the bike. The stiffening up gave me a lot of pain setting off again but I found after a couple of paracetamol taken after or during lunch the pain subsided and getting home was much easier. I can't say the same for time trials, the pain is always the same, acute.


antonio's picture

posted by antonio [1103 posts]
8th November 2013 - 9:52


Anyone tempted to experiment with paracetemol in this way should have a thorough read of this first:

John Stevenson's picture

posted by John Stevenson [1519 posts]
8th November 2013 - 10:44


[Non-serious]Hmm if 1.5g shaves 30s, then 15g will save 5 minutes![/Non-serious]

But as John points out the dangers of paracetamol toxicity is of a concern.
Also to extend what SM says, I wonder if different pain killers produce different effects.
Though it does mean that if we see a cyclist popping a paracetamol the question is are they doing it for the edge or because they have dodgy knees.

posted by Wolfshade [140 posts]
8th November 2013 - 11:00


Paracetamol found to reduce pain and temperature shock...

posted by teaboy [285 posts]
8th November 2013 - 12:33


Step away from the bike, it's only a game...

Gosh! I don't even take Paracetamol when I have a headache. In fact I took it on two occasions when I had a slipped disc, and I was in real pain with that, but for me it was a kinda numbing sensation but I knew the pain was still there.

No this isn't to do with bragging, just my aversion to take any kinda drugs that are not 100% necessary.

Tell 'em William s. Sessions Smile

posted by ronin [260 posts]
8th November 2013 - 12:38


Cheaper than spending £4000 on an aero bike (joke before the dopestasi put in their worth. For someone who suffers back pain I will often take a couple of paracetamol, I can't say i have ever noticed a performance changes but it does allow me to enjoy the ride if having a bad back day.

Eating less fatty food will do much more to improve your times!

'It's the closest you can get to flying'
Robin Williams response when asked why he enjoyed riding so much

posted by Simmo72 [524 posts]
8th November 2013 - 14:39


ronin wrote:

Tell 'em William s. Sessions Smile

Only users lose drugs.

Or something.

posted by farrell [1912 posts]
8th November 2013 - 14:42


farrell wrote:

Only users lose drugs.

Or something.

Road cycling podiums would suggest otherwise Smile

William Black's picture

posted by William Black [196 posts]
8th November 2013 - 15:00


Next up: Shock as new study finds cyclists now using jenkem to increase performance.

zanf's picture

posted by zanf [716 posts]
8th November 2013 - 17:28


OK this is a study of 13 guys who average a little over 20 mph for 10 miles; some took Tylenol and were a little bit faster - So if you ride slow Tylenol might make you a little less slow

posted by chickeee [14 posts]
9th November 2013 - 7:51


We wonder why there has been such a drug problem in the sport but we seem obsessed with performance enhancing supplements - everything from beet root juice - isotonic drinks with caffeine and now paracetamol. It's clear as one climbs the ranks of ability these probably become more and more attractive and at some point a boundary can be crossed. It's the same attitude just lower down the scale.

posted by l4urence [9 posts]
9th November 2013 - 11:44


chickeee wrote:
OK this is a study of 13 guys who average a little over 20 mph for 10 miles; some took Tylenol and were a little bit faster - So if you ride slow Tylenol might make you a little less slow

But as all the pros are already using it, they cannot do the same trial with them?

If bans for drug taking go up to 4 years, taking paracetamol after a night out etc, may need more consideration. Watch out weekend warriors!

I love my bike's picture

posted by I love my bike [99 posts]
9th November 2013 - 12:59


I've worked with addicts in rehab and have seen deaths from paracetamol it takes quite a lot less than you would think to overdose and is a very painful and lengthy end! Anyone thinkin of doing this to them self for a few seconds in a cycle race needs their head looking at! Worried


Baldy1alex's picture

posted by Baldy1alex [54 posts]
9th November 2013 - 16:32