The performance enhancing effects of Tylenol

Athletes tend to be very proactive in searching out new performance enhancers, which is why the more recent substances which have broken through in the field of ergogenic aids tend not to be all that well-known, such as (-)-epicatechin. However, over the last ten years, research has started to emerge showing that a much more well-known, household drug may hold some surprising performance enhancing effects. It is so well known, in fact, that it is likely in your medicine cabinet. That drug is paracetamol, often known as acetaminophen or by it’s brand name in America: Tylenol.

Performance and paracetamol

The initial research in this area was focused primarily on endurance-based performance. A study in this field was published in 2010 an authored by Alexis Mauger, currently based at the University of Kent. In this early study, Mauger and colleagues, including Andy Jones of Nike Breaking-2 fame, put thirteen trained male cyclists through 10-mile time trials, following ingestion of either a placebo or paracetamol at a dose of 1.5g. The subjects completed the time trial an average of thirty seconds quicker in the paracetamol trial when compared to the placebo trial, giving an early clue that paracetamol may enhance performance.

Following this initial finding, 2013 saw a host of additional studies published in this area. A group that Mauger was part of demonstrated that a single dose of 1.5g of paracetamol enhanced repeated sprint cycle performance when compared to placebo. An Austrian group examined the impact of paracetamol on body temperature in runners exercising in the heat; here, a single dose of 500mg of paracetamol reduced the expected increase in core temperature, although this didn’t directly impact performance (perhaps it would have if the paracetamol dose were similar to the other trials). This was followed again by Mauger and colleagues, who put eleven subjects through time to exhaustion exercise trials on an exercise bike in hot (30 degrees Celsius and 50% relative humidly) conditions. Prior to the trials, the subjects consumed either a placebo, or 20mg of paracetamol for every kilogram of lean mass (which, for a 70kg individual with 10% body fat, would equate to just over 1.2g of paracetamol). The results showed that the subjects could exercise for a significantly longer period of time in the paracetamol trial (an average of twenty-three minutes) compared to the placebo trial (an average of nineteen minutes). Earlier this year, researchers showed that a single dose of 1g of paracetamol preserved muscle activation during a set of 60 three-second maximum voluntary contractions.

How it works

The evidence for paracetamol is, therefore, obviously very promising. The mechanism underpinning these performance benefits is likely a combination of a paracetamol’s antipyretic (fever reducing) effects, and its reduction in the sensation of pain. This is a great example of the impact the brain can have on exercise performance; here, sensations from the muscle are interpreted by the brain as pain, and as a result the brain reduces exercise intensity in order to protect the body. This pathway forms a fundamental part of two competing – but similar – theories of how the brain impacts exercise performance; the Central Governor Theory and the Psychobiological model. As such, the impact of paracetamol on exercise performance further adds to our increasing knowledge as the interplay between brain and body in controlling exercise performance.

Outside of paracetamol’s direct performance benefits, there appear to be some potential peripheral benefits that arise from its use, particular around post-exercise recovery. In a 2012 study, 610 runners taking part in a marathon were randomized to receive either 3.9g of paracetamol or placebo daily for four days pre-race. Those in the paracetamol trial reported less muscle soreness following the race, and also better sleep, although this secondary finding is potentially because of their lower muscle soreness made them more comfortable overnight.

The elephant in the room

Given paracetamol’s recently discovered beneficial effects on performance, some researchers are asking whether it should be classed as a performance enhancing drug, and hence banned by the World Anti-Doping Agency (WADA). To be placed on the prohibited list, WADA require it to fulfil two of the following three conditions; it enhances performance, it represents a potential health risk to the athlete, and it violates the spirit of sport. We’ve already covered the evidence that paracetamol likely is a performance enhancer, fulfilling the first aspect, but it also has the potential to be harmful to health. This is often discussed by the authors of these studies, who clearly aren’t keen to see athletes suddenly dosing up with paracetamol in a bid to enhance performance – even though a fair amount already do. Here, paracetamol’s pain reducing properties are a double-edged sword; whilst they imbue its performance enhancing effects, they may also mask the development of more serious injuries, possibly affecting the athlete’s long-term well-being. In addition, there are many legitimate uses of paracetamol that athletes may be pursuing, and so a blanket ban may impact this – and, given the current furor regarding TUEs, they don’t seem like a suitable solution either.

So, what to make of all of this? If you take part in endurance sports, particularly in hot and humid conditions, then based on the evidence present, paracetamol certainly has the ability to enhance your performance . However, it’s use in this way may be perceived by some as morally gray, and may also have some negative health outcomes, so it’s certainly a risky proposition – and I can’t make that decision for you. Alongside this, paracetamol is primarily researched to explore the relationship between exercise-induced pain and performance, and in that regard, we can see that being able to limit or reduce the pain we experience during exercise, we can enhance performance, and it has been successful in supporting this endeavor. Many other agents, including caffeine, have the potential to modify the pain response to exercise, and so athletes needn’t rely on paracetamol – but the modulation of exercise-induced sensations of pain is likely something that should be on their radar.

All in all, the research serves as a valuable illustration of the brain-body interaction in sports and exercise, and gives us some insights on pathways to explore in order to enhance performance.