Updated 07 June 2013

Drugs and the Tour de France

The Tour de France is 'infamous' for drug use. But what drugs? And how do they work? FitnessDoc, Dr Ross Tucker explains the more common ones.


Dr Ross Tucker gives us the scientific low-down on what some of the more commonly used drugs some cyclists use are and how they work.

1. EPO




During shorter, higher intensity exercise, like 1 500m running events, perhaps up to about 15 minutes of exercise. Longer than this, and oxygen supply is not really limiting. So anyone who's ever ridden for five hours will tell you that you never really hit that limit, because you don't exercise near your maximum level. So we believe that EPO must have some other effect in addition to the one it has on the blood and oxygen levels.

EPO use can be dangerous
Bottom line though - EPO works, and so that's why cyclists use it. The problem is that the more red blood cells you have, the thicker the blood becomes - and it becomes more viscous. Imagine adding flour to a mixture of milk and water when you are baking.


There was a spate of sudden deaths during the night in young, fit European cyclists about five years ago - these were all rumoured to be linked to EPO use, because the cyclist's hearts were just not able to pump the blood anymore.


The idea was that they would increase the heart rate and 'protect' the heart from having to pump too much per contraction. The quote was: "Cyclists would live to ride during the day, and then ride to stay alive at night".

EPO has now become much easier to detect, though there are of course still problems. However, I suspect that there are other, similar but undetectable drugs being used. Just because someone has not tested positive does not mean they are not using - some drugs are created specifically to ensure that they are not detectable. So I think there may well be drugs out there that will be discovered in maybe 10 years, but which are improving performance now.

2. Testosterone




Testosterone, as we've said, is an anabolic agent, which increases muscle mass when used in conjunction with training. So why would a cyclist in the Tour de France wish to use it?

For one thing, cyclists need to be small, so that they can climb 10% gradients on mountain passes without having to haul too much mass up the climb. Secondly, testosterone is used best over long periods, in conjunction with training. It would have little effect when used once.

So either we have an anomaly, or perhaps cyclists are using it every day, but not being detected. It's important to remember that one is only picked up if the ratio of testosterone to another hormone, epitestosterone exceeds four, then they do further investigation. So it's possible to use both testosterone and epitestosterone in the right amounts and never be picked up by this screening process.

But we still haven't answered why a cyclist would use it? Some fascinating research from Spain has showed that during the course of the three-week tour, a cyclist's testosterone levels, together with other hormone levels, decrease progressively.



So that's an overview of two of the drugs that have been (and seem to be, and probably will be) used for cycling. Let's hope that the latest Tour is not affected by these or any other doping products, and that we can enjoy writing about the cyclists instead of the doctors.

(Dr Ross Tuckeralso blogs on




Read Health24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Live healthier

Watch out! »

Gross fungal infections you can pick up at the gym


Holiday health »

Your 10-step asthma holiday checklist
