快猫短视频

On Saturday, the greatest cycling race in the world, the Tour de France, starts in D眉sseldorf, ending 22 days and 3540 kilometres later on the Champs-脡lys茅es in Paris.

Between 1999 and 2005, the only winner of the Tour was US rider Lance Armstrong. However, in 2012 he received a lifetime ban for doping, for using among other things the blood-boosting agent erythropoietin (EPO). Stripped of his titles, a glittering career ended in disgrace.

In a memorable scene in The Program, a film based on his fall from grace, Armstrong is portrayed being injected with EPO by his doctor accompanied by the line: 鈥淭his is science; no longer confined to Earth 鈥� now we have learned to fly.鈥�

A new paper by Dutch researchers attempts to send the science used by Armstrong 鈥� and by the Russian state sponsored doping that led to mass bans at the Rio 2016 Olympics 鈥� back down to earth. It suggests that in terms of cycling performance, EPO is no better than a placebo.

More red blood cells

So how is injecting EPO supposed to help improve performance? It is a hormone produced in the kidneys when oxygen tension 鈥� a measure of how much oxygen is in blood 鈥� is low. It then triggers an increase in erythropoiesis, the production of new red blood cells. This is why prolonged exposure to high altitude increases the number of red blood cells 鈥� the basis for altitude training.

However, when oxygen tension normalises, EPO levels fall and red cell production decreases. Injecting EPO removes this feedback mechanism, enabling higher numbers of red cells and increasing the concentration of the oxygen-carrying protein haemoglobin.

The finite amount of oxygen carried by haemoglobin can limit efficient work during prolonged aerobic exercise such as long distance running and cycling. It has long been known that the maximum rate of whole body oxygen consumption (VO₂ max) correlates with increases in total haemoglobin in healthy adults. This is why Lance Armstrong and others used EPO injections and blood transfusions to increase performance.

What this new study does is show 鈥� using the tool of the double-blind, randomised, placebo-controlled clinical trial 鈥� that even though injecting EPO did increase people鈥檚 total haemoglobin and VO₂ max in the laboratory, there was no significant effect on tests more closely related to sports performance 鈥� such as time trials and a road race to the most famous Tour de France summit Mont Ventoux.

So the authors claim that the blood doping emperor has no clothes 鈥� it was all a placebo effect.

Placebo only?

Is this true? Maybe. For ethical reasons, the study only used recreational racers not elite competitors. Blood oxygen content may not have been limiting performance in this group. Also, as the subjects were asked to keep their training constant, they did鈥榦t test any effect EPO might have on increasing the ability to train at higher intensity.

What鈥檚 more, the study doesn鈥檛 address use of a closely related doping technique 鈥� transfusions of blood which directly lead to elevated red cell counts. This was .

Yet, this is still an impressive piece of work. Will it have an impact in the anti doping world? Possibly not. The World Anti-Doping Agency (WADA) will not remove EPO from its banned list as long if there is even the slightest chance that this substance could improve performance. One research paper 鈥� however careful 鈥� would not be enough to sway opinion.

What about use by unscrupulous coaches? Coaching is as much an art as a science. Harnessing the placebo effect is a key part of this art and . If an analyst sees targeted improvements in the real-world performance tests of their athlete, they will dismiss any scientific paper as irrelevant to their individual athlete. Personalised coaching is as hot a current topic as personalised medicine.

Where this paper could make a real difference is in the area where EPO use is increasing fastest. The relatively cheap price on the internet of recombinant drugs such as EPO 鈥� human proteins easily made using bacteria 鈥� has led to a big increase in its use at the non-elite level, in club athletes who know they will never be drug tested.

The knowledge of the genuine risk of blood clotting from EPO use and the, if any, (rather) small benefits may well deter these occasional users. Let鈥檚 hope so.