What exactly are the athletes accused of having done?
The latest accusations have come about after the leaking of an IAAF report containing details of 12,000 blood tests taken from 5,000 athletes between 2001 and 2012.
The report shows 800 athletes - or one in seven - had blood values said by one anti-doping expert to be "highly suggestive of doping or, at the very least, abnormal". A number of factors may elevate blood results, including genetic disposition or illness, but the 800 tests were deemed by experts to be indicative of blood doping.
How does it give them an advantage?
Blood doping essentially pertains to the number of red blood cells in a person's body.
Athletes rely on oxygen, which attaches itself to the haemoglobin in red blood cells. So by increasing the number of red blood cells - either by transfusions or synthetic injections - athletes can increase oxygenation and therefore boost performance.
Studies have shown that blood doping can improve 10,000m race time by more than one minute.
How different are the allegations to previous ones?
Athletics has been blighted by numerous doping accusations in recent years.
Last December, the German documentary maker behind the recent allegations unearthed claims of systematic doping in Russian athletics and implicated the IAAF in covering up the problem.
The latest claims are of a similar nature but on a far larger scale. One doping expert said he had "never seen such an alarmingly abnormal set of blood values".
Does it involve mainly endurance athletes?
Blood doping is predominantly an issue that affects endurance athletes, as it is those who race over middle and long distances who fully deplete oxygen reserves.
Of the 146 Olympic and world medals won by athletes who recorded suspicious tests, 29 were in the 1500m and 28 in the 20km walk.
Other disciplines with a high number of suspicious medals in the 800m, 5,000m, 3,000m steeplechase and 10,000m.
There are seven Britons under suspicion. Is Britain any better or worse than other countries?
British athletes come out of this latest episode far better than the majority of other major nations.
Only 4pc of blood tests from British athletes are abnormal. Russia has 30pc, Ukraine 28pc, Turkey 27pc and Greece 26pc. Kenya is also a major culprit.
Is athletics now a dirtier sport than cycling?
Having conducted research on the leaked IAAF data, the opinion of anti-doping experts is that athletics is now in the same "diabolical state" that cycling was in during the Lance Armstrong era. The data also suggests that the use of blood transfusions and EPO is as commonplace in athletics as it was in cycling.
That would put athletics approximately 15 years behind cycling in terms of attempting to police drugs cheats.
Is it still happening and how can athletics stop it?
The data obtained only relates to a period between 2001 and 2012.
While the IAAF claims the implementation of the biological passport in 2009 has helped in the fight against doping, the data suggests the number of suspicious tests did not decrease from 2009 to 2012.
Therefore the assumption is the trend has continued to the present day.
The question of how to catch the cheats is one that is crucial to the future of the sport. The IAAF spends £130m a year on combating doping, which it says is the highest percentage of overall annual budget in any sport.
Stamping out cheating would require a vast increase in funds available to anti-dopers, alongside harsher punishments.(© Daily Telegraph, London)
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