The Balco investigation and the recent failed testosterone tests by the Tour de France champion Floyd Landis and the Olympic champion sprinter Justin Gatlin have made that obvious.
She's also demolished the field, and she doesn't seem, like so many top female sprinters before, to be an obvious doper.
"The sheer power and natural strength that she had already developed from being a sprinter... that was fairly clear and obvious.
Inge De Bruijn needed only one lap to underscore what has been obvious since May: De Bruijn is the world's finest female sprinter, and her narrow victory in the 50-meter freestyle today gave her a third individual gold medal in these Games.
When you realise that the total distance covered each day can be up to 100km, and bear in mind that pedalling speed is vital for a sprinter such as Cavendish, the benefits of riding the Sixes seem obvious, particularly with the 2015 season so close; Cavendish will kick off on 19 January in Argentina.
"It was obvious to everyone that with the rise of your country's great sprinters and hurdlers, a compelling rivalry between Jamaica and the United States had developed".
"It was pretty obvious he was running in the wrong events," said Smith, who suggested he become a sprinter instead.
With Sprinter Sacre, the highest-rated jumper in training, currently sidelined after cardiac problems and Sire De Grugy on an obvious upward roll in his second season over fences, bookmakers certainly believe the guard may be about to change.
But eventually every sprinter trips.
Cheetahs, the champion sprinters of the animal kingdom, have non-retractable claws that give a similar advantage.The reason for the difference in the Achilles tendons, though, is less immediately obvious.
