It is actually most likely that they are doping, the history of revelations in these sports indicates that at various moments in the past, it WAS the case that any given elite athlete was most likely to be doping, it is probably the case now too.

It is possible to cheat to gain an advantage, and not get detected. People with the drive to become elite athletes in the first place, are very likely to be tempted. Once even 1 athlete in the sport is cheating, others will feel it is necessary to cheat with them to compete. This has happened over and over in every sport I know of.