LONDON - Team Sky cyclists used the sex pill Viagra at altitude to establish whether it had performance-enhancing benefits.
Sportsmail understands the drug was tested while the team was in its infancy, following its foundation in 2010.
No rider is under suspicion of committing a doping offence because Viagra is not on the World Anti-Doping Agency banned list, but experts have suggested it can be used to boost athletic performance.
British Cycling and Team Sky declined to comment on Wednesday night.