Together with her older sister Tamara Press, who was also a track athlete, Irina was half of the "Press Sisters", a duo who won almost everything that there was to win in track and field, except for distance running. The two sisters won five track and field Olympic gold medals for the Soviet Union, and set 26 world records in the 1960s.
Their careers ended abruptly at the time that gender verification was introduced. Critics have suggested that the Press sisters were actually male, or perhaps hermaphrodites. Another allegation was that they were being injected with male hormones in order to make them stronger. Detractors called them the "Press Brothers". Both sisters had left the sporting scene by the time that gender verification for all international sporting female events was made mandatory in 1966. Some Western newspapers[which?] took that as a confession by the Soviet Union, but Russian newspapers still deny the allegations.