The athletic excellence seen at the Tokyo Olympics will live long in the memory, but so will the moment the brilliant US gymnast Simone Biles chose not to compete to safeguard her mental and physical health. US gymnastics is still reeling from the repercussions of a sex abuse scandal - what can go wrong when results are put above care of individual athletes? Stephen Sackur speaks to Aly Raisman, a multiple Olympic gold medallist who testified about being abused by the team's former doctor. Is there a wider lesson for elite sport in the shame of American gymnastics?