 Complete the following phrase:  In December 2014, a documentary aired on German TV in which 800m gold medalist Mariya Savinova allegedly admitted to using banned substances on camera. In November 2015, Savinova was one of five Russian runners the World Anti-Doping Agency recommended to receive a lifetime ban for doping during the London Olympics, along with 800m bronze medalist Ekaterina Poistogova. On 10 February 2017, the Court of Arbitration for Sport upheld a four-year ban that effectively stripped Savinova of her Olympic gold and other medals. On 7 April 2017, CAS refused to decide on disqualification from 2012, and disqualify Ekaterina Poistogova from 2015. Thus, Ekaterina Poistogova retained her Olympic 2012 medal at 