Perri Shakes-Drayton (C) of Britain clears a hurdle next to Lashinda Demus (L) of the U.S. and Natalya Antyukh of Russia in the women's 400 metres hurdles heat during the IAAF World Athletics Championships at the Luzhniki Stadium in Moscow August 12, 2013. REUTERS/Phil Noble (RUSSIA - Tags: SPORT ATHLETICS)