Darren Campbell, 200m silver medallist at the Sydney Olympics, talks BBC Sport's Tom Fordyce through the psychology of the sprint start, and demonstrates with a game of 'slaps'.
Usain Bolt, disqualified from the 100m final at the World Championships last weekend after a false start, goes for gold in the 200m on Saturday in Daegu.
Listen to Darren and the BBC Radio 5 Live team commentate on Bolt's race on Saturday at 1320 BST.
Available to UK users only.