Competitors in Men's 110m hurdles semi-final leave starting blocks, London 2012 Stadium, Summer Olympic Games, London, England, United Kingdom, Europe

Crowds in the stands of Olympic Stadium, with runners on the starting blocks, London 2012, Summer Olympic Games, London, England, United Kingdom, Europe

Olympic rings and starting blocks, track side, busy Olympic Stadium pre-session, London 2012, Olympic Games, London, England, United Kingdom, Europe

Tartan track of a sports field, starting blocks for sprinting disciplines, lane markings

Start block, hundred meter run, detail of the feet

Tartan track of a sports field, starting blocks for sprinting disciplines, lane markings

Sailboats with spinnakers flying maneuver for a starting position at the biginning of the Block Island Race.

Indoor swimming pool, starting block, diving block and marked lanes, flat calm water

Indoor swimming pool, starting block, diving block and marked lanes, flat calm water

Indoor swimming pool, starting block, diving block and marked lanes, flat calm water

Indoor swimming pool, starting block, diving block and marked lanes, flat calm water

Heated indoor swimming pool, diving blocks, starting blocks for competition