Swimmers start the race in the water, pushing off with their legs. Races are four lengths of the pool for the 100m. The turn in Backstroke events is usually a tumble turn, although the International Swimming Federation (FINA) rules state any turn is legal as long as some part of the swimmer’s body touches the end of the pool before the turn, and they are on their back before leaving the wall.
All races start with heats. The top 16 swimmers from the heats progress to the semi-finals, and the top eight then advance to the final. As in the heats, the swimmers’ seedings are used to decide which semi-final they swim in, and which lane they are allocated.
If there is a tie for the last qualifying position, a swim-off decides which athlete progresses.