What are the biomechanical principles of the 'preparation' phase of the turn?

Preparation for the freestyle turn occurs well before the wall is reached and being aware of the biomechanical principles of the preparation phase of the turn can set the swimmer up for a time and energy efficient transition between laps. Blazevich (2012, p. 164) explains that the forward speed of the swimmer is dictated by two factors: 

           1. Forces resisting motion – drag

           2. Forces causing motion – propulsion

Reducing drag and increasing propulsion in the preparation phase will increase the speed of the swimmer and therefore increase the speed into the turn. There are three forms of drag:

          Wave drag

          Form drag

          Surface drag

These can all be manipulated to increase the speed of the swimmer, and the positioning of the hands can be altered to increase the propulsion. This will be discussed below.

As the swimmer approaches the wall a breath should be taken and a full stroke cycle should be completed. The turn should begin after the last stroke of the cycle. The turn is initiated by the flexion of the head and spine along with the dolphin kick. This drives the head and shoulders down and raises the hips. The forward roll is then able to occur due to the torque produced by the dolphin kick and the increased resistance of the head and shoulders as they move out of alignment with the rest of the body. The upper body flexes about the hips, and the knees are tucked close to the chest to reduce the distance from the axis of rotation and decrease the amount of inertia (Lyttle, 1999, p. 8).