Upper view of professional backstroke movementIn the initial position, the swimmer lies flat on his back, arms stretched forward, and legs extended backwards.
Arm movement
In backstroke, the arms contribute most of the forward movement. The arm stroke consists of two main parts: the power phase (consisting of three separate parts) and the recovery. The arms alternate so that always one arm is underwater while the other arm is recovering. One complete arm turn is considered one cycle. From the initial position, one arm sinks slightly under water and turns the palm outward start the Catch phase (first part of the power phase). The hand enters downward about ten inches, catching the water.
During the power phase the hand follows a semi-circular path from the Catch to the side of the hip. The palm is always facing away from the swimming direction, and the elbow always points downward towards the bottom of the pool. This is done so that both the arms and the elbow can push the maximum amount of water back in order to push the body forward. At the height of the shoulders the upper and lower arms should have its maximum angle of about 90 degrees. This is called the Mid-Pull of the power phase.
The Mid-Pull phase consists of pushing the palm of the hand as far down as possible with the fingers pointing upward. Again, the goal is to push the body forward against the water. At the very end of the Mid-Pull, the palm flaps down for a last push forward down to a depth of 45 cm, creating the Finish of the Power phase. Besides pushing the body forward this also helps with the rolling back to the other side as part of the body movement. During the power phase, the fingers of the hand can be slightly apart, as this will increase the resistance of the hand in the water due to turbulence.
To prepare for the recovery phase, the hand is rotated so that the palms point towards the legs and the thumb side points upwards. At the beginning of the recovery phase of the one arm, the other arm begins its power phase. The recovering arm is moved in a semicircle straight over the shoulders to the front. During this recovery, the palm rotates so that the small finger enters the water first and the palms point outward. After a short gliding phase, the cycle repeats with the preparation for the next power phase.
A variant is to move both arms synchronized and not alternating, similar to an upside down butterfly stroke. This is easier to coordinate, and the peak speed during the combined power phase is faster, yet the speed is much slower during the combined recovery. The average speed will usually be less than the average speed of the alternating stroke.
Another variant is the old style way of swimming backstroke, where the arm movement formed a complete circle in a windmill type pattern. However, this style is nowadays no longer used for competitive swimming, as a lot of energy is spent on pushing the body up and down instead of forward. Furthermore, the added strain on the shoulder is considered less than ideal and can lead to injuries.
It is also possible to move only one arm at a time, where one arm moves through the power and recovery phases while the other arm rests. This is slow, but it is used frequently to teach students the movement, as they have to concentrate on only one arm.
Leg movement
The leg movement in backstroke is similar to the flutter kick in front crawl. They make a small contribution to the forward speed, yet are very significant for stabilizing the body.
The leg stroke is also alternating, with one leg sinking down straight to about 30 degree out of the horizontal. From this position the leg makes a fast kick upward, slightly bending the knee at the beginning and then stretching it again in the horizontal. However, there are also frequent variants with four or only two kicks per cycle. Usually, sprinters tend to use 6 kicks per cycle, whereas long distance swimmer may use less.
It is also possible to use a breaststroke kick or a butterfly (dolphin) kick, although this is rare except the butterfly kick after the start and the turns. Breaststroke kicks are most comfortable if the arms are used synchronized, as the breaststroke kick has difficulty to compensate for a rolling movement due to alternating arm cycles. The butterfly kick can be done slightly to one side depending on the rolling of the body.
Breathing
Breathing in backstroke is very easy, as the mouth and nose are almost always over water. Competitive swimmers breathe in through the mouth during the recovery of one arm, and breathe out through the mouth and nose during the pull and push phase. This is done to clear the nose of water.
Body movement
Due to the asynchronous movement of the arms, there is a roll of the body around its own axis. This is normal and helps swimming effectively. The overall position of the body is straight in the horizontal to reduce drag. Beginners frequently let their posterior sink too low and increase drag, because to avoid this the upper legs have to be moved to the extreme down position at each kick even with a little help by the back and the foot tips have to be fixed in the extreme lower position. And the head is held out of the water to act as a counter-weight.