The back crawl or backstroke is the only competitive stroke performed on the back. Like the front crawl, efficient movement and good body position make this stroke more powerful. Keep your back slightly rounded so your legs are horizontal and your upper body is relaxed, your hips and legs are just below the surface. The water line typically runs from the middle of the top of your head to the tip of your chin with your ears underwater. Keep your head still and aligned with your spine as you stroke.
An effective back crawl depends on good body roll with every stroke. Use a regular breathing pattern as you swim, inhale when one arm recovers, exhale when the other recovers. Your body continues to rotate as you're recovering arm enters the water. Body rotation is at its maximum at the start of the catch. The catch for one arm begins as the other arm recovers. This will help you maintain good opposition rhythm in your stroke.
Your arms move in constant opposition to each other. One arm pulls while the other recovers. Each arm is always opposite the other arm. This is called opposition rhythm begin with your arms straight without moving your head. As your arm enters the water, rotate your body toward that side, your hand enters the water just outside the shoulder little finger first, your palm faces out with the wrist slightly bent, your entry hand slices downward 8-12 at a slight outward angle and grabs the water to begin the power phase. The power phase looks like this: Catch, mid-pull, and finish. The power starts with the catch, bend your elbow so your fingertips are pointed toward the side of the pool, your palm and forearm face towards your feet as you push the water back. Follow a straight path towards your feet while your fingertips continue to point to the side. During the finish, your hand speeds up as you follow through, extend your wrist so your palm faces slightly down at the end your arm is straight and your hand is below your hip.
Be sure to keep pressing on the water through the finish to help your body rotate to the other side. Begin the recovery for the arm stroke underwater, with your arms straight, lift your hand from the water first, letting the rest of your arm follow, the palm of your hand faces in your thumb leaves the water first. Keep your arms straight and relaxed throughout the recovery. Good body roll will help keep your recovering arm relaxed. Midway through the recovery, rotate your palm out so that your little finger enters the water first. Now watch the entire arm stroke sequence.
Use the flutter kick for the back crawl, it's a continuous up and down movement that starts at the hip and snaps at the foot. Keep your ankles loose. During the upward kick, the motion begins at the hip with a continuous fluid motion straighten your leg and snap your foot up until your leg is straight and your toes just reach the surface. During the downbeat keep your leg relaxed and almost straight. The distance your legs move up and down during the kick will vary depending on the length of your legs, your hip and ankle flexibility and the pace of the stroke. Most swimmers use a six-beat kick, but your cadence may vary. Now watch the back crawl again, notice how all the elements of the stroke work together to create a smooth motion through the water.