The purpose of the swimming exercise is to be able to maintain a neutral spine, whilst challenging the control of this position through the weight of your arms and legs.
To start the exercise, lie on your front, forehead resting on a small cushion, and back of neck long. Draw your shoulder blades down towards your waist to prevent unnecessary hitching around your neck. Set your lower back to be in a neutral position. As you breathe out, reach your left arm and right leg away from your body, allowing them to hover approximately 5cm off the plinth. As you breathe in, slowly lower this arm and leg to the mat. Now repeat with alternating arms and legs.
Once you are confident in this exercise and at the guidance of your physiotherapist they may recommend that you begin to lift your arms and legs higher. The focus should remain on keeping a neutral position through the lumbar spine whilst performing this exercise.
During this exercise you should expect to feel the muscles working in the legs, abdominals and shoulder region, but there should be no discomfort in the lumbar spine.