Lie on your back with your legs hip-width apart, feet flat on the floor, and with a towel under one heel.
Keep your arms relaxed on the floor by your sides.
Tuck your tailbone between your legs and lift your buttocks up until your hips are straight.
Slide one heel away from you so that your knee straightens.
Keep your pelvis level and hips high.
Then pull the heel back to the starting position and repeat.
You can also use a sliding disc for this exercise.
