Try this exercise, heel slide, it helps us learn how to keep the pelvis and lumbar spine in neutral while the limbs are moved, so working those core/stabilising muscles.
Zip up the core muscles as you exhale and slide one heel along the floor trying to extend the leg. Keep the lower abdominals engaged and the pelvis still, stable and in neutral. Take a breath and when you exhale slowly bring the leg back to the start, repeat on the other side.
Keep the core muscles engaged whilst focusing on the stable spine and pelvis. If it feels comfortable then you can add in taking the opposite arm overhead as you extend the leg, stretching through the sling system of the body.
Give this exercise a go today, follow me for more tips and exercises.