Start in plank position with hands placed directly underneath your shoulders. Arms should form a straight line from shoulder to hands, as should the body.

Ensure the lower back is supported (not sagging nor up too high), by engaging the muscles within the core. Think about tucking your pelvis under to promote this. From plank position, bring the right knee up and across the body, driving it towards the left elbow. On bringing the leg back to starting position (plank), do the same with the other side, driving the left knee towards the right elbow. This is one rep of each leg.