How to do it
Sit upright in a chair (preferably placed against a wall or other solid surface). Place the hands on each side of the chair, and keep the knees bent at approximately 90 degrees. Simultaneously push upward and back against the chair. Hold to feel the top of the thigh muscles and the gluteals contract. Stay in position for 10 seconds and release. Do 3-5 repetitions. Do this exercise slowly and stop if you feel too much strain on your back.
What it does This exercise stabilizes and strengthens the lower-back muscles. Lower-back power is necessary to maintain an upright body position throughout the ski turn.