Start by pulling in your inner core below the belly button while keeping your posture in neutral. Be careful to avoid arching the low back. Keeping your inner core engaged extend the hip with the knee bent at 90 degrees. Hold this at the end range for a few seconds and then bring it back down. Repeat this 10 times 3 sets 3 times per day. This exercise is great to help increase active range of motion extension strength in your hip due to muscle imbalances caused by injury or arthritis in your hip joint.