The Ball Jackknife exercise
This movement will strengthen your core muscles and help with balance and posture.
1. Place your hands on the floor with arms straight and palms flat, as shown in the photo above. Balance on an appropriately sized ball, keeping it between your ankles and shins.
2. Contract your abdominal muscles, squeeze your buttocks together and slowly pull your knees toward your chest while still balancing your shins and feet on the ball, as shown in the photo below.
3. Keep your knees about three inches off the floor and hold this position for 2-to- 3 seconds. Very slowly, straighten your knees back to the start position.
4. Perform at least 8 repetitions, and up to 20 for very advanced exercisers. It should take about 5 seconds to complete each one.
5. The muscles worked include the hip flexors; rectus abdominis on the front of your torso; external obliques along your sides, and the lower back and deep, intrinsic core muscles.
Secondary muscles used for stability and posture in the shoulders, arms, chest, and upper back also get worked out.
6. Keep your back straight during the movement. Avoid letting your head and neck protrude or rounding your upper back. You’ll also want to avoid arching your lower back.
Disclaimer: Do not begin any physical activity described in this column without prior approval from your health care professional.
Elisa Maceo, a staffer at Shula’s Athletic Club, demonstrates the Ball Jacknife exercise. Photos by Megan Jacobo, The Miami Laker.