Jackknifes are amazing for targeting your lower abdominal muscles, and as with all gym ball exercises, the ball provides instability which your body must correct. This means it’s a great core strength exercise too.
Start by kneeling with the swiss ball behind you. Place one foot then the other onto the top of the ball so that you’re in a press up position with both feet on top of the ball, hands placed slightly wider than shoulder width. Just allow your feet to rest naturally on the ball, you don’t have to balance on the ends of your toes.
Once you’re stable, keeping your back straight, draw your knees toward your chest. Breathe out, hold the position for a second or two before returning to the start. Repeat for as many reps as feel comfortable (up to 10 – 15) per set.
My good friend Jane demonstrates the technique beautifully in the video below.
