These exercises target specifically your upper and lower abdominals and are good to improve flexibility
Jackknife
1. Lie flat on your back on a mat with your legs fully extended raised slightly off the ground, and with your arms fully extended behind your head
2. Contract your abs and simultaneously raise your arms and legs so that your fingertips meet your toes to meet in a jackknife position
3. The upper torso should be raised off the floor and then this position can be held for a couple of seconds before gently lowering back down
Gym Ball Jackknife
The instability of the ball provides added resistance for your abs to work against
1. Adopt a pushup position with your feet and shins resting on a gym ball behind you
2. Your body should form a straight line from your head to your feet
3. Keeping your back straight, contract your abs and use your feet to pull the ball towards your chest by bending your knees
4. Pause when your knees are fully flexed, and then slowly extend back to the starting position
Modified V-Sit
This is a slightly easier variation of the jackknife but still works on your abdominals
1. Lie face up on a mat with your legs fully extended in front of you and slightly elevated off the floor
2. Keep your arms extended by your sides
3. Simultaenously crunch up your upper torso while drawing your knees towards your chest and form a V shape
4. Pause for a couple of seconds and go back to the starting position
Gym Ball Passing Jackknife
1. Lie on your back in the standard jackknife position but with a gym ball held between your ankles
2. Keeping your legs straight, lift them up with the gym ball and raise your arms at the same time towards the gym ball
3. Pass the ball from hands to feet at the top of move
4. Lower both your arms and legs but this time with the ball now between your hands
5. Return the ball from your feet to your hands on the next rep.
