The Jackknife is a simple yet beautiful exercise that really engages the core and abdominals while focusing on spinal articulation, pelvic stability and hip movement. The slower and more controlled you perform this exercise the more effective it will be. Try not to use momentum to drive the movement. The Jackknife should be executed at the same speed on the way up as the way down.
1a. Start lying on your back, arms by your side, palms down. Lift your legs straight up in to the air so you have a 90 degree angle at your hips. Point your toes, draw your navel towards your spine and breathe in to prepare.
1b. As you breathe out, in one fluid movement, carry your legs over your head until they are parallel to the floor. Use your abdominals to control the movement and make sure your bodyweight is distributed evenly between your shoulder blades.
1c. Keeping your legs straight, breathe in and lift them straight up towards the ceiling. Squeeze your buttocks as you lift and carefully shift your bodyweight onto your shoulders.
As you breathe out, carefully and slowly roll your spine down vertebra by vertebra back down to the floor keeping your legs stretched straight until you are back in your start position. As you breathe out, keeping your legs straight, in one flowing movement, lower your legs down as close to the floor as you can keeping your back and pelvis stable. Lift them back up to the start position.
N.B. The Jackknife is not suitable for anyone who has a neck, shoulder or lower back problem issues, Do not attempt for the first time without experienced supervision.