Jack Knife is one of the classical Pilates exercises included in Joseph Pilates' book Return to Life Through Contrology. It is a strong intermediate level Pilates exercise that builds on skills learned in the roll over. You should be able to do roll over before attempting jack knife. If you have neck problems, you should skip jack knife.
I like jack knife because of the spinal articulations and that you absoulutely have to use your Pilates powerhouse and sense of the midline to do it well. It's fun when you get it. Here are free Pilates exercise instructions for jack knife:
1. To Begin
Lie on your back with your arms along your sides, palms down. Lightly press the backs of your arms into the mat and open your chest. Your ribs stay down.
Imprint your spine onto the mat as you extend your legs, feet toward the ceiling.
2. Inhale to Bring the Legs Over
Use a deepening scoop of your abdominal musles and some help from the press of your arms to bring your legs over your head, parallel to the floor. Your back is nicely curved so that the weight is across your shoulders and not on your neck.
If you are very flexible, you can take the feet to the floor behind your head.
3. Exhale to Sweep the Legs Up
Keep your chest open and backs of the arms pressing down as you sweep your legs up so that you are a close as you can get to perpendicular to the floor. This is a strong powerhouse move requiring hip extension with upper body flexion. You have to think up, up, up and shoot up through the midline of your body.
You are on your shoulders, not your neck, getting help from the press of your shoulders and arms on the mat.
Suspend at the top of the move.
At this level, your work has gained a lot of flow and control. Use that here, along with your other Pilates principles to keep this exercise moving - not with momentum, but with control.
4. Inhale to Return Legs to Parallel, Exhale to Roll Down
Bring your legs back to parallel to the floor. Do not go all the way to the floor.
Roll down with straight legs, vertebra by vertebra, until you are back to the start position.
Repeat the exercise 2 more times
5. Breathing and Tips
- These instructions give a basic breath pattern - an inhale or exhale for each part of the exercise with the exhale on the most exertion. However, you might want to to try it the way Joseph Pilates has it in Return to Life which is to go over and up into the jack knife on one inhale. Then exhale to legs over. Hold to inhale. Roll down. Then exhale when your are down.
- It is easy to get caught up in the neck and shoulder area. Keep your neck and chest released toward the floor and your shoulders away from your ears. Notice how Jonathan Urla has an open chest with long neck in this angle of Jack Knife.
Next in the classic sequence: side kicks