Juggle a cascade with one arm behind your back, so that the hand sticks out from behind the opposite hip. This is most certainly NOT a pattern for anyone with back problems. The secret to this trick is the stance; the juggling is not that difficult. This tutorial mainly focuses on the stance that I personally use. Everybody is built differently & if you can find an easier or more comfortable stance then use that instead.
Before doing anything, stretch your spine. Stand up straight reach up with your arms & make the tallest shape you can manage. Slowly curl your upper body & hunch your shoulders forwards. Slowly curve over backwards & pull your shoulders back too. Do these stretches SLOWLY & GENTLY.
Stand with your feet just over shoulder width apart & angle your feet so that your toes point outwards. Bend your knees forward & start to lean your body backwards so that your weight is still over your feet. Now lean back as far as you can, you should start to feel the pull on your thigh muscles. Now place one arm behind the back, hunch your shoulders backwards & push the hand as far as you can over to the other side so that it pokes out on the opposite side of your body. It feels like you are leaning against your own arm. Now try waving that hand about but keep the elbow pressed against your back. You will obviously be limited in how far you can move it, but you should have plenty of space to throw & catch a ball.
Start off throwing & catching one ball in the half contortionist position. Throws to the hand behind the back need to be as accurate as you can possibly make them. If you have to move your body to make a catch, try not to stand upright because this will affect the next throw, instead try & move your body using your legs only.
When you are comfortable with one ball, move on to two balls & practise the exchange in both directions. Beware of getting into the habit of 'dipping' before each exchange, you don't have time to dip between every exchange when it comes to juggling all three balls.
Again when you feel comfortable take your third ball. I find it easiest to start with two balls in the hand behind the back. Just relearn to juggle just as you did in front of your body, either throw by throw or just going for it. You may notice that holding the half contortionist position for a long time may affect your breathing as it does constrict your diaphragm. So don't forget to stand upright, stretch & shake yourself down every so often.
When solid there are plenty of things you can do to spice it up. Obviously try going from a standard cascade into a half contortionist cascade using a High Throw. You can also enter the pattern with a Split Multiplex or a Triplex throw. Learn the pattern on both sides & switch between the two by throwing a ball across your body over your stomach. You may also like to try other patterns in the half contortionist style; the Shower, Half Mess & Mills Mess are all possible.