any good execises for the lower back thats not too strenuous at first.
comeing offf of a back injury.
any advice please?????

try supermans. they just use your body weight. here's how to do them:
1


2


Note: you dont need a ball. Also, if that's still too strenuous, use your hand for support like this:



Just put your hands down like youre doing a pushup and crunch you back like the original exercise.

Digweed has it spot on, but if the superman is too tough at first try the right arm left leg raise and visa versa, its a tough exercise at the beginning.
Also with the same ball, sit on it and bounce up and down on it doing mini squats making sure you breath properly.
Another, sit on the ball and roll your hips back and forth using your stabalizing muscles to roll back and forth and again breathing is important.