The "bad" Roman Chair, the one that puts you at a 45 degree angle with your head above your hips, will likely injure your back if you have any pre-existing problem.
Instead use a Roman Chair that puts your feet and hips at the same level and allows you to hang with your head down and your torso vertical. Once you're in position (head straight down), lift yourself slowly to 45 degrees from vertical, no more, lower and try to and relax the back spinal muscles. The whole point is to use your upper-body weight to stretch out those tight spinal muscles.
Over time you can add weight. Put the weight on the floor, get in position (head down) and only then pick up the weight. The greater the weight the more your back stretches. Increase weights only slowly over the weeks.Always warm up with no weight first.
Read about 5BX before starting. The chart 1 exercises are intended to be done for awhile before starting chart 2, etc. That is, don't start at chart 2. Otherwise you may hurt yourself.
a) use a "Roman Chair", but only a particular type of Roman Chair: one that allows the footrest to be at the same level or above the hip/stomach rest. That is this (good) http://www.sport-n-goods.com/acatalog/92625w.jpg rather than this (bad) http://www.donoliver.co.nz/images/CT-2072%2045%20Roman%20Cha...
And don't use it the way they usually illustrate here http://images.google.com/images?um=1&hl=en&client=op...
Your back should never be hyperextended (effectively, leaning backward) as if in orgasmic bliss, as they so often show.
Instead use it like the leftmost 2 photos here http://www.fitsugar.com/Roman-Chair-Explained-946313
The "bad" Roman Chair, the one that puts you at a 45 degree angle with your head above your hips, will likely injure your back if you have any pre-existing problem.
Instead use a Roman Chair that puts your feet and hips at the same level and allows you to hang with your head down and your torso vertical. Once you're in position (head straight down), lift yourself slowly to 45 degrees from vertical, no more, lower and try to and relax the back spinal muscles. The whole point is to use your upper-body weight to stretch out those tight spinal muscles.
Over time you can add weight. Put the weight on the floor, get in position (head down) and only then pick up the weight. The greater the weight the more your back stretches. Increase weights only slowly over the weeks.Always warm up with no weight first.
b) there are good lower back exercises from the Royal Canadian Airforce 5BX Fitness Plan at http://www.corvedale.previewurl.com/5bx/
chart 1, exercise 2
chart 2, exercise 2
chart 3, exercise 2
Read about 5BX before starting. The chart 1 exercises are intended to be done for awhile before starting chart 2, etc. That is, don't start at chart 2. Otherwise you may hurt yourself.