In Pilates, we work the pelvic floor muscles together with the deep abdominal muscles and muscles alongside your spine (multifidus), to stabilise your trunk. We call this action centring and it is one of our basic principles. By strengthening these muscles, they are better able to support your back and can help you manage or alleviate back pain.
The pelvic elevator exercise is good for practising the action of centring. You can do it in any position. I suggest that you start by lying on your back and progress to kneeling on all fours. It is available as an MP3 on my downloads page.
If you specifically want to work in this area, read more about your pelvic floor.