The idea here is to be that much more aware of what is actually going on "behind" us as we play live, or over a backing. I'm sure you've been playing live some time and during your improv the drummer might start playing some rhythmical figure that kind of sticks out at you, and sort of beckons for you to tag along with it.
Eventually both you, the drummer and the bass player might be grooving along on this very rhythm, thus allowing your soloing to go places it would not have gone otherwise. This is great fun, but requires you to be open and aware, and not locked in to what your hands are doing.
Once you feel comfortable with all of the above, move on to the improvisation and study that as a way of guiding you through this backing track.