(This book tries to be two different books. The first part is how muscles work, how forces interact with muscles, bones and joints. There's an interesting chapter on posture and stretching nerves (didn't know you could do that!) Basically the first 80 or so pages are biology and science. The second part is the actual exercises. There lots to look at but they are technically termed such as trunk lateral shift and lateral flexion (with overpressure)