I've been having a nagging backache for weeks now. I finally went to see my doctor. She suggested I try a couple of sessions with a physiotherapist. The therapist just did a little pressing on my spine and I was much better right away. Was this just a psychosomatic response -- I wanted to get better so anything would have worked?

It's possible but not likely. It sounds as though the therapist applied a specific technique called spinal mobilization. Mobilization is the passive movement of the spinal segment (specifically the spinal joints).

The therapist applies a rhythmical, repetitive movement called oscillation. This is usually done in a posterior-anterior direction. In other words, the therapist places his or her hands on your spine and presses downward toward the front of the body. In one-minute, the therapist can move the joint about 30 times.

This type of gentle mobilization can stretch contracted tissue in and around the joint without harming the other soft tissues nearby. Doing the motion over and over helps milk the joint. This means the synovial fluid protecting the joint is evenly redistributed throughout the joint. The result is decreased resistance to motion. This makes for smoother motion and less pain.

Christopher M. Powers, PT, PhD, et al. Effects of a Single Session of Posterior-to-Anterior Spinal Mobilization and Press-Up Exercise on Pain Response and Lumbar Spine Extension in People with Nonspecific Low Back Pain. In Physiotherapy. April 2008. Vol. 88. No. 4. Pp. 485-493.