A Randomized Clinical Trial of Extension for Low Back Pain: Motor Imagery of Extension Versus Physical Extension Exercises

Low back pain (LBP) is the most common musculoskeletal condition treated in physical therapy, accounting for an estimated 25-40% of outpatient physical therapy visits. One strategy commonly used for treating LBP is directional preference. Directional preference is the process of examining a patient with LBP's response to a movement direction, i.e., extension, and if it coincides with improvement, the test becomes part of the treatment. Various studies have shown evidence for, and use of directional preference by physical therapists. Specifically for LBP, directional preference usually involves either an extension-bias or flexion-bias, with various studies indication an extension protocol being the most common (estimated > 80% of patients). With extension exercises, a favorable therapeutic effect result in centralization of symptoms (leg pain migrates proximal), improved range of motion (ROM), decreased pain and decreased fear of movement.

In recent years there has been an increased interest in various pain neuroscience strategies to help people in pain, including LBP. It is well established that the physical body of a person is represented in the brain by a network of neurons, often referred to as a representation of that particular body part in the brain. This representation refers to the pattern of activity that is evoked when a particular body part is stimulated. The most famous area of the brain associated with representation is the primary somatosensory cortex (S1). These neuronal representations of body parts are dynamically maintained. It has been shown that patients with pain display different S1 representations than people with no pain. The interesting phenomenon associated with cortical restructuring is the fact that the body maps expand or contract, in essence increasing or decreasing the body map representation in the brain. Furthermore, these changes in shape and size of body maps seem to correlate to increased pain and disability. Various studies have shown that physical movement is associated with restoring the cortical maps, which in turn may be associated with a decreased pain experience.

In patients with high levels of pain, sensitization of the nervous system and fear of movement, physical movement itself may increase a pain experience. An added therapeutic ability to help restore these cortical maps is motor imagery (visualization). Various studies have shown that motor imagery activate the same areas of the brain as when actually physically moving, thus restoring the altered maps "without moving."