A physical therapy modality is a method, device or substance used to treat a disorder that is normally addressed in a physical therapy clinic or office. If you have low back pain and your doctor prescribes physical therapy, as part of your treatment you may, along with an exercise program, get one or more modalities such as:
Physical therapy modalities are often "done to you." This is in contrast to a home exercise program, which is something you need to actively participate in to relieve your back or neck pain for the long term. While treatment modalities given in a physical therapy clinic are often quite helpful to back or neck pain sufferers, the real progress is most often made when you take responsibility for getting your muscles strong and flexible.
Generally, physical therapy modalities are given to help decrease your pain and increase your mobility. Unfortunately, few research studies have been done on treatment modalities for back pain, and we really don't know if they are substantially helpful or not. Your therapist will decide which modality or combination of modalities to use based on their skill set, instructions from your doctor and the availability of equipment.