A Chiropractor is a primary health care professional that specializes in the treatment of musculoskeletal pain and injury. Like medical doctors, chiropractors first complete the traditional "pre-med" education followed by an additional four years of training in the biological and clinical sciences. Chiropractors are recognized as expert providers of spinal and peripheral joint manipulation and mobilization. Chiropractors may also utilize a variety of supportive and complimentary modalities such as electro-therapy, ultrasound, microcurrent, ice and stretching and strengthening exercises. The range of diagnostic and therapeutic services offered by a Chiropractor is dynamic and is continually modified by education, research, technological change and the patient's evolving health care needs.