Acute low back pain is treated by a variety of health care providers utilizing an array or treatment approaches. In 1995, acute low back pain was the 5th most common reason for all physician visits in the United States over 13 billion dollars of medical expenses per year are attributed to low back pain affecting from 5 to 10% of the adult population annually with a prevelance from 60 to 90% over a ltfetime. Acute low back pain occurs in people with a wide variety of professions including those involving heavy labor, repetitive work activities and extended sedentary postures. Half of the population will have experienced a significant incidence of low back pain by age thirty. There is much controversy in the literature in regards to how to best manage patients with acute low back pain. Much of this controvery stems from two distinctly different philosophies: medical management and physical therapy management. Standard medical management most often emphasizes the need for the patient to remain as active as possible while prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) and/or muscle relaxants to assist in symptom control/relief. Some advocates of medical management believe that physical therapy, especially exercise-based interventions, are contraindicated for patients with acute low back pain. Others feel that the “limited” benefits attained with exercise-based or manual therapy interventions are not worth the increased cost of care. Many proponents of medical management believe that 80 to 90% of all patients with acute low back pain will “spontaneously” improve within three months. However, recent reports in the literature demonstrate that 75% of the patients medically managed for acute low back pain will have recurrent episodes of low back pain within one year after intial onset of symptoms. Clearly, there must be a more efficient method of managing this patient population. Physical therapists attempt to manage patients with acute low back pain by utilizing a wide variety of interventions including exercise and manual therapy. One of the key exercise approaches that can counter the potentially long-term effects of acute low back pain is strength training. Deyol stated that failure to strength train could cause increased severity and frequency of low back pain. According to Twomey and Taylor properly implemented resistance-exercise regimes play a vital role in the treatment of acute low back pain and are crucial for a patient’s successful return to function. The Mayo Foundation for Medical Education and Research advocated the use of a comprehensive, dynamic strengthening program to stabilize the trunk and spine. Unfortunately, the literature is incomplete on issues involving how to best strength train patients with acute low back pain and which specific populations will have the best outcomes with this intervention. Another common treatment for acute low back pain is the use of manual therapy. Manual therapy is a broad term that encompasses numerous techniques with many subcategories. Two of the more popular sub-categories of manual therapy are manipulation and mobilization. DiFabio defined spinal manipulation as a “high velocity thrust momentarily exceeding the available ROM”. While under the broad umbrella of “manual therapy”, muscle energy technique (MET) does not fall into either the manipulation or mobilization sub-categories. Muscle energy technique is an active technique in that the patient supplies the corrective force instead of the care provider. Greenman defined muscle energy technique as a “manual medicine treatment procedure that involves the voluntary contraction of patient muscle in a precisely controlled direction, at varying levels of intensity, against a distictly executed counterforce applied by the operator.” It has been hypothesized that muscle energy technique can be used to lengthen and strengthen muscle(s), increase fluid mechanics and decrease local edema, and to mobilize a restricted articulation. Muscle energy technique has become more popular over the past several years. While originally considered an osteopathic treatement, muscle energy technique has found increased favor with physiatrists, physical therapists, and chiropractors in the treatment of acute and chronic spinal disorders. One of the reasons for this is that it requires active participation on the part of the patient, both in performing and maintaining the effects of the treatment – thus decreasing the risk of patient dependency. DeRosa and Porterfield advocated the use of muscle energy technique as one of the preferred methods to apply “nondestructive forces” in order to facilitate movement at the site of impairment. If the patient is able to tolerate forces into the impaired joint area and more normal motion is restored, the patient should be able to improve spinal mobility with greater ease. Enhanced spinal mobility should lead to improved activity levels, which is imperative for the successful long-term management of low back pain. While muscle energy technique has found an increased audience with clinicians, very little has been published in the peer-reviewed literature on this intervention. Its wide-spread use in the clinic makes it imperative that we determine if this technique is viable procedure for the treatment of acute low back pain. The purpose of this randomized, double-blind, sequential clinical trial was to determine whether patients with acute low back pain would demonstrate a more rapid return to function, as assessed by the Oswestry Disability Index, after being treated with muscle energy technique treatment coupled with supervised strengthening exercises as compared to patients treated with supervised strengthening exercises alone. The following research hypothesis was investigated: There will be a statistically significant difference (p<O.05) between patients diagnosed with acute low back pain with a concomitant diagnosis of an extended lumbar dysfunction treated with muscle energy technique combined with supervised strengthening exercises (experimental group), than patients treated with supervised strengthening exercises alone (control group), in that the experimental group will have a greater percent change in Oswestry Disability Index scores after four weeks of treatment.