The participants in the core stability exercise group will be included in a treatment program for 3 days per week for 6 weeks.

In addition to the core stabilization exercises myofascial relaxation technique will be performed with roller massager (Theraband®, The Hygenic Corporation, Akron, OH.) for 3 days per week for 6 weeks.

The participants in the core stability exercise group will be included in a treatment program for 3 days per week for 6 weeks. Traditional physiotherapy methods will be applied to all participants. Traditional physiotherapy will include heat modality (a hot pack for 15 minutes), electrotherapy (transcutaneous electrical nerve stimulation (TENS), a 50 Hz conventional TENS with a pulse duration <150 microseconds).Each training session will be lasted 60 min, starting with a 10-min warm up program mainly consisting of core strength exercises and ending with a 5-min cool-down program (stretching). Progression of exercises will be tailored to individual patients' ability, fatigue and pain. Exercises will be designed from 1 set to 3 sets, from 8 to 15 repetitions and contractions from 5 seconds to 10 seconds.

The visual analog scale is a validated, subjective measure for pain. Scores are recorded by making a handwritten mark on a 10-cm line that represents a continuum between "no pain" and "worst pain."

An electronic pressure algometer (Algometer commander, JTech Medical, Line; Salt Lake City) is used to measure pressure pain threshold (PPT) with a stimulation surface area of 1 cm2. Three consecutive measurements are performed at each site, with 10 seconds of recovery time allowed between repeated applications. During the algometric measurements, the subjects are asked to say "yes" when the pain is experienced. The amount of pressure-causing pain is recorded as PPT in kg/ cm2. The subjects are required to lie down in a prone position for the measurements. 2 lumbar paravertebral points (bilateral 5 cm lateral to the L3 spinous processes) are evaluated.

It is a self-administered questionnaire divided into ten sections designed to assess limitations of various activities of daily living. Each section is scored on a 0-5 scale, 5 representing the greatest disability. The index is calculated by dividing the summed score by the total possible score, which is then multiplied by 100 and expressed as a percentage. Thus, for every question not answered, the denominator is reduced by 5. If a patient marks more than one statement in a question, the highest scoring statement is recorded as a true indication of disability.

Subjects are asked to sit at the edge of a chair with one leg extend forward with knee straight, heel on the floor and ankle bended as 90o , while the other foot remained flat on the floor. Subjects are instructed to place one hand over the other hand with the middle finger tips even, and tried to reach forward to the toe of the extended leg. The distance between the middle finger tips and the toe are recorded.

Subjects are asked to lie down and bend their knees in full contact with the floor of the feet. In this position (hooked position) they are asked to lift their hips from the bed. The time for the bridge is measured in seconds after stopping the contact of the hips with the bed.