The purpose of the study is to compare the effects of Muscle Energy Technique and Routine Physical Therapy on Quadratus Lumborum in patients with chronic low back pain on Pain, Range of Motion, Quality of Life and Functional Disability.~The study procedure will be explained to the patients and informed written consent will be obtained from those patients who will be willing to participate in the study. Quadratus Lumborum tightness will be assessed using side bending test.~Those fulfilling the requirement of inclusion criteria will be indiscriminately separated into 2 groups. NPRS, Oswestry Disability Index, SF-20 and goniometer will be used to collect data.~Total 68 participants will be recruited in the study. Routine Physical therapy will be provided to group A. Reciprocal inhibition Muscle Energy Technique on quadratus lumborum along with Routine Physical Therapy will be performed on group B.~Both group will receive interventions three sessions in a week for 4 consecutive weeks.~Assessment of Pain, Range of motion, Quality of Life and Functional Disability will be assessed by using goniometer, NPRS, Oswestry Disability Index and SF-20 Questionnaire respectively for both groups at the baseline, end of 6th session (2nd week) and end of 12th session (4th week) and follow up will be obtained after 1 month (8th week).
•Null hypothesis: There is no difference in effects of Muscle Energy Technique and Routine Physical Therapy on Quadratus Lumborum in patients with chronic low back pain.~•Alternative hypothesis: There is difference in effects of Muscle Energy Technique and Routine Physical Therapy on Quadratus Lumborum in patients with chronic low back pain.