This randomized, Single-blind, parallel-group trial will compare the effects of three hamstring stretching interventions-general hamstring Muscle Energy Technique (MET), medial hamstring MET, and lateral hamstring MET-each combined with standardized TENS and progressive hip/knee strengthening, on hamstring flexibility (knee-extension ROM), anterior knee pain (Arabic Kujala score), pain intensity visual analogue scale (VAS), and lower-limb strength (hand-held dynamometer) in adults with patellofemoral pain syndrome (PFPS).
Anterior or retropatellar knee pain lasting at least three months
Pain reproduced by at least two functional tasks: squatting, kneeling, prolonged sitting, stair climbing, hopping or running
Pain intensity of ≥3 on a Visual Analog Scale
positive active knee extension test (inability to achieve greater than 160° of knee extension with the hip at 90° of flexion)
Previous knee surgery
History of knee pathologies, such as meniscal injury' ligament injury, or knee osteoarthritis
Psychological, cardiovascular' or neurological disorders
Dizziness or fainting while doing exercises, pregnancy, or any contraindications to exercise