The patellofemoral pain syndrome (PFPS) is defined as a painful complaint in the anterior aspect of the knee, although peripatellar pain and / or retropatellar are also common. In general, conservative treatment is the initial option of choice for patients with PFPS, however, the lack of a specific causal factor makes it difficult to choose the best treatment so early. This way, the purpose of this study is investigate the effects of the quadriceps femoris strengthening versus hamstring stretching in patients with pattellofemoral pain.

Inclusion Criteria:

• Symptoms of anterior knee pain for at least 1 moth;
• Average pain level of 3 or more on a 10-cm visual analogue scale during stepping up and down a 25-cm height;
• Anterior or retropatellar knee pain on at least 2 of the following activities: prolonged sitting, climbing stairs, squatting, running, kneeling, and hopping/jumping;
• Presence of 2 of the following clinical criteria on assessment: pain during apprehension test, pain during the patellar compression test, and crepitation during the compression test.

Exclusion Criteria:

• Previous knee surgery or arthritis;
• History of patellar dislocation or subluxation, malalignment, or ligament laxity;
• Patellar tendon pathology or chondral damage;
• Spinal referred pain;
• History of other abnormalities such as leg length inequalities (>2 cm);
• Medication as a part of the treatment;
• Previous physical therapy or acupuncture treatment for the knee within the previous 30 days.