This study aims to investigate the relationship between knee joint range of motion and pain in patients with patellofemoral pain syndrome (PFPS). In a cross-sectional observational design, PFPS patients will perform trials involving progressively increased knee joint range of motion in three closed-chain exercises: squat, single-leg squat, and split squat. During each trial, participants will report pain levels on a 0-10 Visual Analog Scale (VAS) until either (1) achieving full depth in the respective exercise or (2) reaching a pain level of >5 on the VAS.

Inclusion Criteria:

• Patients diagnosed with PFP in only one knee by a licensed healthcare professional.
• Aged 15-35 years.
• A physical activity level of 3/10 or higher on the Tegner Activity Scale before the injury.

Exclusion Criteria:

• Any prior injury or condition with residual symptoms that may affect the results.
• Current injury or condition affecting the performance of the test.
• Resting pain greater than 0-1/10 on the Numeric Pain Rating Scale (NRS) and pain greater than 1-2/10 during light daily activities such as walking, sitting, standing, or climbing stairs.

This project will include patients diagnosed with PFP (ICD-10: M22.2).