Patellofemoral pain syndrome (PFPS) is a term for a variety of pathologies or anatomical abnormalities leading to a type of anterior knee pain and is the most common single diagnosis among runners and in sport medicine centers. Despite this high incidence, the exact cause of these disorders remains enigmatic.

The major complain of patients with PFPS is retropatellar pain during activities such as running, squatting, going up and down stairs, prolonged sitting, cycling, and jumping.

Some of risk factors in athletes with PFPS were considered and compared with athletes without PFPS in the present study. In addition, since Tai Chi (TC) helps or reduces the load on the lower limbs joints, particularly in knee, a TC group was chosen to compare with the two other groups.