Patellofemoral pain (PFP) is a common source of anterior knee pain among active adolescents. Those with PFP have pain-limited difficulty with resistance exercises at the recommended load of 60-70% one rep maximum (1RM). As blood flow restriction (BFR) at the targeted muscle has been found to allow for strengthening at 20-30% of 1RM, this study compared the effects of these two types of strength training.

Subjects were between 18 and 40 years of age, with atraumatic PFP. Those randomized to a BFR group were assessed with an arterial occlusion pressure cuff placed at the proximal thigh in a standing position. The cuff pressure was then increased until the pedal pulse was no longer palpable. The BFR restriction exercise was performed at 60% of this pressure. This group exercised at 30% of the 1RM. Those randomized to a standard group exercised at 70% 1RM. Exercises included leg press, leg extension and knee flexion. The primary outcome variable was PFP at eight weeks.

Over eight weeks, those in the BFR group had a 93% greater reduction in pain with activities of daily living, as compared with the standard treatment group (P＝0.022), with no significant difference in worst pain scores. A 49% greater improvement in the extensor torque was found in the BFR group, although this finding did not reach statistical significance (P＝0.073).

This study of patients with patellofemoral pain found that blood flow resistance training can reduce pain with activities of daily living more than can traditional strengthening exercise.