This randomized controlled trial compares blood flow restriction (BFR) resistance training (leg press and seated knee extension at 30% 1RM) versus BFR cycling (stationary cycling at low resistance) in 60 athletes (aged 18-40 years) diagnosed with patellofemoral pain syndrome. Both interventions are delivered over 8 weeks (3 sessions/week) with a pneumatic cuff set at 80% limb occlusion pressure. Primary outcomes include pain intensity (NPRS), quadriceps strength (handheld dynamometer), and functional ability (Kujala Anterior Knee Pain Scale), assessed at baseline and post-intervention.
Male and female athletes aged 18-40 years
Clinically diagnosed with patellofemoral pain syndrome
Anterior or retropatellar knee pain of at least 3 months duration
Pain provoked by at least two functional activities (e.g., squatting, stair climbing, running, prolonged sitting)
History of knee surgery or significant knee trauma in the past 6 months
Presence of ligament, meniscal, or cartilage injuries
Neurological, vascular, or systemic inflammatory conditions
Contraindications to BFR training (e.g., deep vein thrombosis, uncontrolled hypertension)
Parallel
Blood Flow Restriction Resistance Training
DeviceParticipants will undergo blood flow restriction (BFR) resistance training using a pneumatic cuff applied to the proximal thigh at 80% limb occlusion pressure. Exercises include leg press and seated knee extension performed at 30% of one-repetition maximum (1RM). Training will be conducted for 8 weeks, with supervised sessions 3 times per week. Cuff pressure will be monitored and adjusted using BP cuff. The aim is to improve quadriceps strength and reduce pain in patients with patellofemoral pain.
Blood Flow Restriction Cycling
DeviceParticipants will perform stationary cycling combined with blood flow restriction (BFR) applied to the proximal thigh at 80% limb occlusion pressure. Cycling will be performed at low resistance with controlled cadence for 8 weeks, 3 sessions per week under physiotherapist supervision. The protocol includes structured cycling intervals with rest periods and continuous monitoring of pain and perceived exertion. The intervention aims to improve quadriceps strength, reduce pain, and enhance functional outcomes in patients with patellofemoral pain.
Quadriceps Strength - Handheld Dynamometer
Isometric quadriceps muscle strength measured in Newtons using a calibrated handheld dynamometer (ICC \> 0.90). Measurement taken in a standardized seated position at 60° knee flexion.
Pain Intensity - Numeric Pain Rating Scale (NPRS)
Self-reported pain intensity rated on a 0-10 scale (0 = no pain, 10 = worst imaginable pain). The NPRS has excellent test-retest reliability (ICC 0.95).
Functional Outcomes - Kujala Anterior Knee Pain Scale (AKPS)
13-item patient-reported outcome measure assessing functional limitations due to anterior knee pain. Scored 0-100 (higher = better function). High internal consistency (α = 0.83-0.91).
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