The anterior cruciate ligament (ACL) plays a key role in stabilizing the knee joint, and its injury is common, particularly in young athletes and sports-related activities. Even after surgical reconstruction, deficits in quadriceps strength and size can persist, especially in the late rehabilitation phase (12–20 weeks post-surgery), which is critical for returning to sports and advanced activities. Quadriceps weakness compromises knee stability, delays recovery, and increases the risk of reinjury.

Blood Flow Restriction Training (BFRT) is a method that uses controlled restriction of blood flow during low-load resistance exercises, leading to greater muscle activation, metabolic stress, and strength gains. Previous studies suggest BFRT may improve quadriceps strength and muscle mass after ACL reconstruction, but evidence remains limited.

This randomized controlled trial will evaluate the effectiveness of BFRT combined with resistance training versus resistance training alone in participants aged 18–40 years, 10–12 weeks post-ACL reconstruction, with reduced quadriceps strength. A total of 36 participants will be included and randomly assigned to two groups. Group A will receive BFRT with resistance training, while Group B will perform only resistance training. Both groups will train three days per week for four weeks.

Quadriceps strength will be assessed using a hand-held dynamometer before and after the intervention. Exercises will include split squats, medial step downs, single-leg presses, walking lunges, and leg extensions. Data will be analyzed using appropriate statistical tests, with significance set at p < 0.05.

The study aims to determine whether BFRT with resistance training provides superior improvements in quadriceps strength compared to conventional resistance training alone, offering a potentially effective rehabilitation strategy for late-phase ACL recovery.