Rationale Graft maturity is correlated with strength and biomechanical properties of the reconstructed ACL. There are concerns that heavy-load resistance training (HLRT) may have detrimental effects on ACL graft maturation. Therefore, low-load blood flow restriction training (LL-BFRT) has been suggested as an alternative to HLRT. As LL-BFRT is an increasingly popular method for the rehabilitation after an ACL reconstruction, it is important to evaluate the value of this treatment. Objectives The main objective is to evaluate the effect of LL-BFRT on MRI-based graft maturity after ACL reconstruction compared to HLRT. The secondary objectives are the effect of LL-BFRT on donor-site morbidity, range of motion, knee stability, patient reported outcome measurements, muscle strength, safe return to pre-injury level of sport and patient satisfaction. Furthermore, feasibility and safety of rehabilitation will be assessed. Study design Randomized controlled trial . Study population Patients who will undergo primary bone-patellar tendon-bone ACL reconstruction and rehabilitation at Knie-Heup centrum Plus will be assessed for eligibility. The exclusion criteria are: venous thromboembolism, sickle cell anemia, severe hypertension, contra-indication for accelerated rehabilitation, contra-indication for MRI scan or patients who are not willing/able to participate. Intervention LL-BFRT includes 12 weeks of biweekly strength training and starts two weeks after surgery. Comparison HLRT includes 12 weeks of biweekly strength training and starts two weeks after surgery. Main study endpoints The main endpoints are MRI-based graft maturity defined as signal-to-noise quotient three and nine months after surgery.