Blood Flow Restriction Exercise

Anterior cruciate ligament (ACL) injury is one of the most common musculoskeletal (MSK) conditions worldwide. Approximately 250,000 cases per year have been identified8. Over the last number of decades, a variety of rehabilitation methods have been developed postoperatively and they have been differentiated, from an approach of minimal muscle activity and full immobilization7-9-10 towards one of increased muscle activation and range of movement (ROM) in the early stages following surgery7-9. Muscle weakness and atrophy of the quadriceps and hamstrings is a common feature in patients who have operations such as anterior cruciate ligament (ACL) reconstruction1. Furthermore, regarding the consequences of ACL surgery, either short-term or long-term, some of them are the decreased protein turnover, strength loss, muscle activation problems and an increased risk of osteoarthritis and reinjury. Muscle atrophy is unavoidable in the early postoperative stage given the reduced weight bearing and unloading context of ACL rehabilitation4. The American College of Sports Medicine recommends a minimum resistance training load of 60% to 70% of 1 repetition maximum (1 RM) to gain strength and 70% to 85% of 1 RM to achieve muscle hypertrophy. Training with these high loads may not be possible in painful early-operated knees1.

Exercise with blood flow restriction (BFR) is an efficient technique to improve muscle strength and hypertrophy in clinical populations with knee pathologies1-3-5. Specifically, BFR is an innovative training method that aims to partially restrict arterial inflow and fully restrict venous outflow in active musculature during exercise8. According to various surveys, during low-resistance exercises, reduced oxygen is delivered to muscle cells. The induced anaerobic environment has been reported to promote muscle hypertrophy by initiating cell signaling and hormonal changes that stimulate protein synthesis, proliferation of myogenic satellite cells, and preferential activation and mobilization of type II muscle fibers2-6. By using BFR as a rehabilitation tool after ACL reconstruction, it has been proven that exercises performed at lower loads (20%-50% of 1-repetition maximum) can bring muscle hypertrophy similar to traditional strengthening protocols without causing pain or straining the knee joint2.


  1. Barber-Westin, S., & Noyes, F. R. (2019). Blood Flow–Restricted Training for Lower Extremity Muscle Weakness due to Knee Pathology: A Systematic Review. Sports health11(1), 69-83.
  2. DePhillipo, N. N., Kennedy, M. I., Aman, Z. S., Bernhardson, A. S., O’Brien, L. T., & LaPrade, R. F. (2018). The role of blood flow restriction therapy following knee surgery: expert opinion. Arthroscopy: The Journal of Arthroscopic & Related Surgery34(8), 2506-2510.
  3. Hughes L, Paton B, Rosenblatt B, Gissane C, Patterson SD. Blood flow restriction training in clinical musculoskeletal rehabilitation: A systematic review and meta-analysis. Br J Sports Med 2017; 51: 1003–1011
  4. Hughes, L., Rosenblatt, B., Paton, B., & Patterson, S. D. (2018). Blood flow restriction training in rehabilitation following anterior cruciate ligament reconstructive surgery: A review. Techniques in Orthopaedics33(2), 106-113.
  5. Kilgas, M. A., Lytle, L. L., Drum, S. N., & Elmer, S. J. (2019). Exercise with blood flow restriction to improve quadriceps function long after ACL reconstruction. International journal of sports medicine40(10), 650-656.
  6. Loenneke JP, Fahs CA, Wilson JM, Bemben MG. Blood flow restriction: The metabolite/volume threshold theory. Med Hypotheses 2011;77:748-752.
  7. Myer, G. D., Paterno, M. V., Ford, K. R., Quatman, C. E., & Hewett, T. E. (2006). Rehabilitation after anterior cruciate ligament reconstruction: criteria-based progression through the return-to-sport phase. Journal of Orthopaedic & Sports Physical Therapy36(6), 385-402.
  8. Patterson, S. (2020). The use of blood flow restriction in early stage rehabilitaion following acl injury Implications for enhancing return to play. Return to performance after acl reconstruction, 58-61. Retrieved from
  9. Patterson, S. D., Hughes, L., & Owens, J. (2019). Early Postoperative Role of Blood Flow Restriction Therapy to Avoid Muscle Atrophy. In Return to Sport after ACL Reconstruction and Other Knee Operations(pp. 261-274). Springer, Cham.
  10. Paulos, L., Noyes, F. R., Grood, E., & Butler, D. L. (1981). Knee rehabilitation after anterior cruciate ligament reconstruction and repair. The American Journal of Sports Medicine9(3), 140-149.