The process of blood flow restriction (BFR) is to occlude venous outflow and restrict arterial inflow, creating an anaerobic environment that promotes cell signalling, protein synthesis, and myogenic proliferation. This allows for load and training to have similar effects as high-load training (Wengle, 2023).
It’s been documented that post-anterior cruciate ligament repair surgery (ACLR), 20-30% of muscle mass is lost within 3 weeks post-surgery. Additionally, quad weakness can result in functional deficits lasting up to 3 years post-surgery. Wengle (2022) conducted a meta-analysis of the effectiveness of BFR with ACLR and knee arthroplasty and found that low-load BFR was effective in maintaining and improving strength and hypertrophy compared to controls and similar to high-load groups.
Using BFR post-surgery may be an effective way to maintain and improve muscle strength while working within surgical restrictions to allow graft and surgical site healing. Low-load BFR (LL-BFR) may be an effective way to improve muscle strength post-op when pain and weakness are limiting factors.
There appears to be a dose effect when doing BFR training. It is suggested that increased frequency and duration have positive outcomes. For significant strength improvement, it is recommended to do 2-3 sessions for a minimum of 3 weeks. Alternatively, 1-2 sessions/day for 1-3 weeks show similar results (Chulvi-Medrano, 2020).
Three weeks of 3x/week of BFR at 20-40% of 1RM was well tolerated among chronic patellar tendinopathy patients. Patients showed improved 50% reduced pain in single leg stance board squat and 30% reduced tendon vascularity (Skovlund, 2020).
Vergara’s meta-analysis (2023) of low load and BFR compared to high resistance training concluded that low load BFR has similar effects as high resistance. Additionally, in reactive tendinopathies, it’s been shown to have reduced cross-sectional area immediately after exercise, and in disrepair and degenerative tendons, it has been shown to increase cross-sectional area after 8-14 weeks, supporting its use with load intolerant tendon injuries (Vergara, 2023).
Blood flow has been shown to have an impact immediately after 1 bout of calf exercises and 24 hours following training on the Achilles tendon cross-sectional area (Chulvi-Medrano, 2020).
Low-load (30-40% 1RM) BFR showed Achilles tendon cross-sectional area improvement compared to traditional high-load training. However, these may not be directly transferable to pathological tendons (Centner, 2023).
In the context of athletic performance, it is postulated that LL-BFR may reduce the risk of injury in athletes who are subject to high load by increasing CSA and stiffness of the tendon, similar to HL-RT, by allowing higher intensity of training with lower load and reduced duration when the frequency of competition and training is high (Vergara, 2023).
Additionally, BFR has extremely rare adverse events with appropriate screening and presents with the advantages of reduced tissue stress, making it an interesting option for patients who cannot train at sub-maximal loads (Vergara, 2023).
References:
Vergara, I. B., Puig-Diví, A., Alonso, B. A., & Milà-Villarroel, R. (2023). Effects of low-load blood flow restriction training in healthy adult tendons: A systematic review and meta-analysis. Journal of Bodywork and Movement Therapies.
Chulvi-Medrano, I., Picón-Martínez, M., Cortell-Tormo, J. M., Tortosa-Martínez, J., Alonso-Aubin, D. A., & Alakhdar, Y. (2020). Different time course of recovery in Achilles tendon thickness after low-load resistance training with and without blood flow restriction. Journal of Sport Rehabilitation, 30(2), 300-305.
Wengle, L., Migliorini, F., Leroux, T., Chahal, J., Theodoropoulos, J., & Betsch, M. (2022). The effects of blood flow restriction in patients undergoing knee surgery: a systematic review and meta-analysis. The American journal of sports medicine, 50(10), 2824-2833.
Centner, C., Jerger, S., Lauber, B., Seynnes, O., Friedrich, T., Lolli, D., … & König, D. (2023). Similar patterns of tendon regional hypertrophy after low‐load blood flow restriction and high‐load resistance training. Scandinavian journal of medicine & science in sports, 33(6), 848-856.