Tanner E. James, MS1; Brian Gilmer, MD
Introduction
Blood Flow Restriction Therapy (BFRT) is an innovative therapeutic technique that is becoming more widely used. The therapy utilizes a tourniquet to occlude venous blood flow while maintaining arterial blood flow to specific muscles for a short duration of time. Basically, this therapy allows blood flow in but restricts its flow out. Its goal is to increase the amount of blood within the muscle. This has shown to yield many health benefits including increased muscle growth and strength.1
BFRT is commonly used in tandem with either aerobic or anaerobic exercise. It allows for a reduction in exercise intensity while still offering health benefits associated with higher intensity exercise. This is particularly important for weight bearing exercises. Basically, lifting lighter weights with BFRT will have similar effects as lifting heavier weights without BFRT. LIghter weight exercise with BFRT decreases the stress on joints and tendons but allows for muscle hypertrophy. As such, it is widely used in both sporting and postoperative settings.
BFRT was originally developed in Japan by Dr. Yoshiaki Sato in the 1970s and 1980s. It was termed KAATSU training and was used as a weight training method for many years. Recently, it has gained recognition for its clinical utility especially for elderly, injured, and postoperative patients.
How it Works
The specifics of how BFRT works is still under investigation.3 Muscle is dynamic. It is always changing. When muscle is exposed to metabolic and mechanical stress of adequate intensity it will respond by increasing in size and strength. When muscle is not used it will atrophy or shrink. Heavy-load weight training is the common stressor stimulus used to grow muscle. However, postoperative, elderly, and injured patients are frequently not able to perform heavy-load weight training due to concerns about joint and tendon instability. That is where blood flow restriction therapy can be used.
By trapping the blood within the muscle, BFRT creates a low oxygen environment.1 Due to the lack of oxygen, cells within the muscle will begin to use anaerobic metabolic pathways creating specific anaerobic chemicals.3 These chemicals are normally present during heavy-load weight training and act as signals for muscular growth. Additionally, pressure within the muscle will begin to rise proportionally to the amount of blood pooling within the muscle. Increased pressure will push more fluid into muscle cells–a process called cellular swelling.1 Swollen muscle cells will activate intracellular pathways to create more protein.3 Then with less oxygen and a buildup of metabolic waste, the muscle will fatigue which will inturn recruit more type II fast-twitch muscle fibers.3 Traditionally these fibers are only activated with higher intensity exercise.
If that sounds complicated, it is. There is still not wide consensus on how it works; however, data shows that it is effective. Basically, the trapping of blood in the muscle or limb allows the muscle to respond as if it were lifting more weight than it actually is. This means that low-intensity exercise coupled with BFRT can yield results that are traditionally only achieved by higher-intensity exercise. However, it is still not as effective in creating muscle mass and strength associated with normal high-load weight training.1
Procedure
BFRT can be done in many different ways.There are two basic forms of cuffs or tourniquets and both are utilized in the clinical setting. The first type of cuff–the pneumatic cuff–is an advanced surgical tourniquet that is often used in surgeries.1 It will accurately fill to a certain pressure and maintain that pressure throughout the therapy session. Higher occlusion pressures can be safely used with this type of cuff due to its accuracy.3 The second more common type of cuff is usually a strap or elastic band. These are placed around a limb and tightened to apply a specific pressure.These are effective, but this should be done under medical supervision..
At the beginning of the therapy session, a cuff will be placed around either an upper or lower extremity dependent upon the individual case. The cuff is placed with pressure that effectively restricts venous blood flow while still allowing arterial blood flow. This may be slightly uncomfortable; however, it should not be overly painful. Many different exercises may then be done ranging from low-load exercise training to walking on a treadmill. The type of exercise will depend upon individual circumstances and will be set by both patient and provider. Once the exercise is complete, the cuff will be removed and venous blood flow will return to normal.
BFRT can also be performed passively and not coupled with exercise. This can be effective for postoperative or immobilized patients to reduce the amount of strength lost during the period of bedrest.3
Benefits
Many documented benefits are associated with the use of BFRT. In elderly patients, it can decrease knee discomfort associated with exercising. BFRT can also increase muscle mass in patients relative to patients who did not do BFRT, so there was an overall reduction in knee pain associated with osteoarthritis.3 Increased strength also decreases joint instability and increases overall functional movement. The greatest muscular benefits arise from allowing patients to reduce the amount they have to lift in order to see strength and muscle growth. In some cases, muscle growth was noted with as little as 20% of an individual's max load.5 This allows for great benefits with less joint and tendon stress.
This is great news for postoperative patients, especially for patients who have undergone knee surgery. When BFRT has been utilized a few weeks after surgery, muscle strength and functional movement is regained compared to regular rehabilitation regiments. Patients also report better outcomes and overall reduced pain.1
The benefits also continue after the training session is over and the cuff is removed. Due to pooling of blood, muscle tissue will release signals to increase growth of blood vessels. This is a process called angiogenesis. The area where the blood flow was restricted will have an increase in the amount of blood vessels present and will have more blood flow to the muscle to promote rehabilitation.3
Many benefits for the heart and cardiovascular system exist with BFRT use. For example, when blood is pooled in a muscle during BFRT use, less blood will return to the heart. This means that the heart will have to work harder to pump the same amount of blood.2 It also helps to increase the body’s ability to use oxygen.2
Contraindications
- History of Thrombosis4
- Cardiovascular Disease4
- Hypertension4
- Impaired Blood Flow4
Some patients with cardiovascular disease and hypertension are still able to participate in BFRT, but require special consideration and monitoring.2,4
Risks
- Increased pain during exercise4
- Bruising1
- Numbness5
- Delayed Muscle Soreness4
- Muscle Damage5
- Fainting4
Like with any medical procedure or therapy, there are associated risks. However, BFRT has been shown to be a very safe and reliable therapy. Due to the restriction of blood flow, there were concerns that thrombotic events (formation of blood clots) and muscle damage would occur with BFRT. There has been no evidence to support increased risk of blood clot formation compared to other exercise therapy.5 Surprisingly, recent evidence supports that BFRT may help to reduce risk of blood clots.1
The risks arise from improper implementation of BFRT.5 BFRT should always be done under proper medical supervision.
Conclusions
Blood Flow Restriction Therapy is an effective and safe way to increase muscular strength and size while minimizing stress to joints and tendons. It can be especially effective for elderly, injured, and postoperative patients. Furthermore, it can be used in basically any physical therapy situation.
Dr. Gilmer’s Take
Our team adopted BFRT in most knee procedures in 2021. This has been a tremendous adjunct to most all knee procedures as it allows the forces to be kept low while building the strength that so often limits recovery. The data supports a high safety profile and we have seen benefits even in chronic cases of atrophy or in the setting of multiple surgeries. Aside from postoperative use BFRT can be used before surgery or as part of a non-operative treatment strategy to build strength while keeping forces on the joint low. This has been one of the most impactful rehabilitation advances in my career and I utilize and recommend it widely to many patients.
References
- Cognetti DJ, Sheean AJ, Owens JG. Blood Flow Restriction Therapy and Its Use for Rehabilitation and Return to Sport: Physiology, Application, and Guidelines for Implementation. Arthrosc Sports Med Rehabil. 2022 Jan 28;4(1): e71-e76. doi: 10.1016/j.asmr.2021.09.025..
- Miller BC, Tirko AW, Shipe JM, Sumeriski OR, Moran K. The Systemic Effects of Blood Flow Restriction Training: A Systematic Review. IJSPT. 2021 Aug 1; 16(4): 978-990. doi:10.26603/001c.25791
- Vopat BG, Vopat LM, Bechtold MM, Hodge KA. Blood Flow Restriction Therapy: Where We Are and Where We Are Going. Journal of the American Academy of Orthopaedic Surgeons. 2020 June 15; 28(12): e493-e500. doi: 10.5435/JAAOS-D-19-00347
- de Queiros VS, Dantas M, Neto GR, da Silva LF, Assis MG, Almeida-Neto PF, Dantas PMS, Cabral BGAT. Application and side effects of blood flow restriction technique: A cross-sectional questionnaire survey of professionals. Medicine (Baltimore). 2021 May 7; 100(18): e25794. doi: 10.1097/MD.0000000000025794.
- Vanwye WR, Weatherholt AM, Mikesky AE. Blood Flow Restriction Training: Implementation into Clinical Practice. International Journal of Exercise Science. 2017 Sep 1; 10(5): 649-654. PMID: 28966705; PMCID: PMC5609669.
