Blood Flow Restriction Training
There is a new modality that has hit the rehabilitation and performance arenas hard over the past couple of years. It is called blood flow restriction training. Blood flow restriction training (BFR) started being utilized by the United States Military to rehabilitate soldiers injured in the line of duty. During blood flow restriction training, circulation to the working muscle is occluded. To do so, a restrictive implement (ie. blood pressure cuff) is wrapped around the working limb(s) carrying out dynamic exercise. The goal of this type of training is to occlude venous blood flow without significantly affecting arterial circulation. In this way, blood goes into the muscle, but cannot escape. Participants can see anywhere from 70-80 percent strength gains in just a few weeks. It seems that strength gains are not the only proposed benefits. Prospective amputees are now deciding to keep their limbs due to a pain relieving effect. The natural carryover of BFR training into athletics is becoming a reality. Rehabilitation professionals and strength coaches alike are starting to use this method on elite athletes and those with key features such as ACL reconstruction and cartilage lesions get them back on the playing field with greater strength and faster recovery.
What are the mechanisms behind blood flow restriction training?
The effects are likely due to a combination of mechanical tension and metabolic stress that contributes to beneficial adaptations such as hypertrophy and metabolite clearance. This mechanism is very similar to that induced via exercise stress. Specifically, anabolism is enhanced via the production of reactive oxygen species and growth factors, along with cell swelling. The production of these metabolites catalyzes cellular signaling in a way that enhances satellite cell activation and protein synthesis. According to Pearson et al, the muscle group targeted with BFR training is also shown to demonstrate an increase in fast twitch fiber type, limited muscle damage, improved hormone production, cell swelling, nitric oxide, and heat shock proteins. These are many of the key variables needed for muscle growth and repair.
How can BFR training be utilized by physical therapists?
You might be thinking that this type of training can only be limited to athletes or relatively well-trained individuals. However, there is mounting evidence of BFR training being utilized in the elderly population. Vechin, et al. showed that low resistance training with blood flow restriction (LRT-BFR) constitutes an important surrogate approach to high resistance training (HRT) as an effective training method to induce gains in muscle strength and mass in the elderly. This is extremely important because both higher bone density and muscle mass are associated with higher quality of life and improved independence as we age (American College of Sports Medicine, ACSM). Not only is BFR training effective in the elderly, it is also safe. Yasuda, et al. found that elastic band BFR training improves muscle cross sectional area as well as maximum muscle strength, but does not negatively affect arterial stiffness in older adults. This allows for increased effectiveness with a low risk for adverse reactions.
BFR training can be an integral part in the prevention of injury and joint related degeneration. Segal, et al. have shown that BFR training with 30% of a person’s one repetition maximum is effective in increasing the leg press and knee extension strength in women at risk for knee osteoarthritis. I believe that we can combine this type of training with the treatment of other regionally interdependent variables (ie. Impaired hip mobility and weak hip stabilizers) to improve patient outcomes in the clinic and help reduce medical costs due to surgery.
Lastly, BFR training is effective for improving the functional performance of the athletes that we treat, along with those recreationally active adults who participate in competitive sports or exercise (including CrossFit) on a regular basis. Luebbers, et al found that it is possible to increase one repetition maximum squat performance, in addition to a traditional strength-training program. This already exists in the strength and conditioning world in the form of knee and elbow wraps with competitive weight lifters.
Due to the success of BFR training, it is an easy modality to implement in the clinic without breaking the budget over an expensive piece of equipment. The answer is quite simple with the use of relatively inexpensive tools like a blood pressure cuff or mobility bands. Physical therapists like Dr. Kelly Starrett of MobilityWod.com have been using implements like the Voodoo Floss Band (sold on RogueFitness.com) for years to improve mobility, increase strength, decreased edema, and allow for faster recovery from injury.