Blood flow restriction: A potential new approach to rehabilitation?
When the world’s top athletes figured a way around the ban on steroids, they unwittingly sparked a revolution in rehab. Seniors and post-operative patients might soon be taking a page out of Dwight Howard’s playbook to rebuild muscle faster, with lighter weights.
Visit a high-performance training camp and you will spot athletes with a tight band, akin to a blood pressure cuff, tied around their arms or legs. It’s called blood flow restriction (BFR) training, and it uses tourniquets to partially block blood flow to specific muscles while a person is exercising. This makes the muscles work harder by limiting the blood that leaves them during exercise, thus creating an oxygen-poor environment for the exercising muscles. This helps build bulkier biceps or thighs, says Jeremy Loenneke, assistant professor of Exercise Science at the University of Mississippi.
Now it turns out that the same technique may help with a long-standing problem for seniors and people recovering from surgery: How to rebuild muscle quickly without using heavy weights. Restricting the blood that leaves muscles during light exercise potentially opens a broad new door for those who cannot train at high intensity or heavy load. Helping the elderly stay active by lifting light weights can lead to stronger muscles, which may decrease falls and fractures and help mitigate the effects of declining muscle mass in aging bodies.
What the research says about blood flow restriction
A recent review of the literature looked at 11 studies of BFR with close to 240 older adult participants. While muscular adaptations had been recognized in various populations, the evidence was scant in older adults. This review showed greater gains in muscle strength in those who participated in BFR compared to those in traditional training or walking programs.
While promising, more work needs to be done to help patients and providers determine the best training regimens. Currently there is no standard for BFR training, and different researchers and therapists use different cuff pressures, cuff sizes, and numbers of sets and repetitions. Training ranges in frequency from weekly to near-daily.
Post-operatively, patients who have undergone tendon repairs such as anterior cruciate ligament (ACL) reconstruction must wait for their tissues to heal before they start to work out. BFR training decreases this period because patients can start post-operative exercises and muscle strengthening activities earlier, with lighter weights.
Studies from the United States have started blood flow training as early as two days after surgery, although Stephen Patterson, an exercise physiologist at St. Mary’s University in the United Kingdom, sees most BFR training protocols in Britain initiated at three weeks post-op.
This type of training is not new. Yoshiaki Sato first described the technique as Kaatsu, in the 1970s. It gained popularity in North America approximately five or six years ago, according to Loenneke, when the bodybuilding community discovered it as a way to maximize muscle growth.
The premise is counterintuitive. The usual notion is that if you lift heavy things you build muscles, and if you lift heavier things, you build bigger muscles. With BFR training, one lifts only 20 to 30 percent of one’s heavy weight maximum. In general, the cuff pressure depends on the size of the cuff, the size of the limb and the individual’s blood pressure. Most protocols reduce blood flow by 80 percent.
Johnny Owens spent 10 years as the chief of human performance optimization at the Centre for the Intrepid, part of a military medical centre in San Antonio, Texas. He started using BFR training in the early 2000s on wounded soldiers as part of his rehab and recovery protocol. After leaving the service, he moved into sports medicine, where he worked with professional athletes using BFR to recover from injury.
Now, Owens’s team is among several groups doing research with elderly patients where the goal is avoiding muscle breakdown. Owen’s company provides BFR certifications to trainers and other medical professionals; through his website and courses, he sells his own equipment to those who have completed his training program.
A recent literature review done by the University of Guelph looked at the results of 400 young, healthy patients who participated in BFR training. The results appear promising and have shown consistent improvements in muscle strength and size. Practically, for those for whom higher load exercises are contraindicated, BFR training can help to maintain strength while reducing loads on tissues.
Another review looking at studies using BFR specifically as a rehabilitation tool found similar results. BFR training showed an increase in muscle strength and size and an ability to engage in this exercise earlier than heavy-load training.
Those with low muscle mass have the most to gain from this training, Owens says. “If you add a little bit of muscle to an elderly patient, they increase strength, power, muscle endurance.”
While clinically exciting, there remain concerns about moving from research to usual practice. One unknown is whether the technique helps patients change their level of function, improve their recovery process, and ultimately improve their quality of life.
In another potential use of BFR, building on research done by a group in Qatar, Patterson and his colleagues are studying how to optimize BFR protocols to reduce pain. Current information supports the idea that pain can be reduced for up to 24 hours following a BFR session. In a study of 25 patients with knee pain, patients reported decreased pain scores after completing BFR exercises. The exact mechanism behind the pain relief is still under investigation. If the results of this small study are confirmed, it could have big implications.
Safety and side effects
The safety profile of BFR has been studied for the better part of a decade by Loenneke and others. An increased risk of blood clots has been one of the biggest concerns and the focus of much research. Available information suggests that there is no increased risk beyond that of traditional exercise. Short-term use of a tourniquet has not been found to be an independent risk for clot formation.
In fact, says Owens, releasing the tourniquet after restriction releases anti-clotting factors, which may be protective. Research has looked at the potential harm of this type of exercise, including overall safety, muscle damage, blood clots, and concerns related to the heart and nerves. There appears to be no greater risk than traditional exercise when BFR is used by a trained provider. Most of the research to date has been done on small sample sizes, but the early evidence does not suggest cause for concern.
Case reports describe gym-goers who have suffered from increased muscle breakdown, known as rhabdomyolysis, which typically happens when training regimens are not followed. This side effect is generally not due to the blood flow restriction itself, but to the training routine. The amount and intensity of training must be carefully monitored.
Patients are encouraged to follow an individualized exercise prescription optimized for their body. This includes the size of the cuff used, the location of cuff placement and the sets and reps that should be done before taking a break. While rare, the most common side effects appear to be bruising and swelling from cuffs or pressure palsies from superficial nerves being compressed.
With various training protocols being used, standardization is in the works. Patterson, Loenneke and Owens are collaborating with 12 others across eight nations to draft the first-ever position statement for BFR training, which will provide a template for application, safety and guidelines. The goal is to provide patients and providers with clarity on when and how to introduce BFR into their exercise toolbox or their rehabilitation routines.
The possibility of using blood flow restriction in geriatric rehab
Most research, however, has been conducted in healthy individuals. Newer studies are investigating different populations to determine if similar results are found in those with various diseases. This is important, says Dan Liberman, medical leader of the geriatric rehab program at Toronto Rehabilitation Institute.
While he would be open to trying new techniques or rehabilitation tools to help his geriatric rehab patients, he wants to see the research that proves it is safe.
“If the data is there, if the evidence is there in older patients, then of course,” he says. He cares for a vulnerable population that is involved in few big studies. While he sees potential problems in restricting blood flow to frail patients, he would be open to exploring this concept when it is supported with better research in that group of patients.
Dr. Alexandra Rendely is a resident physician in physical medicine and rehabilitation at the University of Toronto who is participating in the Certificate in Health Impact program, which is offered by the Dalla Lana School of Public Health, the University of Toronto Faculty of Medicine and the Munk School of Global Affairs and Public Policy.