When I nervously asked my sports-medicine doctor last fall what he saw in the latest MRI of my left knee, he grimaced. “Extreme atrophy,” he said. After barely using my leg for eight months while suffering from nerve pain following ACL surgery last spring, I now faced the daunting challenge of restoring muscle to a limb so severely weakened it could barely carry me out his office door.
In January 2018, I injured my knee while skiing but waited until March for surgery to reconstruct this crucial ligament. Although the operation was successful, about ten weeks into the recovery, my pain dramatically increased. I couldn’t walk—or even stand—without severe pain, and it took six months to figure out what was wrong and how to fix it. As an avid cyclist who typically trains at least an hour and a half each day, the lack of exercise was difficult to deal with both psychologically and physically.
To build muscle mass, the American College of Sports Medicine recommends lifting heavy weights—around 60 to 70 percent of your one-rep max. While training for a mountainous century ride a few summers ago, I was squatting 100 pounds, but there was no way my knee could tolerate intense training now. Instead my doctor suggested blood-flow-restriction (BFR) therapy.
BFR therapy uses a tourniquet to severely limit blood flowing into and out of a limb. The treatment deliberately deprives muscle tissues of oxygen, metabolically stressing those muscles without overtaxing them physically, according to Brad Grgurich, clinic director at Front Range Physical Therapy in Longmont, Colorado, and one of my physical therapists. The first time I visited Grgurich’s clinic, I watched him carefully Velcro a wide cuff around the top of my shrunken thigh. He then connected a narrow air hose from the cuff to a small box housing a tourniquet system. Once the cuff inflates, Grgurich explained, it temporarily restricts blood flowing into the limb—typically 50 percent into an arm or 80 percent into a leg—and up to 100 percent of the flow back to the heart. This restriction creates an anaerobic environment that triggers a cascade of physiological changes that help reduce muscle atrophy. Even better, when combined with light exercises, BFR stimulates hypertrophy, increasing the size of muscle cells by reproducing the same kind of environment that’s naturally present when you participate in a high-intensity workout, says Dr. Robert LaPrade, one of the country’s top knee surgeons, who practices at Twin Cities Orthopedics. “The muscle cells can be tricked into believing that they need to hypertrophy due to the extra environmental stress created by the BFR,” he explains.
Grgurich first heard about BFR therapy in 2015 when LeVeon Bell, a professional football player, received the treatments while recovering from knee surgery and posted about it on social media. After learning more about the technique and researching its effectiveness, Grgurich decided it was a service he’d like to offer. He attended a training session—a single-day course with both classroom and hands-on instruction—with Owens Recovery Science, the nation’s leading BFR-certification provider, and began offering the treatment shortly afterward.
BFR therapy originated in the 1970s in Japan as a type of resistance training, but it wasn’t until the early 2000s that Johnny Owens, an Army physical therapist who, after experimenting on himself, used BFR to boost strength and hypertrophy in active service members, primarily amputees, and in 2015 began training nonmilitary physical therapists such as Grgurich.
For the past seven or so years, bodybuilders have also dabbled in BFR-like techniques, using knee and elbow wraps, floss bands, and cotton elastic bandages to occlude blood flow in their limbs to create the same benefits. This unsupervised use, however, is potentially dangerous; if performed improperly, BFR has the potential to cause muscle, nerve, and even cardiovascular damage.
The exercises patients perform during physical-therapist-supervised BFR therapy vary widely based upon the type of injury or surgery as well as the patient’s ability, says Grgurich, but they all use low loads (typically about 20 percent of the one-rep max). Post-op protocols like mine usually involve a lot of repetition: one set of 30 reps followed by three sets of 15 reps, separated by 30-second rests with the cuff still inflated.
At my first session, I started with seated leg curls, wearing a two-pound ankle weight, and easy spinning on a stationary bike. Every five minutes, Grgurich deflated the cuff for a minute to prevent me from becoming light-headed. Although my knee felt stable and I didn’t experience pain, the therapy was initially very challenging; I often couldn’t complete all the sets. But I kept at it for three 40-minute sessions per week, and within just a few weeks, Grgurich increased the weight and added calf raises, step-ups, and full-body squats.
Within six weeks, the initial two-inch difference between my lower thigh circumferences had shrunk to 0.75 inch, and my quad and calf muscles were so noticeably larger that several people at the gym complimented me on my progress. According to Grgurich, this much improvement would typically take at least three to four times longer with traditional rehab.
But BFR therapy is not yet widely prescribed by doctors or standardly offered at physical-therapy clinics. Even though I live in a large metropolitan area, the nearest provider was a 45-minute drive away. However, the technique is rapidly gaining ground. There has been a significant increase in BFR-related publications in the past five years, and the number of certifications has expanded rapidly, says Ben Weatherford, the clinical-education coordinator for Owens Recovery Science. In the three-and-a-half years since the company started teaching BFR outside of military applications, he says, it has trained between 4,000 and 5,000 practitioners around the country.
A 2017 study that examined safety concerns, including an increased risk of blood clots, muscle damage, and nerve compression, concluded that BFR therapy “is a safe and effective tool for rehabilitation,” but it also recommended additional research be conducted prior to widespread application. According to Grgurich, there aren’t many concerns with BFR—even following knee surgery—as long as a trained professional is supervising the treatment. He says it’s also important to make sure your therapist is using the Delfi Personalized Tourniquet System, the only device the FDA has cleared for this type of treatment. When conducted properly, the potential side effects of treatments are limited to bruising under the cuff, soreness after exercise, light-headedness, and temporary numbness.
LaPrade, who has used BFR therapy in his clinics since 2017, argues that more research is still necessary to learn how to maximize the therapy’s outcomes and to pinpoint which patients will benefit most. His team is currently conducting a study comparing regular and fake BFR regimens in post-ACL-reconstruction patients. “If we can obtain good and precise science to determine objectively when BFR may be useful,” he says, “this may lead to the opportunity to utilize it more widely.”
Many orthopedic physicians aren’t yet familiar with BFR therapy, says Grgurich, who estimates that less than 20 percent of the patients he’s treated with it were referred to him for BFR. About half of those were recovering from knee surgeries. But Grgurich, who has treated about 100 patients since his 2016 certification, emphasizes that BFR therapy can be used to treat almost any injured limb. Both LaPrade and Grgurich also envision the therapy’s potential for treating seniors. According to Grgurich, research increasingly shows that it’s is a safe and effective way to improve strength and cardiovascular function in older people who are unable to tolerate traditional strength or endurance training.
Looking ahead, Grgurich even believes there’s a niche for endurance athletes looking to gain an edge in their sport, because preliminary research has shown that the treatment could potentially improve one’s VO2 max. What started as a fringe technique is now poised to become a mainstream treatment that promises to dramatically reduce recovery time and may even evolve into a valuable supplement to a typical training program.
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