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The Potential Risks of Blood Flow Restriction Training

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  • Post last modified:September 26, 2023

Ever witnessed someone in the gym with ties around their upper arms or legs and thought they appeared…well, slightly strange? They were probably engaging in blood flow restriction (BFR) training, also known as occlusion training — and they were most likely utilizing BFR bands. While it may appear peculiar to those unfamiliar with it, this method is actually a highly effective way to increase strength and enhance muscle mass using weights that are significantly lighter than what would typically be required to achieve the same results.

However, just because it sounds like a fantastic technique doesn’t mean it’s suitable for everyone. Here’s what you need to understand about BFR, including how to determine if it’s appropriate for you.

How Blood Flow Restriction Training Functions

Blood flow restriction involves the utilization of a specialized tourniquet system (similar to what a nurse or doctor would employ to wrap around your arm prior to drawing blood) in order to reduce blood flow to your limbs, as explained by Hannah Dove, D.P.T., A.T.C., C.S.C.S., a doctor of physical therapy at Providence Saint John’s Health Center in Santa Monica, California. Typically, the tourniquet is wrapped around the arms just below the shoulder or around the legs just above the hip.

When undergoing BFR at a physical therapist’s office, they often use a variation that resembles a blood pressure cuff, allowing the therapist to regulate the level of blood flow restriction. But why would they do that? Well, in traditional strength training, a heavy load (at least 60 to 70 percent of your one rep max) is required to make your muscles stronger and larger. However, with the aid of a tourniquet, you can achieve the same effect with a much lighter load.

Here’s a more comprehensive breakdown: When you lift heavy weights, it creates a localized hypoxic environment in your muscles due to the increased demand, which essentially means that less oxygen than usual is being delivered to the tissue. Hypertrophy training combines load (weight) and repetitions to reach fatigue and oxygen depletion more rapidly. This leads to an accumulation of lactate, which is what causes that sensation of “burning” during intense workouts. By employing a tourniquet, you are replicating this hypoxic environment by reducing blood flow, all without the need for heavy weights, as mentioned by Dove.

“For instance, if you would typically need to perform bicep curls with 25-pound weights in order to enhance your bicep strength and muscle size, with the use of BFR, you would only require a 1- to 5-pound weight to achieve the same level of strength and hypertrophy (muscle growth),” explains Dove. Research has indicated that engaging in BFR training with loads that range from 10 to 30 percent of your one rep max is adequate to stimulate muscle growth, as BFR imitates the lower-oxygen environment in your muscles that would typically be attained through lifting heavier weights.

While this may sound somewhat insane, it’s actually not a new concept at all. “Weightlifters have been harnessing the advantages of BFR for years,” says Eric Bowman, M.D., M.P.H., assistant professor of orthopedic surgery and rehabilitation at Vanderbilt University Medical Center in Franklin, Tennessee.

In reality, a form of BFR known as Kaatsu training was formulated in Japan by Dr. Yoshiaki Sato in the 1960s after he observed significant discomfort in his calves from assuming a traditional posture during a Buddhist ceremony, notes Dr. Bowman. He recognized that this sensation resembled the burning feeling he experienced while working out and began using bands to recreate the effects. “You may have witnessed weightlifters at the gym imitating this by wearing bands on their arms or legs,” says Dr. Bowman. Now, those bands — BFR bands — are readily available, and BFR is being employed worldwide for various purposes.

The Advantages of Blood Flow Restriction Training

Aside from enhanced strength (even outside of your BFR sessions) and muscle growth, there are some extraordinarily impressive benefits of blood flow restriction training.

All in all, BFR is a extensively researched approach to training. “Most of the published studies have been conducted on small groups of individuals, yet the outcomes are significant,” says Dr. Bowman. And since it has existed in one form or another for several decades, there has been a sizeable amount of examination into how it functions and who should give it a try.

Here, some illustrations of advantages you can anticipate from blood flow restriction training:

Enhances the Strength of Healthy Individuals

In individuals without injuries, the research-supported benefits include increases in muscle size, strength, and endurance that are comparable to high-weight exercise routines, says Dr. Bowman. That indicates you could lift significantly lighter weights and still observe progress.

Enhances the Strength of Injured Individuals

Currently, BFR research is being carried out on individuals who have recently undergone surgeries or who require rehabilitation for various reasons. A few studies have recognized benefits for orthopedic patients, with more ongoing, says Dr. Bowman. “This has the potential to be a significant advancement in the way we rehabilitate patients with knee pain, ACL injuries, tendonitis, post-operative knee surgery, and more,” he remarks. BFR is also utilized in elderly patients who need to increase their strength but are unable to lift heavy weights.

Compatible with Virtually Every Exercise

Essentially, you have the option to engage in any physical activity that is part of your regular workout routine, but with a decrease in weight or intensity and the addition of a tourniquet. By doing so, you can achieve the same outcomes. “With BFR, the possibilities are truly limitless,” explains Kellen Scantlebury D.P.T., C.S.C.S., the founder of Fit Club NY.

The Duration of Sessions is Brief (!!)

“Our usual practice in the clinic involves performing one exercise for a duration of seven minutes, and at the most, we perform a total of three exercises,” reveals Jenna Baynes, D.P.T., a doctor of physical therapy at the Hospital for Special Surgery. In other words, you can obtain an effective workout in a fraction of the time because you will be working with significantly lighter loads.

The Potential Dangers of Blood Flow Resistance Training

Before rushing to purchase BFR bands or a DIY BFR kit, there are certain important facts you need to be aware of. First and foremost, it is essential to work under the guidance of a professional when commencing this training.

When you have the proper equipment and are working with a well-trained individual, BFR is considered very safe, says Dove. However, she emphasizes that “attempting blood flow restriction training without proper supervision and guidance from a certified BFR practitioner would be unsafe. It is crucial to possess the knowledge and ensure that the occlusion pressure remains at a safe level.” This is due to the fact that applying and utilizing a tourniquet incorrectly on your limbs can lead to severe complications such as nerve and muscle damage, as well as an increased risk of blood clot formation. Dove adds, “Just like with any form of exercise, it is important to consult with your physician, taking your medical history and conditions into consideration, in order to pursue a safe and effective path towards strength improvement.”

Currently, engaging in BFR requires expertise in the medical or fitness field, such as being a physical therapist, certified athletic trainer, occupational therapist, or chiropractor who has completed a certification course on blood flow restriction.

After training with a professional, you may become capable of practicing BFR on your own. In the case of using a BFR device with a pump, Scantlebury mentions that he typically recommends clients to use the device alongside him for a minimum of six sessions before attempting to use it independently. “When starting with the device, it is crucial to determine the maximum occlusion levels, which refers to the point where blood flow to the extremities is completely blocked,” he explains. Once your maximum occlusion level is determined, your therapist or trainer will establish the appropriate pressure for your training sessions, which will be lower than your maximum level.

However, even if you are using straps without a pump, it can still be challenging to determine the optimal tightness for optimal results. A certified professional can assist you in achieving the correct fit.

Ideally, they should be snug enough that circulation is restrained, but not so snug that you are unable to maneuver.

As well, blood flow restriction (BFR) exercise is not a safe or suitable method for everyone. “Individuals with a prior history of blood clots (also known as deep vein thrombosis or pulmonary embolism) should refrain from participating in blood flow restriction training,” says Dr. Bowman. Additionally, those with significant cardiovascular disease, high blood pressure, vascular disease, impaired blood circulation, or individuals who are expecting should avoid BFR training as it may elevate the risk of stroke.

The Key Takeaway

In summary, BFR is quite impressive in enhancing muscle strength and size if performed correctly under professional supervision. However, it may not be wise to attempt BFR training alone for the first time. If you are interested in trying BFR exercise, it is advisable to seek guidance from a physical therapist or trainer who holds a certification in blood flow restriction. This is especially crucial if you have an injury that you believe BFR could aid in its recovery. Otherwise, it is still preferable to stick with traditional weight training, as lifting heavy weights certainly offers its benefits.

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