Blood Flow Restriction Maximizes Recovery from Injury and Surgery
By Dan Barraclough, PT, DPT, CSCS
Blood Flow restriction (BFR) training has been around since the early 1990’s but has gained popularity in the rehabilitation and athletic worlds more recently. This is largely due to further research on safety, mechanism, protocols and implementation of pneumatic tourniquet devices. A physical therapist and Chief of Human Performance at the Center for the Intrepid has further advanced the research and treatment using BFR through the military, primarily from wounded solders that were returning from war with significant limb traumas and injuries. This has been involved in treating solders in hopes of limb salvage to maximize overall function and possibly prevent ambutation of the limb. This article will further discuss treatment using blood flow restriction and the benefits, mechanism, safety and reasons why this is becoming a crucial component in physical therapy and the Colorado Institute of Sports Medicine (CISM).
Historically, strength and hypertrophy of a muscle requires increased load placed onto the musculature in order to cause an adaptive change. Research has shown that these loads need to be 70% or more of a maximal effort for a change to occur, which involves 8-10 exercises targeting main muscle groups at least 2-3 days per week. This presents an innate difficulty when working with certain populations and within a rehabilitation environment. Loads that are necessary to improve strength are not feasible or safe when working with certain physical therapy populations, especially elderly, children, and those following surgery. Therefore, a modality like BFR can be very effective and crucial to maximize recovery potential during physical therapy.
BFR training allows for strength and hypertrophy changes to occur while completing low-intensity and low load exercise. The load can be as low as 20-30% of a maximal effort and exercises as simple as isometrics, allowing therapist to begin strength progression at early stages in rehabilitation. Many patients are restricted in weight bearing post-surgery or cannot tolerate weight bearing activities due to arthritic or muscle pain, however, when using this tourniquet system, they can complete light exercises in non-weight bearing and with minimal joint movement. It’s the restriction of the venous blood return by using pneumatic restriction cuffs over large muscle groups that provides the necessary environment within the working muscles to promote strength with low intensities.
There are many theories on the exact mechanism in which BFR causes hypertrophy and strength development, however, full understanding continues to be extensively researched. Two prominent mechanisms that are most likely responsible for the changes are; a buildup of metabolites and cell swelling.
Let’s first explore the importance of metabolites in muscle development. Deep within the working muscles a stressful condition occurs due to a shift from aerobic (with oxygen) to anaerobic (without oxygen) metabolism leading to the production of a chemical called Lactate. As BFR creates this anaerobic environment below the tourniquet, it causes our body to produce stronger contractions and increased muscular activation because more “fast twitch” fibers begin to activate versus “slow twitch”. Fast twitch fibers produce more Lactate within the exercising muscle. In the past, Lactate has received a bad name and was frequently referred to as “Lactic Acid”, which is believed to be the reason for exercise induced soreness and fatigue. In actuality, Lactate is not responsible for these adverse side effects, but it plays an important role in signaling pathways within the body and is an energy source for our body and brain.
As the exercising muscle produces Lactate it begins to signal the release of other chemicals and proteins that help in building our muscles. One such hormone is Growth Hormone (GH), and no, this will not turn you into a body builder or the Hulk. GH is beneficial for tissue healing and recovery by promoting collagen synthesis, specifically in muscles, tendons, ligament and bone. This healing environment due can help accelerate general recovery after exercise but more importantly, healing of tissue after injury. Furthering the reason why BFR training has been utilized by CISM to maximize patient outcomes following surgery and injury. Lastly, BFR is responsible in the release of Insulin-like Growth Factor (IGF-1) protein that is directly linked to muscle growth while blocking the production of the Myostatin protein that actually prevents our body from building muscle.
The second main theory behind BFR is cellular swelling that is occurring below the tourniquet occlusion. Naturally, we would think that this is due to blood pooling in surrounding tissue because the tourniquet is blocking venous blood flow causing our limbs to swell. However, research has discovered that this is not the case but is related to an increase in fluid within the cells that signals protein synthesis because the cell is well hydrated.
Concerns on safety have been raised because occlusion of blood and using tourniquets to achieve this. Some of the concerns include blood clots (DVT), nerve damage, tissue and blood vessel damage, and cardiac responses. Extensive amounts of research and literature exist on this possibility with minimal to no safety concerns. Most of the dangers exist when online or aftermarket devices are used for BFR training. Here at CISM, a 3rd Generation Delfi personalized tourniquet system that is FDA approved is utilized that provides built in safety systems. Also, cuff placement prevents many possible safety concerns since they are placed as high on the arm or leg as possible over larger muscle groups and areas where there is more tissue.
Exercising while using the Delfi tourniquet system follows a standardized protocol that every patient participating in this modality will complete regardless if they are young or old, athlete or weekend warrior, or simply suffering from pain and injury. The Delfi system will determine an individual tourniquet pressure and from this the therapist will set the designated limb occlusion pressure from 30-80% for the leg and 30-50% in the arm. 80% for the leg and 50% for the arm are the desired values to produce maximal benefits but lower percentages are effective as well and can be more tolerable with initial treatments. Once the pressure has been determined and set, the fun begins with a determined exercise by the therapist. The exercise will consist of 4 sets of 30/15/15/15 reps with a 30 second rest interval between each set. On average 1-4 exercises may be completed during a therapy session and these exercises may work the injured area and/or surrounding musculature. During training, the tourniquet will provide a strong compressive force on the limb much like traditional blood pressure, which can be uncomfortable but will release once the sets have been completed. The goal with each exercise is for the patient to become very fatigue likely creating a strong “muscle burn” sensation. After all reps have been achieved, the cuff will be deflated allowing the reperfusion of blood into the limb rapidly removing “muscle burn” and an adequate rest will be provided until another exercise can be completed if desired.
One important reminder is that muscle tissue needs to be repaired following exercise and consumption of protein is necessary to provide adequate protein supplies to the body. Generally, 20 grams would be adequate to support your bodies muscle development and repair system following exercise. Also, like any exercise and physical activity, proper hydration is extremely important to prevent dehydration, electrolyte imbalances, cognitive impairments, cardiovascular strain and general decline in physical performance.
Physical therapy, rehabilitation and sports recovery has been steadily advancing throughout the years in techniques, modalities, treatments and knowledge to optimize a return to full function. Here at CISM, we take pride in providing evidence-based medicine to ensure that we provide our patients the best chance to succeed. Many fad treatment options and/or modalities come into existence daily but have not been consistently supported by research or literature. Unlike these fad treatment options, BFR is strongly supported for its effectiveness and safety. BFR does provide us a unique ability to begin strengthening early into the recovery process without harm and/or jeopardizing surgical interventions. We have seen firsthand the benefits on a multitude of patients, which gives us the confidence on continuing the use of BFR here at CISM.
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