- Blood Flow Occlusion Training
- Exercise Physiology of Occlusion Training
- Benefits of Occlusion Training
- Musculoskeletal System Safety (Muscle, Connective Tissue)
- Cardiovascular System Safety (Heart, Blood Vessels & Blood)
- Long-Term Effects of BFR Training
- What Blood Flow Occlusion Bands are Right for Me?
- Conclusion
Blood Flow Occlusion Training
…The Superior Workout Method or a Waste of Time?
Have you ever tried to purposely deprive your musculature of oxygen for superior strength and cardiovascular gains? Sounds pretty intense, doesn’t it? Blood flow occlusion training (also commonly known as blood flow restriction training, BFR training, or occlusion training) is a fitness trend that has gained a significant spike in popularity over the past few decades. It has shown to facilitate the runner’s high experience through the process of exercise-induced euphoria. It originated in Japan in the 1970’s through KAATSU training (Japanese for “added pressure”) and was developed by Dr. Yoshiaki Sato. But how safe is it really, and what are the blood flow occlusion training risks?
Clinically, physical therapists have been incorporating occlusion training into rehabilitation for years now, with great results for many different patient populations. Are there any safety concerns that you should be aware of? What populations are better off not performing blood flow occlusion training? Let us dive deeper into that to make sure you take the proper precautions prior to starting out on an BFR training program.
What is Occlusion Training? Blood flow occlusion training (BFR taining) is an effective and intense way of strength training. The technique allows you to perform low-intensity training through the temporary occlusion of blood flow, while achieving similar results to high intensity training. By wrapping elastic occlusion bands around specific parts of your body, the cuffs temporary decrease blood flow further down the limbs, creating a high-intensity environment within the muscle cells. Many research studies have shown that consistent occlusion training can lead to superior gains when it comes to muscle growth, strength, as well as endurance. Scientific research has made it possible to learn about the proper technique, benefits, as well as the general safety of occlusion training.
BFR Training Technique. In order to take full advantage of the benefits that occlusion training has to offer, it is essential to be aware of the proper training technique first. Too much blood flow occlusion by tightening the occlusion bands too tightly, and you may deprive your tissues of the minimal nutritional needs or compress nerve structures. Not enough occlusion of your blood vessels on the other hand, and you may miss out on the amazing benefits that blood flow restriction training has to offer. To learn about the proper placements of your occlusion cuffs, how tight to wrap your blood flow occlusion bands around your limbs, as well as how much weight to use for when you are just starting out, I recommend that you go ahead and check out this article.
Exercise Physiology of Occlusion Training
Before going deep into the physiology of BFR, you should be aware that scientific research on it is still in its early stages. Over time, the primary hypotheses underlying the physiology of BFR training may change.
In the following few paragraphs I have summarized the current hypotheses on the physiology behind BFR training based on the most current research available on the topic.
Muscle Fibre Recruitment (SOURCE). The occlusion cuffs used for blood flow occlusion training restrict arterial blood flow (oxygenated blood) to make its way to the working muscles, as well as prevents venous blood flow (deoxygenated blood) to return to the heart and lungs. The lack of oxygen-rich blood reaching the working musculature leads to an increased recruitment of type II muscle fibres, as they are able to create contractions without the use of oxygen (as opposed to type I muscle fibres). Type II fibres happen to be your muscle fibres that are primarily involved in producing contractions with greater force. By favouring type II fibre recruitment through the application of BFR cuffs, their glycogen stores (i.e. your available energy stores) deplete at a greater rate than compared to traditional training, leading to a greater fatigue. Fatigue of muscle fibres translates into greater muscular adaptations following appropriate recovery.
Metabolic Stress (SOURCE). Venous blood cannot easily escape from your limbs if their main way of transportation is reduced. Due to the restriction of venous blood vessels, metabolic by-products that are produced with strength training have a tendency to remain in the working musculature. This, in addition to the hypoxic environment (i.e. a low-oxygen environment), causes an accumulation of lactic acid and hydrogen ions in the muscle. This, in turn, results in increased inflammation, as well as muscle cell swelling, resulting in muscle hypertrophy and improved muscle strength. This metabolic stress results in increased production of growth hormone, which are typically only seen in high intensity exercise and is responsible for the maintenance, repair, and building of muscle tissue.
In summary, the combination of mechanical tension in combination with metabolic stress as a result of blood flow occlusion to the working muscle are considered to be the primary mechanisms facilitating muscular adaptations in your musculature (SOURCE).
Benefits of Occlusion Training
Occlusion training has many beneficial effects on your body, on both a local, as well as on a systemic level. Below you can find benefits of occlusion training for strength training, aerobic training, functional training, immobility, as well as systemic benefits.
- Strength Training & BFR (SOURCE). High intensity resistance training and low intensity resistance training with blood flow occlusion were shown to be able to produce similar adaptation, as concluded in this systematic review & meta-analysis conducted by Lixandrao et al. (2017). Significant increases in muscle strength and muscle hypertrophy following both exercise techniques were demonstrated in both younger, as well as older adults.
- Aerobic Training & BFR (SOURCE). A further systematic review examined the effectiveness of BFR training coupled with low intensity aerobic training. Findings of the review showed that low intensity blood flow restriction aerobic training increased aerobic performance and fitness at higher pressures in younger individuals. Older individuals demonstrated greater levels of athletic performance, which did not appear to translate into a significantly greater athletic fitness.
- Walking & BFR (SOURCE). This recent study examined walking performance when wearing occlusion bands. Study participants were composed of sedentary older men and women, which were divided into two groups. The experimental group was asked to wear occlusion bands during their walks and the control group was asked to perform their walks without the use of occlusion bands. Six weeks later, researchers found that the experimental group (participants wearing the occlusion bands during their regular walks) had a 2.5 – 4.5 fold increase in aerobic performance compared to the control group (SOURCE).
- Immobility & BFR (SOURCE). Despite recent evidence concluding that BFR training coupled with low load resistance training is superior in terms of increasing muscle strength, size, and mass, there is reason to believe that occlusion training can yield positive muscular adaptations without performing purposeful exercises. In a study, participants that underwent ankle surgery wore an ankle immobilization cast and wore lower extremity occlusion bands for a period of two weeks. Study participants were not allowed to weight-bear on the surgical side. Results showed that the strength and leg circumference was preserved in individuals that wore occlusion bands after the two week immobilization period, whereas the group that did not wear occlusion bands showed significant muscle loss and size.
- Systemic Effects & BFR (SOURCE). A systematic review by Miller et al. (2021) examined the systemic effects of blood flow occlusion training on the body in healthy individuals. Researchers evaluated the effect of BFR training on cardiopulmonary, musculoskeletal, endocrine, and psychosocial outcomes. Miller concluded that blood flow restriction coupled with aerobic or resistance training showed significant positive adaptations in all examined systems. To learn more about the effects on individual systems, make sure to check out this article.
Key Points (bfr training Benefits)
- High intensity resistance training and low intensity resistance training with blood flow occlusion showed to have similar adaptations in muscle strength and muscle mass (as per this systematic review & meta-analysis by Lixandrao et al. (2017)).
- Light intensity aerobic exercise training coupled with blood flow restriction showed a significant improvement in aerobic performance and fitness in younger adults, as well as significant improvements in aerobic performance in older adults (SOURCE).
- A six-week walking program coupled with blood flow occlusion showed improved aerobic performance and function in older sedentary adults compared to the control group that completed the walking program without BFR training (SOURCE).
- Blood flow occlusion training has shown to be able to prevent muscle atrophy during periods of immobility (SOURCE).
- Systemically, blood flow restriction training has shown to be able to improve cardiopulmonary, musculoskeletal, endocrine, and psychosocial outcomes (SOURCE).
Musculoskeletal System Safety (Muscle, Connective Tissue)
- Musculoskeletal Injury Risk. Your body requires more energy to produce the same amount of work with BFR training. As a result, you will be able to get away with lifting significantly less weight, yet still achieve the same, if not, improved results. Researchers have found that a mere 20% – 40% of your 1-RM (one repetition max, or the maximum weight you can lift with one repetition) is sufficient when strength training and has shown to produce the same results than without blood flow occlusion bands at heavy loads. If, for example, you typically squat 100 lb. at your fitness centre’s squat rack, a 20 lb. weight (the equivalent of ~2x sacks of potatoes), should be sufficient to produce similar gains (SOURCE). This translates into being able to more easily perform strength training workouts during the day. However, do not be fooled. Your perceived level of exertion (i.e. overall perceived difficulty) will likely still approach similar, if not the same levels of intensity as with high-intensity training.
To summarize, this means that during BFR training your muscles will experience less strain compared to traditional strength training. This is because the high-intensity environment is primarily created by the accumulation of metabolic by-products and lack of oxygen. Lower amounts of strain from lower weights, musculoskeletal injuries as a result of slips, falls and poor form are also less likely to occur. Furthermore, musculoskeletal adaptation as a result of BFR training (increases in muscle size, strength, and endurance) will increase the resilience of your muscles to future injury.
- Muscle Damage (SOURCE). There is a common concern that the restriction of blood flow and subsequent deprivation of oxygen to working musculature can lead to muscle damage. A systematic review examining this theory suggests that BFR training does not appear to induce muscle damage when looking at exercise protocols that used up to 5 sets of strength training up until muscular failure.
- Individuals with Musculoskeletal Injuries (SOURCE). A systematic review conducted in individuals that suffered from muscle disorders, achilles tendon rupture, bony fractures, as well as thoracic outlet syndrome showed that BFR training was considered to be a safe and effective method of working out . BFR training is a common method of exercise in physical therapy clinics and is being used in a wide variety of patient populations. The need for supervision and the appropriateness of BFR training will have to be made on a case-by-case basis.
- Connective tissue Adaptations. All throughout your lifespan it is recommended that you perform strength training, with the main reason not only being to get stronger, to gain greater amounts of muscle mass, and become more powerful. Just like muscle, other forms of connective tissue will also be able to adapt to the stressor that you are exposing them to. Without exposing your bones, ligaments, as well as your cartilage to high load training sessions, these structures will have not much to adapt to. One could argue that by increasing your muscle strength, you will be able to lift heavier weights throughout the day and get your adaptations at these time points, however, this is dependent upon many factors.
- Without sufficient levels of bone bending (which is the process your bones undergo during weightlifting), your bone mineral density will remain unchanged, not preventing you from future bone damage. Individuals suffering from osteopenia or osteoporosis (i.e. significantly low bone density levels) may feel safer performing this type of strength training initially. Over time, however, strength training exercises should be progressed in these individuals as well.
- Tendons will not undergo the same strain they would with high loads. As a result, they will likely not adapt at the same rate as your muscles will. This, however, may even itself out once you are lifting heavy weights after your muscles strength increases.
- Without exposing cartilage to greater compressive forces, it will not become more resilient to degenerative diseases such as osteoarthritis. This only plays a role for exercises that increase the compressive forces at the joint.
- Without exposing your ligaments to high-load activities and greater, temporary stretch, your ligaments will not adapt to become more resistant to stretch when needed (e.g. high-risk sprain situations).
In summary, BFR training is very safe method of working out from a musculoskeletal safety perspective. Muscular adaptations that result from this type of training will further improve the resilience to musculoskeletal injuries in the future. Individuals with musculoskeletal injuries may want to reach out to their doctor or physical therapist to ensure to modify their training program appropriately. Blood flow occlusion training is a great way of strength training for individuals that are new to strength training. This may be one of the main reasons that it is frequently used in a clinical setting. Lower weights do not require the same extent of coordination and control that higher weights do. Therefore, it is a great way to induce muscle hypertrophy for beginners. Over time, you should incorporate heavier lifting into your strength training routine so that other bodily tissues (e.g. connective tissues) can adapt to the muscular strength increases.
Key Points (Musculoskeletal safety)
- There is an overall lower musculoskeletal injury risk when using blood flow restriction training due to lighter weights being used, greater ability to control the movement. Muscular adaptations as a result of BFR training will lead to improved resiliency towards future injury.
- Muscle damage as a result of oxygen deprivation and blood flow restriction has not been shown to be a risk when BFR training
- Individuals with musculoskeletal injuries are considered to be safe performing BFR workouts. The appropriateness, as well as need for supervision is recommended to be made on a case-by-case basis.
- Connective tissues (tendons, bone, cartilage, ligaments) do not adapt to BFR workouts the same as traditional strength training would. They likely will, however, adapt to increased loads following muscular adaptations as the ability to lift heavier improves.
Cardiovascular System Safety (Heart, Blood Vessels & Blood)
Below, I have gathered a collection of scientific literature (primarily in forms of systematic reviews) that goes into deeper detail about potential cardiovascular risks and side effects of blood flow occlusion training. The effect on the cardiovascular system (system comprised of your heart, blood vessels & blood) during BFR training appears to be dependent on the mode of training (aerobic versus resistance training), degree of occlusion, as well as the duration of blood flow occlusion. BFR training when combined with both strength or aerobic training, as well as in absence of exercise showed significant cardiovascular responses.
- Heart Rate & Blood Pressure Response (SOURCE). In healthy populations performing BFR strength training, heart rate and blood pressure increased during exercise, but showed a significant decrease following the training session (~5-10 minutes following the termination of exercise). Even though this response is to be expected when it comes to strength training, the addition of blood flow occlusion appears to cause a more significant change of these cardiovascular parameters (heart rate and blood pressure). These effects were found to be prolonged with continuous blood flow restriction training (e.g. during training sessions in which occlusion bands were left on during rest periods). Intermittent BFR strength training appears to mitigate the intensity of this increased cardiovascular response. In addition, higher cuff pressure is associated with greater cardiovascular responses (i.e. higher heart rate & blood pressure). Considering the aforementioned information from the systematic review, individuals with cardiovascular disease are better off decreasing the cuff pressures, as well as follow an intermittent BFR training program. Healthy individuals are considered to be safe performing BFR training in terms of cardiovascular safety.
- Blood Vessel Function (SOURCE). Your blood vessels are composed of three layers. The outer layer is primarily responsible for providing the blood vessel structure, whereas the middle layer is responsible for changing the dilation (i.e. the degree of opening) of the vessel to allow for more or less blood to reach its destination. The innermost layer is called the endothelium. Its job is to control the amount of opening and closing of blood vessels. BFR exercise has shown to improve endothelial function in the short-term. Chronic effects of BFR training on endothelial health are currently unknown, however are being monitored.
- Dizziness/Lightheadedness/Fainting (SOURCE). A mismatch between your cardiac output (the amount of blood that your heart pumps each minute), nervous system control (your brain’s response to requiring higher levels of blood in a certain area), as well as decreased blood flow in occluded areas has shown to be able to cause episodes of orthostatic hypotension (OH). OH results in sudden blood pressure drops, which can cause symptoms of dizziness, lightheadedness, fainting, and falls. Risk factors for OH include a sedentary lifestyle, pregnancy, age (above 65), alcohol consumption (). You can decrease your risk for OH by staying adequately hydrated, avoid sudden positional changes and by increasing your overall activity levels and warming up prior to your workout. Be aware that certain medications can cause you to be at increased risk for developing symptoms associated with OH.
- Blood Clotting. A risk factor that you should be aware of are blood clots as a result of blood pooling in local areas, potentially leading to the formation of blood clots / venous thromboembolisms (VTE). Long-term blood pooling can cause the formation of a thrombus (a solid mass made of a collection of platelets, red blood cells and fibrin). The primary cause of thrombus formations are blood vessel wall injuries (i.e. the blood-thickening response similar to when you have a nosebleed). In some instances, a thrombus can become so large that it occludes blood flow, which may lead to local tissue ischemia and consequent tissue death if left untreated. In rare cases in where a thrombus dislodges, it can travel down your veins (i.e. a deep vein thrombus) into your lungs, which can cause a pulmonary embolism (PE). PE’s can cause significant shortness of breath, dizziness and if left untreated, cause death. With BFR training, you are purposely trying to cause blood pooling and therefore there may be an increased risk for a local thrombus formation (SOURCE). Populations that are considered to be at greater risk for the development of VTE’s are post-operative individuals, pregnant women, sedentary individuals, elderly. Despite the elderly being at greater risk for the development of VTE’s, recent research studies suggest that BFR strength training does not increase the risk for blood clot formation in the elderly (SOURCE). If you do not have a history of cardiovascular disease, are at risks for blood clot formation, or are on any medication that affects the viscosity of your blood, then you should not be at risk for developing blood clots / VTE’s.
Despite the above risk factors, many researchers have found the the benefits of blood flow occlusion training outweigh the risks associated with it. Unless you are suffering from cardiovascular disease, are above 65 years of age, use medications that affect your blood viscosity (all in which you should seek medical advice prior to starting out a BFR training program), blood flow restriction training can be considered a safe training option when it comes to the overall cardiovascular safety of BFR training.
Key Points (cardiovascular safety)
- Heart rate, as well as blood pressure has been shown to increase more significantly when using BFR compared to traditional strength training, with effects being more significant with continuous BFR, as well as larger cuff pressure.
- Blood vessel function has shown to be improved following BFR training. Long-term effects on blood vessel function have not yet been researched.
- Individuals living a sedentary lifestyle, are above the age of 65, are pregnant, dehydrated, or have an increased alcohol consumption are at greater risk for experiencing orthostatic hypotension from BFR training. OH comes from sudden blood pressure drops and may result in lightheadedness, dizziness, or fainting.
- Blood clot formation is a risk factor that comes with BFR training, however appears to be negligent in healthy individuals based on current available research. Individuals with cardiovascular disease or risk factors, the elderly as well as certain medications may increase the risk for blood clot formation.
Long-Term Effects of BFR Training
While the research evidence on blood flow restriction training appears to be quite promising, long-term risks associated with prolonged occlusion of blood vessels have not been documented well. While occlusion training appears to be safe to be performed by healthy individuals in the short-term, many research articles conclude that the long-term risks may be different for everyone, depending on their current health status. I will update this article once new information about the long-term health risks associated with BFR training is published!
What Blood Flow Occlusion Bands are Right for Me?
If you consider yourself a beginner in blood flow occlusion training, I would recommend that you start out with cheaper elastic bands. I have created an in-depth review about the bands that I personally use for blood flow restriction resistance training. Based on personal experience, these beginner’s bands are quite effective and efficient in reproducing feelings of a runner’s high.
On the other hand, if you consider yourself to be at an intermediate or advanced level of BFR training, it may be worth to check out these bands. The occlusion cuffs created by SAGA fitness provide mechanical tension in a way similar to blood pressure cuffs and occlusion pressure can be set on the accompanied phone application tracker.
Conclusion
Based on the current available evidence, blood flow restriction training (BFR training) is considered to be an overall effective, efficient and safe way of working out for healthy populations, as well as individuals with musculoskeletal injuries if the training sessions are supervised. Individuals with cardiovascular disease should seek medical advice prior to starting a BFR training program. It appears to be an effective method in recreating the feelings associated with the runner’s high.
BFR training appears to be safe for the musculoskeletal system in both the short, as well as long-term. It is important to be aware of the fact that connective tissue adaptation (ligaments, cartilage, tendon, bone) is not quite the same as with traditional strength training.
The analysis of cardiovascular parameters (i.e. heart rate and blood pressure response) show that BFR training (particularly if following a continuous BFR training program with high occlusion pressures) can result in significant increases during the workout, but approach normal levels shortly after cessation. Potential risks for the cardiovascular system include blood clot formation as a result of blood pooling and orthostatic hypotension due to sudden decreases in blood pressure potentially resulting in dizziness, lightheadedness and fainting.
If you are suffering from a musculoskeletal injury, cardiovascular disease, are pregnant, above 65 years of age, or are at greater risk for blood clotting, contact your doctor and/or physical therapist to discuss how to modify your program or whether blood flow restriction training may not be an appropriate training method for you.
Anonymous
BFR training has enhanced my running in ways I never thought possible. Endorphun is effective, encouraging, and is my new virtual “personal trainer and life coach” all in one. I always look forward to what’s coming next! So happy I subscribed!!