Blood Flow Restriction
By the time you pass 50 years of age, it becomes fairly evident that building—and even maintaining—your muscle mass becomes increasingly more difficult. This is the result of a process known as sarcopenia (the age-related loss of skeletal muscle mass and function), which poses a significant risk for loss of mobility, function, and independence as we get older. In fact, research has shown that loss of muscle mass is a good predictor of mortality.
The main way to prevent muscle loss as we age is through load-bearing resistance training, although this can present a unique challenge if you don’t have regular access to free weights or other gym equipment.
Moreover, the muscle-building effects of resistance training routines require you to work at near maximal load. This can put you at risk for injury, especially as you advance in age, not to mention the significant time commitment required.
As a group, we're always looking for innovative ways to help you build muscle faster and more safely, that’s why we’ve become very interested in a technique called blood flow restriction (BFR) training.
We did a deep dive into the history and science behind BFR training and took a close look at one of the most popular (and cost-effective) consumer BFR kits available in the market. This is what we found.
What is Sarcopenia
According to scientists, sarcopenia can begin as early as age 30 and cause us to lose muscle at a rate of 3-5% per decade. Sarcopenia puts an individual at increased risk for age-related injuries and accidents like falls, sprains, and strains; some research even suggests that a loss of skeletal muscle is correlated with physical disability, poor quality of life, and death.
The causal mechanisms of sarcopenia are considered multifactorial and are not yet fully understood, but according to a recently published review, some of the more commonly associated causes are:
- Loss of motor neurons and muscle fibers and muscle fiber atrophy
- Anabolic resistance: reduced protein synthesis in old muscle in the presence of normal anabolic stimuli like amino acids, resistance exercise, and insulin
- Impaired regeneration due to reduced stem cell function
- Low-grade inflammation caused by an increase in pro-inflammatory cytokines such as IL6 and TNF-α with age
Aside from leading to an earlier death, sarcopenia impacts longevity indirectly as it makes us more prone to falls and fractures. This is due in part to a loss of type II fast-twitch muscle fibers.
As their name suggests, fast-twitch muscle fibers are the part of the muscle that allow us to react quickly to recover from a loss of balance or an unexpected obstacle. Most people have an even number of slow and fast-twitch fibers, but as we age, slow-twitch fibers remain relatively stable and may even increase, while fast-twitch fibers are quickly lost. Falls often lead to broken hips and other fractures that can increase our risk of early death, and/or the negative health outcomes and declines in mental wellbeing that come from the loss of mobility and independence.
An accompanying effect of sarcopenia is the loss of muscle strength (known as dynapenia), which drops at an even higher rate than muscle mass. Loss of strength not only starts to limit our lifestyle choices as we age, but a loss of strength has been clearly identified as a predictor of mortality.
The good news is that with good nutrition and regular resistance exercise, sarcopenia (and dynapenia) can be slowed and even reversed. Resistance training stimulates the growth of new muscle fibers, and intense resistance training can help regenerate the fast-twitch muscle fibers that are so quickly lost with age.
What is BFR Training And Where Did It Come From?
Blood flow restriction is relatively new to the US, but it is actually several decades old. This method of enhancing muscle mass and overall fitness was developed in Japan in 1966 by Dr. Yoshiaki Sato.
The story goes that after kneeling for a prolonged period during a Buddhist funeral service, Dr. Sato recognized that his lower legs felt as if he had finished an intense workout. Being a scientist, his curiosity overtook him and he started to investigate.
A few years later, Dr. Sato fractured his ankle and injured his knee while alpine skiing. As a result, he was placed in a full-length cast to immobilize his leg. In order to prevent the muscle atrophy that typically results when a broken limb is immobilized, Dr. Sato decided to experiment with some of the techniques he had devised a year prior.
He started performing isometric (static) exercises with his injured leg using different types of belts and bands near the hip to partially restrict the blood flow into his limb. Six weeks later, when his doctors removed his cast they were amazed to find that his leg muscles had not atrophied at all. They were also surprised to find that his bone fracture had healed ahead of schedule. Based on what they observed, they concluded that the blood flow restriction exercises that Dr. Sato had been performing were related to this outcome.
Dr. Sato’s experience while injured inspired him to dedicate himself to researching, perfecting, and applying blood flow restriction methods in various training contexts. Through years of much trial and error, he consolidated his knowledge into a methodology he named Kaatsu, which means “additional pressure” in Japanese.
Dr. Yoshiaki Sato, inventor of blood flow restriction training
What is the Science Behind Blood Flow Restriction Training?
You probably remember from high school biology that veins return blood from muscles and organs back to the heart. As its name suggests,
BFR training consists of restricting the venous outflow from your extremities as you perform any type of exercise. This restriction is achieved by wearing a band or cuff at the top of your arms and/or legs. When you partially compress the veins, you slow the rate at which oxygenated blood flows back into the muscle from the heart.
During any exercise routine, as active muscle fibers work and get fatigued, additional ones are recruited to sustain your efforts. Typically, the first type of muscle fibers that are recruited to work during exercise is the slow-twitch kind (or type I fibers).
Slow-twitch fibers rely on oxygen to fuel muscle contractions. Once their capacity gets depleted, the fast-twitch fibers kick in to continue doing the work. Fast-twitch fibers are anaerobic, which means they don’t need oxygen to power the muscle.
By limiting oxygen availability to the muscles, BFR training accelerates the exhaustion of slow-twitch muscle and the recruitment of fast-twitch fibers to sustain the effort. This allows you to work the entire muscle more quickly and effectively.
When worked to exhaustion, muscle fibers produce lactic acid, which has two effects:
- Locally, it stimulates the activation of the mTOR pathway which triggers protein synthesis in the muscle to produce new muscle fibers.
- The build-up of lactate is also detected by the central nervous system (CNS) which send signals to the pituitary gland to begin repair and recovery processes through the release of certain hormones—growth hormone (GH), vascular endothelial growth factor (VEGF), myostatin (GD8), heat shock protein (HSP), and nitric oxide synthases-1—which also help create new muscle fibers and blood vessels.
One distinctive benefit of BFR training is that you do not need to work as intensely as you normally do to fully recruit and exhaust your muscle fibers.
Whereas the gains from resistance training using weights or machines are achieved at loads that are at 80%-90% of an individual’s one-rep maximum, achieving the same results with BFR training only requires you to work with a load equivalent to 20%-30% of your one-rep max.
Because the intensity of the workout is reduced, BFR helps limit the risk of injury.
Another remarkable effect of BFR is that it helps build up all of the muscles involved in the exercise, not just those that are being subjected to vascular restriction. So, for example, if you are doing a push up while wearing BFR cuffs on your arms, blood flow will be restricted to the triceps but your pectoral muscles will also gain the benefits.
One hypothesis for why this happens is that the brain does not distinguish between the restricted muscles that are sending distress signals to the central nervous system from those that are upstream of the restriction. As a result, all the muscles involved in the exercise benefit from the body's hormonal response.
Recovery after BFR training is also significantly faster when compared to traditional weight or resistance training. This happens because you only need to use a relatively light load and are therefore not tearing the muscle fibers to the same extent. As a result, you don’t experience the same levels of Delayed Onset Muscle Soreness (DOMS).
Some additional benefits of BFR training include:
- Lower joint strain and risk of injury resulting from the use of lighter weight loads
- Increases in bone density, a positive effect on bone health
- Increased formation of blood vessels in the muscle (angiogenic stimulation)
- Rapid Improvement in strength (10-15% improvement after 10-20 sessions)
- Reduction in body fat (the release of growth hormone stimulates the breakdown of fat to use as fuel sources). People become 5%-10% leaner after 10-20 sessions
(To go deeper, see our list of BFR studies below)
How Can I Start Training?
As BFR training gains popularity, systems have emerged in the marketplace to help individuals maximize their workouts, but most elite BRF systems come with caveats—price and availability. For instance, the Kaatsu system (developed by Dr. Sato) retails for $5,350! Other systems, like Delfi’s PTSii Personalized Tourniquet System, are only sold to physical therapy clinics for use with patients.
In our search, we did not come across many options offered by credible, science-based companies. However, one offering clearly stood out: B-Strong Training System, an elite product at a much more attainable price ($430). [Note: we have no affiliation].
The B-Strong Training System
The B-Strong Training System is the brainchild of Dr. Jim Stray-Gundersen, a world-renowned expert in sports medicine, exercise physiology, and training for sports performance. During his career of over 40 years, Dr. Jim has served on the medical committees of the International Olympics, FIFA, as well as the International federations of Ski, Skating and Biathlon. He is also the sports science advisor for the US Ski and Snowboard Federation and leads human performance and altitude camps for many Olympic athletes and the Navy Seals. Lastly, he runs the SG Performance Medicine Center and Sport Technologies for Maximal Athletic Performance in Texas.
In 2012, Dr. Stray-Gundersen was introduced to BFR and it wasn’t long before he saw its potential. The challenge was that the technology wasn’t readily accessible at the time. To learn more, he decided to travel to Japan to learn the science and techniques of BFR directly from Dr. Sato.
When he returned home, he started using BFR with his athletes and saw consistently positive results. Based on this, Dr. Stray-Gundersen decided to design a BFR system that could be portable and accessible to the general public.
He teamed up with entrepreneur Sean Whalen and launched his product in 2017. Now, the B-Strong system is used by elite-level athletes, professional sports leagues, and physical rehabilitation centers as a safe and effective method to maximize human performance, resilience, and health.
According to Dr. Stray-Gundersen,
“B-Strong is a paradigm shift in the way we exercise. You can now exercise smarter, safer, and improve your overall strength and fitness in less time with greater results. The benefits of BFR training lead to overall health and wellness for the entire population. It can be done anywhere, anytime, by anyone – young or old – regardless of your fitness level”.
Our Analysis Of The B-Strong Kit
After analyzing the B-Strong Kit, here’s what we liked best about the system:
The key feature to look for in a BFR system is safety. BFR training systems use pneumatic cuffs that apply pressure to your limbs to restrict venous blood flow. However, the restriction of blood flow to the limbs should never get to a point where the veins are occluded—stopping the blood flow completely.
More importantly, the arterial flow of blood coming into the muscle should not be restricted at all. The B Strong bands are designed to avoid venous occlusion or any restriction to the arterial inflow, making them some of the safest BRF cuffs on the market.
Ease of Use
The B-Strong system is lightweight (<3 lbs), compact, and portable so that you can use it anywhere you go. The system is also supported by a Guidance App that acts as your instructor. It uses proprietary algorithms to choose the appropriate starting cuff-pressures for you based on your age, fitness level, and desired intensity of exercise. It also tracks your history and helps adjust your pressures as you progress.
The app contains video tutorials of sample exercises and supports multiple users, so that you can share your equipment. The only drawback we found with the app is that it is browser-based rather than a full-fledged mobile app.
The B-Strong cuffs are made of industrial-grade materials used in marine applications. The Velcro pads are able to withstand over 10,000 cycles of closing and opening. Once properly placed, the low profile of the cuffs allows for a full range of motion and doesn’t interfere with training. You can use them during any type of exercise including weight lifting, running, biking, yoga, and even swimming.
All in all, we believe that BFR—and the B-Strong system in particular—is a very interesting option for individuals looking to mitigate the dangers of sarcopenia and increase their muscle mass.
We must mention that although BRF is safe, there are contraindications for using blood flow restriction training, such as pregnancy, certain medical conditions, and diseases. As with any other exercise program, we recommend consulting first with your primary care provider.
Additional BFR Resources We Liked
In this video taken at The Institute for Human & Machine Cognition, Dr. Jim Stray-Gundersen presents some of the scientific evidence showing the many benefits of BFR training.
- Stem Talk IHMC - Dr Jim Stray-Gundersen Explains How Blood Flow Restriction Training Builds Muscle And Improves Performance
- Nourish Balance Thrive - Blood Flow Restriction Training for Improved Strength, Performance, and Healthspan
- Effects of Blood Flow Restriction Training on Muscular Strength and Hypertrophy in Older Individuals: A Systematic Review and Meta-Analysis
- Muscle fiber cross-sectional area is increased after two weeks of twice daily KAATSU-resistance training
- Effect of aerobic exercise training with and without BFR on aerobic capacity in healthy young adults: a systematic review with meta-analysis
- Effects of resistance exercise combined with moderate vascular occlusion on muscular function in humans
- Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion
- Proliferation of myogenic stem cells in human skeletal muscle in response to low-load resistance training with blood flow restriction