Blood Flow Restriction Training: What Is Its Value?
Maybe you’ve seen that dapper guy at the gym (or someone other than me) with the Ultimate Warrior style bands around his upper arm. Or more awkwardly, doing goblet squats with leg wraps choking the top of his thighs and bunched up shorts bringing back the classic codpiece. BFR Training, Occlusion Training, KAATSU — even the names are weird.
Well, speaking from personal experience, it’s worth the odd looks and the locker room clearing out when I enter. But I’m ready to make some new friends at the gym, so I’ll share what sold me on Blood Flow Restriction Training (BFR Training), why I’m using it at almost every gym session (spoiler alert: it’s not just for the stylish codpiece effect), and some practical way to implement it into your own training.
What is Blood Flow Restriction Training?
Blood Flow Restriction Training (BFR Training) is a form of low-intensity resistance training performed with a tourniquet-style wrap around the top of the working limb, allowing arterial blood supply but occluding venous return. This slows down the rate at which blood returns to the heart and restricts muscle byproducts from escaping during rest periods.
Occluding blood flow in this way causes blood to remain inside your working muscles for longer than normal, resulting in significant increases in muscle strength, size, and endurance, all while using a very light load, around 20–40% of your 1-rep max, versus conventional training requiring heavier loads of 75% or more.
How Does BFR Training work?
Because the muscle fibers fatigue more quickly with BFR, both Types I and II muscle fibers are activated much sooner. Type II muscle fibers are the ones we use for high levels of force, power, and speed, like lifting a heavy load or sprinting. Type I slow-twitch fibers are used for low-intensity activities, like lifting a dozen donuts to your mouth.
Muscle fibers are recruited sequentially based on need (See Henneman’s Size Principle). The body recruits the smaller lower threshold motor units first (Type I slow-twitch fibers), followed by the larger higher threshold motor units (Type II fast-twitch fibers), and continues to recruit and fire motor units until you’ve applied enough force to get the job done or you run out of muscle fibers to activate. This muscle fiber recruitment system is convenient, otherwise lifting that donut would mean uncontrollably smashing it into your face (on second thought, maybe I do use fast-twitch fibers for donut consumption).
BFR effectively hacks Henneman’s Size Principle. Because Type I muscle fibers are aerobic and require oxygen as fuel, the blood flow restriction causes them to exhaust quickly, causing more Type II fast-twitch muscle fibers to be recruited.
This increase in Type II muscle fiber activation with BFR is important, because these fast-twitch fibers have the highest energy expenditure and growth potential, while they’re also the hardest to activate without intense heavy training.
BFR is nothing new — the research on it has been around for well over a decade, with more than 160 peer-reviewed articles in the scientific literature. These studies have looked at everything from using BFR in injured individuals to reduce atrophy from immobilization, all to way to NASA investigating how to use BFR in order to protect skeletal muscle integrity while in the confines of zero G.
What Are The Benefits of BFR?
The practical benefits of this type of training are really cool. BFR training has been shown to demonstrate substantial physiologic enhancements versus traditional training:
- Increased muscle growth (hypertrophy and hyperplasia)
- Increased muscle strength
- Enhanced endurance through oxygen delivery and utilization (VO2Max)
- Enhanced collagen-dependent tissue repair
- Enhanced bone healing
A recent study in the Scandinavian Journal of Medicine and Science in Sports found that subjects who followed a BFR lifting protocol for six weeks had muscle gains similar to a control group doing traditional lifting, but they also had even better strength gains: a 10% increase, versus just 7% for the control.
BFR Training also is superior in efficiency. Academic studies have shown that low weight BFR training seems to require a substantially shorter period of physical activity (3–6 weeks) compared to traditional heavy lifting (8–12 weeks) to achieve the same results — less than half the time! Beyond that, due to the shorter rest periods employed with BFR, I find that total time requirements for equivalent training volumes are reduced.
The endurance enhancements are also well documented. One study examined BFR cycling at 40% VO2 Max for 15 minutes compared to a control group that cycled for 45 minutes at 40% VO2 max without BFR. Thigh and quad muscle volume increased, extension strength increased, and VO2 max increased substantially in the BFR group compared to the control group (Abe 2010). Beyond that, walking with BFR has been shown to have a hypertrophy effect. Jeremy Loenneke, Ph.D., assistant professor of exercise science at the University of Mississippi, says “There’s evidence that applying BFR and walking slowly may result in small but meaningful increases in muscle size and strength.”
Additionally, by using lighter weights, your tendons, ligaments, and joints aren’t placed under as much strain, which allows you to do more volume with less risk of injury or overtraining. You’re also able to achieve higher levels of muscle activation with less muscle damage than would otherwise occur, requiring less recovery and allowing a higher level of training volume.
My Personal Experience Using BFR
One reason I originally began using BFR was to rehabilitate the accumulated injuries I’ve suffered from for years, including severe knee and elbow tendinopathy (tendinosis and tendinitis), a partial tear in my quadriceps (shown on the MRI), SI joint dysfunction, bursitis, and a load of undiagnosed shoulder issues. Finally, after my last powerlifting meet, competing with the partial tear and hoping it held for my squat and deadlift attempts, I realized how foolish I was and started a focused rehabilitation program.
Along with extensive mobility work and physical therapy including ART (Active Release Therapy), I revamped my training program and started implementing BFR in it extensively. My results in rehabilitation were great, but the muscle and strength gains I achieved using BFR training were so great that I’ve kept it in my regular training, using it for about 20–40% of my total weekly volume. I really appreciate the time efficient nature of the BFR training, as well as the lower recovery demands, allowing me to train and see results with more volume and less overall time!
What Is The Science Behind BFR?
Put simply, muscle growth involves a positive balance of adding more protein to your muscles than you breakdown. This is really where BFR training shines — muscle protein synthesis is greatly increased, while at the same time muscle protein breakdown and damage is eliminated or dramatically reduced because of the lighter loads!
This part gets a little dry, but here’s a summary of the primary mechanisms that BFR training works through.
Metabolic mechanism: Type II muscle fibers use the Lactic Acid Cycle (Cori Cycle) for energy. Lactic acid is the key metabolite responsible for a host of anabolic signaling pathways, activating positive anabolic signaling pathways like mTORC1, and inhibiting the negative muscle anabolic pathways, such as Myostatin. Lactate also raises systemic growth hormone, providing additional superstructure to tendons, ligaments, bone, and muscle.
Translation: The buildup of waste products from the energy production results in enhanced muscle growth and hormonal benefits, including elevated growth hormone levels.
Cell swelling mechanism:
As a direct result of venous blood flow occlusion with BFR, there continues to be an increase in fluid supplied to the working muscle, leading to the “pump.” As the muscle cells increase in size there is a stress placed on the cellular walls. This stress leads to a protective response leading them to adapt and grow.
Translation: BFR gives you a skin-splitting pump, and the muscle fibers adapt to this pumped up size by growing.
Growth Hormone Effects: As a direct result of increased lactate, the pituitary gland up-regulates the formation of endogenous growth hormone (GH). In fact, the data has demonstrated that following BFR, increases in GH have been seen to rise up to 300% from baseline and 170% higher than traditional resistance training. Growth hormone is associated with bone, muscle and other tissue’s growth and repair, increased fat mobilization and metabolism, blood sugar control, muscle protein synthesis, and immune function among other positive benefits.
Translation: Growth hormone levels go up, which helps make you stronger, leaner and healthier, and is associated with decreased shirt wearing.
Myogenic stem cells: IGF-1 induces hyperplasia through the fusion of satellite cells to muscle fibers, which is thought to play a role in the donation of additional myonuclei to a muscle cell. This is accompanied by substantial muscle contractile protein synthesis, increasing muscle size and strength.
Translation: The ultimate muscle party — not only are muscle cells growing, but new muscle cells are being added.
Does this training method only have an effect locally?
Multiple studies indicate that the response from BFR training is not only local to the occluded arm or leg, but can have a significant effect on non-occluded parts as well. In other words, performing BFR training can have a local as well as a systemic effect on our body, where the output of a chest and back workout can be increased by occluding either your arms or legs.
My personal experience reinforces this, with my chest and shoulder muscles (with BFR on the arms for push-ups), or glutes (with BFR on the legs for Goblet Squats), feeling absolutely destroyed after one set. With the additional fatigue to the occluded working limb, the muscles that are not occluded enjoy (ironic choice of word) enhanced activation.
Is BFR Training Safe?
The body of research on BFR training indicates it’s generally safe (Scott 2014). In fact, research has found significant improvements in the results of several health questionnaires following blood flow restriction training (Mattar 2014). There are a few contraindications, and these should be screened for before implementing BFR:
Beyond those conditions, BFR has been shown to be generally safe. Several studies have examined the blood clot risk and found that not only does BFR not increase blood clot risk (Jarrett 2004), it’s actually associated with the release of several anti-coagulation factors (Jarrett 2004).
Another concern is the effect on the heart and blood vessels with BFR. Research has shown that BFR actually results in lower blood pressure values than those seen in conventional heavy resistance training (Takano 2005), along with improvements in capillarity, arterial compliance, and stiffness (Hunt 2013, Kim 2009, Fahs 2011, Ozaki 2013, Ozaki 2011).
TL;DR: BFR Training is great. I love it. You’ll love it.
Next up, I’ll be addressing how to use BFR in your training, along with a review and comparison of the available products you can use for BFR occlusion. References for this article are listed here.
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