The Science and Application of Blood Flow Restriction Training
Here’s What You Need To Know…
1. Blood Flow Restriction (BFR) training is currently one of the most highly debated training methods throughout the fitness and medical communities for good reason; it’s showing remarkable results in muscular hypertrophy and strength.
2. As the body of research continues to grow, BFR is advancing our knowledge in both mechanisms of muscular growth but also in the ways in which we can program non-traditional resistance training for maximal benefits.
3. At lighter relative loads and increased set/rep schemes, BFR training is not only a powerful bodybuilding method, but a technique that can change the game in rehabilitation and post-operative strength and recovery.
4. Though BFR has gotten a bad rep for being dangerous, this method is one of the safest forms of strength and muscular hypertrophy training, period. With a simple wrap and light weights, joint stress and non-contractile tissue damage is minimized.
5. Use these two templates for a chest and lower body emphasis training day to start safely implementing BFR into your training routine and reap the benefits that have been heavily backed by science.
Beyond the passion, drive and motivation for lifting, comes experience; and with it those most aware realize that skill, strength, and hypertrophy do not come for free. Successful lifters who have years of experimentation with forging muscle intuitively know when to push and when to give, in order to allow muscle growth to occur.
The concepts of muscle adaptation are steeped in the intricacies of manipulating mechanical stress and metabolic stress in order to create the pre-requisite environment that is ripe for muscle hypertrophy. What we are learning now from blood flow restriction (BFR) training is furthering the understandings of the underlying mechanisms that are required to stimulate muscle hypertrophy and how with this novel approach we may be able to reach a broader section of the lifting population with the potential to see changes occur at a safer and quicker rate when compared to traditional methods.
The Stimulus of Increasing Muscular Size and Strength
Protocols, prescriptions, standardizations, and programs in general are all designed to develop isolated lagging areas, or create synergy amongst parts that lead to a whole/skill. All of these unique approaches, though different in execution, all use stress in order to influence an adaptation. It is within the exercise induced stress and the understanding of how to manipulate that stress, that we find a proportionate level of adaptation based on frequency, and amount of mechanical and metabolic demands placed on the body. This is where BFR research and science gets interesting in the world of lifting and muscle hypertrophy.
Recent Evidence of BFR and Hypertrophy
Blood flow restriction or KAATSU training is a type of training intensity or technique that aims at occluding venous return while maintaining arterial blood flow via that use of specialized blood pressure cuffs or elastic wraps (practical BFRT), which are placed just proximal on an extremity (Scott et al. 2015). Blood flow restriction training research has been around for the last decade and has looked at everything from using BFR in individuals that are cast immobilized to reduce atrophy (Kubota et al. 2008) all to way to NASA investigating how to use BFR in order to protect skeletal muscle integrity while in the confines of zero G (Hackney et al. 2012).
Studies have also explored its safety with hemostasis (blood clotting) and have shown that BFR in two well respected studies reduced the risk of blood coagulation via tissue plasminogen activator (tPA) an anti-clotting serine protease that is secreted from endothelial cells which line our blood vessels (Clark et al.2011, Nakajima et al 2007).
Simply stated at the most passive of approaches, just placing a tourniquet on a limb decreases muscle atrophy by means of inducing protein synthesis as a direct response to proposed metabolic triggers that are required to stimulate muscle building/growth Kubota et al. (2008).
More frequently have studies investigated the effects on using BFR with cycling, walking and resistance training in protocols ranging from six to 90 days in duration and are showing similar to slightly inferior results in measured variables; such as knee extensor strength, 1RM squat (Fujita et al (2008), Yasuda et al (2005).
In the field of strength training when comparing BFR at low relative mechanical loads (20% 1RM – 30% 1RM) vs conventional resistance training using high relative loads (70% 1RM-75% 1RM) BFR training is showing quite dramatic changes “((post-mean − pre-mean)/pre-standard deviation and adjusted for sample size bias) for muscle hypertrophy and strength for BFR resistance exercise are 0.39 and 0.58, respectively (compared to 0.01 and 0.000 for low-load training without cuff inflation)”.( Loenneke et al (2012) Karabulut (2010), Clark (2011), Karabulut (2011), Laurentino (2012), Martin-Hernandez (2013), Thiebaud (2013), Vechin (2014), Libardi (2015).
Practical BFR is becoming more popular due to its ease of application, thus this bares taking a quick look into pressure standardization before we continue. Research performed by Loenneke et al (2014) has shown that cuff/doppler arterial occlusion pressures of 40% to 50% are optimal to stimulate the greatest acute muscular response. The specificity of this pressure occlusion would not be attainable without similar equipment thus Wilson et al. (2013) put in place a perceived wrap tightness scale. The scale is subjective so education behind the parameters should be discussed and understood. A perceived wrap tightness of 7 out of 10 has demonstrated to be correlated with complete venous occlusion without reducing arterial inflow. Using this PWT scale muscle hypertrophy has been shown Lowery et al. (2014).
The Science and Physiology Behind Why BFR Works
Within normal human physiology, resistance exercise induced stress, either mechanical or metabolic, stimulates a neuroendocrine up-regulation of growth hormones (Testosterone, GH, IGF-1, myogenin, and MyoD), and down-regulation of inhibitory growth factors (myostatin) in attempts to create balance or homeostasis at the tissue level and at the systemic level. The potential that resistance exercise plays at the level of our genes is quite astonishing; with recent studies showing an effect on over 70 different genes.
Learning how to influence the timing of up-regulation is critical, because the scale can and will tip in the other direction of down-regulation if the environment isn’t right. Hence, one must disturb to a degree muscle tissue in order for the cascade of homeostatic regulations to take place and lead to changes in the structure and nature of the proteins that are being built.
Priorities always take precedence in our day to day lives; we do what is most important first as such our muscles also prioritize repair based on the demand and exposure to stress. When mechanical loads are high, the priority of the body is to repair contractile muscle fibers (actin/myosin); when the metabolic demands are high, the priority becomes the building or anabolism of non-contractile units that provide structure and integrity to muscle, as well size. In fact, non-contractile proteins are rebuilt first as part of the coordinated development of muscle size. This may have more to do acute bouts of elevated cortisol (stress/anti-inflammatory hormone) as when cortisol is exposed to muscle it breaks down amino acids for conversion into glucose (get your BCAA’s in).
None the less, let’s continue to explore what occurs in normal physiology to see what BFR is teaching us.
We by now should know that skeletal muscle is often categorized by its fiber type (slow-twitch vs fast-twitch) and how potential for growth is largely dependent on our genetic make-up of these fiber distributions; as well biological age (non-modifiable factors), and to a greater extent environmental factors such as diet, sleep, depression, and stress in general (modifiable factors).
Recruitment or facilitation of the different muscle fibers types is dependent on the speed of the movement, the duration of the activity, and the work:rest ratio. Again, in normal physiology high-threshold motor units or type 2 fast-twitch muscle fibers have the greatest potential for growth. These motor units though are often selectively shut down or reserved in the activation process at low threshold levels or low load levels (i.e most sub-max ADL’s). Hence, in order to stimulate the contractile units that can grow the quickest and biggest we have to respectively work at a higher threshold level in order to stimulate the anaerobic pathways (lactate production, hydrogen ion productions, low Ph metabolite production) in order to recruit more muscle fibers to potentially increase the extent of the remodeling (hormone, immune, and metabolic regulation).
The Latest Trends in BRF Training
Again, in general most of the literature on BFR training is being performed with standardized whip or blood pressure cuff bladders, which are filled to percentages of total occlusion via Doppler validation. Practical BFR training is performed with the use of knee wraps (cloth or elastic) used in conjunction with perceived wrap tightness (PWT) scale
[1-10].
What BFR is showing is that when low loads are used with an occlusion percentage to shunt of venous blood flow (superficial veins that take low oxygen blood and waste away from tissues) to the working muscle, there begins to be an increase in the surrounding environment of low Ph, and potential low oxygen due to a buildup of metabolite waste product (lactate, and Hydrogen ions) that in turn stimulates the same anaerobic pathways seen in heavy resistance training.
“An important difference between high-load and BFR training is that increased muscle strength corresponds with muscle hypertrophy within the first 4 weeks of BFR exercise training, which is in contrast with the nervous system adaptations that result in enhanced muscle strength over the same duration of high-load resistance exercise training [26].” (Hackney et. al (2012))
Some current theories are that the increase in metabolites off-set to a degree the available oxygen in the area momentarily switching the recruitment of type 1 (oxidative) fibers to the type 2 (non-oxidative) fibers (Loenneke et. Al 2011). This theory though being validated is in general terms, skipping some of the normal phases of muscle adaptation, and allowing for muscle hypertrophy to occur at a faster rate.
The Relative Safety of Restricting Blood Flow
BFR training in the general population appears to be relatively safe (Mattar et al. 2014). With regards to the injured populations, some early evidence is showing that BFR “may actually be beneficial in healing injured bone” (Loenneke et al. 2013). Blood flow restriction is also showing that within the unhealthy population occlusion training “produce similar post-exercise hypotensive results to that of resistance training with normal blood flow” (Neto et al. 2015) stating that the normal hypotension seen with exercise “may be an important strategy in controlling resting blood pressure in hypertensive individuals” (Kenny and Seals, 1993), suggesting potential health benefits for the unhealthy populations. Moreover, a study aimed at BFR and its interaction with ischemic heart disease (Maderame et al. 2013) reported positive safety finding as BFR “did not adversely affect exercise-induced hemostatic and inflammatory responses”.
As with anything precautions should be taken into consideration as when working with certain subgroups of the population such as the presence of deep-vein thrombosis, pregnancy, varicose veins, high blood pressure and cardiac disease. Remember that “prolonged ischemia can lead to necrosis of muscle tissue. As such, it may be sensible to avoid performing continuous blood flow restriction training for very prolonged periods of time” (Pope et al. 2013).
The Application of BFR Into Training and Programming
Current literature on practical BFR training use knee lifting wraps or straps placed just proximal to either upper or lower extremity. This would look like wrapping at the level of the deltoid tuberosity, and at or slightly beneath the greater trochanter of the femur. The literature states that when applying by means of practical BFR use the PWT scale between 7 out of 10, ensuring the wrap is tight enough to cause venous occlusion and allow for again arterial inflow. Some recommendations to be aware of with wrapping are pain prior to an exercise indicating the wrap is too tight, and unsuccessful completion of the following protocol indicating again that the wrap is too tight.
The generally prescribed protocol is as follows:
Using a weight that is 20% 1RM – 30% 1RM
Set 1: 30 reps / Rest: 30-60 seconds
Set 2: 15 reps / Rest: 30-60 seconds
Set 3: 15 reps / Rest: 30-60 seconds
Set 4: 15 reps / Rest: 30-60 seconds
*Varying tempo schemes can be implemented to aid in increasing intensity via longer eccentric times and shorter concentric times with alternating holds at either contraction or rest. Starting with the tempos 3-2-1-0 and 5-0-1-1 will be where most novice to BFR training have the greatest amount of success.
What We Can Take Away From Occlusion Training
The research on BFR training is rolling out steadily and with hopes of reaching a broader audience both in the rehab setting and in the competitive sports setting it will soon become common within exercise prescriptions. With BFR training protocols soon to be standardized, we should all continue to express caution and use our best judgment towards occlusion intensities, time under occlusion and methods of off label tools (compressive wrapping, Elastic bands, BP cuffs, ect) to reach this effect.
“Learning is the only thing the mind never exhausts, never fears, and never regrets” –Leonardo Da Vinci
Let’s learn from this research on what occlusion stimulates in the body and apply it towards other methods and strategies within our resistance training.
Within our own muscles is the potential for growth and learning from what longer occlusion can create lets attack each exercise with this knowledge. Before we jump into this lets quickly get a visual going.
In normal human muscle physiology, a contraction shunts fluid away from it (think squeezing a sponge) and when a muscle relaxes is draws fluid back in (release the sponge). This active pumping phenomenon is what allows muscles to obtain nutrition and remove waste, and follows the basic principles of a pressure gradient (high pressure wants to go to low pressure).
One example to see this pumping action in place is by using strength principles of increasing time under tension (TUT). Time under tension can be expressed in many ways, either via manipulating lifting tempo (time spent in the eccentric/rest/concentric/contraction phase), holds at various degrees, isometrics, partial reps/cheat reps, drop sets, supper sets, active rest, and even rates of rest between sets. All of these variables have one thing in common, increasing blood flow to the working tissue to provide the essential element of oxygen for repair and maintaining homeostasis. But perhaps this notion of blood flow is only what we can perceive from the exterior. Maybe what we can extrapolate from the BFR research is that the increase in blood flow is relative to the time spent in occlusion via the normal characteristics of muscle contractions. Hence, longer periods of contraction lead to longer occlusion times, which in turn increase the metabolite build up triggering the cascade of neuroendocrine, immune, and circulatory responses.
The key is in designing a program that embodies all of these elements together. Could this program look like a blend of power lifting with holds in the rack, followed by ratchet sets to optimize fiber recruitment along the range of motion, and ended with a pump chasing partial reps exercise or a tempo driven 4012 scheme, and maybe a Waterbury 5 hold-5 rep, 4 hold-4 rep, 3 hold-3 rep destroyer set to finally end on a high note with BFR occlusion set at a 7- 10 PWT scale to lock in the nutrients for growth.
Once we fully understand the mechanism for growth we will be able to fully tap into each of our own genetic strengths and control our own potential to its fullest, with a mix of training and nutrient timing, but that is for another post.
Keep learning, and never stop lifting for life.
Example Bodybuilding Style Chest Emphasis Training Day 
1. Barbell Bench Press 80-85% 1RM
5 sets, 6-8 reps (vary grip width), 1 min rest, 2-2-1-1 tempo
During the last rep hold the contraction position (full elbow extension) for 10 seconds before racking weight.
*perform with safety pins in squat rack or in smith machine
2. Dumbbell Reverse Grip Ratchet Set Incline Bench Press (60-45-30 degree) 65-75%1RM
3 sets, 12-15 reps, 1 min rest, 4-0-1-0 tempo
Start with bench at 60 degrees incline. Perform dumbbell reverse press with a weight that you can complete 12-15 reps with. Use a 4-0-1-0 tempo.
Immediately set the weight down and reposition bench at 45 degrees and repeats to failure.
Finally, drop bench down to 30 degrees and complete AMRAP
3. Decline Cable Moon Walk
2 sets, 15 reps in each position, 45 second rest, 3-0-1-3 (induce a longer hold)
Start with the tension starting at a near stretch on the pecs then as you complete the reps you take a step back to a midrange tension position and finally you take one more step back until the tension is in front of your body to focus on the main squeeze.
4. BFR Pec Dec
3 sets, 15 reps, 30 second rest, 3-2-1-0 tempo
Example Power and Jump Specific Lower Body Emphasis Training Day
1. Kettlebell ¼ Pause Goblet to Overhead Press with Super Set Jump Squats
3 sets, 8- 10 reps, followed by 5-8 jump squats, 2 min rest, 2-0-1-0 tempo
Use 2 kettle bells for this exercise or use a landmine press. Squat to your depth of comfort (lower offers more sports specific injury prevention) and on the rise out of the squat stop a ¼ to ½ of the way up, now return to the bottom position and finally rocket out of it.
The jump squats are with no weight and plenty of correct arm swing.
2. Reverse Lunge to Jump Super Set Single Leg Step-Up
2 sets of 10 per leg, 2 min rest, 2-0-1-0 tempo
Position into a reverse lunge and rise up with the trailing leg into small hop and land on the leading leg.
Peterson Step up
Perform first set alternating leg 12-15 reps at body weight or grab a kettle bell in the opposite hand. Use the heel up method on the ground leg.
3. Side Skater to Resisted Side Walking
2 sets of 10 per leg (count 20), 1 min rest, 1-1-1-0
Use t-band and drop into a squat position and perform 8 steps to the right and 8 steps back to the left.
4. Bulgarian Split Squats to Hip Thrusters
2 sets of 20 per leg and 20 total hip thrusters
Perform Bulgarian split squats with balance assistance (set up with something nearby to hold onto)
5. End with BFR (remove band for 1 min following each group)
A. 3 sets of knee extension/swiss ball bridge and roll in’s
B. 3 sets of sidelying clamshells
C. 3 sets of heel rise to toe raise
About The Author
Dr. Mario Novo is a results driven sports orthopedic physical therapist who specializes in strength and conditioning. Known well by his clients/patients as a mentor and educator, Mario’s passion is to unify the highest levels of rehab science with successful mind and body strength coaching. With Mario’s research having focused on new advancements in muscle hypertrophy periodization and joint health, his goals are to share his knowledge and improve on the human condition through personalized cutting edge program design. Mario is also the Owner of The Lifter’s Clinic
References
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