18 Aug Blood Flow Restriction Training in a Nutshell
Personalized blood flow restriction training is an exercise modality that involves using a cuff to occlude venous blood flow out of a limb while restricting arterial blood flow into a limb. A growing body of evidence now supports the use of blood flow restriction at rest, combined with aerobic training, or combined with low-load resistance training to mitigate disuse muscle atrophy and enhance hypertrophic and strength responses in skeletal muscles. Learn more about blood flow restriction training with this article!
Sample Blood Flow Restriction Training Protocol
Going for a walk with blood flow restriction (BFR) to improve VO2 max, or lifting light weights with BFR to improve muscle mass may sound too good to be true. The reality is that BFR training makes an easy walk in the park or light exercise very difficult. This does not make gains come easy by any means! Watch the video above to get a general idea of how challenging BFR truly is. Craig is only working at 20% of his 1 rep-max with this sample protocol!
Muscle Hypertrophy With Low Loads
It has been generally accepted that muscle hypertrophy requires high-intensity training utilizing loads of at least 70% of 1-repetition max or lower loads (30-50%RM) until failure. However, there is mounting evidence that now supports low-load resistance training (20-40%RM) combined with blood flow restriction can similarly induce muscle hypertrophy and strength gains. What we used to know and understand about muscle cell physiology and hypertrophy has been turned upside down through blood flow restriction research. We are learning that metabolic stress (created through BFR training) can be similarly as effective as mechanical stress in inducing hypertrophic changes!
Blood flow restriction training can be used when the goal is to increase muscle hypertrophy and strength with an individual that is load compromised. While we do not recommend replacing high load resistance training with blood flow restriction training, it can be used in the rehabilitation setting as a bridge to increase muscle strength and size when a person might not be able to lift heavier loads. For example, after most surgeries and musculoskeletal injuries, there is a period of time that as rehabilitation specialists we must respect the surgical site and tissue healing timelines by employing lower load exercises. These lower load exercises are not heavy enough to induce a hypertrophic or strength stimulus to the exercising muscle. However, by adding blood flow restriction to these same low load exercises we are able to induce significant strength and hypertrophy gains in as little as 2-4 weeks (it takes 8-12 weeks to gain muscle size with regular high load resistance training)! The rehabilitation setting seems to be where blood flow restriction training will have the greatest impact, speeding up recovery times and getting people stronger, faster, utilizing lower load exercises that are friendly and safe to healing joints, tendons, or other surgically repaired tissues.
If you’re interested in learning more about BFR from us in person, come take a course with us!
Want To Learn How To Maximize Recovery with BFR?
Yes, BFR can also help improve VO2max when an aerobic protocol is administered! VO2max is derived from V (volume), O2 (oxygen), and max (maximum). VO2max means the maximum volume of oxygen used during exercise. It is expressed as liters of oxygen per minute (L/minute) or milliliters per kilogram of body weight per minute (mL/kg/minute). VO2 max is a measure of your cardiorespiratory fitness, especially during prolonged exercise. It is also called maximal oxygen uptake, peak oxygen uptake, maximal oxygen consumption, or maximal aerobic capacity. Anything over 60 ml/kg/min is known to be an excellent VO2max.
A study published by the Journal of Sports Science & Medicine reported that low-intensity (40% VO2 max) cycling exercise with a short-duration (15 minutes) combined with BFR can produce a significant increase in thigh muscle volume as well as aerobic capacity in young men.
Typically training at about 80% Vo2 for 45 minutes would be required to see this type of enhancement!
Blood Flow Restriction Training: Adaptive Responses And Potential Mechanisms
Using blood flow restriction, muscular hypertrophy and strength benefits are seen in both untrained and athletic populations (3, 4, 7, 8, 9-15). Interestingly, blood flow restriction creates hypertrophic muscular responses without high mechanical loads, but the underpinning physiological mechanisms are not fully understood. One theory proposes that downstream of the blood flow restriction cuff, greater accumulation of metabolites act as primary moderators of an anabolic response, due to increased production and limited removal (1). Importantly, this accumulation of metabolites may increase muscle cell swelling, intramuscular anabolic/anti-catabolic signaling, and muscle fiber recruitment. Also, blood flow restriction may increase the activation and number of myogenic stem cells, enhancing the hypertrophic response(16). All of these responses are thought to be beneficial for muscular adaptation.
Although there is growing interest in the mechanisms by which blood flow restriction can augment resistance training adaptation, we do not yet fully understand all of the physiological processes involved, and further research is required. However, with that said, it is now well acknowledged that blood flow restriction can enhance the adaptive responses to low-load resistance exercise and the adaptations seen are dependent on both the blood flow restriction stimulus itself and the exercise protocol performed.
Blood Flow Restriction Training: Cuff Applications
One of the most important factors to consider when applying BFR is the width of the cuff. Researchers have used a range of cuff widths for both the upper and lower limbs (17):
- Legs (4.5–18.5 cm)
- Arms (3–12 cm)
Wider cuffs, up to 13.5 cm, can increase ratings of pain and perceived exertion and limit exercise volume when compared with narrow cuffs, as low as 5.0 cm, when inflated to the same restrictive pressure (18). Also, wider cuffs transmit pressure through soft tissue differently than narrow cuffs. Wide cuffs restrict arterial blood flow at lower pressures compared to narrow cuffs. Also, limbs with a larger circumference require higher occlusive pressures to reach the same level of arterial occlusion(19). Knowing this, when implementing blood flow restriction training, it is important to consider both cuff width and limb circumference.
It is our recommendation to use a cuff that is wide, as you need less pressure to the restrict arterial inflow. A wider surface area means lower pressure distributed below the cuff – potentially a safer environment for the more delicate neurovascular structures that are also below the skin.
Practical & Narrow Vs. Pneumatic & Wide
We recommend using an FDA listed personalized tourniquet system to perform personalized blood flow restriction training. Shown in the video above include a SmartCuff used on one side and a resistance band on the other. A study by Bell et al. was recently released showing that the “7/10” perceived tightness scale is not reliable. This is extremely important as understanding what pressure you are applying on a limb will reduce the risk of adverse events. Keep reading to better understand how to get limb occlusion pressure of the lower extremity.
Getting Limb Occlusion Pressure – Assess Don’t Guess
From our friend Dr. Nicholas Rolnick: “Imagine using the same pressure for a geriatric client as a bodybuilder? What would you think the stimulus would be given the same pressure? You might be completely occluding arterial flow for the geriatric client but barely occluding arterial flow for the bodybuilder! This can lead to sub-optimal outcomes and an increased risk of adverse events. This is why determining arterial occlusive pressure is CRITICAL to the administration of BFR. Without this knowledge that is easily obtained using an external doppler device, you are guessing in the dark about the exact stimulus you are applying to yourself or your clients. Be better than arbitrary, you and your clients deserve better.”
Shown below is an example of getting the limb occlusion pressure utilizing an external or handheld doppler with the Generation 2 SmartCuffs.
The video above will demonstrate how you can find the limb occlusion pressure, or the minimum pressure required to completely occlude the arterial flow. If you are looking for a similar video for the upper extremity, check out this video!
Blood Flow Restriction Training: Restrictive Pressures
Another important variable involves the pressure used through the blood flow restriction cuff. Optimal blood flow restriction pressure has been hypothesized to follow a hormetic-like relationship (6). If the restrictive pressure is too low, muscular responses may not be significantly augmented (1). On the other hand, extremely high pressures can be a safety concern and may not enhance muscular development more than moderate pressures (6). This is important to consider; if blood flow restriction stimulus or prescribed training doesn’t follow scientific rationale, sub-optimal training responses could result (1).
Blood flow restriction pressure should be high enough to occlude venous return, yet low enough to maintain arterial inflow into the muscle (6). Following this, blood flow restriction pressure should vary relative to each individual and be dependent on both cuff width and the size of the limb to which blood flow restriction is being applied.
For cardiovascular and resistance training protocols we recommend utilizing 60-80% of limb occlusion pressure in the lower extremity and 40-50% of limb of occlusion pressure in the upper extremity.
Pressure Load Continuum
From Dr. Nicholas Rolnick
Here is a good breakdown showing how pressure and load are inversely related.
Blood Flow Restriction Training: Practical Applications
ELDERLY & POST-SURGERY:
Muscular adaptations achieved with blood flow restriction training may benefit populations with compromised strength and/or joint stability (25). For example, blood flow restriction alone during periods of cast-immobilization can reduce normal muscle atrophy seen, and limit functional declines in muscular strength (2, 26, 27). Also, speeding up post-surgery recovery is a potential use, as using light load exercise can reduce the risk of injury post-op. For example, simply walking or cycling, when combined with blood flow restriction, can lead to small yet significant improvements in the strength and size of the leg muscles (21-24).
From Dr. Nicholas Rolnick
Healthy & Athletic Populations
Due to the low loads used with blood flow restriction and the limited muscle damage that occurs, athletes can benefit from decreased training loads, whilst still gaining a physiological stimulus for muscular adaptation. Similarly, athletes looking to increase their longevity in sport may benefit from the decreases in mechanical stress with BFR training. The changes in muscle strength following blood flow restriction training are more closely related to rapid increases in muscle hypertrophy as opposed to neural adaptations. These adaptive responses can enhance performance across a range of athletic tasks, including maximum strength (5, 9, 14), countermovement jump power (5), maximal and repeated sprint performance (5, 8, 14), agility performance (9), and the aerobic shuttle run test (9). The research data clearly demonstrates that low-load blood flow restriction training can enhance markers of physical performance in already well-trained athletes.
With blood flow restriction, the biggest concern always brought up is safety. In a 2006 large survey of Japanese facilities employing blood flow restriction exercise (28), the most common side effects included subcutaneous hemorrhage (13.1% of participants), and numbness (1.3 % of participants). However, these symptoms are often discovered at the beginning of a blood flow restriction training program and dissipate as the individual becomes more accustomed to this training modality. To determine a participant’s level of risk during blood flow restriction exercise, Nakajima et al. have proposed a points system whereby the practitioner assigns each patient a numerical score based on the number and severity of blood flow restriction contraindications they exhibit (28). This approach may be beneficial for identifying those at risk of detrimental complications during blood flow restriction, however, general contraindications and precautions should still be considered.
- History of deep-vein thrombosis
- Varicose veins
- High Blood pressure
- Cardiac Disease
- Subcutaneous hemorrhage
- “Feeling Cold”
Nonetheless, when used in a controlled environment by trained and experienced personnel, blood flow restriction training appears to provide a safe training alternative for most individuals regardless of age and training status. This is a brief summary of contraindications and precautions. Learn more here!
There are a plethora of uses for BFR, here are the pillars of implementing BFR sequentially from the individual who is bedridden to the high performing athlete. When implementing blood flow restriction, cuff width must be appropriate and restrictive pressure must be specific to each individual limb. Muscles of the limbs and trunk can benefit from blood flow restriction training, meaning both single and multi-joint exercises can be prescribed for training programs. To create a sufficient physiological stimulus, training plans should include, low exercise loads (20–40 % 1RM), short inter-set rest periods (30 seconds), and relatively high training volumes (50–80 repetitions per exercise). Because blood flow restriction training does not markedly increase muscle damage, brief periods of high training frequencies may be possible. The research is starting to show the overwhelmingly positive effects of blood flow restriction training, especially in clinical settings aimed at rehabilitation. BFR is quickly growing in popularity and is one of the most exciting new clinical tools of the decade.
Want to learn how to safely and effectively utilize blood flow restriction training in your practice? We teach courses around the world! Check out our course dates HERE.
- Scott et al., 2014. Exercise with Blood Flow Restriction: An Updated Evidence-Based Approach for Enhanced Muscular Development. Sports Med. DOI 10.1007/s40279-014-0288-1
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About The Author
Growing up in Oregon, Dalton graduated in 2015 with honors from Southern Oregon University earning a Pre-PT Health and Science Bachelor’s degree with a minor in Business. Following a non-traditional route, Dalton then attended Robert Gordon University in the United Kingdom, where he completed a CAPTE accredited Msc in Physical Therapy in 2018, undertaking multiple clinical rotations across Scotland and Sydney, Australia.
Currently, Dalton lives in London and works in a private orthopedic outpatient clinic called Anatomie Physiotherapy. Dalton has a passion in sports orthopedics with a focus on rehabilitation of the knee joint. In Dalton’s spare time, he practices and coaches wrestling and Brazilian jiu-jitzu, and enjoys cycling, weight training, and anything outdoors. Dalton has a strong interest in applying sports biomechanics to his extracurricular activities with a focus on rehab and sports performance for grappling athletes.
Dalton also started and runs the Instagram handle @physicaltherapyresearch; where he summarizes physical therapy-based research articles to help himself and others learn and stay up-to-date on recent research, and ultimately bridge the delay between research and clinical practice.