Blood flow restriction (BFR) training was initially developed in Japan in the 1960s and is also referred to as Kaatsu training. At first glance, BFR may appear to be an experimental and perhaps fringe training practice, yet it has received a lot of attention and research in the past few years.
BFR training has proven useful, and effective in certain populations, especially in the rehab setting following injury (Vanwye, 2017). Bodybuilding coaches and sports performance coaches can really benefit from applying this practical knowledge.
Does the research support its use? Let's take a closer look.
What is blood flow restriction training (BFR)?
BFR involves placing an occlusion cuff on the top of the upper or lower limb when performing the exercise. The occlusion cuff restricts venous return (blood being pumped from the muscles back to the heart) though it does not restrict arterial blood flow (blood being pumped to the muscles) to the same degree (Patterson et al., 2019).
It is theorized that this intervention leads to higher metabolic stress on the muscle, stronger muscle contractions, and localized hypoxia (low oxygen delivery) favoring the recruitment of type II muscle fibers. It is also thought that heat-shock chaperone proteins, which play a role in the rebuilding of muscle tissue, may be upregulated because of metabolic stress induced by BFR leading to more muscle growth (Allsopp & May 2017).
Does it help with muscle hypertrophy?
Muscle hypertrophy refers to the process of increasing the size of muscle tissue. This occurs primarily by increasing the muscle fiber cross-sectional area via increasing the amounts of actin and myosin in the muscle fibers. This process also allows the muscle fibers' ability to create force improving the strength of the muscle (Powers & Howley, 2018). This process occurs as the result of exercise-induced muscle damage (training) and metabolic stress leading to hormonal changes that signal the body to rebuild the damaged muscle tissue.
Generally, muscle hypertrophy is achieved using relatively high loads coupled with moderate repetitions. The recommended ranges for sets, loads, and repetitions in this phase of training are typically 3-5 sets, 75-85% 1RM, and 6-12 repetitions (Clark et al., 2014). Let's be honest- training at this volume is difficult and does place quite a bit of stress on the muscles, tendons, ligaments, and joints. BFR creates conditions of higher metabolic stress minus the heavy mechanical stress still allowing for similar gains in muscle size and strength. It would be awesome if gains in muscle size and strength could occur while training with low loads, right?
There has been quite a bit of research on the topic of muscle hypertrophy and BFR conducted over the past two years. Slysz et al (2016) conducted a systematic review of 19 studies examining the relationship of BFR and its effects on muscle hypertrophy and strength. The authors reported that the difference between the average gains in muscle mass was significant and the signs of muscle damage (i.e., delayed onset muscle soreness and other hormonal markers) were significantly lower in the group that used BFR.
Similarly, a small study was conducted on young healthy men separating them into BFR and non-BFR groups for a training period of 2 weeks. The men were asked to perform bench presses at 30 percent of their 1RM (far below typical hypertrophy training protocols) completing a total of 4 sets with 30,15,15,15 and 15 reps respectively (a total of 75 reps) daily for 6 days per week.
The bench press strength of the BFR group increased by 6 percent, whereas the non-BFR group lost strength at an average rate of -2 percent (Yasuda et al., 2010). Yes, BFR can induce muscle hypertrophy under much lower loads than typically used leading to bigger gains in muscle strength.
Who is it for and why is it used?
Rehab/Recovery
Improvements in muscle hypertrophy and strength are desirable for those who are recovering from an injury or surgery or have limited mobility (elderly and/or bedridden). However, typical muscle hypertrophy training parameters are often not recommended in this population due to the high stress placed on the body (Patterson et al., 2019). BFR can induce these improvements at much lower intensities making it an effective tool in aiding this population.
To illustrate, BFR has been studied extensively in patients who have undergone various knee surgeries such as ACL repair. The main benefit of BCR in this group is to maintain muscle strength and improve recovery time. The current research shows that these goals are achieved at least in the short term (2 to 16 weeks after surgery) but has not been well researched to gauge long-term improvements as compared to traditional therapy. BFR therapy is widely available, though not the standard of care (DePhillipo et al., 2018).
Athletes
BFR also has applications in the athletic population if used in conjunction with conventional strength and conditioning programs. Scott et al (2015) published a systematic review of available research related to the application of BFR to athletic training programs. The authors determined that the application of BFR improved both muscle strength and muscle hypertrophy in study participants while using light loads as compared to controls.
It is important to note that in athletes, BFR cannot be used exclusively as it does not improve lifting technique and may not lead to improvements in speed or power. It is recommended that trained athletes use BFR during a deload period or ad an adjunct to regular training rather than as primary training (Scott et al., 2015).
How do you perform Blood Flow Restriction Training?
Specialized bands or cuffs are needed for BFR but are widely available as straps or inflatable cuffs. Some BFR devices can allow for pressure control from a smartphone. It is advisable to set the cuff pressure to a rating of 4-7 out of a possible 10 though there are cuffs available that can be set to specific pressures. Typically, the limb occlusion pressure (LOP) should be set at 40-80 percent of the upper operational pressure (UOP) of the device.
Specific pressure recommendations can vary based on individual tolerance and limb size. It is also important to point out that most studies on occlusion pressure were conducted on the lower body and it is therefore recommended that the user exercise more caution when setting pressures for the upper body (Loenneke et al., 2013).
BFR can be used with any strength exercise though the intensity must be altered. Training must occur with lower loads and higher repetitions. A typical training scheme for BFR involves completing four sets of an exercise at 20 to 50 percent 1RM at 30, 15, 15, and 15 repetitions respectively with a 30 to 60-second rest interval between sets. The cuff will remain intact during the rest intervals but should be removed or deflated in between exercises.
Pros, cons, and potential dangers of Blood Flow Restriction
Overall, BFR is safe for most people, but comes with some risk, especially in individuals with certain medical conditions.
Pros
- Can increase muscle strength and hypertrophy at lower training intensities.
- Prevents muscle loss in individuals who are injured or recovering from surgery.
- Can improve rehab time after injury/surgery.
- Gives the appearance of larger muscles due to local swelling (beneficial to bodybuilders and physique athletes).
Cons
- Training may feel very intense and uncomfortable.
- May cause bruising or numbness though this is often temporary.
- There is a small risk of blot clots.
- Optimal cuff pressures may be difficult to determine.
- Cannot be used in those with diabetes, hypertension, vascular disease, cancer, sickle cell anemia, has any diseases or is taking any medication that increases clotting risk. Clinical judgment must be used before recommending BFR. *this is not an all inclusive list
Needs to be performed by an experienced practitioner.
(Brandner et al., 2018)
(Patterson et al., 2019)
Conclusion
BFR can be a useful tool at increasing muscle hypertrophy and strength if used properly. This will hold true for both load-restricted individuals and athletes under certain conditions. It is important to review the pros and cons of BFR training to decide if it will be beneficial to you. While there is no specific certification needed to perform BFR, it is important to get advice from an experienced practitioner before engaging in this type of training.
References
Allsopp, G. L., & May, A. K. (2017). Can low-load blood flow restriction training elicit muscle hypertrophy with modest inflammation and cellular stress, but minimal muscle damage? The Journal of Physiology, 595(22), 6817–6818. https://doi.org/10.1113/jp275149
Bowman, E. N., Elshaar, R., Milligan, H., Jue, G., Mohr, K., Brown, P., Watanabe, D. M., & Limpisvasti, O. (2019). Proximal, Distal, and Contralateral Effects of Blood Flow Restriction Training on the Lower Extremities: A Randomized Controlled Trial. Sports Health: A Multidisciplinary Approach, 11(2), 149–156. https://doi.org/10.1177/1941738118821929
Brandner, C. R., May, A. K., Clarkson, M. J., & Warmington, S. A. (2018). Reported Side-effects and Safety Considerations for the Use of Blood Flow Restriction During Exercise in Practice and Research. Techniques in Orthopaedics, 33(2), 114–121. https://doi.org/10.1097/bto.0000000000000259
DePhillipo, N. N., Kennedy, M. I., Aman, Z. S., Bernhardson, A. S., O’Brien, L., & LaPrade, R. F. (2018). Blood Flow Restriction Therapy After Knee Surgery: Indications, Safety Considerations, and Postoperative Protocol. Arthroscopy Techniques, 7(10), e1037–e1043. https://doi.org/10.1016/j.eats.2018.06.010
Loenneke, J. P., Fahs, C. A., Rossow, L. M., Thiebaud, R. S., Mattocks, K. T., Abe, T., & Bemben, M. G. (2013). Blood flow restriction pressure recommendations: a tale of two cuffs. Frontiers in Physiology, 4. https://doi.org/10.3389/fphys.2013.00249
Lorenz, D., Bailey, L., Wilk, K., Mangine, B., Head, P., Grindstaff, T. L., & Morrison, S. (2021). Current Clinical Concepts: Blood Flow Restriction Training. Journal of Athletic Training. https://doi.org/10.4085/418-20
Patterson, S. D., Hughes, L., Warmington, S., Burr, J., Scott, B. R., Owens, J., Abe, T., Nielsen, J. L., Libardi, C. A., Laurentino, G., Neto, G. R., Brandner, C., Martin-Hernandez, J., & Loenneke, J. (2019). Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. Frontiers in Physiology, 10. https://doi.org/10.3389/fphys.2019.00533
Powers, S. K., & Howley, E. T. (2018). Exercise physiology : theory and application to fitness and performance (10th ed.). Mcgraw-Hill Education.
Scott, B. R., Loenneke, J. P., Slattery, K. M., & Dascombe, B. J. (2016). Blood flow restricted exercise for athletes: A review of available evidence. Journal of Science and Medicine in Sport, 19(5), 360–367. https://doi.org/10.1016/j.jsams.2015.04.014
Slysz, J., Stultz, J., & Burr, J. F. (2016). The efficacy of blood flow restricted exercise: A systematic review & meta-analysis. Journal of Science and Medicine in Sport, 19(8), 669–675. https://doi.org/10.1016/j.jsams.2015.09.005
VANWYE, W. R. (2017). Blood Flow Restriction Training: Implementation into Clinical Practice. International Journal of Exercise Science, 10(5), 649. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5609669/
Wortman, R. J., Brown, S. M., Savage-Elliott, I., Finley, Z. J., & Mulcahey, M. K. (2020). Blood Flow Restriction Training for Athletes: A Systematic Review. The American Journal of Sports Medicine, 363546520964454. https://doi.org/10.1177/0363546520964454
