Written by: Christopher Pawliuk, SPT
Greetings everyone, this is the third part of my three-part blog series on different topics in physical therapy. For this blog post, I’ll be talking about a relatively new training method that allows people to lift less weight but still gain strength as if they were lifting heavy weights. Crazy, right?!
While it may seem pretty far-fetched, there have been numerous studies on this type of training that have shown these effects are real. Not only can you gain strength by lifting less weight, but by doing so you are also putting less stress on your joints. This means you can still get the benefits even if you feel like your joints aren’t strong.
Now you may be wondering what this is and how you can learn more. This training method is called blood flow restriction training, and we will discuss exactly what it is, who should use it, and how physical therapy can maximize the gains someone makes to help them recover from injuries.
What Is Blood Flow Restriction Training?
Blood flow restriction training induces similar hypertrophy (muscle growth) with less force and stress on a person’s joints compared to traditional high-load resistance training (training while using loads approximately 70–85% of a person’s one repetition max).
This decreased load on a joint is extremely important for patients whose tissues cannot handle higher levels of stress or force. This typically applies to people who have recently experienced an injury or have had surgery, but it also applies to many elderly adult patients who would benefit from strength training but cannot handle high loads on their joints.
Blood flow restriction training involves restricting blood flow to an extremity to partially block circulation in order to increase muscle strength and mass effects from exercising. It is used with the intent of allowing blood to pool in the capillary beds past the device being used to restrict blood flow.
It is believed that this lack of blood flow puts metabolic stress on the body and, when combined with mechanical tension from resistance training, leads to increased strength and muscle hypertrophy. The metabolites that mediate muscular hypertrophy have been found to be amplified by the lack of blood flow and are believed to produce greater motor recruitment (more fibers of your muscle working at once).
The type 2 muscle fibers (your fast-twitch muscle fibers) have been shown to be recruited at lower loads with blood flow restriction training.
Effects Beyond the Cuff
What is interesting is that it’s been found that this increase in motor recruitment is not just for muscles past the cuff or tourniquet, but also for the muscles above the tourniquet. For example, if the cuff was placed on the leg, it’s been shown that the gluteus maximus muscle in our hips shows greater motor recruitment, as well as the muscles past the cuff.
Blood flow restriction training shows the best benefits for a patient when it is paired with exercise and enhances the stimulus on muscular development. What is also interesting is that it’s been found that low-intensity aerobic exercise can facilitate improvements in muscular strength and size, even though traditionally those benefits do not typically occur from aerobic exercise. Currently, the literature shows that blood flow restriction training, even at low loads (20 to 30 percent of someone’s one-rep max), is effective at increasing both muscular strength and size.
Understanding One Rep Max and Training Duration
Now you may ask, what is a one-rep max? This is the maximum amount of weight you can lift for one repetition. So with blood flow restriction training, if someone’s one-rep max is 20 pounds, they could get similar strength gains to their bicep muscle by only lifting a 4-pound weight. Of course, there are many variables that may influence the amount of strength and muscle someone gains with blood flow restriction, such as intensity, frequency, volume, and pressure of the cuff. The length of the training program overall and the number of times you use blood flow restriction training also influence how much muscle someone may gain.
It is generally recommended that people use blood flow restriction therapy three days per week for around six weeks. It was found in the literature that training durations at or above six weeks produce greater strength gains than programs under six weeks.
Who Could Benefit from Blood Flow Restriction Training?
As mentioned above, blood flow restriction training can be very helpful for people who have sustained an injury or elderly patients who can’t handle heavy loads. We know that extended rest after an injury or surgery can decrease muscular strength up to 15% per week with total bed rest. So for patients who have undergone surgery or are generally pretty inactive, this increases their risk of injury when they return to exercising and being active.
Blood flow restriction training acts as a way to speed up recovery after a period of prolonged bed rest or for patients who cannot handle higher loads on their joints. Especially for people who are recovering from an injury, the use of blood flow restriction training can be a great way to regain strength quickly and rebuild muscle.
Precautions
While blood flow restriction training has great effects on skeletal muscle and can be immensely helpful in some patients, it is not perfect for everyone. A patient population for whom blood flow restriction training is absolutely not appropriate includes patients who have peripheral vascular disease, a history of previous vascular surgery to the affected limb, or an arteriovenous fistula.
Sometimes it is appropriate to use blood flow restriction training as long as the practitioner proceeds with caution and monitors vitals, such as if a patient has hypertension, a venous thromboembolism (including a deep vein thrombosis or pulmonary embolism), sickle cell disease, hemophilia or other bleeding or clotting disorders, a history of stroke, or peripheral neuropathy.
There is a risk stratification tool that clinicians should use before implementing blood flow restriction training to assess risk of use and how appropriate it is for that patient.
Where Physical Therapy Comes In
If you are interested in participating in this kind of training method, it is very important that you work with either a physical therapist or a physician, especially if you have any of the past medical history listed above. A physical therapist will be able to work with you every step of the way and evaluate whether it is a good fit for you, along with setting the correct parameters for use of the device.
They will be able to incorporate this into your current rehabilitation or strength program in order to help you get the most out of your exercises, while also prescribing the right amount of weight for you to use. Working with a physical therapist also allows you to try this training method in a safe environment, with the therapist there to monitor your vital signs and help if anything starts to go wrong. The physical therapist will also be there to help you progress and improve at an appropriate rate.
If you are currently rehabbing an injury, are about to undergo orthopedic surgery, or want to generally get stronger and think that blood flow restriction training could help, come see us.
Citations
Bloomfield SA. Changes in musculoskeletal structure and function with prolonged bed rest. Med Sci Sports Exerc. 1997;29(2):197-206. doi:10.1097/00005768-199702000-00006
Cognetti DJ, Sheean AJ, Owens JG. Blood Flow Restriction Therapy and Its Use for Rehabilitation and Return to Sport: Physiology, Application, and Guidelines for Implementation. Arthrosc Sports Med Rehabil. 2022;4(1):e71-e76. Published 2022 Jan 28. doi:10.1016/j.asmr.2021.09.025
Dittmer D, Teasell R. Complications of immobilization and bed rest – Part 1: musculoskeletal and cardiovascular complications. Can Fam Physician. 1993;39:1428-1437.
Lorenz DS, Bailey L, Wilk KE, et al. Blood Flow Restriction Training. J Athl Train. 2021;56(9):937-944. doi:10.4085/418-20
Miller BC, Tirko AW, Shipe JM, Sumeriski OR, Moran K. The Systemic Effects of Blood Flow Restriction Training: A Systematic Review. Int J Sports Phys Ther. 2021;16(4):978-990. Published 2021 Aug 2. doi:10.26603/001c.25791
Slysz J, Stultz J, Burr JF. The efficacy of blood flow restricted exercise: A systematic review & meta-analysis. Journal of Science and Medicine in Sport. 2016;19(8):669-675. doi:https://doi.org/10.1016/j.jsams.2015.09.005