This post was written by Seth Blankenship, SPT – Texas State University, Doctorate of Physical Therapy, Class of 2023 – who recently finished a clinical rotation at Symmetry.
It is widely accepted that when weight training, accomplishing muscle hypertrophy (the increase in size of your muscles) requires doing exercise repetitions with a resistance of 65-70% of your one repetition maximum (the heaviest weight you can lift just once). For avid gym goers and bodybuilders, this translates to long sessions at the gym, because lifting weights this heavy necessitates long recovery breaks between activities, causing a gym trip to take up a significant amount of time during the day. Working out in this manner is an admirable goal for fit individuals with plenty of time on their hands, but for people recovering from an injury, this is an unsustainable approach. In particular, during the beginning stages of rehabilitation after an injury, an individual often should not participate in heavy weight training exercises with large volumes of repetitions, due to risk of damaging healing tissue. A technique to build muscle size while also avoiding the heavy loads and extensive time required to build large amounts of muscle is to utilize blood flow restriction training (BFR).
WHAT IS BLOOD FLOW RESTRICTION TRAINING?
Blood flow restriction training involves exercising while partially restricting arterial inflow and fully restricting venous outflow in working musculature during exercise. 1 This process basically “tricks” the body into thinking that it is working harder than it is, and the greater perceived level of fatigue triggers processes that then build muscle. The body thinks that it is in “overload” while training via BFR. Overload is the underlying principle of all fitness training, which states that if you want to improve your fitness level you must continually increase the demands placed on that specific body system. When you challenge your body to perform at new levels, various adaptations occur to help you meet said challenges. By manipulating the processes that stimulate muscle fiber recruitment, BFR training provides a way to increase muscle size and strength at much lower training volumes than during traditional strength training — with effects seen with loads as low as 20-30% of one’s one-rep-max, as opposed to the traditional 65-70% needed to result in muscle size increases.3
For example, if you could press 200 pounds with your legs only one time, the 65-70% level you would need to work at to generate increased muscle size would be 130-140 pounds. Using blood flow restriction training, you could achieve similar muscular gains by lifting only 20-30% of the 200 pound one-rep max, or 40-60 pounds. Blood-flow restriction training can help patients to make greater strength training gains while lifting lighter loads, thereby reducing the overall stress placed on the muscle being worked.2 Does this sound too good to be true? Is it possible that lifting light weights can lead to the same muscle size building benefits as lifting heavy weights? The reality is that BFR training makes a light exercise very difficult.
Blood flow restriction training can be used when the goal of exercise is to increase muscle hypertrophy and strength for an individual that is load compromised.4 Additionally, a study published in 2022 suggests that BFR exercises not only were superior to traditional exercises for the purposes of increased strength, but also had benefits for participants’ dynamic balance, short-term memory, and cognitive abilities.5 BFR can be a great tool to be used when bridging the gap between injury and normal function. This type of training should not, however, entirely replace typical, high-load resistance training.
HOW BLOOD FLOW RESTRICTION TRAINING WORKS:
Prior to training with blood flow restriction, the amount of pressure that it takes to occlude (restrict blood flow to) the limb is measured using a Doppler ultrasound device and a cuff that restricts blood flow – similar to what is used to measure blood pressure during a medical exam. Some BFR cuffs allow you to measure occlusion pressure precisely, with the recommended restriction for the lower body being 80% and 50% for the upper body. For example, if it takes 150mmHg to occlude the arterial blood flow in your leg, a BFR cuff would be pumped up to 120 mmHg, so that you would perform a specific exercise with 20% of the blood flow that your leg normally receives. Once your specific occlusion number is established, a tight cuff or band is applied to your upper arm or upper leg, which limits the blood flow to that limb during your exercise set.
An example of a research backed BFR exercise protocol is as follows: Perform a 30-15-15-15 repetition pattern at roughly 20% of a one repetition maximum load. The first 30 repetitions drain the muscle of oxygen due to limited oxygen in the muscles to begin with, and the last three sets of 15 repetitions feel like the end of a very heavy weight training set. Because BFR training uses considerably light loads, strain on muscle fibers is minimal. During any particular exercise session, an individual might perform 2-4 different exercise activities while using the blood flow restriction equipment.
IS BLOOD FLOW RESTRICTION TRAINING SAFE?
When utilized appropriately, research supports blood flow restriction training as safe for a fairly broad variety of patient types. Some individuals find the process of exercise with blood flow restriction uncomfortable, while others are not bothered by the process. Sometimes, short-term effects after training are noted, including things like localized bruising in the area where the pressure cuff was applied, or delayed onset muscle soreness (DOMS) associated with the exercise process.
Blood flow restriction training is NOT a good choice for patients that have a history of blood clots, are pregnant, or have other systemic health issues such as diabetes or hypertension. It is a good practice to check with your physician and discuss your specific health history with your physical therapist prior to determining whether or not blood flow restriction training is appropriate for you.
Physical therapists have an extensive knowledge of therapeutic exercise, anatomy, physiology, and the cardiorespiratory system, as well as advanced clinical reasoning skills, all of which are components of the safe application of blood flow restriction training protocols.2 If you are looking to take your rehab and/or your general strength training to the next level, ask your physical therapist for more information about BFR training!
1. Patterson SD, Hughes L, Warmington S, Burr J, Scott BR, Owens J, Abe T, Nielsen JL, Libardi CA, Laurentino G, Neto GR, Brandner C, Martin-Hernandez J, Loenneke J. Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. Front Physiol. 2019 May 15;10:533. doi: 10.3389/fphys.2019.00533.
2. Blood-flow restriction training. APTA. https://www.apta.org/patient-care/interventions/blood-flow-restriction. Accessed October 2, 2022.
3. Matte M, (required) YN. Trends in training: Blood flow restriction training for strength and hypertrophy. W.I.T.S. https://www.witseducation.com/fit/blog/trends-in-training-blood-flow-restriction-training-for-strength-and-hypertrophy/. Published July 7, 2020. Accessed October 12, 2022.
4. [P]rehab. Blood flow restriction training in a nutshell – the prehab guys. [P]rehab. https://theprehabguys.com/blood-flow-restriction-training-in-a-nutshell/. Published September 8, 2022. Accessed October 12, 2022.
5. Mehranian A, Abdoli B, Maleki A, Rajabi H. The Effect of Unstable Resistance Training with Blood Flow Restriction on Short-Term Memory, Strength and Dynamic Balance in Older Adults. Polish Journal of Sport & Tourism. 2022;29(3):3-8. Accessed October 13, 2022. https://search-ebscohost-com.libproxy.txstate.edu/login.aspx?direct=true&db=s3h&AN=159441729&site=eds-live&scope=site