The pioneer of BFR training is Dr. Yoshiaki Sato of Japan, who at a young age observed that his calves, after kneeling for an extended period of time, were painful and had the characteristic “muscle pump” appearance seen following an intense leg workout. This experience launched his investigative and innovative inquiry into what he referred to as Kaatsu or “training with added pressure”. Today this training method is commonly known as Blood Flow Restriction (BFR)training.

It is now a commonly accepted method (or complimentary accessory component) of resistance training that has consistently shown to increase muscle size (hypertrophy) and strength when working at intensities much lower than the traditional guidelines.

Blood flow restriction training uses cuffs or bands (similar to a blood pressure cuff) to apply an external resistance around the muscle(s) being worked. The band is placed around the proximal end of a body limb, arm or leg, and inflated to specific pressures to produce a partial restriction (not occlusion) of blood flowing through arteries into the exercising muscle or muscle group, while significantly restricting the venous blood flow return out of the muscle.

The Proposed Mechanisms for developing Muscle Size and Strength of BFR Training

This disruption of blood flow to and from the muscle(s) produces a partial ischemic/hypoxic condition of inadequate oxygen supply within the exercising muscle tissue, and a simultaneous buildup of metabolic waste byproducts of muscle metabolism. Collectively this condition is known as metabolic stress and is similar to the physiological changes a weightlifter experiences when he/she engages in an intense workout of the arms or legs. Research on BFR training has shown to enhance the training effect in exercising muscles leading to increased muscle mass and strength in the exercising muscles.

This condition of metabolic stress combined with the mechanical tension created within the muscles is theorized to be the primary factors to mediate numerous secondary associated mechanisms that have been shown to stimulate autocrine and/or paracrine actions for the induction of muscle hypertrophy through BFR resistance training. These include systemic and localized anabolic hormonal production, increase fast-twitch muscle fiber recruitment, cell swelling, muscle damage, and increased reactive oxygen species (ROS) production, all of which are thought to mediate muscle protein signaling and/or satellite cell proliferation for the stimulation of muscle protein synthesis.

The Experts Weigh In

Because of the consistent and growing evidence of the significant muscle hypertrophic (increase in size) adaptations BFR training has shown in muscles worked at intensities below the current recommendations for muscle size and strength development, expert scientists focused in blood flow restriction training research came together to develop a manuscript that establishes a series of guidelines for blood flow restriction exercising, focusing on the methodology, application, and safety of this mode of training. The article is titled, https://ncbi.nlm.nih.gov/pmc/articles/PMC6530612/)

These guidelines for Blood Flow Resistance Training are being applied to voluntary resistance exercise, aerobic exercise, and passively without exercise.

Application of The Blood Flow Restriction Training Guidelines

This table provides a summary of their Model of Exercise Prescription Guidelines for Blood Flow Restriction “Resistance Exercise” for Enhanced Muscle Strength and Hypertrophy. [Table 1]

This table provides a summary of their Model of Exercise Prescription Guidelines for Blood Flow Restriction-“Aerobic Exercise” for Enhanced Muscle Strength and Hypertrophy. [Table 2]

This table provides a summary of their Model of Exercise Prescription Guidelines for Blood Flow Restriction-“Passive” use for Enhanced Muscle Strength and Hypertrophy. [Table 3]

Safety Considerations of Blood Flow Resistance Training

As with any exercise there are safety considerations that must be evaluated when implementing Blood Flow Resistance Training. What follows are the guidelines summary statements of safety considerations.

• Central Vascular Response to Blood Flow Resistance Exercise Training: The effects of BFR Resistance Exercise on the central cardiovascular response is dependent upon the level of BFR, mode of exercise and mode of application (i.e., continuous vs intermittent BFR), with heart rate (HR), systolic blood pressure (SbP), diastolic blood pressure (DbP) or double product (HR x SbP) compared with the same exercise in free flow conditions. However, some studies have reported contrary evidence. Cardiac output seems not to be affected by BFR during exercise compared to free flow conditions. Studies removing the cuff between sets or between exercises have found no further variations in HR, SbP, DbP, CO or SV in BFR compared to non BFR exercising.
• Peripheral Vascular Response to Blood Flow Resistance Exercise Training: BFR exercise has been shown to affect arterial compliance and endothelial function, increasing large artery compliance to the same extent as low level and high level free flow resistance exercise conditions, whereas small artery compliance was more affected by high level resistance exercise free flow exercising with no differences between low level free flow resistance exercises and BFR resistance training exercises. These data suggest a transient improvement of endothelial function following BFR resistance exercises.
• Systemic vascular resistance (SVR) falls in muscle exercise due to vasodilation. The threat of the systemic pressure not meeting new regulatory set-point during exercise is compensated by an increased CO and sympathetic vasomotor tone. Syncope episodes have not frequently been reported in BFR resistance exercise literature. Although the relationship between Co and SVR does not seem to represent a cardiovascular threat in BFR exercise, a steady CO coupled with an increased SVR could drive an increase in blood pressure, and adverse individual responses may not be discarded.
• Venous Thromboembolism (VTE): The totality of the literature reveals minimal adverse events pertaining to VTE and clinically reported events have not been reported. Acute studies have not demonstrated a significant increase in blood coagulations via D-dimer and values, one of the most utilized clinical tests to rule out the presence of a deep-vein thrombosis after BFR resistance exercise. Additionally, C-reactive protein (CRP), a protein that has been linked to clot formation, was also assessed in one study and was not significantly elevated.
• Muscle Damage: A common concern of applying BFR with or without exercise is the possibility that this stimulus may lead to or even augment muscle damage through ischemic-reperfusion injury. In addition, muscle soreness, an indirect marker of muscle damage, is consistently elevated above baseline in the days following BFR training. The available evidence suggests that the application of BFR does not appear to induce a muscle damage response to low level resistance exercise using single exercise protocols of up to 5 sets to volitional failure.

Concluding Statement of the authors of the “Blood Flow Restriction Exercise: Considerations for Methodology, Application, and Safety” article. “The aim of this article was to give an overview of the adaptations to the different modes of BFR, methods of application and the safety considerations. The authors recommend the use of BFR combined with different forms of exercise (resisted, aerobic, passively), considering the volume and intensity, as well s the among of cuff pressure, restriction time, size and cuff material. Tables 1-3 set out the parameters by which practitioners should use BFR based on up to date and current research I the area.”

It is recommended that you review the complete article for background and compete information it provides. Blood Flow Restriction Exercise: Considerations for Methodology, Application, and Safety. Front Physiol. 2019; 10:533. (https://ncbi.nlm.nih.gov/pmc/articles/PMC6530612/)