Blood Flow Restriction User Guide

What is blood flow restriction (BFR)?

See our blog post on what blood flow restriction is, and how it works.

The following tables are extensions of a review paper by Patterson et al., 2019.


Set - up of BFR?

Table 1 describes the set-up of BFR, regarding where to place the cuffs, how to determine the appropriate pressure, and how long to keep them on for.

Table 1: Set-Up of Blood Flow Restriction

 

 

Parameter

Guidelines

Considerations

Evidence

Laterality

Unilateral or Bilateral

-

-

Location

Proximal Limb

(As proximal as possible)

-

-

Cuff Pressure

40-80% AOP

(not % systolic BP*)

40% for exercise intensities at 20-40% 1-RM

Up to 80% if loads are < 20% 1-RM

Do not set based on absolute pressure!

Patterson 2017

Loenneke 2012

McEwen 2018

Mouser 2017

Cuff Width

“small” (< 10 cm)

“medium” (10-12 cm)

“large” (>17 cm)

If setting cuff pressure (as % AOP), then cuff material and width won’t matter for effectiveness.

Mouser 2017

Loenneke 2013

Loenneke 2014

Fahs 2015

Kim 2017

Cuff Material

Elastic or Nylon

Restriction Time

5-10 minutes

5-10 minutes per exercise (reperfusion between exercise)

-

Restriction Method

Intermittent or Continuous

“Continuous” refers to keeping occlusion within exercise during rest periods. Increased accumulation. More effective.

“Intermittent” refers to reperfusion during each rest, can be used for patients who are cardiovascular compromised.

-

Abbreviations: AOP, Arterial Occlusion Pressure; BP, Blood Pressure.

* % AOP and % BP are not equivalent.  It is not appropriate to set to % Systolic Blood pressure, only because units of measure and reliability of measure across devices will be different—i.e., measurement error between BFR cuffs and BP cuff.


One thing to know note: cuff pressure must be set to % of arterial occlusion pressure (AOP), not % systolic blood pressure. What’s the difference? Essentially it comes down to measurement error between the devices. The best way to do this is using the BFR cuff to determine AOP and then setting it to 40%-80% of that.

AOP is the absolute pressure of the cuff that results in cessation of pulse. Once found, adjust cuff pressure to 40%-80% AOP for training.


Exercise Prescription with BFR

Table 2 describes how to go about determining exercise prescription in terms of sets, reps, load, rest periods, and training frequency to get the best result.

Table 2: Prescription of Blood Flow Restriction

Parameter

Guidelines

Considerations

Evidence

Frequency

2-3x/week

Similar to high-load resistance exercise.

Can do short bouts of high-frequency for most impaired patients—e.g., 1-2x/day 5x/week for 1 week

Fleck 2004, Kraemer 2004;

Ohta 2003, Ladlow 2018

Duration

>3 weeks

Load

20-40% 1-RM

Consistently produce muscle adaptations with BFR.

Lighter loads should be accompanied by higher % AOP.

Lixandrao 2015

Counts 2016

Sets

2-4

Training volume of 75 repetitions across four sets of exercise is most reported. Performance until concentric failure is also effective but is not required.

Yasuda 2006, 2010, 2011, 2012

Loenneke 2016

Reps

75

(30 x 15 x 15 x 15)

Rest

30-60 seconds

Inter-set rests are typically short (<60s). Longer rests do not significantly increase metabolic stress.

Loenneke 2012

Tempo

1-2 seconds Con/Ecc

-

-

End Point

Planned rep, or failure

-

Loenneke 2011; Martin-Herandez 2013

Abbreviations: Con, concentric; Ecc, eccentric


For the most part, training regimen needs to be similar to that of high-load training (3x/week for at least 6 weeks). In rare cases, high-frequency training (2x/day) has been applied as well, but only for short periods (1 week).


Other Effects (AKA Side-Effects), Risks, and Other Considerations of BFR

Table 3 describes the other effects of blood flow restriction. Everything from common (muscle soreness) to exceedingly rare (syncope and clotting).

Table 3: Other Effects, Risks, and Contraindications of Blood Flow Restriction

Effects

Risks + Considerations

Evidence

Muscle Damage

Resistance training results in muscle damage. In extreme cases, exertional rhabdomyolysis can result. This risk is increased with inappropriate training loads, dehydration, or certain medications. There is no evidence to suggest BFR increases risk of rhabdomyolysis.

Zimmerman and Shen 2013

Nakajima 2006

Muscle Soreness

Muscle soreness is consistent elevated above baseline in the days following BFR with low-load resistance training. The associated decline in torque output and range of motion are similar to those observed in high-load resistance training.

Umbel 2009

Wernbom 2012

Loenneke 2014

Increased Systolic Blood Pressure

The arterial and interstitial effects of BFR stimulate the exercise pressor reflex (EPR). This reflex acutely increases HR and BP. It may make exercise with BFR dangerous for individuals with cardiovascular disease. Although not necessarily a contraindication, keep in mind that systolic BP will increase 10-30 mmHg higher when using BFR vs no BFR.

Intermittent cuff pressure (reperfusion during rest) may mitigate this effect.

Rossow 2012

Vieira 2013

Downs 2014

Staunton 2015

Neto 2016

Improved Arterial Compliance

Similar to low load and high load training, BFR has the peripheral vascular benefit of improved large artery compliance in the extremities. However, small artery compliance is better treated with high load resistance training than by BFR.

Lixandrao 2015

Counts 2016

Oxidative Stress

Reactive oxygen species are increased following all types of exercise (including use of BFR). However, there is no evidence to suggest BFR increases oxidative stress over resistance training along.

Garten 2015

Patterson 2019

* Syncope?

The application of BFR in the absence of exercise stimuli can result in systemic vascular resistance with a concomitant decrease in CO – possibly resulting in hypotensive syncope. Clinicians should be aware of these effects when using with patients.

Hogan 2009

Patterson 2017

* Clotting?

Although seemingly related, there are no documented increases in venous thromboembolism (deep vein thrombosis or pulmonary embolism) with either acute or chronic use of BFR. It is recommended that clinician use published clinical prediction rules to identify patients at high risk for venous thromboembolism and avoid use in those patients.

Patterson 2019

Wells 2000

Abbreviations: BFR, Blood Flow Restriction, EPR, exercise pressor reflex; HR, heart rate; BP, blood pressure, mmHg, millemeters of mercury;

* Not reported in the literature, but may be more common with less regimented use in clinical practice.

Who should not use BFR?

Be cautious with using BFR with patients who have diagnoses of:

  • Sick Cell Trait or Disease

  • Recent Vascular Surgery

  • Chronic Venous Disease

  • Reynaud’s Phenomenon

  • Bleeding Disorders (or who are taking blood thinners)

  • Peripheral Vascular Disease

  • POTS Syndrome

This is not a comprehensive list, and it may change over time.  Patients should not apply BFR without first consulting a physician or physical therapist about the risks and benefits.


How does BFR Work?

Mechanisms of BFR.

Blow flow restriction works through two main mechanisms:

  1. Mechanical tension of muscle fibers - By applying a partial tourniquet to the limb, venous pooling and intramuscular tension allows patients to achieve high levels of mechanical tension during low-load exercise (20-40% 1 rep max [1RM]). This means the muscle feels like it is lifting heavy weight.

  2. Metabolic stress - In parallel, increased levels of metabolic stress drive systemic hormone production and fast-twitch (anaerobic) muscle fiber recruitment.

Together, these stimuli promote gains in muscle hypertrophy and strength despite training with low-loads. (Pearson and Hussain, Sports Med, 2015)

Does BFR address muscle inhibition?

Not directly. Neural inhibition persists, but BFR does encourage selective activation of high-threshold fast-twitch muscle fibers. This means effects similar to high-training loads despite low-resistance in rehabilitation -- albeit inhibited muscle fibers theoretically remain unrecruited. That being said, it absolutely combats the metabolic atrophy cascade that occurs in the presence of muscle inhibition. See our other blog post on BFR for more on this topic.

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