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.
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Parameter |
Guidelines |
Considerations |
Evidence |
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Laterality |
Unilateral or Bilateral |
- |
- |
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Location |
Proximal Limb (As proximal as possible) |
- |
- |
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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 |
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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 |
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Cuff
Material |
Elastic or Nylon |
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Restriction
Time |
5-10 minutes |
5-10 minutes per exercise (reperfusion between
exercise) |
- |
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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. |
- |
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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. |
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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.
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Parameter |
Guidelines |
Considerations |
Evidence |
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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 |
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Duration |
>3 weeks |
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Load |
20-40% 1-RM |
Consistently produce muscle adaptations with
BFR. Lighter loads should be accompanied by higher %
AOP. |
Lixandrao 2015 Counts 2016 |
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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 |
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Reps |
75 (30 x 15 x 15 x 15) |
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Rest |
30-60 seconds |
Inter-set rests are typically short (<60s).
Longer rests do not significantly increase metabolic stress. |
Loenneke 2012 |
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Tempo |
1-2 seconds Con/Ecc |
- |
- |
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End Point |
Planned rep, or failure |
- |
Loenneke 2011; Martin-Herandez 2013 |
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Abbreviations: Con, concentric; Ecc, eccentric |
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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).
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Table
3: Other Effects, Risks, and Contraindications of Blood Flow Restriction |
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Effects |
Risks + Considerations |
Evidence |
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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 |
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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 |
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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 |
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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 |
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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 |
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* 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 |
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* 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 |
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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. |
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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:
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.
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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