What is Blood Flow Restriction?
Blood Flow Restriction (BFR) is growing in popularity these days in the fitness and rehab world, but there are still a lot of questions about what exactly is happening during BFR training, what populations it works best in, and what benefits can be gained from it.
What’s going on when I occlude blood flow?
BFR training is characterized by restricting blood flow distal to an applied cuff on either the upper arm or upper thigh. By restricting venous return to the heart, these cuffs effectively create an environment that mimics very high intensity exercise in terms of hormone release, metabolic environment, and physical sensation to the person wearing the cuffs. This means Hydrogen, Lactate, and other metabolic waste products build up in the muscle, and serve as signals for muscle and strength gains. The best part of BFR training is that these signals can be sent at MUCH lighter loads than typical training.
Who can benefit from it? What benefits will they see?
The truth is that almost anyone can benefit from BFR training in some way. Research shows that muscle strength and hypertrophy can be improved from only using 20-30% 1RM loads, meaning that any post operative or post injury patient could potentially still elicit a training effect earlier in their rehab. It also means that lifters looking to add volume to their workouts can now do so with a little bit less strain on their joints.
The benefits aren’t that much different than regular exercise, but those benefits can be accomplished at lighter loads. There has been some additional research on positive changes in hormone levels associated with muscle growth or blood vessel integrity, but to my knowledge these claims haven’t been substantiated fully yet.
Image from Spinalmanipulation.org
Who shouldn’t perform BFR?
While BFR training is quite safe, like everything, it’s important to understand who should be excluded from using it. The contraindications range from relative to absolute and require that a doctor trained in BFR to evaluate the client/patient before using the cuffs. Most of the definite contraindications stem from a history of venous thromboembolism, heart conditions, pregnancy, or infection. These situations are either pretty clear no-no’s or haven’t been studied rigorously enough to make a decision on. For now, clients or patients with these issues should avoid BFR training and opt for different rehab protocols. The other group of contraindications are considered relative and have a scoring system applied to them to help clinicians navigate safe BFR training for every population. If a client exhibits a few of the relative contraindications, they may be considered not able to perform BFR, however if they only exhibit one of them they may still be a fit for BFR provided a proper history and exam was done. It’s important to stress that these situations require someone who knows what they’re doing when it comes to BFR!
Hx of DVT
Acute sickness or fever
BP > 180/100 mmHg
Acute Post-Operative Arrhythmia
Varicose veins (clinician judgement)
Atrial Fibrillation or Heart Failure
BP 160 to 179/95 to99 mmHg
BMI > 30 kg/m
Image from TheBarbellPhysio & The Prehab Guys
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