Blood Flow Restriction (BFR) training is redefining how we approach rehab and recovery. By safely applying controlled pressure to limbs during low-load exercise, BFR allows clinicians to stimulate muscle adaptation earlier in the healing process—helping patients recover faster, with less mechanical stress on injured tissues.
How Does Traditional Physical Therapy Work?
Traditional physical therapy is designed to restore and improve functional capacity typically after an injury or surgery.
In simpler terms, functional capacity is what your body is physically capable of doing.
Regular physical exercise and training are designed to improve functional capacity. Physical therapy is similar, but extra attention and detail are required to respect the injured/recovering body part to fully rehab it. To better understand why traditional physical therapy has limitations, we need to better understand injuries.
How do Injuries Occur?
The simplest way to understand injuries is to look at the relationship between external demand and functional capacity. When the external demand is greater than the body's functional capacity, tissue failure can occur
When tissues fail, they're exposed to excessive amounts of mechanical stress that can cause injuries such as muscle tears, tendon/ligament ruptures, bone fractures, you name it.
And unfortunately, when an injury occurs, the functional capacity of the tissue significantly drops
This is where physical rehab comes into play. During physical therapy, we want to protect the injured tissue that's why the extra attention and details matter while we carefully and gradually stress the tissue to increase its functional capacity. The ultimate goal is to improve the tissue's functional capacity to get it back (at least) to baseline, but ideally even greater than baseline so that there is less risk of the same injury (or others) happening again.
Why Are Injuries Challenging to Treat As Is? Mechanical Stress Issues
With most injuries, there is always a component of rehab that focuses on improving muscle. From research, we know that muscle hypertrophy (increase in muscle size) occurs in response to stress. There are two main types of stress, mechanical and metabolic stress.
Traditional rehab typically involves therapeutic exercises with resistance bands or weights, which is a mechanical load imposing a demand on the tissue. However, rehab can be really hard and challenging because injured tissue is really sensitive to mechanical load.
If the mechanical load is too much or the exercise volume is too high (too many sets and reps), patients can end up dealing with excessive pain and may have a hard time going about their life outside of rehab. If patients cant tolerate rehab exercises that truly challenge the injured tissue or the total exercise volume necessary, then there may be not enough optimal stress to increase the injured tissue capacity. This ultimately leads to poor rehab results, frustrated patients, and the next thing patients know they out of available physical therapy visits according to their insurance company even when they still need help.
So, the question is how do we challenge injured tissue without excessive mechanical load or exercise volume
Treating Injuries With BFR
When mechanical stress is not tolerated, we can turn to metabolic stress to improve muscle.
So, what is metabolic stress? Its that terrible muscle burn you feel when you're working really hard for long periods of time. But again, a common issue with treating injuries is that patients cannot tolerate excessive exercise volume, which is typically needed to cause metabolic stress. So thats where BFR excels compared to traditional physical therapy because it can initiate metabolic stress with minimal exercise volume.
According to an article by Ozaki et al. 2015, the hypertrophic effect on muscle via metabolic stress is significantly exaggerated when you combine exercise with BFR.
The true beauty of BFR is that you can exercise with really low mechanical loads (as low as 20% 1RM) and still elicit muscle hypertrophy. The best part is, it doesn't take much exercise volume as BFR induces metabolic stress relatively fast due to the restricted blood flow increasing muscle oxygen demand, so muscles end up having to work really hard in a short time period leading to earlier onset of fatigue. Earlier onset of fatigue means less total exercise volume, which can mean happy patients with faster results.
References
- Ozaki H, Loenneke JP, Buckner SL, Abe T (2016) Muscle growth across a variety of exercise modalities and intensities: contributions of mechanical and metabolic stimuli. Med Hypotheses 88:22–26. doi:10.1016/j.mehy.2015.12.026
- Fry CS, Glynn EL, Drummond MJ, Timmerman KL, Fujita S, et al. Blood flow restriction exercise stimulates mTORC1 signaling and muscle protein synthesis in older men. J Appl Physiol.
- Centner C, Lauber B, Seynnes OR, et al. Low-load blood flow restriction training induces similar morphological and mechanical Achilles tendon adaptations compared to high-load resistance training. J Appl Physiol. November 2019. doi:10.1152/japplphysiol.00602.2019
- Bittar ST, Pfeifer PS, Santos HH, Cirilo-Sousa MS (2018) Efects of blood fow restriction exercises on bone metabolism: a systematic review. Clin Physiol Funct Imaging. https://doi.org/10.1111/ cpf.12512
