Top Line
Blood flow restriction (BFR) is a unique training method that goes as far back as the 1960’s when it was originally developed by Yoshiaki Sato in Japan.
Why it Matters
Training with BFR is believed to increase muscle hypertrophy and strength at much lower loads.1,2 In other words, you maximize the benefits of strength training while significantly reducing the risk of injuries to your joints and muscles.
Key Takeaways
- BFR elicits the largest increases in muscular development (hypertrophy) and strength when combined with low-load resistance exercise as low as 20%-40% of an individual’s 1-RM strength.1,2,3 The largest effects have been observed training 2–3 days per week. A frequency greater than this appears to be less effective, possibly due to overtraining.3
- For healthy individuals, training adaptations are likely maximized by combining low-load BFR resistance exercise with traditional high-load resistance exercise.1
- High volume is ideal; a standard structure for low-load-BFR training is 75 repetitions over 4 sets (i.e., 30/15/15/15) with 30-second rest periods between sets.1,2,3 This repetition scheme has been demonstrated to aid in rehabilitation from knee injury 4, enhance acute muscle activation 5, and increase muscle strength and size 6, without increasing indices of muscle damage.2
Article:
Blood flow restriction (BFR) goes as far back as the 1960’s when it was originally developed by Yoshiaki Sato in Japan and termed KAATSU training. Currently, BFR training has become a popular way to train, particularly in the clinical population.
In simplest terms, the mechanisms behind BFR are believed to be attributed to a reduction in the amount of blood flow into and out of the working muscles by using elastic bands or KAATSU cuffs wrapped around the legs or arms. This keeps the blood from being fully recirculated leading to a pooling of blood and buildup of metabolites, which is believed to increase muscle hypertrophy and strength at much lower loads.1,2 As a result, this is shown to be an effective way to train the muscles while inducing minimal damage to the muscles overall.3,5 However, keep in mind that any exercise that stresses the muscles can induce muscle damage and soreness, especially if you are a beginner, BFR has just been shown to induce muscle damage and soreness to a lesser degree.
The above image shows a muscle relaxed on the left and a muscle contracted on the right. As the muscle contracts blood with get pushed out of the vein. The BFR bands will limit the amount of blood that gets pushed out causing the blood to pool up in the working muscle.
The research and understanding of how to practically apply BFR across the various populations (clinical, elderly, athletic, etc.) are still ongoing and there is still much to be learned about the full benefits, risks, and implementation of BFR training.
Below are some highlighted studies and recommendations of how to currently practically apply BFR training across the various populations:
BRF training effects in some clinical populations: Post injury, surgery, and chronic diseases (cardiovascular, etc.)
- Low-load BFR (LL-BFR) can increase Achilles tendon mechanical and morphological properties to a similar extent as conventional high-load resistance training.7 This is of particular importance for individuals who may not tolerate heavy training loads but still aim for improvements in myotendinous function, improve recovery post knee surgery, have knee osteoarthritis, and are older adults at risk of sarcopenia.7,8
- Utilizing BFR training early in the rehab phase after ACL surgery can reduce muscle atrophy in the quads and improve functionality 9,10 and reduce pain during rehab training leading to overall improvement in physical function due to an increased ability to induce muscle hypertrophy and strength compared to heavy load resistance training when limitations such as this exist.11,12,13
- BFR may have beneficial effects for those with high blood pressure and hypertension as it induces a significant reduction in blood pressure post exercise compared to traditional resistance exercise.14,15,16,17 Although, higher systolic blood pressure and/or diastolic blood pressure values have been observed during exercise with BFR compared to traditional exercise, especially in hypertensive individuals. Thus, exercise with BFR should be prescribed with caution when BP control is necessary during exercise.18 Research is ongoing in this area.
The above image shows some examples of the nutrients the body uses to provide energy when exercising. During BFR lactic acid and other metabolites are accumulated in the pooling of blood from the working muscle burning those nutrients for energy.
Current BFR training guidelines: For clinical populations and athletes:
- BFR elicits the largest increases in muscular development (hypertrophy) and strength when combined with low-load resistance exercise as low as 20%-40% of an individual’s 1-RM strength.1,2,3 The largest effects have been observed training 2–3 days per week. A frequency greater than this appears to be less effective, possibly due to overtraining.3
- Some benefits may be seen using BFR alone during immobilization or combined with low-workload cardiovascular exercise.2
- When using unpressurized cuffs, outside of KAATSU, it is suggested that pulling the wraps tight to a moderate perceptive pressure (e.g., a 7 on a scale of 0 to 10) would be sufficient. This protocol has since been shown to be effective in occluding venous return while sufficiently reducing arterial delivery.1
- For healthy individuals, training adaptations are likely maximized by combining low-load BFR resistance exercise with traditional high-load resistance exercise.1
- High volume is ideal; a standard structure for LL-BFR training is 75 repetitions over 4 sets (i.e., 30/15/15/15) with 30-second rest periods between sets.1,2,3 The goal being to increase metabolite production and build up. Wraps or cuffs are kept on during rest. This repetition scheme has been demonstrated to aid in rehabilitation from knee injury 4, enhance acute muscle activation 5, and increase muscle strength and size 6, without increasing indices of muscle damage.2
Finally, remember that research is ongoing and this review only highlights some, not all, of the current recommendations regarding the practical use of BFR training. However, these recommendations are a good place to start should you choose to try BFR training. Click here for some cheap yet reliable BFR bands to get you started if you don’t want to shell out for KAATSU.
Jon Esposito MA, CSCS, CISSN, USAW