The science and application of blood flow restriction training (BFR)
Origin of BFR:
Blood Flow Restriction (BFR) Training is a new training strategy that involves wrapping the proximal end of the limb with a cuff or bandage, with the aim of maintaining arterial inflow during exercise while blocking venous return. (Scott et al. 2015)
The predecessor of BFR is an efficient training method invented by Dr. Yoshiaki Sato in 1966. He found that during prolonged meditation, the limited blood flow makes the legs numb, and eventually produces a burning sensation similar to muscle fatigue. So he did his own experiments to restrict blood flow to working muscles, and later joined forces with Japanese scientists to conduct further research, resulting in the current patented KAATSU principle.
Purpose of BFR training:
Air pressure cuffs are placed on the arm or thigh. The cuff is then inflated to a specific pressure measured in millimeters of mercury so that venous return of blood flow is restricted while arterial blood flow remains unrestricted. This training method, also known as occlusion training, is very popular in Denmark for fitness and rehabilitation.
BFR training mechanism:
International research supports that by restricting only venous rather than arterial blood flow, blood begins to pool in the muscles, causing increased muscle pressure while fatigued muscles faster and recruiting more type II muscle fibers than regular training. Studies have shown that BFR training produces good muscle and vascular fitness without any apparent side effects and should be considered a safe alternative to regular high-load training.
Therefore, BFR training is very suitable for ordinary people in the gym, professional athletes, and patient groups who cannot perform heavy training due to injury or post-operative rehabilitation.
Applications and scientific research of BFR:
1. BFR can be trained with resistance training, physical therapy equipment, or walking. Evidence shows that BFR resistance training can prevent muscle atrophy in bedridden patients, and can effectively promote muscle hypertrophy for athletes and fitness enthusiasts with high training intensity.
2. Resistance training combined with BFR can improve muscle strength:
①Conventional low-resistance training combined with BFR is similar to traditional high-resistance training. Karabulut (2010), Clark (2011), Karabulut (2011), Laurentino (2012), Martin-Hernandez (2013), Thiebaud (2013), Vechin (2014), Libardi (2015).
②Studies have shown that BFR is more effective in preventing muscle loss than isometric contractions for people who have fixed their ankles for two weeks. Kubota et al. (2008).
③In terms of the maximum sprint time of sprint, the blood flow restriction group has a great improvement compared with the conventional group. Cook (2014).
④ Resistance training combined with BFR can improve muscular endurance. Cook (2010).
In conclusion, combining BFR improves muscle strength, endurance, hypertrophy, and athletic performance, without at least not getting worse.
20%-30% of 1RM wraps to train the proximal end of the limb,
7/10 points are tight. The rest interval frequency and number of sets are adjusted according to the individual.
Contraindications to blood flow-restricting training include a history of deep vein thrombosis, pregnancy, varicose veins, hypertension, and heart disease. Pope et al. (2013 ) emphasized that prolonged ischemia can lead to necrosis of muscle tissue. Therefore, prolonged continuous blood flow restriction training should be avoided.