The technique involves applying a tourniquet or adjustable band to the proximal portion of an extremity to partially occlude venous blood flow from the muscle group that you are focusing on. This is then coupled with a form of sub-maximal exercise, with the goal to induce metabolic stress and promote an exercise adaptation response. The most accurate approach applies the BFR band to the limb with a connection to a pressure meter, like a blood pressure cuff.
Does Blood Flow Restriction Training Actually Work?
The research supports blood flow restriction (BFR) to induce similar strength gains and hypertrophy while lifting 20 to 30 percent of a patients 1 rep max (1 RM) when compared to lifting 65-plus percent of their 1 RM. This is important for patients who are unable to lift at higher percentages of their 1 RM without pain or risk of injury, or when higher loads are prohibited while recovering from an injury or surgery, or when athletes need a lower loading period to prevent overtraining.
To date, there have been over 200 research studies to substantiate BFR as an effective training tool. This technique has been widely used in the elderly (or those unable to lift heavy loads) to preserve muscle mass, in athletes to improve performance, or to accelerate post-surgical rehabilitation.
One recent randomized controlled trial evaluated healthy participants completing a standardized 6-week course of BFR training and found low-load BFR training led to approximately twice as much increase in muscle strength and limb circumference. Interestingly, BFR training also lead to gains in the contralateral extremity not using the tourniquet, suggesting a systemic or crossover effect.
Another study examined the impact of BFR to the upper arms during a low-intensity bench press workout. Compared to a control group, the BFR group showed dramatic results with an increase in muscle thickness in the triceps, pectoralis major and an increase in bench press strength.
Overall, the literature suggests that BFR training is safer than traditional weight-training, which is performed with heavier loads. Some patients complain of a local discomfort due to the band digging into their skin as well as a general limb discomfort at higher levels of compression. There have been a few reports of rhabdomyolysis with an incidence of 0.008 percent, although this may be influenced by lifestyle factors, infection, or immobilization.
How Does Blood Flow Restriction Work?
Blood flow restriction creates an ischemic and hypoxic environment within the muscles, elevating metabolic stress. This is proposed to cause cell swelling, production of reactive oxygen species, elevations in systemic hormone production (e.g., growth hormone and testosterone) and increased fast-twitch muscle fiber recruitment.
Under load, muscle fibers are recruited from smallest to largest. As the aerobic type 1 fibers fatigue under a hypoxic environment with increased metabolic stress, larger type IIA and type IIX muscle fibers are recruited. The large motor units take over while still only moving a low-load. The end result is enhanced muscle hypertrophy and strength gains with low-level exercise, comparable to that with more high-intensity weight lifting.
What is truly amazing is that you will get the benefits of BFR training for muscle groups like the chest and back-even when the bands are on the arms and not directly occluded.
Almost any exercise used to build strength and hypertrophy can be performed with blood flow restriction. From bodyweight to weighted, from open kinetic chain to closed. Power, speed, and jumping exercises should not be used. Five basic exercises to start with are bench press, bicep curls, tricep pull-downs, shoulder press, and squats or leg press. The bands could also be worn on the legs while performing a light cardio routine on alternate days.