Methodological considerations for blood flow restricted resistance exercise

“KAATSU Training”, was first made available for public use in Japan.1 Since then, numerous studies have examined the effects of BFR resistance exercise on skeletal muscle hypertrophy and strength gains, as well as on neural, endocrine, and cardiovascular responses. The novelty of BFR resistance exercise is that relatively low exercise intensities (e.g. 20% of one-repetition maximum, 1-RM) can be utilized to elicit skeletal muscle hypertrophy and increase muscular strength. Even low-intensity aerobic exercise (e.g. walking, cycling), when combined with blood flow restriction, may be effective for increasing strength and hypertrophy.2 Thus, BFR exercise has a wide range of practical applications, from performance enhancement in athletes to combating muscle atrophy in clinical populations. To restrict blood flow during resistance exercise, a restrictive cuff or band (typically a pneumatic cuff) is placed on the most proximal portion of the exercising limb which reduces arterial blood inflow to the working muscle and occludes venous return resulting in the pooling of venous blood around the exercising muscle. Although there are likely many mechanisms involved in the adaptations to BFR exercise, optimizing muscle fiber recruitment appears to be critical. Thus, low-load BFR resistance exercise serves as an effective way to reach the same endpoint as reached with other forms of resistance exercise. However, BFR resistance training introduces more variables than standard training. Individual differences (e.g. limb size) as well as methodological differences (e.g. restrictive cuff size and pressure and resistance exercise protocol) are variables that must be considered with BFR resistance exercise. Manipulation of these variables will affect the degree to which blood flow is restricted during exercise. This may affect the acute responses and ultimately training adaptations to this type of exercise. Therefore, the purpose of this article is to summarize the different methodologies used in BFR resistance training studies to provide a resource for individuals who may be interested in utilizing this training technique and for researchers who are interested in studying the acute and chronic effects of BFR resistance exercise.