Occlusion (Kaatsu) Training and Muscle Hypertrophy

Occlusion (Kaatsu) Training and Muscle Hypertrophy

We’ve already discussed the possibilities of experimenting with the whole spectrum of repetitions available to maximise muscle hypertrophy, as well as Hybrid Training. In this article, we’ll explain a technique to enhance Hypertrophy without the need to use large loads or intensities: Occlusion Training (Blood Flow Restriction)

Hypertrophy-Oriented Training

Bodybuilding training is classically understood as a high-volume workout. This is because it exerts a positive effect on muscle mass gain. This was shown by Krieger et al. (2010) in their meta-analysis, where multiple sets generated a greater effect on muscle hypertrophy than single sets:

2-3 sets generate greater effects than 1 set; and 4-6 sets have greater effects in turn than 2-3 sets; although it’s then no longer a statistically significant benefit.

Response to training volumeFigure I. Response to training volume

This is in line with the inverted U model outlined by Schoenfeld (2016) in their book where they explain how an increase in volume results in an increase in hypertrophy until an optimal threshold is reached; at which point efficiency decreases to the point of doing more harm than good.

What is Occlusion Training?

Also known as Blood Flow Restricted Training “BFRT” (Blood Flow Restriction Training), it is based on restricting venous blood flow, i.e. venous return, to generate a greater accumulation of blood in the trained muscle.

Occlusion Training and Tourniquets

How is it done?

The principle of this training is based on the use of clinical, pressure-controlled tourniquets, usually used for limb work, which generates the necessary pressure to restrict blood flow.

Occlusion training is usually carried out at a low intensity to reduce the potential vascular risk factors.

Anabolic Environment

It creates a more anabolic environment induced by metabolic stress, increasing autocrine (such as stimulation of protein synthesis, increased release of growth hormone and other anabolic hormones, and attenuation of the catabolic response induced by physical exercise) and paracrine (increased satellite cell activity) actions.

Occlusion Training and Muscle Mass Gain

Pearson & Hussain (2015) conclude in their research that the mechanisms by which BFRT induces such significant muscle hypertrophy are still partially unknown.

This training technique is known as the Kaatsu Method, as it originated in Japan, which studied the physiological responses produced in the absence of blood flow or ischaemia, generating temporary hypoxia in the tissues.

Time Saving

If we know that the most effective approach to generate muscular hypertrophy is to successfully combine mechanical tension + metabolic stress, we can conclude that training focused on hypertrophy becomes extremely time consuming.

Occlusion and Hypertrophy Training

Occlusion Training can reduce training times and achieve satisfactory results

For people who don’t have 2 hours a day to invest in the gym, increasing the training density is a solution; supersets are a useful tool to increase metabolic stress by generating the possibility of increasing the workload in a short period of time.

Scientific Evidence of Kaatsu Training


Loenneke et al. (2012) conducted a meta-analysis comparing the effect of low-intensity training with and without blood flow restriction. They found out that BFRT generated “significantly greater improvements in strength and hypertrophy”.

The result of the strength gain for low-intensity BFRT was 0.58 vs 0.00 for low-intensity training without BFR, in mean values. While the effect on muscle hypertrophy was 0.39 vs -0.01 between BFRT and low-intensity training without occlusion.

Occlusion training advantages

As discussed above, occlusion training generates an endocrine response that promotes muscle mass gain and strength improvement even when applied at low intensity:

The use of low-intensity BFRT has shown hypertrophy adaptations that can be induced with much lower exercise intensities than traditional paradigms (<50% 1RM). (Pearson & Hussain, 2015).


BFRT is a method widely used by physiotherapists in rehabilitation work. A very recent meta-analysis by Hughes et al (2017) analysed a total of 20 articles where the potential of BFRT use on strength enhancement in rehabilitation patients (ACL reconstruction, knee osteoarthritis, elderly at risk of sarcopenia and patients with myositis) was determined.

Occlusion and Strength Training

The article compared strength gains between the application of low load vs low load training with BFR vs high load.

Training benefitsFigure II. Tree diagram comparing low load training (left) and BFR training (right)

In this first diagram, the results are clearly favourable towards training with BFR.

Favourable resultsFigure III. Tree diagram comparing training with BFR (left) and training with a high load (right)

In this second diagram, the results favour the groups that have trained without occlusion but with a high load. The authors concluded:

Low-load BFR training had a moderate effect of increasing strength (Hedges’ g=0.523, 95% CI 0.263 to 0.784, p<0.001), but was less effective than high-load training (Hedges’ g=0.674, 95% CI 0.296 to 1.052, p0.001). (Hughes et al. 2017)


Occlusion training is a newly emerging tool, so there are still ways of its mechanism of action to be determined before it is fully understood. The conclusions are very varied, but here are a few key points:
  • BFRT is a fantastic tool for generating an increase in muscle hypertrophy and metabolic stress-induced strength without using a high load.
  • BFRT is a very useful tool in populations where training with high loads may be contraindicated, such as the elderly or injured patients.
  • Even though the strength gain is lower than with high load training, the sustainability is greater, as it drastically decreases the risk of suffering an acute injury through working with high intensities.


  1. Hughes, L., Paton, B., Rosenblatt, B., Gissane, C., & Patterson, S. D. (2017). Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis. British Journal of Sports Medicine, 51(13), 1003 LP-1011. Retrieved from http://bjsm.bmj.com/content/51/13/1003.abstract
  2. Krieger, J. W. (2010). Single vs. multiple sets of resistance exercise for muscle hypertrophy: a meta-analysis. Journal of Strength and Conditioning Research, 24(4), 1150–1159. https://doi.org/10.1519/JSC.0b013e3181d4d436
  3. Loenneke, J. P., Wilson, J. M., Marín, P. J., Zourdos, M. C., & Bemben, M. G. (2012). Low intensity blood flow restriction training: a meta-analysis. European Journal of Applied Physiology, 112(5), 1849–1859. https://doi.org/10.1007/s00421-011-2167-x
  4. Pearson, S. J., & Hussain, S. R. (2015). A Review on the Mechanisms of Blood-Flow Restriction Resistance Training-Induced Muscle Hypertrophy. Sports Medicine, 45(2), 187–200. https://doi.org/10.1007/s40279-014-0264-9
  5. Schoenfeld, B. (2016). Science Development Muscle Hypertrophy.

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About Alfredo Valdés
Alfredo Valdés
He is a specialist in metabolic physiopathology training and in the biomolecular effects of food and physical exercise.
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