Blood Flow Restriction Training

Written by Sam Moylan

What is it?

Blood flow restriction (BFR) training is the restriction of blood flow to a targeted limb during exercise. BFR was first used by a Japanese bodybuilder in the 1960’s and was called Kaatsu training. Since then it has spread throughout the health and rehab world with some very exciting research being published in recent years.  BFR training appears to help close the gap between low intensity and high intensity exercise in terms of improvements in strength, hypertrophy and function.

What does it involve?

BFR training is generally performed with low intensity aerobic or resistance exercise, it can also be used passively with no exercise or with electrical stimulation; however we will focus mostly on its more active uses. To restrict blood flow a cuff is applied at the top of the targeted limb, the cuff is then inflated with an aim to occlude 80% of blood flow to the limb. Low intensity resistance exercise is performed at 20-40% 1RM and low intensity aerobic exercise at least 40% below VO2 max.

While 80% of arterial blood flow is restricted, venous outflow is completely blocked, this leads blood pooling in the muscles and subsequent reduction in oxygenated blood in the tissues. This is medically described as ischemia and hypoxia.

How does it work?

On a base level three main things are required to stimulate muscular adaptation:

  1. Mechanical tension
  2. Degree of myotrauma
  3. Metabolic stress

If we look at low intensity exercise it doesn’t meet these parameters:

  1. Low mechanical tension
  2. No/minimal myotrauma
  3. Minimal metabolic stress

High intensity exercise:

  1. High mechanical tension
  2. Degree of myotrauma
  3. High metabolic stress

This is why we see adaptations with high intensity exercise and not with low intensity exercise.

In BFR training, ischemia and hypoxia stimulate anabolic metabolism. This creates metabolic stress which then leads to earlier onset of fatigue and the recruitment of type 2 fast twitch muscle fibers. These fibers have a higher activation threshold and are usually only activated by high intensity exercise.

So BFR training can be used as a ‘bridge’ in those who are limited to low intensity exercise, allowing them to meet the requirements for muscular adaptation without doing high intensity exercise.

How can we apply it?

Low intensity aerobic exercise with BFR

  • Walking/exercise bike with blood flow restriction cuff
  • Has been shown to improve muscle mass, strength and aerobic capacity (fitness)

Abe et al. 2010 – Study on Aerobic Capacity

  • Group 1: 45 min at 40% VO2 max (10 people)
  • Group 2: 15 min at 40% VO2 max with BFR (9 people)
  • 3 x wk for 8 wks
  • BFR group significant improvements in:
    • VO2 max
    • Exercise time to exhaustion
  • No significant change in non-BFR group
  • BFR = better results with less volume of training

Low intensity resistance exercise with BFR

  • Low intensity exercise around 20-30% 1RM, high reps, 5-6 min per exercise
  • Has been shown to improve muscle mass, strength and pain

Hughes et al. 2019

  • Post ACL repair, either standard care (heavy load resistance training – 70% 1RM) or BFR (low intensity resistance) training
  • Tested pre surgery and 3 x post surgery
  • No significant differences between groups in 10RM strength or quadriceps muscle thickness
  • BFR group had significantly higher reported function & greater improvements in balance exercises
  • BFR group had significantly greater improvements in pain, swelling and ROM


BFR training is an exciting form of exercise rehabilitation, and has great value in transitioning an injured person back to full activity. This is due to its ability to improve pain and induce muscular adaptations with a reduced amount of time and effort. BFR can also be used as a warm up prior to a game or a training session for its ability to ease any annoying pains and niggles.

At Darch Physio we have specialised BFR cuffs ready for use. If you are post operation, struggling with an injury that is limiting your ability to exercise, or just have an ongoing niggle, then this may be the bridge that can get you back to doing what you love!


  1. Abe, T., Fujita, S., Nakajima, T., Sakamaki, M., Ozaki, H., Ogasawara, R., … & Ishii, N. (2010). Effects of low-intensity cycle training with restricted leg blood flow on thigh muscle volume and VO2max in young men. Journal of sports science & medicine9(3), 452.
  2. Hughes, L., Rosenblatt, B., Haddad, F., Gissane, C., McCarthy, D., Clarke, T., … & Patterson, S. D. (2019). Comparing the effectiveness of blood flow restriction and traditional heavy load resistance training in the post-surgery rehabilitation of anterior cruciate ligament reconstruction patients: A UK national health service randomised controlled trial. Sports Medicine49(11), 1787-1805.