The results of Blood Flow Restriction (BFR) training during exercise are overwhelming, but how does it work? And is it safe? Read all about it in this new article!
If you haven’t heard about it BFR yet, I’m sure this will change in the near future. Every week new studies are published talking about the great results of BFR. But to understand all the new results of scientific studies, it is important to know the basics. In this article I’ll summarize all you need to know, based on a recent scientific review about Blood Flow Restriction.
What is Blood Flow Restriction Training?
Blood flow restriction (BFR) is a new training method in which you restrict blood flow during exercise. It is also called KAATSU or Vascular Occlusion training. The idea is to restrict blood flow towards the working muscle by using a cuff. This will partially restrict blood inflow and will fully restrict blood outflow. This results in inadequate oxygen supply and blood pooling in the restricted muscle. These conditions create an environment as if you are exercising very hard. Research shows that this will let you gain more results while needing less effort. You can use blood flow restriction training in resistance training, aerobic training and even passively. More on the results later, first some practical tips.
Blood Flow Restriction Cuffs
In BFR, you use a cuff that can increase and decrease pressure like an instrument for measuring blood pressure. Literature tells us that cuff material does not have an impact on the results, but cuff pressure and cuff width do. Since it is not necessary to fully restrict blood inflow, the goal is to add enough pressure to only cease blood outflow. As you can imagine, a bigger muscle needs more pressure to fully restrict blood outflow than a smaller muscle. On the other hand, if you add the large muscle pressure to a small muscle, you’ll experience discomfort.
A good way to determine the right pressure is to first use a pressure that will fully restrict blood in- and outflow (100%). You then decrease the pressure to allow a certain amount of blood inflow. In literature they use and recommend 40-80% of the pressure that will fully restrict blood in- and outflow.
In practice, this means that a smaller cuff width will need more pressure than a larger cuff. In other words, a greater surface area will restrict blood flow faster with less pressure than a small surface. So, don’t use the same pressure when using different cuff widths. If you work with a pressure of 40-80% of full blood flow restriction, the cuff width does not influence the results.
How to use Blood Flow Restriction in Strength and Resistance Training
Typically, BFR training is done with low resistance and high volume. Studies suggest a load of only 20-40% of maximum strength (1RM) and about 75 repetitions across 4 sets (e.g. 30, 15, 15, 15). An alternative you’ll find in research is to not count the reps but do 4 sets of weightlifting until you can’t lift them anymore.
Most studies used short rest periods between sets of only 30 to 60 seconds. Restriction is maintained throughout this period. Recovery between workout days is about 2 days resulting in a frequency of about 2-3 workouts per week.
How to use Blood Flow Restriction in Aerobic Training
Blood flow restricted training in aerobic exercise usually occurs during walking or cycling. Similar to BFR in resistance training, intensities are low at about 40% of VO2max. Restriction time is between 5 and 20 minutes per exercise, with no difference in training frequency and cuff pressure when comparing to resistance training.
When both resistance- and aerobic training are impossible, for instance when having an injury, passive BFR is an option as well. In this case you can’t expect the same results, but it may offset muscle atrophy and strength loss.
What are the Results of Blood Flow Restriction Training?
Research shows greater gains in muscle hypertrophy and strength in blood flow restricted training when comparing to the same low-load resistance exercise without BFR. These results have been observed after only 1-3 weeks. BFR training however has the same or even a little less effect when comparing to high-load resistance exercise without BFR. When it comes to resistance training, the best conclusion for now (!) would therefore be that there are two reasons for choosing BFR training.
- You don’t want to do high-load resistance training, but still want close to similar gains
- You are not able to do high-load resistance training because of an injury, but still want close to similar gains.
The results in BFR for aerobic training are less well documented. Studies again show increase in muscle strength and hypertrophy. Some studies show significant improvements in aerobic capacity but this is not always the case.
Is Blood Flow Restricted Training Safe?
A scientific review summarized the answer to this question as: “the available evidence suggests that the application of BFR does not appear to induce a muscle damage response”. For strengths training it is suggested to “ease an individual into the exercise program”, to see how someone responds to it. For aerobic training, there is too little information to say anything about a possible damage response.
Now you know the basics of Blood Flow Restriction training, we can soon dive into deeper details and results of recent research. Stay tuned!
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Founder of Molab, Human Movement Scientist and a sports enthusiast.