The Barbell Physio: The Science of Blood Flow Restriction

08 October 2021

The majority of research focuses on looking at strength and hypertrophy gains during BFR training. Research on traditional loading requirements for hypertrophy during weightlifting suggests loads as heavier than 65% of an individual’s one rep max (1rm) must be used to create hypertrophy gains. So a 200lb bench presser must bench at loads greater than 130lbs to create a hypertrophy response.

Research on blood flow restriction training shows that loads as low as 20-30% of 1rm can create the same hypertrophy stimulus!

This is a very significant difference in two specific training goals:

  1. The athlete recovering from an injury or surgery that isn’t able to load the injured tissue with heavy weights. BFR will allow us to get strength & hypertrophy gains even at light loads. One systematic review wrote, “Compared with low-load training, low-load BFR training is more effective, tolerable and therefore a potential clinical rehabilitation tool.”
  2. The athlete already doing a lot of heavy lifting that needs extra hypertrophy work but can’t tolerate adding more heavy volume to their program.
Blood Flow Restriction Hypertrophy

Comparison of traditional high-intensity resistance exercise (HIT) to BFR training and low-intensity training (LI)

Other research looking at strength gains has shown significant increases in strength during BFR training. It’s important to note these strneght gains are less than that seen with heavy loading. But, again, during times where we can’t load heavy this is very promising that we can still get stronger!

Blood Flow Restriction Strength

Comparison of traditional high-intensity resistance exercise (HIT) to BFR training and low-intensity training (LI)

So how does BFR create this hypertrophy and strength stimulus? Let’s first look at a simplified formula for muscle growth:

 

AMOUNT OF MUSCLE GROWTH =

MUSCLE PROTEIN SYNTHESIS – MUSCLE PROTEIN BREAKDOWN

Simply put, if you add more protein to your muscles than you breakdown, you will build muscle. If you breakdown more than you synthesis, you lose muscle.