Traditional strength training requires an individual to utilize resistance at least 65% of their 1 repetition maximum. This means if you can maximally lift 100 pounds you need to lift at least 65 pounds to see a gain in your muscle size.
With the localized and systemic release of specific hormones in addition to other factors related to muscle growth during BFR, an individual only has to lift 20 to 30% of their 1 repetition maximum. In the previous scenario this means you only have to lift 20 – 30 pounds.
65% non-BFR. 20 – 30% BFR