BFR plus Low Intensity (LI using approximately 25% of normal resistance or 1RM) produces systemic results nearly identical to HIITs (High Intensity Interval Training) and physiological results similar to heavy lifting.
High Intensity and Heavy Lifting result in profound fatigue. When fatiqued, the body has the propensity to fall "out of form" and when it does, injury can result.
Low Intensity - 25% or 1RM
It is highly likely that unless you are a highly trained athlete you really do not know what your One-Rep-Max (1RM) really is and that is ok.
For the purposes of BFR training, lets start by using 25% to 30% of what you normally lift. For example, if you normally do a bicep curl with 40 lbs, start by using just 7.5 lbs to 10 lbs during your workout using the BFR straps.
Believe us, doing the 30 - 15 - 15 - 15 reps for bicep curls, you will experience fatigue.
What is fatigue? We expect that during the last set of 15 reps, somewhere between rep 1 and rep 15, you will feel like you cannot do another curl! However, if you feel that that around rep 7 or 8, next time you workout you should either 1) loosen you BFR bands a little or 2) use less resistance.
Similarily, if you complete the full set of 15 reps without feeling fatigue, next time tighten your straps or add a little weight. It is that easy!