when doing 21s, how do you select the best weight to use..is it close to 1RM or a lighter one...I have never used this technique before, but am not progressing with my usual routine. Also, do you do them at the end of a set or as a stand-alone exercise
you couldnt do 21's with your i rep max.
to shock your bi's into growth they work great...do 2 sets...and whatever weight it takes for you to do them strict...i sometimes do them and i do them like so
7 half way up...7 half way down...7 full reps...you wont need much weight.
your going to be performing 21 reps, albiet not all full reps. So you should be using say around 60% of your 1RM, but it depends on your strength endurance. Ultimately, your gonna have to use a lower weight.