21’s is a power workout for the biceps, indeed and it has to be done standing up.
You will have to do 21 counts of bicep curls using barbells or dumbbells – up to you.
The first seven counts are from all the way down to your thighs and work it up to your waist area.
After that, another seven counts from the waist and curling up to your shoulders.
The last seven counts are from all the way down to all the way up.
This should be really good for your biceps.
(It is recommended by fitness experts that you do this workout first for your biceps before anything else.)