you can do it either way but i prefer 21s you start at 180 degrees which is arm straight down and lift to 90 degrees you do this 7 times each hand then you lift 90 degrees to 0 degrees 7 times then 180 degrees to 0 7 times but if you dont do these i prefer 180 degrees for it gets all the muscles or you the same thing s the 21s just take out the 3rd step and go up to 10 reps instead of 7