One of the training techniques that Arnold used to build his massive arms was Positions Of Flexion.
This basically means
training each muscle group through different ranges of motion; starting
with a compound mid-range exercise, then moving to an exercise that
works the muscle in the stretched position, and then
finishing off with an exercise that works the muscle in the fully contracted
position.
Hands down this is one of the most effective methods that I have used for maximizing muscle hypertrophy.
At the link below you can see an example of Arnold Schwarzenegger's full Positions Of Flexion Bicep Workout for building sleeve stretching arms! | 
