I know better than anyone that my arms are shit, they allways were shit and still are shit. Though I keep in mind that they both work ok and generally do as they are told, EXEPT GROW and Ive been telling them to grow for most of my life.
I do not and will not except that they will allways be pathetic, so Ive been trying somthing new. This is what Ive been doing.

Tuesdays I train back and biceps and generaly my back allways aches and my biceps or brachialis somtimes do. Ive allways thaught once a muscle aches it should be left to recover, though on the wednesday, thurs, fri and sat, Ive been dragging out that ache from the tuesday session. I have a rusting old armblaster in the garage and Ive been putting it on each day for 3 x20 straight bar curls it feels nice on the allready aching muscle and Ive managed now to keep them aching most of the week alowing Sunday (day of rest) and monday for them to recover for the next Tueday back/bicep session.
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Arms are leanish over 17" but under 18" ATM . We will see.
Experiment