Etymology: Modern English.
1 : arm and shoulder strain suffered by a new user of Nintendo’s Wii video game system, caused by the multiple and sudden arm movements required to play games on the Wii.
Your arm begins to ache, and somewhat burn slightly... Using your arm for any kind of quick movements, or outstretching of the arm generates pain.
sort of like a trucker's tan.
Did you see Stephens wii arm? He can lift, like, 115 lbs. with it now! But its really awkward cuz his other arm is totally useless.