I'm a reasonably strong and capable woman. Recently, I've started to turn a corner in my playing and can lead a set in our local session. And I don't know if it's because I used to play tunes twice over and now do it thrice or even four times (if the situation calls for it), but my upper arms (deltoids/triceps) feel like overcooked spaghetti noodles at the end of an exuberant set. Muscle fatigue via polkas, I guess.
Any suggestions on excercises to strenghthen the pushing and pulling muscles?