Yes. I've learned to alleviate it by breaking every so often between hits to do a mix of: those arm-circly things from elementary school PE calisthenics, a few yoga poses for shoulders/neck, flapping my arms like a chicken, and if the back is hurting too, I do a full-on Axl Rose move to wiggle the knot out. On the plus side, it also keeps me entertained. Oh, and Squatty's spot-on on making sure to check and re-check your posture every so often.
Okay name twin, I have to note that it's giggleworthy that we both started doing yoga today. I mean, I used to do it, but today was the first day in a long while that I decided "hey, you should do this".