I dunno man. Sounds like a good reason not to do shrugs to me...lol.
What can I say though? I did heavy GM's last week followed by squats...then hurt my back while warming up on calf raises...lol. I went on to set a PR on the Conans Wheel and carried 375 farmers and picked up some heavy stones. Not sure what gave on the calf raises either.
Seriously...it couldn't hurt to do some gm's on a weekly basis, train the abs for strength, and hit those back extension hard again.
B True