Especially form the stabilizer muscles. Those objects are awkward and unbalanced. I was a granite worker for a few works and had to move some crazy big pieces and it was tough. Very hard.
Member of DaJoGen MMA school under Dave Hagen and Team Chaos fight team under Denver Mangiyatan and Chris Toquero, ran out of Zanshin Martial Arts in Salem Oregon: http://www.zanshinarts.org/Home.aspx