Her back had stiffened, and her hazel eyes looked steadfastly ahead.

I could see the back of his neck stiffen as he came upon the corpse.

Aton's back stiffened, and Arlo knew that he had made a mistake.

Her back stiffened, but she kept her mouth shut.

Wynn's back stiffened, and she could not contain her anger.

Then his back stiffened as he noticed a sudden change on his board.

Castillo's back stiffened, but he complied without a word of protest.

At one point, her back stiffened, and he figured she'd been told something she hadn't expected.

It encouraged him to talk because his back had stiffened in the night and it hurt truly now.