Other times two guys were literally running up each other's back in transition.

A few seconds later the barrel of the revolver ran up my back.

Then she turns the water cold and watches a shudder run up his back.

A sudden shiver ran up her back at that thought.

Retch sprang through the door, with me running up his back.

Ice that had nothing to do with the weather ran up his back.

"And it just makes the chills run up my back."

Not a claw, she thought as a chill ran up her back.

Her voice was a thing to make warm waves run up your back.

Perhaps by then the nagging chill I feel running up my back will be gone.