He gave no sign of having heard, but his body tensed.

He reached into the box again, and his body tensed.

Even before she reached out to touch him, his body tensed.

But the boy's body had tensed for either flight or fight.

He looked over to the living room, his body tensing to take off for the blood supply.

His body tensed, but he did not make a hostile move.

His whole body tensed as if an electric current had run through it.

Then she saw it, and her whole body tensed in shock.

I especially liked the way his body tensed, as if that much pleasure was hard work.

His body tensed as love and desire flooded through him.