Sentence:  It is the gait of the human who must run to live : arms dangling , legs barely swinging over the ground , head hung down and only occasionally <WSD>swinging</WSD> up to see the target , a loose motion that is just short of stumbling and yet is wonderfully graceful . 
Meaning of the word marked with <WSD> tags:  move in a curve or arc, usually with the intent of hitting