I heard a movie description
With the reindeer's legs churning, they fly directly toward the moon.
Can a galloping/running ungulate be described as "legs churning"? Or did I hear it wrong? I don't think it's journeying either, because a person journeys, not legs. I am putting the audio clip here (uploaded to an audio sharing site Clyp) for reference.
Also what are other verbs that describe the legs of a galloping four-legged animal like shown in this pic?