forward roll vs swaying

forward roll

noun
  • A movement in which one's body is rolled forward, by putting the head on the ground and swinging the legs over the head. 

swaying

noun
  • The motion of something that sways. 

  • An injury caused to a horse's back by violent strains or overloading. 

How often have the words forward roll and swaying occurred in a corpus of books? (source: Google Ngram Viewer )