bend over backwards vs break a sweat

bend over backwards

verb
  • To make a great effort; to take extraordinary care; to go to great lengths. 

  • Used other than figuratively or idiomatically: see bend over, backwards. 

break a sweat

verb
  • To put effort into something. 

  • To start sweating. 

How often have the words bend over backwards and break a sweat occurred in a corpus of books? (source: Google Ngram Viewer )