put one's back into vs strive

put one's back into

verb
  • Synonym of strive: to apply oneself. 

strive

verb
  • To try to achieve a result; to make strenuous effort; to try earnestly and persistently. 

  • To struggle in opposition; to be in contention or dispute; to contend; to contest. 

  • To vie; to compete as a rival. 

How often have the words put one's back into and strive occurred in a corpus of books? (source: Google Ngram Viewer )