energize vs knock out

energize

verb
  • To invigorate; to make energetic. 

  • To supply with energy, especially electricity; to turn on power to (something). 

knock out

verb
  • To exhaust. 

  • To fall asleep, especially suddenly. 

  • To lose the scent of hounds in fox-hunting. 

  • To eliminate from a contest or similar. 

  • To put to sleep. 

  • To complete, especially in haste; knock off. 

  • To render unconscious, as by a blow to the head. 

  • To strike or bump (someone or something) out. 

  • To cause a mechanism to become non-functional by damaging or destroying it. 

  • To communicate (a message) by knocking. 

How often have the words energize and knock out occurred in a corpus of books? (source: Google Ngram Viewer )