invigorate vs overstrain

invigorate

verb
  • To impart vigor, strength, or vitality to. 

  • To heighten or intensify. 

  • To make lively. 

  • To give life or energy to. 

overstrain

verb
  • To subject to an excessive demand on strength, resources, abilities, or the imagination. 

noun
  • excessive strain 

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