constrained vs strained

constrained

adj
  • Forced; compelled. 

  • Kept within close bounds; confined. 

strained

adj
  • Forced through a strainer. 

  • Under tension; tense. 

  • Not natural or spontaneous but done with effort 

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