intensification vs stretching

intensification

noun
  • The act or process of intensifying, or of making more intense. 

stretching

noun
  • The act by which something is stretched. 

  • A form of physical exercise in which a specific skeletal muscle (or muscle group) is deliberately elongated to its fullest length in order to improve the muscle's felt elasticity and reaffirm comfortable muscle tone. 

adj
  • Requiring a high level of effort or performance. 

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