sinew vs tone up

sinew

verb
  • To knit together or make strong with, or as if with, sinews. 

noun
  • That which gives strength or in which strength consists; a supporting factor or member; mainstay. 

  • A cord or tendon of the body. 

  • A cord or string, particularly (music) as of a musical instrument. 

  • Muscular power, muscle; nerve, nervous energy; vigor, vigorous strength. 

tone up

verb
  • To cause to give a higher tone or sound; to give a higher tone to; to make more intense; to heighten; to strengthen. 

  • To firm and strengthen the muscles of the body by regular exercise. 

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