keep fit vs tune-up

keep fit

noun
  • exercises designed to promote physical fitness if performed regularly. 

  • Organised group aerobics class 

verb
  • To exercise for physical fitness. 

tune-up

noun
  • A series of preparations for vigorous exercise; a warm-up 

  • A series of adjustments to an engine in order to improve its performance 

  • A match or race (frequently one exhibition in nature) contested as preparation for a match or race of high stakes. 

How often have the words keep fit and tune-up occurred in a corpus of books? (source: Google Ngram Viewer )