impediment vs shot in the arm

impediment

noun
  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

  • A hindrance; that which impedes or obstructs progress. 

shot in the arm

noun
  • An injection of a drug into the arm, whether for medical or recreational purposes. 

  • A stimulus; a boost in energy, morale, or well-being. 

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