aerobics vs cardio

aerobics

noun
  • A form of exercise, designed to enhance one's cardiovascular fitness, normally performed to music. 

cardio

noun
  • Exercise with the goal of raising the heart rate. 

adj
  • Cardiovascular; pertaining to the health of the circulatory and respiratory systems. 

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