isometrics vs exercising

isometrics and exercising both are nouns.

Word	Noun	Adjective	Verb	Adverb
isometrics	Yes	No	No	No
exercising	Yes	No	No	No

As nouns, exercising is a hypernym of isometrics; that is, exercising is a word with a broader meaning than isometrics:

isometrics: muscle-building exercises (or a system of musclebuilding exercises) involving muscular contractions against resistance without movement (the muscles contracts but the length of the muscle does not change)
exercising: the activity of exerting your muscles in various ways to keep fit

Other hypernyms of isometrics include exercise, physical exercise, physical exertion, workout.

isometrics (noun)	exercising (noun)
muscle-building exercises (or a system of musclebuilding exercises) involving muscular contractions against resistance without movement (the muscles contracts but the length of the muscle does not change)	the activity of exerting your muscles in various ways to keep fit