Anything vigorous is done with force and energy. Vigorous exercise makes you sweat, and a vigorous denial makes someone else sweat.
Vigorous is a description for something strong or enthusiastic. It comes from the French word vigour, meaning "liveliness, activity." An active, physically energetic person is vigorous, and mental activities can be vigorous too, when they require a lot of mental effort. A vigorous argument doesn’t have to include physical wrestling; it just might involve verbal sparring.