But it must be understood, that unless designed otherwise, i.e. unless the Units of Analysis are chosen from all people, most studies are generalizable only for a much narrower population of the people w/in a nation, region, city, etc.
exercising - the activity of exerting your muscles in various ways to keep fit; the doctor recommended regular exercise; he did some exercising; the physical exertion required by his work kept him fit. exercise, physical exercise, physical exertion, workout.
Exercise is exertion. noun. Exertion is defined as physical or mental effort, or to the use of force or influence. Doing an extremely hard crossword puzzle that taxes your brain is an example of mental exertion.