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.
[+ object] : to make (something) smaller in size, amount, number, etc. By exercising often, you can decrease [=reduce, lower] your chance of developing heart disease. The driver decreased her speed as she approached the curve.