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.
When we talk about exercise, we nearly always refer to physical exercise. Exercise is the physical exertion of the body-making the body do a physical activity which results in a healthy or healthier level of physical fitness and both physical and mental health. In other words, exercise aims to maintain or enhance our physical fitness and general health.