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.
In an ideal world, people would be physically active and fit. However, people often confuse the difference between physical activity and exercise. Physical activity includes body movement that utilizes muscles and requires more energy than rest. Examples include gardening, raking the leaves, vacuuming and grocery shopping. Exercise is a form of physical activity that is planned, structured and maintains your heart rate at a certain level for a specific length of time. This includes group fitness classes, jogging, lifting weights or swimming.