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.
Quick Answer. Strenuous exercise is scientifically defined as any activity that expends 7 metabolic equivalents (METS) per minute or more, according to the 2008 Physical Activity Guidelines for Adults issued by the Department of Health and Human Services.