title: What is exercise? A primer for practitioners.
abstract: Physical exercise has proven to be an extremely useful tool in health enhancement, health maintenance, and rehabilitation in addition to its role in conditioning for competitive sports. Exercise is defined as activity that involves the generation of force by the activated muscles. While various sport activities and events involve a wide range of metabolic power production, exercise for fitness and health occupies two discrete areas of the power scale: relatively low intensity that promotes cardiovascular or aerobic fitness and very high intensity that develops strength and maximal power. In both cases, exercise intensity can be quantified and prescribed in highly definitive terms.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, 02114-1198, USA. hknuttgen@partners.org.
authors.forename: Howard G
authors.initials: HG
authors.lastname: Knuttgen