It is now clear that
regular physical activity—bodily movement that is produced by the
contraction of skeletal muscle and that substantially increases energy
expenditure—reduces the risk for coronary heart disease, diabetes,
colon cancer, and several other major chronic diseases and
conditions.1 Exercise, as a subset of physical
activity,1 is planned, structured, and repetitive bodily
movement done to improve or maintain 1 or more components of physical
fitness. For many people, the New Year's resolutions to get more
exercise have been on target. How to get that exercise or, to use
today's favored terminology, physical activity, is the subject of 2
articles in this issue of THE
JOURNAL.2,3 Since the term
aerobics was first adopted as a popular description for
endurance exercise in the 1960s, the health and fitness benefits of 20
or more minutes per day of vigorous exercise such as jogging, swimming,
or cycling have been touted.1,4 However, during the past 5
years, there has been a reassessment of the original epidemiologic
evidence linking physical activity with health and a growing body of
new research demonstrating that lesser quantities and intensities of
exercise or physical activity also lead to health
benefits.1,5 Publications of the surgeon general, National
Institutes of Health, Centers for Disease Control and Prevention, and
American College of Sports Medicine have focused on the important role
that moderate-intensity physical activity plays in improving and
maintaining good health.1,5,6