Ten years ago it was unusual to find the words "arthritis" and "aerobic" in the same sentence. Times are changing, and so are our rheumatologic vocabulary and syntax.In December 1994, Arthritis Care and Research published a topical issue on exercise and arthritis. Participants in the American College of Rheumatology and Association of Rheumatology Health Professionals annual meetings in San Francisco this past fall had the opportunity to attend a plenary session reporting the results of a study of aerobic walking for persons with osteoarthritis (OA) of the knee (1). In this issue of Arthritis Care and Research, we find a review of resistance exercise for persons with rheumatoid arthritis (RA) by Rall and Roubenoff (2). Pumping iron and aerobic weight-bearing exercise performed by persons with arthritis are no longer radical notions. A number of events have led us to this point and challenge us to further explore exercise and physical fitness within the context of rheumatic disease processes and outcomes.Early reports that persons with arthritis were less fit than their nonaffected peers (3) have been followed by prospective trials demonstrating that persons with both systemic inflammatory disease and OA could participate in aerobic, conditioning exercise programs at levels of intensity sufficient to produce improvements in function, cardiovascular health, and fitness without aggravation of disease signs and symptoms (4,5 physical condition because of the disease itself; that the presence of rheumatic disease precluded meaningful exercise stress testing; that persons with arthritis could not safely participate in exercise vigorous enough to produce a training effect, and that weightbearing exercise was not appropriate for persons with lower extremity joint involvement.As a result of research reported over the past 20 years, we now know that persons with various forms of arthritis can: 1) undergo meaningful diagnostic and prescriptive exercise stress testing; 2) participate in regular conditioning exercise programs of moderate intensity, using exercise modes such as walking, aquatic exercise, stationary bicycle, low-impact aerobic dance, and resistance training; and 3) achieve clinically meaningful improvements in cardiovascular health and fitness, muscle strength and endurance, flexibility, function, and psychosocial status without injury or aggravation of disease.In addition to the general health and function benefits, cumulative experience with various modes of exercise in patients with various diagnoses is beginning to indicate that there may be differential effects of exercise. For persons with RA, range of motion exercise performed in the evening (6) and thrice-weekly aquatic aerobic routine both produced significant reductions in morning stiffness. However, in a study comparing aquatic to land-based exercise, increases in range of motion were greater for exercise on land (7). Aerobic aquatic classes have been associated with significant short-term improvements in depression and anxiety, whereas walking was ...