Dorothy Dunlop, Northwestern University – Older Adults, Exercise and Arthritis

Is merely being active enough, or is there a right way to stay in motion?

Dorothy Dunlop, professor of medicine at Northwestern University, explores this question.

Dr. Dunlop is a health services researcher with expertise in statistical methodology. Her applied research interests include the investigation of physical activity to prevent disability in older adults and to understand the consequences of arthritis and other musculoskeletal disorders. She co-authored a book on statistical methodology; she has published and applied statistical methods for analyzing longitudinal data. Dr. Dunlop is the principle investigator on an NIH-funded epidemiologic study on the relationship of physical activity to reduce disability and an NIH-funded study to evaluate the cost effectiveness of a physical activity intervention. She has served on data safety monitoring boards, on executive committees of federally funded clinical trials, and on the editorial boards of medical journals.

Older Adults, Exercise and Arthritis


Older adults with arthritis need to keep moving to stay functioning.  But few are active enough to meet the physical activity guideline of 2 ½ hours a week of moderate activity recommended to prevent serious illness.  We investigated if there were a less demanding goal to motivate people to start moving.  We wanted to know how much activity would simply support future function.  The answer was 45 minutes each week of moderate activity, like brisk walking. 

We evaluated over 1600 adults from a national study called the Osteoarthritis Initiative. They had pain, aching or stiffness in their knees or hips.  Their physical activity was measured by a sophisticated monitor.   After 2 years, only 1/3 improved their function or maintained high function compared to baseline.   Doing light activities like pushing a grocery cart helped people have better function. But those who also did moderate activities like brisk walking did better. People who spent at least 45 minutes in moderate activity were 80 percent more likely to improve or maintain high future function compared with those who did less.  The 45 minute a week threshold held for both women and men. 

This evidence-based 45 minutes a week threshold of moderate activity is a first step.  It does not replace the recommended 2 ½ hour physical activity guideline which supports other benefits like heart health.  45 minutes a week is a starting point towards that goal. What is important is to begin moving.

Our advice is to stay as active as possible.  But even a little activity is better than none.


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