One reason why winters are so tough on arthritis is that people get less exercise. A lot less. A study of arthritis sufferers in Chicago, a place that knows something about winter, found that they were a third less active in November than they were in June. Essentially, they were spending three more hours a day just sitting around as the days grew shorter and temperatures dropped. And winter hadn't even officially begun.

Exercise eases arthritis pain. It increases strength and flexibility, reduces joint pain, and helps combat fatigue. And clearly the study subjects weren't getting much in November. Cold temperatures and rainfall (but not snowfall) all contributed to this decline. But the greatest factor was the lack of daylight hours later in the year.

Essentially, they were spending three more hours a day just sitting around as the days grew shorter and temperatures dropped. And winter hadn't even officially begun.

The study tracked 241 Chicagoans with arthritis for three years by using accelerometer readings, which measure a person's energy expenditure.

Most of the participants were over 60. All had been diagnosed with knee osteoarthritis or rheumatoid arthritis. Over a three year period, they wore an accelerometer up to six days a week, at three to six-month intervals. Their energy expenditure readings were compared to Chicago's daily weather conditions and the amount of daily sunlight over the three-year period.

Many of the participants would get their exercise from a brisk walk, an idea that was much less appealing during the cold Chicago winter.

The researchers blame part of the decline on a lack of indoor exercise facilities for the urban elderly. Just as cities have food deserts, they also have exercise deserts and the lack of convenient places to exercise grows during the year's colder months. Looking at Chicago specifically, the researchers note that there's a great deal of money spent on outdoor activities for younger and healthier people in the summer but little spent on indoor activities for the elderly in the winter, an inequality they'd like to see addressed.

Does cold weather itself aggravate arthritis? Studies have given conflicting results. Some suggest that cold, damp weather aggravates arthritis while others have found no such link. The current consensus is that the cold makes some people's arthritis worse but not everybody's.

The tendency to get less active and hibernate during the winter isn't just an issue for arthritis sufferers, it seems to affect everyone. And the human body wasn't meant to sit around. Long periods of sitting produce many ill effects. Everybody needs to be aware of and cope with this.

One way is to keep more active indoors. Indoor malls can serve as a replacement site for outdoor walks when the weather gets chilly. And joining a swimming, yoga or dancing class will also keep you active. Exercise doesn't have to be boring. Anything that keeps you moving works.

There's also good reason to spend time outdoors. When going outside, dressing warmly is the key. Dressing in layers traps body heat and helps keep you warm. And since most heat is lost from the extremities, you need to pay special attention to your head, hands and feet. This means a hat, gloves or mittens, and warm shoes with good traction.

Marilyn Monroe beat the summer heat in The Seven Year Itch by keeping her undies in the icebox. You can take the chill off of winter by putting your clothes in the dryer for a few minutes before going outside. This warms them up and make sure you start out nice and toasty. In fact it might even make you want to go outside to cool off.

An article detailing the study appears in the September 2011 issue of the Journal of Physical Activity and Health.