Although she has had crippling rheumatoid arthritis for more than 40 years, Maria Johnson doesn’t like to focus on her disease.

Her hands are misshapen, and her left shoulder movement is limited, but she stays upbeat.

Her positive attitude comes from exercise, she said.

“When I wake up in the morning, I am tired,” said Johnson of Corpus Christi, Tex. “But after exercise, I am energized.”

Sufferers of chronic joint pain sometimes think they can’t exercise or risk further injury or inflammation. Doctors even didn’t understand the importance of exercise, said Dr. Jack Klippel, medical director of the Arthritis Foundation.

But studies in the past 10 years have shown that exercise actually improves joint pain and movement, Klippel said.

The reality is “use it or lose it.”

Johnson and Kathy Wheeler, director of the Corpus Christi chapter of the Lupus Foundation, are organizing exercise groups to teach exercises specifically adapted for people with joint pain or injuries. Joint pain is common in people with rheumatoid arthritis, osteoarthritis, fibromyalgia or lupus.

Wheeler and Johnson teach “PACE” classes, which stands for “People with Arthritis Can Exercise,” a program created by the Arthritis Foundation.

Part of the program includes a workout while sitting in a chair. While it doesn’t sound too strenuous, sitting exercises allow people with limited movement to get a fairly good cardiovascular workout.

Chair exercise classes are offered at the Lawrence Senior Center, 745 Vt., at no charge. The classes are from 10:30 a.m. to 11 a.m. Wednesdays and Fridays. Call 842-0543 for more information.

A chair workout is similar to regular aerobics. The classes stretch before and after, and they do cardiovascular exercises for at least 15-20 minutes, Johnson said.

PACE classes include one important element that regular aerobics do not: They highlight fine motor skills, like opening and closing the mouth, playing a piano, scratching and lifting the foot as if putting on shoes.

It all comes back to the “use it or lose it” premise, Johnson said. Each joint needs to be flexed several times so it will stay flexible.

Exercise helps people with joint problems by keeping the joints moving, strengthening supporting muscles, increasing range-of-motion and flexibility, increasing self-esteem and improving circulation, Klippel said.

“The problem with arthritis is that it’s painful to move a joint,” Klippel said. “The tendency is to not move it. What that leads to over time is loss of muscle, then they’re unable to move a joint, simply because they don’t have the muscle.”

Johnson leads her seated class through neck, back, leg and arm stretches. Feet should be kept firmly on the floor during most exercises, she said.

Then comes the hard part: marching in place while seated. If the left arm is up, the right leg should be lifted, too, Johnson said. Then switch, just like a march. Keep a rapid pace. After a few minutes, she switches to arm punches and leg kicks, again using opposite arms and legs, then “crunches” where opposite legs are brought to the elbow at about stomach level.

The movements can be modified according to a person’s mobility, she said; what’s important is to keep active for at least 15 minutes or so.

“People with chronic illness have so many problems — depression, anger — it helps to interact with other people,” Wheeler said. “You see people come and change, like a flower emerging and brightening.”