Walking in water.

Peggy can't walk, at least not on land. The 56-year-old wife, mother, and former registered nurse was diagnosed with MS 14 years ago. She has been using a scooter for the past eight years. She can still stand up for two to three minutes at a time--long enough to brush her teeth--and she can even drag her feet the short distance from her bedroom to the bathroom, as long as she's holding on to something.

That all changes when she's in a swimming pool. Not only can she swim and exercise, but when she's in cold, chest-high water, Peggy can pick up her foot and put it back down. She can walk.

The benefits of cold-water exercise have many people with MS heading for swimming pools. They go for recreation, they go because swimming is good exercise, and they go because the cold water is an ideal place for them to work out, since one of the classic symptoms of MS is sensitivity to heat.

Away from the heat, sipping coffee and eating carrot cake in her air-conditioned kitchen, Peggy looks strong and energetic. She has feathery black and gray hair, a contagious smile, and the ability to talk nonstop for long stretches. She sits as erect as a bird on a perch, her scooter the only outward sign of her MS.

Exercise has the same benefits for people with MS that it has for everyone. But people with poor balance, impaired coordination, and difficulty walking--not to mention just standing up unassisted--need to exercise with care. They' re at risk of injuring themselves.

The risk diminishes in a swimming pool. You won't fall and break a bone if you lose your balance. You' re working with less than 20% of your full body weight, which is why Peggy can lift her foot--it just doesn't weigh as much in the water. The cooling effect of 85[degrees] Fahrenheit--the temperature of a typical swimming pool, and more than 10[degrees] cooler than human body temperature--also makes it possible to be active without overheating: the water continuously lowers the body heat generated by the exercise.

The first aquatics programs for people with disabilities in this country were developed for people with arthritis and polio back in the early 20th century. Franklin D. Roosevelt, who contracted polio at the age of 39, discovered the rejuvenating properties of water eight years before he was elected President, when he visited the Meriwether Inn Resort in Warm Springs, Georgia. He ended up buying the place, and the Georgia Warm Springs Foundation was established to treat people with polio. Renamed the Roosevelt Warm Springs Institute for Rehabilitation, it is now operated by the state of Georgia, and serves people with a wide range of disabilities.

The Fairfax County Park Authority in Northern Virginia where Peggy lives offers a comprehensive adapted exercise program for people with disabilities. It includes land-based classes--such as yoga, stretching, and exercises for seated people--and water-based exercise classes and swimming. The program was set up about 20 years ago in response to requests from the community.

Peggy was one of the first students in Bryna Helfer's class. "Having an instructor like Bryna has made all the difference in the world. She has such a positive attitude," Peggy's husband, Dan, said.

Helfer, a therapeutic recreational specialist, has been working in adapted aquatics since she was 16 years old, when she started out as a volunteer. She has been teaching adapted aquatics classes for Fairfax County for the past 10 years. Most people in her class have a neurological problem, but it's a mixed group: MS, chronic pain, and visual impairment.

Helfer counsels students and volunteers before they get in the pool. She knows all her students' limitations and cautions people not to overdo it. Some students do walking exercises--forward, backward, and sideways to ensure that they use as many different muscles as possible. Others do leg and arm lifts, using the resistance of the water to press against their muscles. Some use lightweight dumbbells.

People don't have to swim if they don't want to. If they do, Helfer teaches them some tricks to make it easier. She taught Peggy how to do the front crawl without kicking her legs. Then she taught her how to roll over on her back and do a butterfly stroke. That way she can be face up and relax a little if she's tired. It's also a good safety procedure in case she gets a mouthful of water.

Jean Skinner, who is adapted aquatics supervisor for the Fairfax County Park Authority, organizes the exercise classes and recruits and trains all the instructors.

"I've done a lot of MS awareness days for families," she said. "Whoever has MS in the family might not be able to get out there and kick a soccer ball around, but they can all go swimming together. Water is magical."

For people who sit most of the day, walking or even just floating in the water helps the circulation in the lower part of their bodies. The benefits follow people home in the form of improved endurance and flexibility, plus the self-esteem and sense of accomplishment that go hand in hand with a good physical workout.

"I've met a lot of people at the pool, too," Peggy said. Is socializing an important component of the aquatics class?

"Big time," Dan said.

Peggy nodded. "It gives me an emotional high. It's something normal people do."

Cay Butler is a freelance science and nature writer living in Virginia.