Georgia Braxton has long been an avid athlete, pounding the pavement as a runner or leading the rigorous moves during step aerobics class.

Concerned about all the stress on her knees, she took a friend's advice and tried water aerobics.

JENNIFER BRETT/AJC (ENLARGE)

Georgia Braxton, in front, leads students Michelle LaPlaca, left, and Edlaine Cordeiro through a watery workout in one of the pools at Georgia Tech's Campus Recreation Center.

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The petite — but strong — Braxton was such a star student that she eventually became a teacher, and today she leads classes three times a week at a pool in Georgia Tech's Campus Recreation Center.

You'd never dream it, but she can't swim.

"I was so petrified of water," Braxton said. "I've overcome my fear."

A Clinton, S.C. native who now lives in Dallas, Braxton's dry-land job is in the office of Tech's Student Government Association. Her sweet voice is the first thing you hear when dialing the number. In the pool, though, she barks orders like a drill sergeant.

"Stomachs in!" she shouted again and again during a recent evening class.

"I give an aerobic workout, but it's less strenuous on your joints," she said.

Classes, open to Tech students, faculty, staffers and spouses of such, begin with a "jog" from one end of the pool to the other, and include underwater jumping jacks, high kicks and work with resistance arm bands.

"It keeps me energized," said Chaohua Ou, an associate academic professional of instructional technology.

Tech staff member Donna Castenell says she's lost 20 pounds as a result of Braxton's classes. She's had one knee replacement surgery and is due to have a second, and says the low-impact classes have helped her flexibility.

"It's really crucial to helping me recover," she said.

Donna Brown, who is retired from Tech's staff, likes an indoor exercise option during hot weather.

"It's a lot less stressful on my joints," she said.

Braxton, who has been teaching the classes for more than five years, says she's gained stamina and muscle tone. She says she'd love to be able to dive and swim like athletes she sees elsewhere in the recreation center, but so far hasn't taken the plunge.

"I'm more muscle than fat," said Braxton, who does not give her age. "I sink to the bottom every time I've tried."