The equivalent of baseball's seventh inning stretch is helpful to "desk jockeys," workers who sit a lot on the job, says a Chicago orthopedist.

"Sitting still for long periods of time is not good for the body," says Dr. Gunnar B. Andersson, professor and co-chairman of the department of orthopedics at Rush-Presbyterian-St. Luke's Medical Center in Chicago. "Bones, joints, muscles and other tissues need movement to thrive," he says, suggesting that workers stand and stretch when they take a break.Andersson and his colleagues are studying low back pain in research supported by a grant from Bristol-Myers Squibb Co. and its Zimmer subsidiary.

"People who sit at a desk or a computer terminal all day suffer from posture strain, which can lead to back, neck and shoulder problems," Andersson says. He advises taking a 10-minute break or change of activity for every hour spent sitting still.