However, instead of chairs, her students sit on exercise balls. Several elementary school buildings in Howell Public Schools have been joining this trend.

Whether students or adults are sitting on traditional chairs or using core strength to balance on exercise balls, she said, everyone needs to stand and move around after 20 to 30 minutes of sitting.

A 2006 study by a different group of researchers from the same university was even more damning. That group had volunteers sit for 30 minutes each on an exercise ball and a wooden stool.

One of these solutions is switching to exercise balls when it comes to sitting. It is an excellent way to engage the core of the body, correct the back’s posture, and have some fun along the way.

The trouble is, the ball only works if you sit up straight—which most people don't. Dr. Nick Shamie, an associate professor of spine surgery at the University of California, Los Angeles ...

Most people with rheumatoid arthritis need to improve stability, balance, and core strength. An exercise ball can help you work on all three aspects. Learn how to get started.

“For one, people tend to slouch and use poor posture, and sitting in a chair puts your abs on ‘slack’ and decreases core strength. Using an exercise ball counteracts both of these things.” ...

Key Specs Colors: 7 Sizes: 5 Pump Included: Yes This is one of the most affordable exercise balls on our list at only $13. It has an anti-slip design and is resistant to bursting, though reviewers ...

THE BOTTOM LINE Sitting on an exercise ball burns more energy than sitting on an office chair, but the evidence that it improves posture is lacking. scitimes@nytimes.com ...

Tighten Up Your Tush With 3 Exercise-Ball Moves Sizing and Sitting You need to buy the correct size ball for your height. The diameter of the ball makes all the difference — size does matter.