lumbar curvature

They may help by pushing the internal organs against the spine hence alleviating the lumbar curvature but they can't rotate the pelvis backward while in a standing position.

A more recent study from 2008 confirms that "ergonomically designed kneeling chairs set at +20 degrees inclination do maintain standing lumbar curvature to a greater extent than sitting on a standard computer chair."

A 1989 study on a sample of 20 subjects concluded that the Balans chair promoted greater lumbar curvature than the "straight back chair" during relaxed sitting, typing and writing and that it could contribute to treatment of lower back injuries.