A kneeling chair is a type of chair for sitting in a position with the thighs dropped to an angle of about 60 to 70 degrees from vertical (as opposed to 90 degrees when sitting in a normal chair), with some of the body's weight supported by the shins.
Despite the name, the posture of a person in a kneeling chair is not the same as kneeling on the ground. It is sometimes assumed that the knees bear most of the body's weight when sitting in a kneeling chair, but this is incorrect – the shins bear some weight for stability, reducing the weight borne by the upper thighs and buttocks, but the body is still sitting, not kneeling. During actual kneeling, most of the weight rests on the knees with feet providing balance against tipping backwards.
A proper kneeling chair creates the open body angle by lowering the angle of the lower body, keeping the spine in alignment and the sitter properly positioned to task . The benefit of this position is that if one leans inward, the body angle remains 90 degrees or wider. One mis-perception regarding kneeling chairs is that the body's weight bears on the knees, and thus users with poor knees cannot use the chair. This mis-perception has led to a generation of kneeling chairs, which vary from the original design, that attempt to correct this by providing a horizontal seating surface with an ancillary knee pad. This design wholly defeats the purpose of the chair. In a proper kneeling chair, some of the weight bears on the shins, not the knees, but the primary function of the shin rests (knee rests) are to keep one from falling forward out of the chair. Most of the weight remains on the buttocks. Another way to keep the body from falling forward is with a saddle chair. This type of seat is generally seen in some sit stand stools, which seek to emulate the riding or saddle position of a horseback rider, the first "job" involving extended periods of sitting.
As in any chair, movement and variation are the key to long term comfort. The human body was built to move, not sit still. As for the kneeling chair, proper understanding of its basic concept and use can lead to a higher level of success. Proper use of the chair involves periodic relief of the bent knees which can easily be accomplished by alternatively flexing or extending each leg from time to time. The original kneeling chairs created by Peter Opsvik like the Variable balans took this into account, and were designed on rocker runners to encourage one leg to be extended to rock the chair. This "movement while seated" concept as well as "open body angle sitting" were developed by Opsvik in the 1960s and 1970s but now, in 2009 are gaining more widespread acceptance by ergonomists and chair manufacturers as being a key component to extended seating success and comfort.
Mass produced kneeling chairs are readily available; the best are adjustable with high-density padding instead of cheaper types of foam.