A knee chair is used for sitting in a position where your thighs are at an 60 or 70 degree angle from vertical. The shins are holding some of the body weight. A normal chair has your thighs 90 degrees from vertical.
Your knees are not touching the ground. Most people imagine the knees are bearing the weight of the body when using a knee chair but that is not the truth. The shins are actually reducing the weight of the upper thighs and rear, you are still in a sitting position, not a kneeling position. In a kneeling position, most of the weight is on the knees while the feet are balancing from tipping backwards.
The best kneeling office chair allows the body an angle that is open by lowering the lower body angle. This keeps the alignment of the spine and the sitter is positioned correctly to perform their duties.
When you lean forward your body is at a 90 degree angle or more. Most people think the knees bear all the weight and if you have bad knees you can’t use a knee chair but that is incorrect. This had led to many variations of the original design that offer a horizontal seat with an additional knee pad. Actually this defeats the purpose of the kneeling chairs.
Because in a proper knee chair the shins bear some weight and not the knees, the shin rest are meant to stop from falling off the chair. The rear holds the majority of your weight. For another option that will stop from you falling is called a saddle chair. These are similar to saddle that horseback riders use.
The most important feature of any type of chair is comfort and freedom of motion. Humans are meant to move about and not stay in one position. If you understand this idea you will be focusing on the proper functions and features of the kneeling posture chair.
To get the most benefit of the knee chair the bent knees need to be relieved periodically. This can be accomplished by doing simple leg exercises such as alternating flexing and extending each leg.
The first knee chair was invented by Peter Opsvik and were designed on a rocker base which would naturally extend one leg to rock the chair. This encourage movement while you are sitting and open angle sitting. This is becoming more popular by manufacturers and ergonomic practitioners have developed ergonomic kneeling chairs to offer the most comfort and least amount of stress on the body.
Today you can buy a knee chair from many manufacturers that have available many options that are completely adjustable and offer high density padding for comfort and durability.