Cross-performance design

Functionally, it ought to move and adjust as simply and naturally as possible. It should support a person in any position he cares to assume, at any task his office job serves up.

Reclining in an Aeron chair

Growing concern about the incidence of repetitive motion disorders and other detrimental effects of computer-related work on the body has led, in recent years, to highly adjustable task seating that supports the body in optimal positions for computer use. Besides the fact that ergonomists have yet to agree on what this optimal position is - some advocate a forward bias, others a rearward tilt - these highly specialised chairs can be problematic for the increasing number of office workers whose days include some hours of intense computer use as well as a variety of other tasks.

Like the time-honoured Swiss army knife, the Aeron chair is a cross-performance tool that answers a variety of needs with a single design. It supports a person in postures for computer-related, task-intensive work, as well a number of other postures for writing, reading, phoning, meeting, or any other task a person cares to be intense about.

Ergonomists agree that the most healthful position for the body is the one it assumes in a weightless state, when no other forces (chairs, gravity, high-heeled shoes) are acting on it. This natural posture has open angles between the trunk and the thighs as well as between the thigh and the lower leg.

Arm movement diagram

It can be achieved in an upright chair with a seat that tilts forward slightly to open the trunk-to-thigh angle and that can be raised high enough to permit an open angle at the knee. This forward-bias position is advocated by Danish surgeon A C Mandal.

A natural, open posture can also be attained in a reclining chair adjusted low enough to prevent undue pressure on the backs of the thighs when the legs are slightly extended. This semi-reclined position was observed by Swiss ergonomist Etienne Grandjean in his studies of VDU workers.


Armrests pivot inward 17.5 degrees to support forearms for keying, and outward 15 degrees to provide a comfortable base for using a mouse. Better positioning and exceptionally soft and supportive armrest pads may reduce the risk of repetitive motion injuries.

The Aeron chair's broad range of seat-height adjustment allows its users to choose either the forward-bias or semi-reclined position - or anywhere in between - over the course of a long day and through a variety of tasks. Its smooth-riding Kinemat tilt mechanism allows people to move between the two extremes with ease while maintaining proper geometric relationships among seat, back and armrests.


Seat height Forward tilt Tilt limiter and tilt lock

Adjust to fit height of worksurface or keyboard, if possible. Feet should rest flat on floor or footrest. Avoid dangling legs, which puts pressure on and restricts blood flow in the back of thighs.

Normally, forward tilt position is used with increased chair height. This relaxes the bend of your waist, knees and ankles. To support back, set tilt limiter after assuming forward position.

If you want to sit in an upright position, set the tilt limiter when the seat is in a horizontal or forward position.


For information about how to adjust your Aeron chair, please see the Aeron User Information (pdf format).

Aeron, Kinemat and Herman Miller are registered trademarks of Herman Miller, Inc.