The chair can be a crucial factor in preventing back pain as
well as in improving employee performance in office work. As the
majority of office workers spend most of their time sitting, a
properly designed and adjustable chair for comfort, efficiency, and
for the task being performed is critical. All adjustments should
easily be made from the seated position. Specific chair criteria are
discussed in the following paragraphs.
When an employee spends from 6 to 8 hours in the
chair, the height of the chair and the work surface are critical.
The human body dimension that provides a starting point for
determining correct chair height is the "popliteal" height. This is
the height from the floor to the point at the crease behind the
knee. The chair height is correct when the entire sole of the foot
can rest on the floor or footrest and the back of the knee is
slightly higher than the seat of the chair. This allows the blood to
circulate freely in the legs and feet.
Size and shape are two factors to consider in the
design of the seatpan of the chair. The seatpan should be slightly
concave with a softly padded, rounded, or "waterfall" edge. This
will help distribute the weight and may also prevent sliding forward
in the chair. The angle of the seatpan should also be considered.
Some options include a seatpan that slopes slightly down at the back
or one that has a forward tilt that produces less stress on the
Armrests should be low and short enough to fit under work
surfaces to allow users to get close enough to the work surface.
Chairs can be purchased with adjustable armrests.
A proper backrest should support the entire back including
the lower region. The seat and backrest of the chair should support
a comfortable posture that permits frequent variations in the
sitting position. The backrest angle and chair height should be