This article is from the Ergonomics and Typing Injury FAQ, by Dan Wallach firstname.lastname@example.org with numerous contributions by others.
A. Expensive motors and adjustable sections are not necessary if the
backrest has firm support for the inward curve of the lower spine (lumbar)
and outward curve of the upper spine (thoracic). Wether you need upper
body support to help keep your torso and head vertical is a matter of