The unique lower thoracic support of the ZACKBACK chair immediately promotes proper diaphragmatic breathing. Leaning against other so-called ergonomic backrests restricts diaphragmatic breathing and promotes unhealthy upper chest breathing. This results in overuse of the scalene muscles, a major cause of neck pain, referred arm pain, thoracic outlet syndrome, and fatigue
The unique, multi-adjustable, dual back support system of the ZACKBACK chair elongates (lengthens) your spine for healthy, elegant posture. Chairs with lumbar support shorten and distort your spine! Elongation gives a feeling of weightlessness to your lower back when sitting. Lumbar support gives a feeling of compression to your lower back when sitting.
More information: http://www.yogaback.com/zackback/zackback.html