Research and ergonomics:

Common causes of lower back pain can be due to bad posture, poor working environment, being overweight and over stimulating the discs. The condition can cause you to get sciatica (nerve root inflammation that causes radiant pain, and numbness, loss of sensation, etc. in the back and thighs down towards the feet) and chronic back pain. Stiffness is common, and is usually the worst in the morning and when sitting through out the majority of the day.

Sitting upright with a straight back and with the thighs parallel to the floor, at 90 degrees, (as on a regular chair) increases the load on the lower part of the disks in the back. A position of 135 degrees (saddle-sitting), however, reduces the pressure on the discs and therefore the blood circulation improves in the body (J Van. 11/28/06).
RELIEF is a brand new saddle chair that is designed to reduce the strain and pressure on the disks, ligaments and muscles. Thanks to the heart-shaped seat, the pressure on the spine has reduced to a minimal when sitting on the chair. The moving seat also enables the back muscles and core stability to be activated and trained during the work day. Together, there features creates the conditions for a strong and healthy back.
The chair is designed to create a work-adapted pilates ball where function, training and relief are combined.

The balancing chair provides a more natural posture and therefore reduces the pressure on the disks (Berglund, 2001). Our bodies are created for movement and physical activity and therefore it does not take long before the body takes damage by sitting incorrectly through out the day. We have combined balance and movement to create the most natural way of sitting to fit everyone’s body conditions.
The chair has a small base and is easy to roll, and follows your movements, which makes it easier for you to perform your tasks in a relaxed manner. David Trippany, who works with the manufacture of office chairs with a focus on ergonomics, believes that flexibility is the key to getting the blood circulation started and kept in movement.
Ergonomists argue that a sitting position with an open hip angle is the most ergonomic, reduces the highest risk of becoming static and promotes a healthier posture (Silva, 2017).  


Read more about ergonomics here:
https://www.autonomous.ai/modernofficefurniture/4-incredible-health-benefits-of-using-a-saddle-chair

https://www.tandfonline.com/doi/full/10.1080/00140139.2012.721521?scroll=top&needAccess=true
 
http://www.dentistrytoday.com/ergonomics/5361-move-to-improve-your-health-the-research-behind-static-postures
 
http://news.bbc.co.uk/2/hi/health/6187080.stm

https://patentimages.storage.googleapis.com/8f/7a/46/34da5acf78b9c2/US8317267.pdf