We sit upright when seated on a chair initially. This upright position holds for 10 to 20 minutes. The back is tired, the body moves against the backrest. The seated position creates a backward pressure and a downward force. The downward pressure pushes the buttocks forward. Next, we end up sitting on the tailbone and at the edge of the chair.
The spine is transformed into a "C" slouch. The slouch compresses the organs housed in upper chest chamber and muscle strain in the lower back. The discomfort causes one to reposition; (sit upright) only to continue the same vicious cycle minutes later.
We find it hard to sit upright because leaning is part of our sitting culture. In leaning, we rely on the backrest to support our body, thus the unused back muscles become weaker over time. The result is structural collapse, back pain sets in.
The best of "ERGO" chairs with many features provide support to the body but does not encourage movement. The body does little to support itself as is supported by the "ergo" features to maintain proper posture. According to research, the spine stops receiving nourishment from direct blood supply when over the age of 10 years but is kept flexible through exercises and movement.
Sitting on the Ball is an ongoing exercise. When seated on the Ball, the feet, legs, hips, in conjunction with the hamstring and quadriceps muscles, support the body to maintain control of the ball. The neuro system coordinates various parts of the body to balance and maintain stability on the ball. The Ball's unstable surface prompts the user to reposition and maintain balance of body on the ball (encouraging movement). The weak trunk muscles (transverse abdominus and multifidus) supporting the spine, the cause of back pain, work on reflex. Sitting on the Ball stimulates the weak trunk muscles to keep the spine in "S" profile. Slouching is not possible as it causes one to fall off the ball while slumping creates an off balance from the center of Gravity.
Ball sitting strengthens the trunk muscles, improves postural control, keep the nerves, muscles and neuro system (activity center for "Proprioception") constantly on the alert to maintain balance. This ongoing activity burns calories. Bouncing on the ball during breaks help relieve tension and eases muscular spasm.