Figure 1 Distorted sitting posture with lumbar support.

Lumbar support can only firmly contact one’s lower back in a reclined posture (Figure 1). However, such a reclined posture results in an unhealthy backwards displacement of the upper trunk behind the hips.

In order to maintain contact with the lumbar support while using the microscope or microtome, the common postural distortion involves rounding the upper back and shoulders, and bending the head and neck excessively forward. Maintaining this distorted posture increases stress to the neck, upper back, and mid-back.
Using lumbar support is also a passive sitting posture, resulting in a relaxation and overstretching of the deep lower abdominal muscles. Over time, the gradual loss of lower abdominal muscle tone from sitting with lumbar support increases the compressive stress on the lower back.
As almost every so-called “ergonomic” chair features lumbar support and a reclining backrest, these chairs are not only ineffective in promoting a healthy upright posture, they are also a major factor in the very high incidence of back and neck pain among microscope and microtome users!

The ZACKBACK Chair promotes one's optimal healthy, upright posture by stabilizing two key areas ignored by chairs with lumbar support and reclining backrests: the pelvis and the rib cage (Figure 2).

• ZACKBACK’s Sacral Support (adjustable in height, depth, and angle) reduces stress to the lower back by stabilizing the pelvis in its proper neutral position and promoting activation of the deep lower abdominal muscles.
• ZACKBACK’s Lower Thoracic Support (adjustable in height and depth) reduces stress to the mid-back, upper back, and neck by elevating the rib cage, elongating the spine, and properly aligning the head, neck, upper back, and shoulders. This support also reduces fatigue and increases alertness at the microscope and microtome by promoting proper diaphragmatic breathing.

These dramatic results are possible because ZACKBACK’s Lower Thoracic Support moves independently forward to firmly support the user’s back in a healthy upright posture. In traditional “ergonomic” chairs with lumbar support and reclining backrests, the microscope/microtome user is forced to pull away from the backrest in order to sit upright. The end result is a slumped posture, the posture with the greatest risk for developing back, neck, and upper extremity pain!

Forward-Leaning Work Posture

If the microscope/microtome user is forced to assume a forward-leaning work posture, no lumbar support is possible. However, unlike lumbar support, sacral support can still provide proper pelvic and spinal stabilization in a forward-leaning posture (Figure 3).

As noted by Cotton in 1904, when leaning forward there is a slight rocking over the ischial tuberosities, and a tendency for the pelvis to slide backward on the seat. The combination of proper sacral support from the ZACKBACK chair, along with an open space below the sacral support for the buttocks, allows the microscope/microtome user to still obtain sacral support in a forward-leaning posture.

References
Cotton, F.J.: School furniture for Boston schools. American Physical Education Review, 9:267-284, 1904.

Remember . . . ZACKBACK is guaranteed to relieve your pain and improve your posture more effectively than any other chair!

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