Sitter-Selected Postures in an Office Chair with Minimal Task Constraints

Studies of office workers' postures indicate that reclined postures are less common than upright or forward-leaning postures. Laboratory studies have shown that back extensor activity and internal pressure in the lumbar intervertebral disks are lower in reclined postures. Given these advantages, why don't workers recline more often? Postural constraints imposed by their work, particularly vision and hand-reach requirements, may preclude more upright postures. In a study at a large office facility, side-view photographs were used to measure the postures that 80 men and women chose when sitting in an office chair without a work task. All sitters chose substantially reclined postures, with backrest angles averaging 25 degrees from vertical. The findings provide evidence that office work should be designed such that workers can sit more frequently with the reclined torso postures that they would choose if they were not working.