D. H.Wickett, R. Mootanah, D. Gordon
Bioengineering Research Group, Department of Design & Technology/Anglia Ruskin University, Chelmsford, UK
Unit for Sport and Exercise Sciences, Department of Life Sciences/Anglia Ruskin University, Cambridge, UK
The Kirton Healthcare Group Ltd, Haverhill, Suffolk, UK

This study is part of a series of investigations aimed at quantifying some of the effects of reclinable seating, with particular focus on lower back pain. A multi-adjustable test-rig was built for the investigations. The postures measured were a relaxed upright sitting posture, a standard recline posture, three different tilt-in-space postures and lying supine. Measurements were made to quantify changes in intervertebral disc pressure, using a stadiometer to measure spinal shrinkage.

Measurements were also made to quantify changes in muscle activity of the back muscles using surface electromyography (EMG). Significant differences were found for spinal recovery T = 3, p < .01, r = -.76. Initial results from the EMG are reported and show some significant differences between the postures however these were not consistent across all of the muscle groups. The results with the highest statistical power were recorded for the longissimus muscle group. For this muscle group, significantly more workload was found for the tilt-in-space postures. In most cases there was a high significance and effect size, T = 0, p < .01, r = -.88.

In general, the results recorded for the other muscle groups were in agreement with the stadiometry results such that they could be explained by changes in spinal loading. 15 volunteers were tested, 7 male and 8 female, mean age 42 years (29-56 years). This study has demonstrated that tilt-in-space postures are effective in reducing spinal load, resulting in an improvement of disc recovery. However, initial results from the EMG study suggest that for some muscle groups acting on the spine, tilt-in-space postures can increase muscle activity. Hence, there is need for however ffurther investigation is required to identify the exact parameterss.

Based on these results alone, a tilt-in-space recline which articulates the upper body to maintain good head position and sense of orientation could provide an optimum solution.

Corresponding author: D. H.Wickett
Email: davidwickett@kirtonhealthcare.co.uk