The effect of task asymmetry, age and gender on dynamic trunk motion characteristics during repetitive trunk flexion and extension in a large normal population

Management of low back pain (LBP) has remained a major challenge to both clinical and engineering communities. With present technology, the lack of anatomical finding in a majority of LBD patients has increased the interest in objective quantification of trunk performance from all areas of rehabilitation: diagnosis, treatment, disability evaluation, return to work determination, ergonomic intervention and prevention. Different dimensions of trunk performance have been quantified with a diverse set of technologies. It is essential that a normative database be established to facilitate the use of these quantitative measures in both the ergonomics and rehabilitation fields. The present study provides a new technique to measure dynamic trunk performance characteristics during repetitive flexion and extension of the trunk at the preferred speed in a large, healthy population (N=351). The effects of task asymmetry, gender and age on these dynamic parameters were investigated. Significant results were found due to task asymmetry, age and gender on dynamic parameters of trunk performance. The higher derivative motion parameters such as velocity and acceleration were more sensitive to the main effects than the range of motion. In general, increased asymmetry and age caused diminished dynamic trunk capability. These results were compared to an industrial surveillance study that identified the injurious levels of high trunk velocity and acceleration. Clinically, these results have provided the basis for quantifying the extent of trunk dysfunction of patients with different low back disorder diagnoses