Impact of an ergonomic seat on the stand-to-sit strategy in healthy subjects: Spinal and lower limbs kinematics.

PURPOSE: To assess differences in spinal, pelvic and lower limb parameters in healthy individuals during a stand-to-sit task using three different seating conditions.

METHODS

Ten healthy adults carried out three stand-to-sit movements on different stools: a high ergonomic stool with the seat tilted 10° forward; a standard stool (adjusted to the same height as the ergonomic stool) and a standard stool at a lower level (so their thighs were horizontal). Movements were recorded by an optoelectronic Vicon system.

RESULTS

Hip flexion was altered by the height of the seat (significantly greater for the low standard stool in comparison to either the ergonomic stool or the high standard stool (p < 0.0001)). There was also significantly less knee flexion with the ergonomic stool in comparison to the low standard stool (p < 0.0001) and to the high standard stool (p = 0.0017). Lumbar lordosis was not significantly altered by seat height, although it was less pronounced with the ergonomic stool, with a significantly higher range of motion for the pelvis (p = 0.015). At the thoracic level, no differences were observed, except that the stand-to-sit movement on the lower stool produced greater flexion.

CONCLUSION

Lumbar lordosis was not increased by the ergonomic stool and the range of lower limb motion was reduced by the high seat. These findings contrast with current opinion that ergonomic seats promote lumbar lordosis.