Flexed sitting posture is commonly adopted in daily sitting activities and when sustained has been proposed to affect biological properties of spinal tissues and act detrimentally on proprioception. The objective of this study by using an optoelectronic motion analysis system was to assess sitting posture regarding the head, spine and pelvis, in healthy individuals; the time effect of flexed posture (FSP) on proprioception and the impact of an MDT (Mechanical Diagnosis and Therapy) procedure on proprioceptive deficit.
Using a cross sectional repeated measures design (N=47) physically active subjects were assessed regarding their habitual sitting posture (HSP), perception of optimal posture (SPOP), ability to adopt an instructed sitting posture (IOSP) and accuracy to reproduce the criterion posture immediately, after 10 and 30 minutes in FSP and after the “slouch-overcorrect” procedure (SOP). Dependent variables were nine sagittal upper body angles.
Results revealed that HSP was more flexed than SPOP and IOSP (p<.05) and SPOP was significantly more flexed than IOSP (p<.05) in most measured angles. There was no significant difference in immediate repositioning to IOSP, while significant differences were identified in the lumbar angle (LU) after 10 minutes in FSP and in LU, head (HE) and cervico-thoracic (CT) angles after 30 minutes in FSP. Repositioning to IOSP after SOP abolished proprioceptive deficit in head and spine. Postural repositioning error showed significant differences for LU and HE angles.
The findings suggest that healthy individuals habitually sit in more flexed posture than SPOP and IOSP. Postural education can be actualized in a reliable way and subjects can adopt an educated posture. Furthermore FSP challenged postural proprioception, but SOP increased proprioceptive accuracy.