The influence of different sitting postures on head/neck posture and muscle activity.

To date the influence that specific sitting posture has on the head/neck posture and cervico-thoracic muscle activity has been insufficiently investigated. Therefore the aim of this study was to investigate whether three different thoraco-lumbar sitting postures affect head/neck posture and cervico-thoracic muscle activity. Twenty (10 men, 10 women) asymptomatic subjects were placed in 3 standardized thoraco-lumbar sitting postures (lumbo-pelvic, thoracic upright and slump) to investigate their influence on cervico-thoracic muscle activity and head/neck posture. There were significant differences in lumbar and thoracic curvatures in the 3 different sitting postures (P<0.002). Slump sitting was associated with greater head/neck flexion, anterior translation of the head (P<0.001) and increased muscle activity of cervical erector spinae (CES) compared to thoracic and lumbo-pelvic sitting (P=0.001). Thoracic upright sitting showed increased muscle activity of thoracic erector spinae (TES) compared to slump and lumbo-pelvic postures (P=0.015). Upper trapezius (UT) demonstrated no significant difference in muscle activation in the 3 sitting postures (P<0.991). This study demonstrates that different sitting postures affect head/neck posture and cervico-thoracic muscle activity. It highlights the potential importance of thoraco-lumbar spine postural adjustment when training head/neck posture.