Effect of Touch on Trunk Sway

Gait and Posture published some intriguing research on the effects of touch and trunk sway in a seated position.  There were 13 healthy, adult subjects who participated in the study.  Each participant performed a total of 12 trials of 60-seconds duration in a randomized order, combining the experimental conditions of no-touch, hand-touch (right index finger touching an object) or back-touch (maintaining an object touching the back at mid level T10) with no sensory perturbation, paraspinal muscle vibration or galvanic vestibular stimulation - GVS (sending of electrical messages to a nerve in the ear that controls balance). The results showed the following:

• touch through hand or back decreased trunk sway and decreased the effects of muscle vibration and GVS 
• GVS led to a large increase in sway 
• muscle vibration was only observed as an increase of drift and not of sway 
• the stabilizing effect of touch was strong enough to mask any effects of perturbations of vestibular and paraspinal muscle spindle afference 

The researchers concluded that tactile information, whenever available, seems to play a dominant role in seated postural sway and therefore has important implications for studying trunk control.  

Although this research was performed in healthy adult subjects, perhaps this gives us some suggestions to try with children to help to decrease postural sway in sitting.  Is this why sometimes holding a fidget helps a child to sit more upright and stay more alert?  Perhaps that child who is constantly slumping to one side could use some tactile input to maintain a more upright posture.  Thoughts?  Experiences?

Reference: Maaswinkel E | Veeger Hej | Dieen JHv.  Interactions of touch feedback with muscle vibration and galvanic vestibular stimulation in the control of trunk posture Available online 19 October 2013 at Gait and Posture