Discussion
visual illusions, closed-eye, Proprioceptive sensations
This study aimed to clarify the effects of NMV on standing postural orientation and spatial perception in healthy participants, depending on differences in stimulation duration and simultaneous stimulation of trunk muscles. The results of this study showed that compared to the control condition, ML-COP was biased to the stimulus side and AP-COP was to the anterior side immediately following NMV and trunk muscle vibration for 10 min. There were no significant differences between 30 s and 10 min of NMV with the control condition, and SSA showed no significant differences. Thus, the results suggest that combining NMV with vibratory stimulation of the trunk muscles intensifies the effect on the standing postural orientation.Proprioceptive sensations from cervical muscles contribute to body representations, including the position and hierarchical arrangement of limbs and the organization of segments in space [In healthy participants, the trajectory of gait is modulated by vibration stimulation of the trunk muscles [SSA is ipsilateral to the stimulus after the end of vibratory stimulation in healthy participants [This study was conducted in young individuals, mainly in their 20s, which is a limitation of this study. Whether similar results occur in other age groups is unclear. The effects of sex differences have also not been taken into consideration.In conclusion, the findings suggest that proprioceptive input to the trunk muscles would amplify the central nervous system’s modulator effect of NMV in the standing position. It is also possible that SSA based on proprioceptive sensation is not biased under closed-eye measurement conditions where visual illusions are not produced. Combining NMV with vibratory stimulation of the trunk muscles may be a new method for intensifying an effect in the standing postural orientation.