Background: Strategic vibration of musculotendinous regions of a limb elicits illusionary sensations of movement. As a rehabilitation technique, this 'kinesthetic illusion' has demonstrated beneficial results for numerous sensory-motor disorders. However, literature shows little consistency in the vibration parameters or body positioning used, and their effects have yet to be comprehensively investigated.
Objective: To characterize the effects of the vibration amplitude, frequency, and limb position on the kinesthetic illusion.
Methods: Movement illusions were induced in 12 participants' biceps and triceps. The effect of amplitude (0.1 to 0.5 mm), frequency (70 to 110 Hz), and two limb positions were quantified on the strength of illusion (SOI), range of motion (ROM) and velocity.
Results: Amplitude significantly affected the illusionary SOI, ROM and velocity in the biceps and triceps (p< 0.05). Increasing amplitude resulted in an increase of all three output variables. Limb position showed an effect on illusionary velocity in the biceps as well as ROM and velocity in the triceps (p< 0.05). Frequency demonstrated no statistical effect.
Conclusions: Amplitude demonstrated the most profound impact on the kinesthetic illusion in the experimental ranges tested. This work may help guide clinicians and researchers in selecting appropriate vibratory parameters and body positions to consistently elicit and manipulate the kinesthetic illusion.
Keywords: Kinesthetic illusion; factorial design; movement illusion; vibration illusion.