Vibration applied to relaxed muscle or tendon causes tonic reflex contraction in a muscle. Furthermore, when vibration is applied to a muscle, involuntary enhancement of EMG and contraction is induced. Regarding this finding, many studies on the influence of vibration on a muscle and static posture have been performed. However, precedent studies have limitations in applying single characteristic-vibration without any consideration on personal difference on vibration. And studies have been performed to research the change in dynamic state according to the intensity of sensing vibration, but no analysis has been performed on the biomechanical aspect of the lower-limb joints. Nor any consideration was given on the effect of vibration frequency. Therefore, the purpose of this study was to analyze the biomechanical variation in the lower-limb joints according to the characteristics of the mechanical vibration stimulation flowing into Achilles tendon and tibialis anterior tendon during gait, in consideration of the vibration perception threshold and vibration frequency. For this purpose, this study measures the vibration perception threshold according to vibration frequency at each tendon exposed to the stimulation. According to the result, vibration perception threshold varies according to vibrating tendon and vibration frequency. Based on the measurement result of vibration perception threshold, vibration is applied to an Achilles tendon and tibialis anterior tendon during gait. In order to analyze the biomechanical variation in the lower-limb joints according to the characteristics of vibration stimulation applied to each tendon during gait, the angle, moment and power of the lower-limb joints is analyzed using 3D motion analysis system. As a result, biomechanical variation, when vibration lower than a perception threshold is applied, is similar to the variation when vibration at perception threshold is applied. This result implies that vibration stimulation may cause biomechanical variation of lower-limb joints. Furthermore, this means that its biomechanical variation may vary according to the characteristics of the vibration applied.

Abstract. In this study, the researchers examined the changes that took place in the somatosensory cortex area in the brain when subthreshold mechanical vibratory stimulation was applied to the lower limb of the elderly. For this, a subthreshold vibratory stimulation of 190 Hz as applied to the tibialis anterior tendon, and the Electroencephalography was measured. In order to examine the changes in the somatosensory cortex, the amplitude of the Somatosensory Evoked Potentials (SEPs) was analyzed. When the subthreshold vibratory stimulation was applied to the tibialis anterior tendon, the SEPs amplitude was increased more than the amplitude under none stimulation setting. This result means that the subthreshold mechanical vibratory stimulation may affect the nervous system of the elderly.