Fundamental Study on the Influence of Muscle Fatigue on Tonic Vibration Reflex

The tonic vibration reflex (TVR) phenomenon refers to the sustained involuntary contractions induced in skeletal muscles when subjected to mechanical vibration stimulation. Thus, utilizing vibration stimulation to induce involuntary limb movements promises to become a novel technique for human motion adjustment based on external devices. In recent years, an increasing number of studies have focused on how to apply TVR in welfare domains, such as tremor suppression and rehabilitation training. However, the characteristics of the TVR induced by vibration stimulation may vary across different muscle states, and changes in TVR effects under conditions of muscle fatigue have not been systematically investigated. In this study, by applying mechanical vibration stimulation to the tendon of origin in biceps brachii, the primary muscle in elbow flexion movements, the changes in the effects of TVR induced by vibration stimulation under muscle fatigue conditions are compared. Through experimentation, this study confirmed the efficacy of vibration stimulation-induced TVR in producing limb movements and investigated the variations in reflex intensity under different muscle fatigue states.

I. Introduction

In recent years, welfare robots have been extensively employed to assist the elderly and disabled with daily tasks, social interactions, and rehabilitation training [1]. Among these, the technique of utilizing external devices, such as actuators, to exert external forces and adjust human movements plays a critical role in assisting individuals [1]. On the other hand, when mechanical vibratory stimulation is applied to muscles, it can induce a phenomenon known as the tonic vibration reflex (TVR), characterized by sustained contractions of the stimulated muscles [2]. Since this reflex can lead to involuntary muscle contractions and consequently alter human movements, numerous studies are dedicated to exploring mechanical vibratory stimulation as a novel motion adjustment technology within the field of welfare robotics [3]–[5].