H-Reflex Suppression by Bone Myoregulation Reflex During Mechanical Loading in Standing Humans

Neuronal Mechanisms Underlying H-Reflex Suppression During Mechanical Loading: The Role of Bone Myoregulation Reflex in Standing Humans

This study aims to investigate how standing posture and mechanical loading affect reflex responses in the lower limb. Specifically, it focuses on the H-reflex-a type of spinal cord reflex-and how it changes during quiet standing and whole-body vibration. Ten healthy adult volunteers will participate. Researchers will record electrical responses from the calf muscle (soleus) while participants stand still or are exposed to gentle vibration. The goal is to better understand how the nervous system and skeletal system interact in regulating balance and movement.

This study investigates the neural mechanisms responsible for suppression of the H-reflex-a spinal monosynaptic reflex-during mechanical loading in the standing position. Previous research has shown that H-reflex amplitude decreases with increasing postural demand, such as during walking or standing compared to lying down. One hypothesis suggests that this suppression may be mediated not only by vestibular and cutaneous afferents, but also by a bone-derived reflex mechanism called the Bone Myoregulation Reflex (BMR).

In this study, 10 healthy adult volunteers will undergo H-reflex measurements while standing in various loading conditions, including quiet standing and during whole-body vibration (WBV). Participants will stand with one foot isolated from vibration while the other foot is on a vibrating platform. H-reflexes will be recorded from the soleus muscle using standard surface electromyography.

The primary aim is to determine whether BMR contributes to H-reflex suppression during loading. The findings may provide insight into the interaction between skeletal loading and spinal reflex modulation, with potential relevance to balance, gait, and rehabilitation science.

Inclusion Criteria:

• Healthy adults aged 20 to 45 years
• Able to stand independently for at least 10 minutes
• No known neurological, orthopedic, or balance disorders
• Willingness to participate and provide informed consent

Exclusion Criteria:

• History of spinal cord injury, peripheral neuropathy, or muscle disease
• Recent lower limb surgery or musculoskeletal trauma
• Current use of medications affecting neuromuscular function
• Pregnancy
• Any contraindications to exposure to mechanical vibration