Studying How Mechanical Loading and Bone Loss Affect Motor Neuron Activity and H-Reflex in Postmenopausal Women

What this Trial Is About

Researchers are studying how weight-bearing exercises like running, jumping, and whole-body vibration affect bone health and the nervous systems role in these benefits, especially relating to osteoporosis in postmenopausal women. The study focuses on two neuromodulatory mechanisms that may explain these effects spinal reflexes from muscle spindles and the bone myoregulation reflex BMR controlled by load-sensitive bone cells called osteocytes. The goal is to understand if reflex control during exercise is mainly driven by bone cells rather than muscle sensors, which could differ in women with osteoporosis due to reduced osteocyte function. Participants will be divided into two groups those with femoral osteoporosis and those without osteoporosis or osteopenia. During testing, researchers will measure the H-reflex amplitude under six different mechanical loading conditions, including standing on one leg with varied weight percentages and during whole-body vibration at different frequencies. Surface EMG signals, force from the heel, and reflex responses will be recorded using specialized equipment. Whole-body vibration will also be applied to assess the bone myoregulation reflex latency. Participants will stand and place specific amounts of weight on their right leg while researchers measure reflex responses and muscle electrical activity. The study will include data collection with electrodes, accelerometers, and force sensors, with careful skin preparation for accurate signals. Researchers will analyze reflex amplitudes and muscle activity during different loading and vibration conditions. Safety and eligibility will be monitored, and the primary outcome is the H-reflex amplitude measured during the testing day, with bone myoregulation reflex latency as a secondary outcome. The study is expected to run until April 2026.

Effect of Mechanical Loading and Bone Loss on Motor Neuron Activity-H-Reflex Relationship