FREQUENCY-DEPENDENT SOLEUS REFLEX MODULATION DURING WHOLE-BODY VIBRATION
Enrolling by invitation · Not applicable
Conditions studied: Healthy Adult, Whole Body Vibration
In brief
Exposure to microgravity leads to pronounced impairments in neuromuscular control, postural stability, and spinal reflex regulation that cannot be attributed to muscle atrophy alone. Rather, these deficits point to a disruption of load-dependent sensorimotor mechanisms and highlight the essential role of gravitational loading of the skeleton as a critical source of sensory input for spinal motor control. Spinal reflex behavior during upright stance has traditionally been explained primarily by muscle spindle-mediated pathways. However, this framework does not fully account for the reflex alterations observed under conditions of altered mechanical loading, including microgravity, prolonged unloading, or exposure to vibration. In parallel, advances in bone biology have identified osteocytes within the lacuno-canalicular system as highly sensitive mechanosensors that preferentially respond to dynamic loading and changes in strain rate. This insight has given rise to the concept of bone myoregulation, in which bone-derived mechanosensory signals contribute to the modulation of spinal excitability. A defining characteristic of this process is the poroelastic nature of bone tissue. As a fluid-saturated porous medium, bone exhibits frequency-dependent mechanical behavior, such that oscillatory loading modifies both the temporal profile and magnitude of interstitial fluid flow within the lacuno-canalicular network. As a result, loading frequency is expected to influence not only the timing of reflex responses but also their amplitude. Whole-body vibration offers a controlled experimental paradigm to probe these frequency-dependent, load-sensitive mechanisms in humans. Accordingly, the aim of the present study was to identify the whole-body vibration frequency band that most effectively induces soleus reflex responses during quiet standing, considering both reflex latency and response amplitude. Investigators hypothesized that these responses would display frequency-dependent behavior consistent with poroelastic bone-mediated myoregulation and would be modulated by individual anthropometric characteristics, with potential implications for vibration-based countermeasures under altered gravitational loading.
Key facts
- Study ID
- NCT07408570
- Run by
- Istanbul Physical Medicine Rehabilitation Training and Research Hospital
- People needed
- 27
- Starts
- 2025-11-30
- Expected to finish
- 2026-06-30
- Last updated by the study team
- 2026-02-13
Who can join
Age: 20 and older, up to 45. Sex: any. Healthy volunteers: accepted.
You may qualify if…
- Healthy adults aged between 20 and 45 years,
- Absence of regular exposure to whole-body vibration (WBV) training.
You may not qualify if…
- A history of intolerance to whole-body vibration,
- Vertigo history,
- Any medical or neurological condition that could be exacerbated by vibratory stimulation.
- All participants will provide written informed consent prior to participation.
Where it is running
- Istanbul Pmr Training Hospital — Bahçelievler, Istanbul, Turkey (Türkiye)
Full record on ClinicalTrials.gov
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