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

NCT07253493 | Recruiting

• 1 other identifier: MLBLHR
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

Weight-bearing exercises (e.g., running, jumping, whole-body vibration) are widely practiced due to their beneficial effects on bone development and their role in the prevention and treatment of osteoporosis. However, the underlying neuroregulatory mechanisms responsible for these positive effects have not yet been fully understood. Two main neuromodulatory mechanisms have been proposed in the literature: (i) spinal reflexes originating from muscle spindles (stretch reflex, tonic vibration reflex), and (ii) the bone myoregulation reflex (BMR) based on load-sensitive osteocytes. It is well established that increased voluntary contraction and the associated rise in background EMG activity, that is, motor neuron pool activity, enhance muscle spindle-based reflex responses (such as the H-reflex and tendon reflex). In contrast, it has been demonstrated that the H-reflex is suppressed during bone-loading activities such as single-leg stance, jumping, or whole-body vibration. This study is based on two hypotheses:

• As mechanical loading increases, Ia inhibitory effects intensify, leading to greater H-reflex suppression.
• During whole-body vibration, the H-reflex is suppressed due to Ia inhibition. If this inhibition originates from load-sensitive receptors-osteocytes-and thus from the BMR, then in osteoporosis, where osteocyte number and function are reduced, H-reflex suppression will be diminished. The aim of this research is to test these hypotheses. Confirmation of these assumptions would suggest that reflex control during weight-bearing exercise occurs predominantly through osteocyte-mediated BMR mechanisms rather than muscle spindle-based mechanisms such as the stretch or tonic vibration reflex.

Conditions

Osteoporosis Postmenopausal

Keywords

H-reflex; osteoporosis; whole-body vibration; mechanical load; osteocyte; bone myoregulation reflex; background EMG activity

Outcome Measures

Primary Outcomes (1)

• H-reflex Amplitude

  H reflex will be measured 10 times each in 5 different mechanical loads and during 1 minute whole-body vibration. Average amplitude of 10 measurements will be calculated.

  During the day of testing

Secondary Outcomes (1)

• Bone myoregulation reflex latency

  During the day of testing

Study Arms (2)

Postmenapausal femoral osteoporosis

OTHER

Subjects with diagnosed femoral osteoporosis will be in this arm. Femoral osteoporosis is defined as T-scores of -2.5 or lower in femoral neck or total femur obtained in dual energy x-ray absorptiometry. Subjects will have their H-reflex amplitude measured in 6 different settings and will be applied 10 seconds whole-body vibration in 4 different frequencies to measure bone mroregulation reflex.

Diagnostic Test: H-reflex; Diagnostic Test: Bone myoregulation reflex

Healthy control

OTHER

Subjects who do not have osteoporosis or osteopenia will be in this arm. Subjects in this group will have L1-L4, L2-L4, femoral neck and total femur T-scores of greater than -1 obtained in dual energy x-ray absorptiometry. Subjects will have their H-reflex amplitude measured in 6 different settings and will be applied 10 seconds whole-body vibration in 4 different frequencies to measure bone mroregulation reflex.

Diagnostic Test: H-reflex; Diagnostic Test: Bone myoregulation reflex

Interventions

H-reflex DIAGNOSTIC_TEST

H-reflex will be measured during 5 different mechanical loads and whole body vibration.

Also known as: Hoffmann's reflex

Healthy control; Postmenapausal femoral osteoporosis

Bone myoregulation reflex DIAGNOSTIC_TEST

Bone myoregulation reflex will be measured by applying 10 seconds whole body vibration of 4 different frequencies.

Healthy control; Postmenapausal femoral osteoporosis

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Being in the postmenopausal period
• For the osteoporosis group: having femoral osteoporosis (femoral neck or total femur T-score ≤ -2.5)
• For the control group: having no osteoporosis or osteopenia (femoral neck and total femur T-scores \> -1, and L1-L4 and L2-L4 T-scores \> -1)
• Being a volunteer

You may not qualify if:

• Receiving osteoporosis treatment
• Having a peripheral or central nervous system disorder (e.g., stroke, polyneuropathy, radiculopathy, entrapment neuropathy, etc.)
• Having acquired or hereditary muscle diseases (myopathies)
• Having active painful lower extremity pathologies (e.g., osteoarthritis, inflammatory joint diseases, etc.)
• Having cardiac arrhythmias
• Having a history of other metabolic bone diseases
• Having skin lesions at the electrode placement sites on the lower extremities
• Being older than 65 years

Sponsors & Collaborators

• Istanbul Physical Medicine Rehabilitation Training and Research Hospital: lead

Study Sites (1)

Istanbul Physical Medicine Rehabilitation Training & Research Hospital

Bahçelievler, Istanbul, 34180, Turkey (Türkiye)

RECRUITING

MeSH Terms

Conditions

Osteoporosis, Postmenopausal; Osteoporosis

Interventions

H-Reflex

Condition Hierarchy (Ancestors)

Bone Diseases, Metabolic; Bone Diseases; Musculoskeletal Diseases; Metabolic Diseases; Nutritional and Metabolic Diseases

Intervention Hierarchy (Ancestors)

Reflex, Monosynaptic; Reflex; Nervous System Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena

Study Officials

• İlhan Karacan, Prof. Dr.

  stanbul Physical Medicine Rehabilitation Training and Research Hospital

  STUDY CHAIR

Central Study Contacts

Fuat Orhun Alayoğlu, Attending doctor

CONTACT

+905348431984; f.orhunalayoglu@gmail.com

İlhan Karacan, Prof. Dr.

CONTACT

+905327005361; mdkaracanilhan@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Outcome assessor and statistician will be blinded to the groups of participants.
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Attending physician

Study Record Dates

• First Submitted: November 19, 2025
• First Posted: November 28, 2025
• Study Start: November 18, 2025
• Primary Completion: March 1, 2026
• Study Completion: April 1, 2026
• Last Updated: November 28, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: For 5 years after the publication date
• Access Criteria: The individual participant data (IPD) that support the findings of this study will be available from the corresponding author upon reasonable request and with permission of the Istanbul Physical Medicine and Rehabilitation Training and Research Hospital Ethics Committee. Data will be anonymized prior to sharing.

Locations

TU (1)