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Completed

NCT Number: NCT07524491

taVNS During Exercise and Recovery in Chronic Spinal Cord Injury

This study investigates the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on autonomic cardiovascular regulation during exercise and recovery in individuals with chronic spinal cord injury (SCI). Participants undergo two experimental conditions (active taVNS and sham stimulation) in a randomized crossover design while performing a standardized exercise protocol.

Heart rate variability (HRV) is used as a non-invasive biomarker to assess autonomic nervous system dynamics across different phases (baseline, exercise, and recovery). The aim is to characterize physiological responses to neuromodulation and explore whether taVNS modulates autonomic adaptability in this population.

This is a mechanistic physiological study designed to improve the understanding of autonomic regulation in SCI and to explore potential biomarkers of response to neuromodulation.

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Key information

Conditions

Spinal Cord Injury, Chronic Bronchial Diseases Bronchiolitis Bronchiolitis Obliterans Bronchiolitis Obliterans Syndrome Bronchitis Central Nervous System Diseases Graft vs Host Disease Immune System Diseases Lung Diseases Lung Diseases, Obstructive Nervous System Diseases Organizing Pneumonia Respiratory Tract Diseases Spinal Cord Diseases Spinal Cord Injuries Trauma, Nervous System Wounds and Injuries

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of the Balearic Islands

Palma de Mallorca, Balearic Islands, 07122, Spain

About this study

Spinal cord injury (SCI) is associated with significant impairments in autonomic nervous system function, particularly affecting cardiovascular regulation. These alterations reduce physiological adaptability to internal and external stressors and may contribute to increased cardiovascular risk.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique that has been proposed as a potential tool to influence autonomic function. However, its effects on dynamic autonomic regulation during physiological stress, such as exercise, remain insufficiently characterized in individuals with SCI.

The present study is a randomized, controlled, crossover experimental protocol designed to investigate the acute effects of taVNS on autonomic cardiovascular dynamics during a structured exercise and recovery paradigm. Participants with chronic SCI are exposed to two conditions: active taVNS and sham stimulation, applied in a randomized order.

Each experimental session includes three phases: baseline (rest), exercise (submaximal effort), and recovery. Continuous electrocardiographic recordings are obtained to derive heart rate variability (HRV) metrics. Both linear (time and frequency domain) and non-linear analyses are performed to characterize autonomic regulation and system dynamics.

The primary objective is to evaluate whether taVNS modulates autonomic responsiveness and adaptability across different physiological states. Secondary objectives include the exploration of HRV-derived biomarkers that may reflect autonomic complexity and the identification of response patterns to neuromodulation.

This study is not designed to evaluate clinical efficacy or therapeutic outcomes but to provide mechanistic insight into autonomic regulation and neuromodulation effects in SCI. The results may contribute to the development of personalized approaches in neurorehabilitation and autonomic monitoring.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults (≥18 years) with chronic spinal cord injury
  • Medically stable condition
  • Ability to perform the exercise protocol
  • Ability to provide informed consent

Exclusion criteria

  • Acute spinal cord injury
  • Severe cardiovascular or respiratory instability
  • Use of medications significantly affecting autonomic function
  • Skin lesions or contraindications to transcutaneous stimulation
  • Cognitive impairment preventing protocol compliance

Treatment and study plan

Transcutaneous Auricular Vagus Nerve Stimulation

Device

Non-invasive electrical stimulation applied to the auricular branch of the vagus nerve using transcutaneous electrodes during the experimental protocol.

Sham stimulation

Device

Sham stimulation delivered with identical device setup but without effective activation of the vagus nerve.

Primary outcomes

  1. DFA α2

    Time frame: Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes.

    Detrended fluctuation analysis (α2) derived from RR intervals to assess long-term fractal scaling properties of heart rate variability. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. The value reported at each specific time point represents the calculation for the preceding 5-minute window to characterize autonomic regulation across the session.

Secondary outcomes

  1. RMSSD (ms)

    Time frame: Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes.

    Root mean square of successive differences (RMSSD) of RR intervals to assess short-term heart rate variability and parasympathetic activity. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. The value reported at each time point represents the calculation for the preceding 5-minute window..

  2. HF power (ms²)

    Time frame: Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes.

    High-frequency (HF) power (0.15-0.40 Hz) derived from RR intervals to assess parasympathetic modulation. Spectral analysis is performed using standard frequency-domain methods. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point.

  3. LF power (ms²)

    Time frame: Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes.

    Low-frequency (LF) power (0.04-0.15 Hz) derived from RR intervals to assess combined autonomic modulation. Frequency-domain analysis is performed after preprocessing of RR interval data. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point.

  4. SD1 (ms)

    Time frame: Baseline (last 5 minutes of rest), 10, 15, 20, 25, 30, 35, and 40 minutes.

    SD1 derived from the Poincaré plot of RR intervals, representing short-term beat-to-beat variability. RR intervals are recorded continuously and analyzed offline. Data are processed using 5-minute overlapping windows. Each reported value corresponds to the preceding 5-minute window at the specified time point.

Sponsors and collaborators

Lead sponsor

University of the Balearic Islands

Other

Collaborators

  • Health Research Institute of the Balearic Islands (IdISBa, Spain)
  • University of the Balearic Islands - Institute for Health Sciences Research (UNICS)

Registry information

Official study title

Transcutaneous Auricular Vagus Nerve Stimulation Modulates Autonomic Dynamics During Exercise and Recovery in Chronic Spinal Cord Injury

Acronym: taVNS-HRV-SCI

Important dates

Study start
2024
Primary completion
2024
Study completion
2024
First posted
Apr 13, 2026
Registry last updated
Apr 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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