Exploring how gentle nerve stimulation in the ankle affects the body’s automatic functions in healthy people

ISRCTN	ISRCTN17718049
DOI	https://doi.org/10.1186/ISRCTN17718049
Sponsor	Servicio de Salud Aysén
Funder	Investigator initiated and funded

Submission date: 19/12/2025
Registration date: 29/12/2025
Last edited: 29/12/2025

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Other

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Not provided at time of registration

Contact information

Dr Javier Muñoz
Public, Principal investigator, Scientific

21 de mayo 145
Coyhaique
5950000
Chile

ORCID ID	0009-0002-7381-8797
Phone	+56 991588386
Email	doctormunozquintana@gmail.com

Study information

Primary study design	Interventional
Allocation	N/A: single arm study
Masking	Open (masking not used)
Control	Uncontrolled
Assignment	Single
Purpose	Basic science
Scientific title	Healthy volunteers receiving transcutaneous tibial nerve stimulation to assess acute changes in heart rate variability across baseline, stimulation and post-stimulation phases
Study objectives	Primary objective: To quantify acute changes in autonomic nervous system activity during and immediately after transcutaneous tibial nerve stimulation (TTNS) in healthy volunteers, using heart rate variability (HRV) metrics (e.g., RMSSD and SDNN) derived from standardized 5-minute segments. Secondary objectives: 1. To compare sympathetic and parasympathetic indices and frequency-domain HRV measures (e.g., LF, HF, LF/HF) across baseline, stimulation, and post-stimulation phases 2. To assess the temporal pattern of autonomic modulation (during TTNS vs recovery) under a controlled supine resting protocol
Ethics approval(s)	Approved 08/10/2024, Comité Científico y Ético del Servicio de Salud Aysén (General Parra N°551, Coyhaique, 5950000, Chile; +56 67 226 1400; arriagadapau@saludaysen.cl), ref: Ordinario N°59-2024 (CEC)
Health condition(s) or problem(s) studied	Acute autonomic nervous system modulation (heart rate variability, HRV) in healthy volunteers during transcutaneous tibial nerve stimulation (TTNS).
Intervention	Intervention: Transcutaneous tibial nerve stimulation (TTNS) delivered with a TENS device (TENS 7000®), continuous stimulation for 10 minutes at 30 Hz and 200 μs pulse width. Two self-adhesive surface electrodes were placed on the left foot/ankle (one at the heel and the other 3–5 cm above the medial malleolus). Correct positioning was initially confirmed by a brief motor response (toe flexion) at suprathreshold intensity, then stimulation was reduced and maintained below motor threshold at a comfortable sensory level. Comparator: None (single-arm, within-subject baseline vs stimulation vs post-stimulation).
Intervention type	Device
Phase	Not Applicable
Drug / device / biological / vaccine name(s)	Transcutaneous tibial nerve stimulation (TTNS) delivered using a TENS device (TENS 7000®).
Primary outcome measure(s)	Heart rate variability (RMSSD, ms) measured using Kubios HRV from R–R intervals recorded with a wearable heart rate monitor; analysed using a 5-minute segment at minutes 5–10 of each 10-minute phase: baseline, TTNS (stimulation), and post-TTNS (recovery). Heart rate variability (SDNN, ms) measured using Kubios HRV from R–R intervals; analysed using a 5-minute segment at Minutes 5–10 of each 10-minute phase: baseline, TTNS (stimulation), and post-TTNS (recovery).
Key secondary outcome measure(s)
Completion date	30/12/2024

Eligibility

Participant type(s)
Age group	Mixed
Lower age limit	18 Years
Upper age limit	99 Years
Sex	All
Target sample size at registration	20
Total final enrolment	20
Key inclusion criteria	1. Adults (≥18 years) 2. Healthy volunteers without known chronic disease 3. Able to provide written informed consent 4. Comply with the study procedures
Key exclusion criteria	1. Recent surgery within 3 months 2. Current medications affecting autonomic function 3. Any condition preventing safe participation or valid HRV measurement
Date of first enrolment	11/12/2024
Date of final enrolment	30/12/2024

Locations

Countries of recruitment

Chile

Study participating centres

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not expected to be made available
IPD sharing plan

Editorial Notes

29/12/2025: Study's existence confirmed by the Comité Científico y Ético del Servicio de Salud Aysén.