Effect of Hot Spring Therapy on Autonomic Nervous System and Exercise Performance During Altitude Training

May 19, 2026 updated by: Ziyue Ou, Macao Polytechnic University

A Randomized Controlled Trial Investigating the Effects of Balneotherapy on Cardiac Autonomic Modulation and Athletic Performance in Healthy Adults Undergoing Simulated Altitude Training Undergoing Simulated Athlete Training

This randomized controlled trial aims to investigate the effects of balneotherapy (hot spring bathing) on cardiac autonomic nervous system function and exercise performance in healthy athletes undergoing high-altitude training. Participants will be randomly assigned to the intervention group (receiving hot spring baths three times per week (38°C, 20 minutes) combined with high-altitude training), the control group (receiving routine recovery protocols combined with high-altitude training), or the hot water immersion group (receiving hot water baths three times per week (38°C, 20 minutes) combined with high-altitude training). Primary outcome measures include heart rate variability (HRV) indices and exercise performance indicators. Secondary outcomes include blood lactate, peripheral oxygen saturation (SpO2), and subjective fatigue. These findings may provide evidence for non-pharmacological interventions to enhance high-altitude training adaptation and exercise recovery.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

27

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • China
      • Macao, China
        • Recruiting
        • Macao Polytechnic University
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Male or female aged 11-17years
  • Regular endurance training (≥3 sessions/week) for ≥2 years
  • No history of altitude exposure >2000m in the past 3 months
  • No contraindications to hot water immersion (e.g., uncontrolled hypertension, severe cardiovascular disease, open wounds, pregnancy)
  • Ability to provide written informed consent- Willingness to abstain from other recovery modalities (e.g., massage, cryotherapy, compression garments) during the study period

Exclusion Criteria:

  • History of cardiovascular, respiratory, renal, or endocrine disorders
  • Current use of medications affecting autonomic function (e.g., beta-blockers, anticholinergics)- History of syncope or heat intolerance
  • Acute musculoskeletal injury within the past 6 months- Regular use of sauna, hot tub, or spa within the past month
  • Pregnancy or breastfeeding (for female participants)- Shift work or trans-meridian travel within 2 weeks prior to baseline assessment
  • Alcohol consumption >14 units/week or smoking

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Natural Recovery Group
Control group participants will undergo the same altitude training protocol (altitude 1600 meters) for 4 weeks. After each training session, participants will receive standard recovery procedures, including 20 minutes of passive rest in a thermoneutral environment (room temperature 24°C), supplemented with mild hydration and self-selected stretching. No hydrothermal intervention will be provided.
Behavioral: Control Group：Natural Recovery
Control group participants will undergo the same altitude training protocol (altitude 1600 meters) for 4 weeks. After each training session, participants will receive standard recovery procedures, including 20 minutes of passive rest in a thermoneutral environment (room temperature 24°C), supplemented with mild hydration and self-selected stretching. No hydrothermal intervention will be provided.
Other Names:
  • NR
Active Comparator: Hot water immersion group
The hot water immersion group will undergo a 4-week altitude training at 1600 meters above sea level. Subjects will receive a 20-minute hot water immersion (daily tap water, 38°C±1°C) in a standardized indoor hot spring facility. The immersion protocol includes whole-body immersion up to the neck for 20 minutes, followed by a 10-minute rest before leaving the facility. Three times per week.
Behavioral: Hot water immersion group
The hot water immersion group will undergo a 4-week altitude training at 1600 meters above sea level. Subjects will receive a 20-minute hot water immersion (daily tap water, 38°C±1°C) in a standardized indoor hot spring facility. The immersion protocol includes whole-body immersion up to the neck for 20 minutes, followed by a 10-minute rest before leaving the facility. Three times per week.
Other Names:
  • HWI
Experimental: Hot Spring Immersion Group
The hot spring immersion group will undergo a 4-week high-altitude training at an altitude of 1600 meters. Subjects will receive a 20-minute hot spring therapy (natural hot spring water, 38°C ± 1°C) in a standardized indoor hot spring facility. The immersion protocol includes whole-body immersion to the neck for 20 minutes, followed by a 10-minute rest before leaving the facility. Three times per week.
Behavioral: hot spring immersion group
The hot spring immersion group will undergo a 4-week high-altitude training at an altitude of 1600 meters. Subjects will receive a 20-minute hot spring therapy (natural hot spring water, 38°C ± 1°C) in a standardized indoor hot spring facility. The immersion protocol includes whole-body immersion to the neck for 20 minutes, followed by a 10-minute rest before leaving the facility. Three times per week.
Other Names:
  • HSI

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Heart Rate Variability (HRV) - RMSSD
Time Frame: Baselines were measured at the formal start of the experiment, at night during the 2nd, 3rd, and 4th weeks (post-intervention) after ascending the plateau, and post-tests were conducted one week after descending the plateau.
Root mean square of successive differences (RMSSD) between normal heartbeats, measured from a 5-minute seated ECG recording in a quiet, temperature-controlled (22-24°C) room after 15 minutes of rest. A higher RMSSD value indicates stronger parasympathetic activity. Unit: milliseconds (ms). Baseline, Week 2, Week 3 (post-intervention).
Baselines were measured at the formal start of the experiment, at night during the 2nd, 3rd, and 4th weeks (post-intervention) after ascending the plateau, and post-tests were conducted one week after descending the plateau.
1000-meter ergometer test.
Time Frame: Baseline measurements were taken before the official start of the experiment and during the 3rd and 4th weeks after ascending to the plateau.
Perform a 1000-meter all-out test on a rowing ergometer. Protocol: sprint at maximum effort to measure the shortest time. Record time. Units: seconds. Baseline, Week 3, Week 4.
Baseline measurements were taken before the official start of the experiment and during the 3rd and 4th weeks after ascending to the plateau.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
HRV - SDNN
Time Frame: Baselines were measured at the formal start of the experiment, at night during the 2nd, 3rd, and 4th weeks (post-intervention) after ascending the plateau, and post-tests were conducted one week after descending the plateau.
Standard deviation of NN intervals (normal-to-normal R-R intervals), reflecting overall autonomic modulation. Unit: milliseconds (ms). Baseline, Week 2, Week 3, Week4, post-tests
Baselines were measured at the formal start of the experiment, at night during the 2nd, 3rd, and 4th weeks (post-intervention) after ascending the plateau, and post-tests were conducted one week after descending the plateau.
Peripheral Oxygen Saturation (SpO2)
Time Frame: one month.
Resting peripheral oxygen saturation measured via fingertip pulse oximeter after 10 minutes of seated rest. Unit: percentage (%)
one month.
Rating of Perceived Exertion (RPE)
Time Frame: one month.
Borg 6-20 scale rating of perceived exertion recorded immediately after each training session. Higher scores indicate greater subjective effort. Unit: score (6-20). Daily during intervention
one month.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Macao Polytechnic University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

May 25, 2026

Primary Completion (Estimated)

June 25, 2026

Study Completion (Estimated)

June 25, 2026

Study Registration Dates

First Submitted

May 14, 2026

First Submitted That Met QC Criteria

May 19, 2026

First Posted (Actual)

May 27, 2026

Study Record Updates

Last Update Posted (Actual)

May 27, 2026

Last Update Submitted That Met QC Criteria

May 19, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 202502AS100005

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

The current research project has not yet been completed, and the data have not been publicly released. After publication, sharing will be decided on a case-by-case basis.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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