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ORIGINAL RESEARCH article

Front. Physiol.

Sec. Autonomic Neuroscience

Volume 16 - 2025 | doi: 10.3389/fphys.2025.1642779

Autonomic and Physiological Stress Responses in Navy Divers: The Protective Role of Diving Experience

Provisionally accepted
  • 1National Defense Medical Center, Taipei, Taiwan
  • 2Kaohsiung Armed Forces General Hospital Zuoying Branch, Kaohsiung, Taiwan
  • 3Tri-Service General Hospital Department of Medicine, Taipei City, Taiwan
  • 4Taichung Hospital, Taichung, Taiwan

The final, formatted version of the article will be published soon.

Deep diving presents significant physiological stress, yet reliable indicators for monitoring autonomic and stress responses remain underdeveloped. This study examined how prior deep diving experience influences autonomic regulation and stress biomarkers during a simulated dive to a depth of 220 feet. Twenty-eight Navy divers (15 experienced, 13 novice) underwent psychological assessments (perceived stress, anxiety, fear) and salivary biomarker analysis (cortisol, amylase) pre- and post-dive. Heart rate variability (HRV), including linear (rMSSD, HF) and non-linear indices (SD1, SD1/SD2, sample entropy), was measured at four dive stages (pre-dive, bottom, decompression, and post-dive). After adjusting for age and perceived stress, experienced divers exhibited greater post-dive reductions in cortisol (p = 0.015) and amylase (p = 0.022). Additionally, after controlling for age, perceived stress, and respiratory rate, they demonstrated significantly higher parasympathetic activity (p ≤ 0.001) and greater HRV complexity (sample entropy, p = 0.023) during decompression. We found no significant differences in self-reported psychological stress. These findings suggest that diving experience facilitates enhanced autonomic control and stress adaptation, with implications for real-time physiological monitoring and training protocols to mitigate risk during deep dives.

Keywords: Autonomic Nervous System, Heart rate variability, salivary cortisol, amylase activity, psychological distress, Deep diving

Received: 07 Jun 2025; Accepted: 04 Aug 2025.

Copyright: © 2025 Chen, Tzeng, Tang, Li, Wu and Huang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Shu-Yu Wu, National Defense Medical Center, Taipei, Taiwan
Kun-Lun Huang, National Defense Medical Center, Taipei, Taiwan

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