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Updated: Jul 21, 2025
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Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response
Published on: November 12, 2014
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Altered Sympathoadrenal Activity Following Cold-Water Diving
Summary
Elite military personnel experienced a rapid stress response and suppressed recovery hormones during extreme cold-water diving. Core body temperature was maintained, but skin temperature dropped significantly with repeated dives.
Area of Science:
- Environmental Physiology
- Human Physiology
- Extreme Environment Adaptation
Background:
- Limited data exists on the hormonal and metabolic effects of extreme cold-water diving.
- The impact of repetitive cold-water dives on the physiological stress response remains largely unknown.
Purpose of the Study:
- To investigate the effects of twice-daily Arctic dives on the hormonal and metabolic profiles of elite military personnel.
- To assess the acute stress response induced by extreme cold-water immersion.
Main Methods:
- Five healthy, male Norwegian Special Forces operators participated in the study.
- Physiological and hormonal data were collected before and after twice-daily dives in 3.3°C Arctic water.
Main Results:
- Core body temperature was maintained, while skin temperature significantly decreased during dives.
- Adrenocorticotropic hormone (ACTH) and cortisol levels decreased, indicating HPA axis suppression.
- Adrenaline and noradrenaline levels increased, showing a sympathetic nervous system activation, while leptin, testosterone, and IGF-1 decreased but recovered between dives.
Conclusions:
- Cold-water diving elicits a rapid sympathetic-adreno-medullary (SAM/SNS) response and suppresses the hypothalamic-pituitary-adrenal (HPA) axis.
- Hormones crucial for repair and recovery were suppressed following cold-water immersion.
- The study highlights physiological adaptations to extreme environments, though the small sample size limits definitive conclusions on specific hormonal roles.
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