rac - Extreme Adaptation of the Cardiovascular System: A Look from Antarctica

The extreme living conditions in Antarctica represent a unique natural setting for studying human physiology. Recent work by Puigdomenech et al., carried out at the Belgrano II Antarctic Base, analyzes how prolonged confinement, photoperiod alteration, and extreme isolation affect cardiovascular function in a group of healthy military personnel over a 12-month period. (1)

The study shows a significant decrease in heart rate and blood pressure, both at rest and during exercise, accompanied by an increase in heart rate variability. This pattern, consistent with a predominance of vagal tone, suggests a positive neurovegetative adaptation, with no differences between the months of continuous light and darkness. The absence of atmospheric pollution may have favored this behavior.

These findings are consistent with previous studies conducted in similar contexts. Arendt et al. described how changes in light exposure at Antarctic bases affect circadian rhythms and autonomic functioning. (2) Mairesse et al. after a prolonged stay in Antarctica, also observed neurobehavioral and sleep adaptations reflecting a favorable physiological reorganization. (3) Garrett-Bakelman et al., as part of the NASA Twins Study, reported a decrease in heart rate and blood pressure during prolonged space flights, findings that reinforce the analogy between Antarctic conditions and space missions. (4)

In addition, Rajagopalan et al. highlighted the direct link between exposure to environmental pollution and cardiovascular dysfunction, emphasizing the importance of the environment in regulating autonomic tone. (5) In this sense, Antarctica's clean air is positioned as a relevant modulating factor.

The article by Puigdomenech et al. not only provides original data, but also invites us to consider Antarctica as a valuable experimental model for research in extreme and space medicine. The implications of these results range from occupational medicine in remote conditions to the preparation of extra-planetary missions. Understanding how the cardiovascular system adapts in these contexts is key to addressing new challenges in science and global health.

Ethical considerations

Not applicable.

Conflicts of interest

None declared. (See authors' conflict of interests forms on the web).

REFERENCES

1. Puigdomenech M, Iglesias R, Bertarini A, Schachtel BS, Pérez Lloret S, Azara A, et al. Extreme living conditions in Antarctica and their impact on the cardiovascular system. Rev Argent Cardiol 2025;93:121-30. https://doi.org/10.7775/rac.v93.i2.20882

2. Arendt J, Middleton B. Human seasonal and circadian studies in Antarctica (Halley, 75°S). Gen Comp Endocrinol 2018;258:250-8. https://doi.org/10.1016/j.ygcen.2017.05.010.

3. Mairesse O, MacDonald-Nethercott E, Neu D, Tellez HF, Dessy E, Neyt X, et al. Human sleep and performance during a 13-month stay in Antarctica. Sleep 2019;42(4):zsy206. https://doi.org/10.1093/sleep/zsy206

4. Garrett-Bakelman FE, Darshi M, Green SJ, Gur RC, Lin L, Macias BR, et al. The NASA Twins Study. Science 2019;364(6436):eaau8650. https://doi.org/10.1126/science.aau8650.

5. Rajagopalan S, Al-Kindi SG, Brook RD, et al. Air Pollution and Cardiovascular Disease: JACC Review. J Am Coll Cardiol 2018;72(17):2054-70. https://doi.org/10.1016/j.jacc.2018.07.099.

AUTHORS’ REPLY

Dear Dr. Brunella Bertazzo

We would like to thank you for your opinion about our work.

We agree with your opinions and the comparisons with other experiences in extreme living conditions.

We observed an increase in autonomic nervous system activity over cardiac function, which suggests an increased neurovegetative pattern, predominantly vagal.

This hibernation state resembles that of another mammal, the bear. In the boreal winter, it initiates a state of lethargy that allows it to conserve energy and survive the scarcity of food and the low temperatures typical of this season. Hibernation is not a constant deep sleep, but rather a significant reduction in metabolism, heart rate and body temperature.

Physiologically, its heart rate drops from 40-50 to about 10 beats per minute, respiratory rate drops by half, and temperature is reduced by 4 to 5 degrees Celsius.

Future research will provide us with additional information on biochemical parameters (acetylcholine, melatonin, cortisol, noradrenaline, etc.) that will explain more clearly the mechanisms involved in this physiological adaptability to these extreme conditions.

Ricardo Iglesias