ARKHANGELSK, January 21. /TASS/. Scientists developed a new method to assess adaptive reserves of people participating in short-term (up to one month long) expeditions in extreme climatic conditions, like for example, in marine expeditions to the Arctic, senior researcher at the Tkachev Laboratory of Endocrinology at the Federal Research Center for Integrated Arctic Studies (the Russian Academy of Sciences' Urals Branch), Alexandra Elfimova, told TASS. The assessment is based on the ratio of hormones in saliva, which is more convenient than analyzing blood samples.

"We have taken the ratio of dehydroepiandrosterone (DHEA) and cortisol levels. Cortisol is a catabolic hormone released mainly under stress, and DHEA is an anabolic hormone, released simultaneously with cortisol to help in compensating for this stress. Within a rather short, three-week, expedition, hormones in the blood almost do not react, while free forms of hormones are present in saliva, and there good dynamics is recorded. Therefore, we can take these two indicators and evaluate the body's adaptive reserves by the index and ratio between them. Most importantly, this is a non-invasive method, as it is easier to sample saliva than blood. Additionally, this way we can evaluate the ratio of testosterone and cortisol in both men and women," the expert said.

The research was conducted during the Arctic Floating University voyages in 2024 and 2025. Blood and saliva samples were taken from the expeditions' participants at the voyages' beginning, middle and end. The expeditions lasted for about three weeks, where hormone levels in the blood did not change significantly. In saliva, however, they reacted quickly to changes in the body.

Adaptation during polar voyages

An Arctic marine expedition, even if it is not very long, is a major stress for the body. People remain in the enclosed space of a ship, they are surrounded by new people. They have to work in difficult climatic conditions: at low temperatures, heavy rolling, wind, and during long trips ashore islands. Photoperiods are also very important - in the Arctic it is a polar day in summer, and it is quite difficult for the body to get adjusted to constant light. At the same time, during expeditions, people work very intensively - the body mobilizes, and adaptive changes are aimed at maintaining stable working capacity.

Cortisol is significantly high in saliva when the expedition begins - the person mobilizes for new challenges. Almost immediately, DHEA is rising, but testosterone remains quite low. In case of good adaptation, in the middle of the expedition, cortisol begins to lower, while testosterone increases. By the end of the term, the DHEA/cortisol and testosterone/cortisol indices must be higher than they were at the beginning.

"The dynamics of testosterone, DHEA and cortisol levels reflects the regulatory systems are restructuring towards anabolic processes starting from the expedition's middle, thus contributing to adaptation during the intense physical work period," the scientist told TASS. "Therefore, we can determine two indicators. For example, if the ratio is below a certain limit, it means that adaptive reserves are depleted, and in that case rehabilitation measures are needed."

For example, using adaptogenic herbs to help the body get adjusted during the expedition or recover after it is over. The method may be used to assess adaptation in participants in scientific expeditions to the Arctic, as well as tourists who travel to high latitudes, since the Arctic tourism has a high development potential.

How anxiety levels effect hormones

During the past expeditions, physiologists studied mood and anxiety levels to find that the higher the cortisol level was at the beginning of the voyage, the worse were the health conditions and the lower were mood and activity indicators. And, vice versa, the lower was the cortisol level, the better people were feeling. Additionally, they found that the level of reactive (situational) anxiety in women is significantly higher than in men at each stage of the expedition.

"In women, we have found a connection between the DHEA content and the level of personal anxiety," the scientist added. "The higher was a woman's personal anxiety, the less DHEA was growing."

The scientists plan to conduct additional research on this topic.