Hormonal changes in acclimatized soldiers during a march at a high altitude with mountain skis

Abstract

Background: The aim of the present study is to identify the physiological impact of acute exposure to high altitudes on special acclimatized troops of the Chilean Army. Twenty-nine soldiers carried out a nocturnal winter march on mountain skis at an initial altitude of 2,800 m and up to 3,640 m. Two separate blood measurements were taken. The first one was taken the day before the march (Pre-sample) and the second one just after returning to the base camp (Post-sample). All subjects had been acclimatized prior to the study. For hypothesis comparison purposes, the normality of the distribution was tested using the Shapiro-Wilk test. To determine if there were significant differences between the Pre and Post tests, a paired-samples Student t-test was applied for the variables with a normal distribution, and the Wilcoxon test was applied for the variables without a normal distribution. In all cases, a level of significance of 95% (p<0.05) was taken into consideration. Results: Exposure of acclimatized troops to altitudes of 2,800 m to 3,640 m has an impact on the endocrine parameters and on the reduction of cortisol (p<0.01), total testosterone (p<0.0001), free testosterone (p<0.0001) and the free testosterone-cortisol ratio (p<0.01). Likewise, an increase in total leukocytes (p<0.0001), neutrophils (p<0.0001), monocytes (p<0.0001) and basophils (p<0.001), as well as a decrease of eosinophils (p<0.0001) and lymphocytes (p<0.01), was observed. No hematological changes were detected. Conclusions: Endocrine changes were observed during high-altitude winter marches on mountain skis carried out by accli­matized Special Operation Troops, resulting in decreased cortisol and free and total testosterone levels. A stress condition due to the high altitudes also affected the anabolic/catabolic environment, which manifested as a significant decrease in the free testosterone/cortisol ratio. No hematological changes were identified. Marked changes were observed in some white cell series.

Background: The aim of the present study is to identify the physiological impact of acute exposure to high altitudes on special acclimatized troops of the Chilean Army. Twenty-nine soldiers carried out a nocturnal winter march on mountain skis at an initial altitude of 2,800 m and up to 3,640 m. Two separate blood measurements were taken. The first one was taken the day before the march (Pre-sample) and the second one just after returning to the base camp (Post-sample). All subjects had been acclimatized prior to the study. For hypothesis comparison purposes, the normality of the distribution was tested using the Shapiro-Wilk test. To determine if there were significant differences between the Pre and Post tests, a paired-samples Student t-test was applied for the variables with a normal distribution, and the Wilcoxon test was applied for the variables without a normal distribution. In all cases, a level of significance of 95% (p<0.05) was taken into consideration. Results: Exposure of acclimatized troops to altitudes of 2,800 m to 3,640 m has an impact on the endocrine parameters and on the reduction of cortisol (p<0.01), total testosterone (p<0.0001), free testosterone (p<0.0001) and the free testosterone-cortisol ratio (p<0.01). Likewise, an increase in total leukocytes (p<0.0001), neutrophils (p<0.0001), monocytes (p<0.0001) and basophils (p<0.001), as well as a decrease of eosinophils (p<0.0001) and lymphocytes (p<0.01), was observed. No hematological changes were detected. Conclusions: Endocrine changes were observed during high-altitude winter marches on mountain skis carried out by accli­matized Special Operation Troops, resulting in decreased cortisol and free and total testosterone levels. A stress condition due to the high altitudes also affected the anabolic/catabolic environment, which manifested as a significant decrease in the free testosterone/cortisol ratio. No hematological changes were identified. Marked changes were observed in some white cell series.