Hormonal responses to a long duration exploration in a cave of 700 m depth

Abstract

We studied the hypothalamus-pituitary adrenocortical, hypothalamus-pituitary and hypothalamus-pituitary thyroid system responses to a long duration activity (about 20 h) practiced in a demanding environment, characterized by darkness, low temperature and high humidity, namely alpine potholing. We performed four blood drawings in five elite potholers: (1) the morning before the performance, (2) at the bottom of the cave (-700 m), (3) at the end of the ascent, and (4) after 24 h of recovery. Two blood drawings as controls were performed on the same potholers, at the same resting time and with the same experimental procedures as the previous ones. Friedman two-way ANOVA test evidenced significant changes through the different time intervals for detrended (i.e., test values minus control values) growth hormone (GH) (P = 0.003), detrended cortisol (P = 0.004) and FT4 (P = 0.002), while this was not true for TSH and FT3. Successively pairwise comparisons were done both through the different time intervals and between test and control values. The rise of GH values during the performance underlines the great intensity and long duration characteristic of potholing as well as the possibility that the climbing sit harness can cause problems due to vascular hypo-perfusion. Cortisol data, peaking before entering the cave, suggest that there was a marked anticipatory stress reaction followed by less stressing phase during the performance. Finally, the rise of FT4 is likely due to the typical increase of free fatty acids that usually occurs during endurance exercise.

Expedition Cognition: A Review and Prospective of Subterranean Neuroscience With Spaceflight Applications

“…However, its capacity to support multiple experiments is limited by tight personnel scheduling. Expeditions of other organizations may therefore be more suitable for a given research question, taking into consideration the specific expedition's space analog suitability (for recent examples of cave-based human research and a description of the cave conditions and mission, see Stenner et al, 2007 ; Antoni et al, 2017 ; Pinna et al, 2017 ). Cave expeditions may vary due to differences in cave environments (temperature, presence of water, remoteness and access, difficulty level, etc.…”

Human Physiology During Exposure to the Cave Environment: A Systematic Review With Implications for Aerospace Medicine

“…Equally, previous research related to endocrine and immune-hematological changes not only showed the potential for an anticipatory stress reaction to the cave environment, based on increased cortisol levels (Stenner et al, 2007a), but also suggested that there may be a compensatory response to both exercise and environment [evidenced by decreased cortisol levels and restoration of GH levels 24 h post cave exit (Stenner et al, 2006, 2007a,b)]. Due to the pulsatile nature of GH levels in the blood, conventional measurements of serum GH are highly variable dependent on a number of environmental stressors.…”

“…Cave/lab simulation exercises were performed in all studies; exercise can be classified as cave progression (characterized by atypical, strenuous movement, often combining ascent, descent, and scrambling activity) in all studies apart from one, where an exercise stress test in the simulated cave-environment condition was completed (Maura et al, 2008). Anthropometric characteristics were measured in the majority of the studies (Vacca et al, 1994; Bratima et al, 1999; Stenner, 2002; Bregani et al, 2005; Stenner et al, 2006, 2007a,b; Maura et al, 2008; Antoni et al, 2017; Pinna et al, 2017). Overall, study subjects were healthy with heterogeneous anthropometric characteristics.…”

“…Previous work focused on hypothalamus-pituitary adrenocortical, hypothalamus-pituitary and hypothalamus-pituitary thyroid system responses to duration cave activity of ~ 20 h. Results demonstrated an evident elevation of serum cortisol prior to cave entry, even in elite cavers. This initial anticipatory stress reaction was reportedly reduced over time, followed by a noticeable increase in growth hormone (GH) production during prolonged explorative cave activity (Stenner et al, 2007a). Recently, Antoni et al (2017) reported that total energy expenditure (TEE) was in the range 225–287 kcal.h −1 for women and men for a standardized cave progression (i.e., 10 h subterranean exploration), which is equivalent to an average metabolic equivalent of task (METs) of 4.1 METs.…”

Laboratory Investigation of the 900-km Lapland Extreme Challenge

“…This was in part unexpected considering that long duration exercise, sleep deprivation, and extreme conditions seem to increase the pituitary-adrenal cortex response [8]. However, another study regarding cortisol responses to extreme sports highlighted a significant drop during the performance, ending with values below the basal value [9]. A possible explanation could be that for these elite athletes, including the one we monitored, the extreme challenge is essential for their psychological well-being [10].…”