A 32-day long fieldwork in Antarctica improves heat tolerance during physical exercise.

Ygor A.T Martins,Danusa D Soares,Rosa M.E Arantes,Thiago T Mendes,Dawit A.P Gonçalves,Alice L Marques,Luiz O.C Rodrigues,Michele M Moraes,Renata L.F Passos,Samuel P Wanner,Cristian Núñez-Espinosa

doi:10.1590/0001-3765202220210593

Abstract

We evaluated the influence of a 32-day camping in Antarctica on physical performance and exercise-induced thermoregulatory responses. In Brazil, before and after the Antarctic camping, the volunteers performed an incremental exercise at temperate conditions and, two days later, an exercise heat stress protocol (45-min running at 60% of maximum aerobic speed, at 31°C and 60% of relative humidity). In Antarctica, core temperature was assessed on a day of fieldwork, and average values higher than 38.5°C were reported. At pre- and post-Antarctica, physiological (whole-body and local sweat rate, number of active sweat glands, sweat gland output, core and skin temperatures) and perceptual (thermal comfort and sensation) variables were measured. The Antarctic camping improved the participants' performance and induced heat-related adaptations, as evidenced by sweat redistribution (lower in the chest but higher in grouped data from the forehead, forearm, and thigh) and reduced skin temperatures in the forehead and chest during the exercise heat stress protocol. Notwithstanding the acclimatization, the participants did not report differences of the thermal sensation and comfort. In conclusion, staying in an Antarctic camp for 32 days improved physical performance and elicited physiological adaptations to heat due to the physical exertion-induced hyperthermia in the field.

Highlights

Moving to or staying in Antarctica under isolation, confinement, and extreme (ICE) conditions challenges the human body (Palinkas & Suedfeld 2008)
There were no intertrial differences during Exercise heat stress (EHS) in the final Heart rate (HR), rate of perceived exertion (RPE), Urine specific gravity (USG), thermal sensation and thermal comfort, the participants exhibited a moderate increase in water intake in the post-Antarctica trial (Table II)
The core temperature elevation observed during the Antarctic field displacements, associated with the insulative clothes, was a thermal stimulus sufficiently strong to induce heat adaptations

Summary

Introduction

Moving to or staying in Antarctica under isolation, confinement, and extreme (ICE) conditions challenges the human body (Palinkas & Suedfeld 2008). During Antarctic expeditions, the distress posed by the climatic conditions (i.e., low temperatures, strong winds, and snowstorms) is enhanced by the difficulties of long walks on rugged and snow-covered terrain. In extreme cold weather with no or insufficient insulative clothes, the maintenance of core body temperature (TCORE) is achieved by the association of physiological (i.e., vasoconstriction and shivering) and behavioral mechanisms (Romanovsky 2018). The ICE conditions of Antarctica are faced by researchers who participate in field activities. According to previous data from our group, throughout a fieldwork day, displacement activities in rugged terrain generate physical efforts classified as moderate- to high-intensity levels and represents an effective training load for the researchers, thereby increasing aerobic capacity and reducing cardiac strain, after 24days in the field (Moraes et al 2018)

Methods

Results

Conclusion