Real-time thermoregulatory and cardiovascular monitoring of non-acclimatised mountaineers in extreme cold: a 10-day field expedition study

Background: The primary aim of this study was to characterise the thermoregulatory and cardiovascular responses of non-acclimatised mountaineers during different exercise modalities and camping conditions in extreme cold. A secondary aim was to assess the feasibility of real-time transmission of physiological data to enhance safety during cold expeditions. Methods: This study assessed thermoregulatory and cardiovascular responses of 18 non-acclimatised mountaineers from the United Arab Emirates during a 10-day winter expedition in Skeikampen, Norway. Participants performed daily cross-country skiing or snowshoe walking (∼5–6 h/day) and experienced two camping conditions (quinzhee and tent). Core temperature (Tc) was measured via ingestible telemetric pills, and heart rate (HR) via chest straps. Data were transmitted in real-time using a wearable ecosystem comprising Bluetooth gateways and eSIM-enabled smartwatches. Results: Cross-country skiing elicited significantly higher mean Tc (+0.20 °C, p < 0.01) and HR (+12.8 bpm, p < 0.01) than snowshoe walking. Peak Tc during quinzhee camping was significantly higher than during tent camping (+0.55 °C, p = 0.03), suggesting superior insulation. No cases of hypothermia were recorded. Real-time data transmission enabled continuous remote monitoring, with actionable alerts triggered when Tc dropped below safety thresholds. Conclusion: This study demonstrates the feasibility of real-time physiological monitoring in extreme cold, offering practical insight into activity-specific thermoregulatory strain. The findings underscore the importance of shelter design, physical activity selection, and wearable monitoring to enhance safety and decision-making in cold environments.