Abstract
Background
Multistage desert rally competitions combine prolonged environmental heat exposure, mechanical workload, altitude exposure, and restricted recovery, potentially increasing thermal and sleep-related strain. However, integrated field data collected during authentic competition remain limited.
Methods
Forty-six competitors (44 males, 2 females) participating in the 2018 Dakar Rally were monitored across 14 stages performed in South America under hot desert conditions. Gastrointestinal core temperature, in-vehicle microclimate temperature, actigraphy-derived sleep parameters, and perceptual measures were collected during competition. A total of 204 in-vehicle temperature recordings, 122 core temperature profiles, 131 questionnaires, and 36 nights of actigraphy were analyzed.
Results
Stages were prolonged (623±206 km; 9 h 56 min ± 4 h 05 min) and environmentally variable, with 43±31% sand sections and 47% of stages exceeding 2500 m altitude. In-vehicle temperatures exceeded 50°C across all vehicle categories. Mean peak gastrointestinal core temperature reached 38.3±0.4°C; approximately one third of recorded values exceeded 38.5°C, and values ≥39°C were observed. Terrain difficulty was positively associated with peak core temperature, whereas stage duration showed weaker associations. In contrast, total sleep time and low-activity sleep were negatively associated with stage duration and altitude, largely due to earlier wake-up times. Reduced sleep duration was associated with daytime sleepiness.
Conclusions
Thermoregulatory strain and sleep restriction during prolonged desert rally competition appear driven by distinct operational determinants: terrain difficulty for heat strain and logistical scheduling constraints for sleep loss. Ecological physiologic monitoring may help inform medical oversight strategies in extreme motorsport.
Keywords
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