Training in the Shadow of War: Exertional Heat Illness During the "Iron Swords" War.

INTRODUCTION: High-intensity physical exertion in combat zones under harsh environmental conditions is associated with exertional heat illness (EHI). However, the impact of a full-scale war on the incidence and severity of EHI in training settings remains insufficiently investigated. MATERIALS AND METHODS: We analyzed EHI data obtained from the IDF Institute of Military Physiology database for three years (October 2022 to September 2025). The cohort included 174 soldiers diagnosed with EHI, stratified into three phases: Pre-War, Acute-War, and Late-War. RESULTS: Despite massive deployment to combat zones, 93.1% of EHI cases occurred in training settings. Of the cohort, 46 (26.4%) were classified as exertional heat stroke (EHS) and 128 (73.6%) as less-severe EHI (LSEHI). The proportion of life-threatening EHS cases increased to 36.7% during the Acute-War phase, compared to 20.7% Pre-War and 21.4% Late-War (P < .05). Although insufficient sleep was the strongest predictor of EHS across the entire cohort (OR 2.75, 95% CI, 1.34-5.65), its prevalence remained stable across periods. In contrast, the Acute-War phase was distinguished by a significant surge in exceeding effort scale (P = .019), inadequate nutrition (P = .021), and late recognition of underperforming soldiers (P = .049), driving the specific spike in severity during this period. CONCLUSION: During the Acute-War phase (October 2023-September 2024), EHI cases occurred predominantly training-based and were markedly more severe. These findings suggest that a wartime context may influence risk perception and decision-making within training systems, contributing to the accumulation of multiple interacting risk factors and an increased likelihood of progression from LSEHI to EHS.