Familiar name, unfamiliar reality: a case study of heat illness knowledge gaps among Japanese junior high and high school students.

Early recognition of exertional heat illness (EHI) is critical for preventing severe outcomes. However, the relationship between perceived knowledge and actual understanding remains unclear. This study investigated the recognition and correct matching of EHI and its symptoms among Japanese junior high and high school students. A paper-based, self-administered questionnaire was distributed under conditions of anonymity and voluntary participation. The questionnaire included recognition of the term "EHI" and its condition types and severity classifications (mild, moderate, and severe). EHI knowledge was evaluated by asking students to select all symptoms corresponding to each EHI condition and severity classification from a predefined list, based on previous guidelines. Valid responses were obtained from 533 junior high and 646 high school students. Almost all students recognised the term "EHI," with most reporting school health education as the primary source of learning. However, correct matching of EHI types with their associated symptoms was low (junior high school/high school): 1.9/3.1% for heat syncope, 22.1/26.9% for exercise-associated muscle cramps, 4.1/7.9% for exertional heat exhaustion, and 0.4/0.5% for exertional heat stroke. These results indicate that, although recognition of EHI terminology was nearly universal, correct matching of symptoms was extremely low. These findings reveal a substantial gap between perceived knowledge and actual understanding of EHI. This discrepancy may lead to delayed recognition and inappropriate responses in real-world situations, potentially increasing the risk of adverse outcomes during heat exposure. Addressing this gap may be important for improving safety and public health preparedness in school-based settings.