W.R. Yaku, C.P. Connolly

Washington State University, Pullman, WA

Elite athletes compete annually at the Ironman and half Ironman World Championships in Kona, Hawaii. An immense degree of metabolic stress during these events is induced in competitors due to their long durations, multisport nature, and rigorous environmental conditions. This presumably results in increased risk of heat-related illness (HRI) ranging from dehydration to heat stroke, causing more frequent medical tent visits. PURPOSE: To determine and compare incidence levels of HRIs for full Ironman and half Ironman championship competitors. METHODS: Medical records for athletes receiving treatment from 2013 to 2019 were examined, including complaints, illnesses, and treatments. For this study, HRIs included dehydration, hypotension, hyponatremia, hypokalemia, and heat stroke. Rates of athlete withdrawal from competition (DNF) as well as intravenous (IV) fluid administration were also investigated. Data were examined for 2,329 medical tent visits (n=333±45 per year) for the full Ironman and 425 visits (n=61±8 per year) for the half Ironman. RESULTS: The mean percentage of competitors reporting to the medical tent was greater for the full Ironman (15±2%) than the half Ironman (4±0.5%). However, the athlete DNF percentage was greater for the half Ironman (7±2%) than the full Ironman (5±1%). Differences were observed between the full Ironman and half Ironman for incidences of dehydration (30±4% vs. 13±6%), hypotension (12±2% vs. 9±5%), hyponatremia (5±1% vs. 1±1%), hypokalemia (6±3% vs. 0.5±0.8%), and IV administration (32±7% vs. 27±10%). All recorded cases of heat stroke were found in the full Ironman; however, serious heat illness was observed and likely common in competitors that did not report for treatment. CONCLUSION: These findings indicate that the full Ironman competition may carry a greater risk of HRI compared with the half Ironman. However, the remarkably greater DNF rate in the half Ironman may point to greater HRI severity. These findings may assist competition organizers and medical professionals in accommodating and providing treatment for medical tent visitors.

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