Incidence of Hyponatremia During a Continuous 246-km Ultramarathon Running Race

Adam D. Seal, Costas A. Anastasiou, Katerina P. Skenderi, Marcos Echegaray, Nikos Yiannakouris, Yiannis E. Tsekouras, Antonia L. Matalas, Mary Yannakoulia, Fani Pechlivani, Stavros A. Kavouras

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Abstract

Purpose: The purpose of this observational study was to examine the incidence of exercise-associated hyponatremia (EAH) in a 246-km continuous ultra-marathon. Methods: Over 2 years, 63 male finishers of the annual Spartathlon ultra-marathon foot race from Athens to Sparta, Greece were included in the data analysis. A blood sample was drawn from an antecubital vein the day before the race as well as within 15 min post-race and analyzed for sodium concentration. During the second year of data collection, blood was also drawn at the 93-km checkpoint (n = 29). Height and weight were measured pre and post-race. Results: Mean race time of all subjects was 33 ± 3 h with a range of 23.5 and 36.0 h. Of the 63 finishers recruited, nine began the race with values indicative of mild hyponatremia. Seven runners were classified as hyponatremic at the 93-km checkpoint, three of whom had sodium levels of severe hyponatremia. After the race, 41 total finishers (65%) developed either mild (n = 27, 43%) or severe hyponatremia (n = 14, 22%). Mean change in bodyweight percentage and serum sodium from pre-race to post-race was −3.6 ± 2.7% (−2.5 ± 1.9 kg) and −6.6 ± 5.6 mmol·L−1, respectively. Pre-race serum sodium level was not a significant predictor of post-race serum sodium levels (β = 0.08, R2 = 0.07, P = 0.698), however, there was a significant negative association between change in bodyweight percentage and post-race serum sodium concentration (β = −0.79, R2 = 0.29, P = 0.011). Conclusion: The incidence of EAH of 52 and 65%, when excluding or including these individuals with pre-race hyponatremia, was the highest reported in current literature.

Original languageEnglish (US)
Article number161
JournalFrontiers in Nutrition
Volume6
DOIs
StatePublished - Oct 11 2019

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Keywords

  • dehydration
  • electrolyte balance
  • fluid balance
  • heat
  • hypohydration
  • sodium
  • sweat
  • thermoregulation

ASJC Scopus subject areas

  • Food Science
  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

Cite this

Seal, A. D., Anastasiou, C. A., Skenderi, K. P., Echegaray, M., Yiannakouris, N., Tsekouras, Y. E., Matalas, A. L., Yannakoulia, M., Pechlivani, F., & Kavouras, S. A. (2019). Incidence of Hyponatremia During a Continuous 246-km Ultramarathon Running Race. Frontiers in Nutrition, 6, [161]. https://doi.org/10.3389/fnut.2019.00161