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Pre- and Post-Race Hydration Status in Hyponatremic and Non-Hyponatremic Ultra-Endurance Athletes


Chlíbková, Daniela; Rosemann, Thomas; Posch, Lenka; Matoušek, Radek; Knechtle, Beat (2016). Pre- and Post-Race Hydration Status in Hyponatremic and Non-Hyponatremic Ultra-Endurance Athletes. Chinese Journal of Physiology, 59(3):173-183.

Abstract

The monitoring of body mass, plasma sodium [Na⁺] and urinary specific gravity (Usg) are commonly used to help detect and prevent over- or dehydration in endurance athletes. We investigated pre-and post-race hydration status in 113 amateur 24-h ultra-runners, 100-km ultra-runners, multi-stage mountain bikers and 24-h mountain bikers, which drank ad libitum without any intervention and compared results of hyponatremic and non-hyponatremic finishers. On average, pre-race plasma [Na⁺] and both pre- and post-race levels of Usg and body mass were not significantly different between both groups. However, nearly 86% of the post-race hyponatremic and 68% of the normonatremic ultra-athletes probably drank prior the race greater volumes than their thirst dictated regarding to individual pre-race Usg levels. Fluid intake during the race was equal and was not related to plasma [Na⁺], Usg or body mass changes. A significant decrease in post-race plasma [Na⁺], body mass and an increasement in post-race Usg was observed in hypo- and normonatremic finishers. Moreover, pre-race plasma [Na⁺] was inversely associated with post-race percentage change in plasma [Na⁺], and pre-race Usg and urinary [Na⁺] with percentage change in Usg in both groups with and without post-race EAH. Thirteen (11.5%) finishers developed post-race EAH (plasma [Na⁺] < 135 mM). The incidence of EAH in ultra-endurance athletes competing in the Czech Republic was higher than reported previously.

Abstract

The monitoring of body mass, plasma sodium [Na⁺] and urinary specific gravity (Usg) are commonly used to help detect and prevent over- or dehydration in endurance athletes. We investigated pre-and post-race hydration status in 113 amateur 24-h ultra-runners, 100-km ultra-runners, multi-stage mountain bikers and 24-h mountain bikers, which drank ad libitum without any intervention and compared results of hyponatremic and non-hyponatremic finishers. On average, pre-race plasma [Na⁺] and both pre- and post-race levels of Usg and body mass were not significantly different between both groups. However, nearly 86% of the post-race hyponatremic and 68% of the normonatremic ultra-athletes probably drank prior the race greater volumes than their thirst dictated regarding to individual pre-race Usg levels. Fluid intake during the race was equal and was not related to plasma [Na⁺], Usg or body mass changes. A significant decrease in post-race plasma [Na⁺], body mass and an increasement in post-race Usg was observed in hypo- and normonatremic finishers. Moreover, pre-race plasma [Na⁺] was inversely associated with post-race percentage change in plasma [Na⁺], and pre-race Usg and urinary [Na⁺] with percentage change in Usg in both groups with and without post-race EAH. Thirteen (11.5%) finishers developed post-race EAH (plasma [Na⁺] < 135 mM). The incidence of EAH in ultra-endurance athletes competing in the Czech Republic was higher than reported previously.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Institute of General Practice
Dewey Decimal Classification:610 Medicine & health
Date:30 June 2016
Deposited On:14 Jul 2016 13:14
Last Modified:08 Dec 2017 19:55
Publisher:Chinese Physiological Society
ISSN:0304-4920
Publisher DOI:https://doi.org/10.4077/CJP.2016.BAE391
PubMed ID:27188470

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