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Maintained Hydration Status After a 24-h Winter Mountain Running Race Under Extremely Cold Conditions


Chlíbková, Daniela; Nikolaidis, Pantelis T; Rosemann, Thomas; Knechtle, Beat; Bednář, Josef (2018). Maintained Hydration Status After a 24-h Winter Mountain Running Race Under Extremely Cold Conditions. Frontiers in Physiology, 9:1959.

Abstract

To date, no study has examined the hydration status of runners competing in a 24-h winter race under extremely cold environmental conditions. Therefore, the aim was to examine the effect of a 24-h race under an average temperature of -14.3°C on hydration status. Blood and urine parameters and body mass (BM) were assessed in 20 finishers (women, = 6; men, = 14) pre- and post-race. Five (25%) ultra-runners had lower pre-race plasma sodium [Na] and 11 (52%) had higher pre-race plasma potassium [K] values than the reference ranges. Post-race plasma [Na], plasma osmolality, urine osmolality and urine specific gravity remained stable ( > 0.05). The estimated fluid intake did not differ ( > 0.05) between women (0.30 ± 0.06 L/h) and men (0.46 ± 0.21 L/h). Runners with a higher number of completed ultra-marathons ( = -0.50, = 0.024) and higher number of training kilometers ( = -0.68, = 0.001) drank less than those with lower running experience. Pre-race and post-race plasma [Na] were related to plasma osmolality ( = 0.65, = 0.002, = 0.69, < 0.001, respectively) post-race, but not to fluid intake ( > 0.05). BM significantly decreased post-race ( = 0.002) and was not related to plasma [Na] or fluid intake ( > 0.05). Post-race hematocrit and plasma [K] decreased ( < 0.001) and transtubular potassium gradient increased ( = 0.008). Higher pre-race plasma [K] was related to higher plasma [K] loss post-race ( = -0.85, < 0.001). Hydration status remained stable despite the extremely cold winter weather conditions. Overall fluid intake was probably sufficient to replenish the hydration needs of 24-h runners. Current recommendations may be too high for athletes competing in extremely cold conditions.

Abstract

To date, no study has examined the hydration status of runners competing in a 24-h winter race under extremely cold environmental conditions. Therefore, the aim was to examine the effect of a 24-h race under an average temperature of -14.3°C on hydration status. Blood and urine parameters and body mass (BM) were assessed in 20 finishers (women, = 6; men, = 14) pre- and post-race. Five (25%) ultra-runners had lower pre-race plasma sodium [Na] and 11 (52%) had higher pre-race plasma potassium [K] values than the reference ranges. Post-race plasma [Na], plasma osmolality, urine osmolality and urine specific gravity remained stable ( > 0.05). The estimated fluid intake did not differ ( > 0.05) between women (0.30 ± 0.06 L/h) and men (0.46 ± 0.21 L/h). Runners with a higher number of completed ultra-marathons ( = -0.50, = 0.024) and higher number of training kilometers ( = -0.68, = 0.001) drank less than those with lower running experience. Pre-race and post-race plasma [Na] were related to plasma osmolality ( = 0.65, = 0.002, = 0.69, < 0.001, respectively) post-race, but not to fluid intake ( > 0.05). BM significantly decreased post-race ( = 0.002) and was not related to plasma [Na] or fluid intake ( > 0.05). Post-race hematocrit and plasma [K] decreased ( < 0.001) and transtubular potassium gradient increased ( = 0.008). Higher pre-race plasma [K] was related to higher plasma [K] loss post-race ( = -0.85, < 0.001). Hydration status remained stable despite the extremely cold winter weather conditions. Overall fluid intake was probably sufficient to replenish the hydration needs of 24-h runners. Current recommendations may be too high for athletes competing in extremely cold conditions.

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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
Language:English
Date:2018
Deposited On:06 Jun 2019 15:05
Last Modified:01 Jul 2019 12:34
Publisher:Frontiers Research Foundation
ISSN:1664-042X
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.3389/fphys.2018.01959
PubMed ID:30687135

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