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Title: Hypohydration impairs endurance performance: a blinded study
Authors: James, Lewis J.
Moss, Jodie
Henry, Joshua
Papadopoulou, Charikleia
Mears, Stephen A.
Keywords: Dehydration
Drink
Hydration
Placebo effect
Time trial
Water balance
Issue Date: 2017
Publisher: © the Authors. Published by Wiley.
Citation: JAMES, L.J. ...et al., 2017. Hypohydration impairs endurance performance: a blinded study. Physiological Reports, 5: e13315.
Abstract: The general scientific consensus is that starting exercise with hypohydration >2% body mass impairs endurance performance/capacity, but most previous studies might be confounded by a lack of subject blinding. This study examined the effect of hypohydration in a single blind manner using combined oral and intragastric rehydration to manipulate hydration status. After familiarization, seven active males (mean ±SD: age 25± 2 years, height 1.79±0.07, body mass 78.6±6.2, VO2peak 48 ±7 mL.kg.min -1) completed two randomized trials at 34°C. Trials involved an intermittent exercise preload (8x15 min exercise/5 min rest), followed by a 15-min all-out performance test on a cycle ergometer. During the preload, water was ingested orally every 10 min (0.2 mL.kg body mass -1). Additional water was infused into the stomach via a gastric feeding tube to replace sweat loss (EU) or induce hypohydration of ~2.5% body mass (HYP). Blood samples were drawn and thirst sensation rated before, during, and after exercise. Body mass loss during the preload was greater (2.4 ±0.2% vs. 0.1± 0.1%; P < 0.001), while work completed during the performance test was lower (152± 24 kJ vs. 165 ±22 kJ; P < 0.05) during HYP. At the end of the preload, heart rate, RPE, serum osmolality, and thirst were greater and plasma volume lower during HYP (P < 0.05). These results provide novel data demonstrating that exercise performance in the heat is impaired by hypohydration, even when subjects are blinded to the intervention.
Description: This is an Open Access Article. It is published by Wiley under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/
Version: Published
DOI: 10.14814/phy2.13315
URI: https://dspace.lboro.ac.uk/2134/25695
Publisher Link: http://dx.doi.org/10.14814/phy2.13315
ISSN: 2051-817X
Appears in Collections:Published Articles (Sport, Exercise and Health Sciences)

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