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James et al. 2017. Hypohydration impairs endurance performance. a blinded study.pdf (235.89 kB)

Hypohydration impairs endurance performance: a blinded study

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posted on 2017-07-04, 10:15 authored by Lewis JamesLewis James, Jodie Moss, Joshua Henry, Charikleia Papadopoulou, Stephen MearsStephen Mears
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.

History

School

  • Sport, Exercise and Health Sciences

Published in

Physiological Reports

Volume

Vol. 5

Issue

Iss. 12

Pages

e13315 - e13315 (10)

Citation

JAMES, L.J. ...et al., 2017. Hypohydration impairs endurance performance: a blinded study. Physiological Reports, 5: e13315.

Publisher

© the Authors. Published by Wiley.

Version

  • VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

2017-05-14

Publication date

2017-06-22

Notes

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/

ISSN

2051-817X

Language

  • en