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Journal of Cognitive Enhancement

, Volume 3, Issue 3, pp 338–348 | Cite as

Maintaining Euhydration Preserves Cognitive Performance, But Is Not Superior to Hypohydration

  • Stephen P. J. GoodmanEmail author
  • Ashleigh T. Moreland
  • Frank E. Marino
Original Research

Abstract

Maintaining optimal physical and cognitive performance are keys to success for most exercise contexts. However, consensus on the effects of dehydration for cognitive function is equivocal, particularly given the addition of confounding variables when hypohydration (HYPO) results. Therefore, this study aimed to examine whether maintaining euhydration (EUH) would preserve cognitive function, and whether this physiological state would be superior than if HYPO were evoked in an identical exercise task. In a crossover design, 15 participants (12 males, age 27.93 ± 6.81 years, height 177.20 ± 6.95 cm, mass 84.40 ± 12.35 kg) completed a 90 min self-paced simulated military march in the heat, whilst either maintaining EUH by consuming fluid ad libitum or becoming hypohydrated via fluid restriction. A cognitive testing battery was administered pre-exercise and following a rest period (55 ± 8 min), and evaluated information processing, memory, impulsivity, attention and concentration, and response time domains, whilst subjective estimates of performance were also quantified. Aspects of memory and impulsivity were not comparable to pre-exercise data (both P ≤ 0.05), whilst a shift in the speed-accuracy trade-off was apparent in the switching attention task, with accuracy decreasing (P = 0.003), and reaction time being supplemented (P = 0.028). Despite body mass losses of 2.28%, hydration status did not influence performance for any of the measured cognitive domains (all P > 0.05). When hypohydrated, subjective estimates of thirst were significantly greater post-exercise (P = 0.004), whilst medium effect sizes were found for lethargy (d = 0.532) and task difficulty (d = 0.553) post-exercise. Although maintaining EUH by en-large preserves cognitive function, this does not produce superior cognitive performance compared with fluid restriction following an identical exercise task. Therefore, despite losses in body mass exceeding 2%, cognitive performance remains largely stable.

Keywords

Cognition Hydration Dehydration Fluid consumption Military Performance 

Abbreviations

°C

Degrees Celsius

ADF

Australian Defence Force

cm

Centimetre

EUH

Euhdyration

fMRI

Functional magnetic resonance imaging

HYPO

Hypohydration

kg

Kilogramme

km

Kilometre

min

Minute

mL

Millilitre

mm

Millimetre

mmol/L

Millimoles per litre

ms

Millisecond

RPM

Revolutions per minute

Tc

Core temperature

USG

Urine specific gravity

Notes

Acknowledgements

The authors would like to thank all the participants of the study who volunteered their time freely, independent of any duties associated with the Australian Defence Force.

Funding

Stephen Goodman held an Australian Postgraduate Research Scholarship from Charles Sturt University (Australia), and this research was sponsored by a grant from the Spitfire Association (grant number 0000101840), awarded to Professor Marino as the Memorial Spitfire Fellow 2016. No further funding was provided by agencies in the public, commercial, or not-for-profit sectors.

Compliance of Ethical Standards

Conflicts of Interest

The authors declare that they have no conflict of interest.

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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.School of Exercise Science, Sport and HealthCharles Sturt UniversityBathurstAustralia
  2. 2.School of Health and Biomedical SciencesRoyal Melbourne Institute of TechnologyMelbourneAustralia

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