Influence of Hypohydration on Intermittent Sprint Performance in the Heat

Maxwell, Neil; Mackenzie, Richard W.A.; Bishop, David J.

doi:10.1123/ijspp.4.1.54

Cited by 11 publications

(16 citation statements)

References 31 publications

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“…Dehydration and rehydration protocols were heterogeneous amongst included trials. In 57 out of the 61 trials reviewed, dehydration was accomplished via passive heat exposure ( n = 11) [42, 47, 50–56] or physical activity ( n = 47), conducted in a thermoneutral laboratory ≤25 °C ( n = 16) [24, 25, 29, 35, 48, 55, 57–61], heated environmental chamber ( n = 28) [22, 29, 33, 36, 37, 41, 46, 49, 62–71] or environmental conditions not specified ( n = 3) [72, 73]. The remaining trials reduced body water content through warm water immersion ( n = 2) [74, 75] or dietary fluid restriction in combination with 2-h moderate intensity exercise 24 h prior to testing performance ( n = 2) [76, 77].…”

Section: Resultsmentioning

confidence: 99%

“…The remaining trials reduced body water content through warm water immersion ( n = 2) [74, 75] or dietary fluid restriction in combination with 2-h moderate intensity exercise 24 h prior to testing performance ( n = 2) [76, 77]. In 46 trials (74%) [22, 24, 29, 36, 37, 41, 42, 46, 47, 49–53, 55–59, 61–63, 66, 67, 71, 73–77], dehydration yielded BM losses ≥2%. Of these, 27 trials (43%) dehydrated participants by ≥3.0% of initial BM [22, 24, 29, 37, 41, 42, 46, 50, 52, 53, 56, 61, 62, 66, 67, 74–77].…”

Section: Resultsmentioning

confidence: 99%

“…Studies administering carbohydrate-containing fluids were often excluded due to unequal provision of macronutrients on control and intervention trials. Two included studies failed to specify the type of fluid consumed (this was presumed to be water) [42, 56], and one study did not report dietary standardization procedures or specify whether subjects consumed food during the prolonged (>12 h, overnight) period of intervention [22]. The volume of fluid administered ranged from 0.40 [72] to 1.55 L kg −1 BM lost [65].…”

Section: Resultsmentioning

confidence: 99%

“…In 20 trials (33%), participants ingested a volume of fluid to replace <100% of sweat losses [24, 25, 33, 35, 47, 57–59, 62, 68, 70–72, 76, 77]. Only 2 trials [22, 65] provided a volume of fluid that complied with current recommendations for restoring fluid loss (1.25–1.50 L kg BM lost −1 ) [16, 17]. In 14 trials, dehydrated control subjects ingested a small volume of non-nutritive fluid (≤200 mL) [42, 55, 56, 62, 63, 66, 71] or mouth rinse [33].…”

Section: Resultsmentioning

confidence: 99%

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The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: a Systematic Review and Meta-analysis

2017

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BackgroundThe deleterious effects of dehydration on athletic and cognitive performance have been well documented. As such, dehydrated individuals are advised to consume fluid in volumes equivalent to 1.25 to 1.5 L kg−1 body mass (BM) lost to restore body water content. However, individuals undertaking subsequent activity may have limited time to consume fluid. Within this context, the impact of fluid intake practices is unclear. This systematic review investigated the effect of fluid consumption following a period of dehydration on subsequent athletic and cognitive performance.MethodsPubMed (MEDLINE), Web of Science (via Thomas Reuters) and Scopus databases were searched for articles reporting on athletic (categorized as: continuous, intermittent, resistance, sport-specific and balance exercise) or cognitive performance following dehydration of participants under control (no fluid) and intervention (fluid intake) conditions. Meta-analytic procedures determined intervention efficacy for continuous exercise performance.ResultsSixty-four trials (n = 643 participants) derived from 42 publications were reviewed. Dehydration decreased BM by 1.3–4.2%, and fluid intake was equivalent to 0.4–1.55 L kg−1 BM lost. Fluid intake significantly improved continuous exercise performance (22 trials), Hedges’ g = 0.46, 95% CI 0.32, 0.61. Improvement was greatest when exercise was performed in hotter environments and over longer durations. The volume or timing of fluid consumption did not influence the magnitude of this effect. Evidence indicating a benefit of fluid intake on intermittent (10 trials), resistance (9 trials), sport-specific (6 trials) and balance (2 trials) exercise and on cognitive performance (15 trials) was less apparent and requires further elucidation.ConclusionsFluid consumption following dehydration may improve continuous exercise performance under heat stress conditions, even when the body water deficit is modest and fluid intake is inadequate for complete rehydration.Electronic supplementary materialThe online version of this article (doi:10.1186/s40798-017-0079-y) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: a Systematic Review and Meta-analysis

2017

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“…As individuals become dehydrated this puts further strain on the cardiovascular system due to an increase in heart rate, diminished plasma volume, stroke volume and cardiac *Address correspondence to this author at the Faculty of Health and Science, Medical and Sports Sciences, University of Cumbria Bowerharm Road, Lancaster, LA1, UK; Tel: +44 1524 590839; Fax: +44 1524 384385; E-mail: susan.dewhurst@cumbria.ac.uk output, reducing venous return and cardiac filling during both exercise and rest [7][8][9]. Furthermore, dehydration inhibits thermoregulatory control due to alterations in sweat rate and blood flow.…”

Section: Introductionmentioning

confidence: 99%

Loaded and Unloaded Marching: Implications for Fluid Replacement

Dewhurst¹,

Bargh²,

Davidson

et al. 2014

TOSSJ

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Usage of any items from the University of Cumbria's institutional repository 'Insight' must conform to the following fair usage guidelines.Any item and its associated metadata held in the University of Cumbria's institutional repository Insight (unless stated otherwise on the metadata record) may be copied, displayed or performed, and stored in line with the JISC fair dealing guidelines (available here) for educational and not-for-profit activities provided that• the authors, title and full bibliographic details of the item are cited clearly when any part of the work is referred to verbally or in the written form• a hyperlink/URL to the original Insight record of that item is included in any citations of the work • the content is not changed in any way• all files required for usage of the item are kept together with the main item file. You may not• sell any part of an item• refer to any part of an item without citation • amend any item or contextualise it in a way that will impugn the creator's reputation• remove or alter the copyright statement on an item.The full policy can be found here. Alternatively contact the University of Cumbria Repository Editor by emailing insight@cumbria.ac.uk. Send Orders for Reprints to reprints@benthamscience.net 16The Open Sports Sciences Journal, 2014, 7, (Suppl-1, M4) Abstract: Marching with essential survival equipment is a fundamental military exercise. A consequence of this increased load is an increased risk of dehydration. Dehydration may have fatal consequences in a combat situation where performance must be optimal. This risk can be minimized with an understanding of the additional fluid needs of soldiers marching when loaded compared to unloaded. The aim of this study was to quantify fluid loss caused by marching with a loaded Bergen rucksack and webbing of 33.5 kg for 45 minutes when compared to unloaded carriage in eight healthy male officer cadets (age, 20.5 ± 0.9 years; body mass 80.2 ± 9.2 kg). The findings demonstrate an increased rate of sweat loss (0.6 ± 0.2 L·h -1 to 1.2 ± 0.4 L·h -1 ; p<0.001) and increased average heart rate (105.5 ± 17.7 beats·min -1 to 136.6 ± 28.3 beats·min -1 ; p<0.001) for unloaded and loaded trial respectively. Urine osmolality significantly increased pre-to postmarch (p<0.05), however there was no difference in this increase between the loaded and unloaded trial. The present study demonstrated that marching with a loaded rucksack and webbing increased sweat rate by 100% compared to the same march with no additional load. For soldiers to prevent dehydration and the potential detrimental effects on performance, fluid replacement should also be doubled when marching with loading in a temperate environment, however individual differences in sweat rate should be taken into account.

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