Intravenous Versus Oral Rehydration During a Brief Period: Responses to Subsequent Exercise in the Heat

Casa, D. J.; Maresh, Carl M.; Armstrong, Lawrence E.; Kavouras, Stavros A.; Herrera-Soto, Jorge A.; Keith, NiCole R.; Elliott, Tabatha A.; Hacker, Frank T.

doi:10.1097/00005768-199805001-01889

Cited by 7 publications

(13 citation statements)

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“…A water loss equivalent to 2% or more of body mass appears to reduce enduranceexercise performance in both temperate and hot environments, espe cially when the duration of exercise is around 90 min or more. Casa, Maresh, et al (2000) reported that oral replacement of even 50% of a 4% bodymass loss during a 20min break was effective in restoring exercise capacity (mean perfor mance time 35 ± 4 min) compared with a trial in which no rehydration was allowed (mean performance time 19 ± 3 min). It must, of course, be recognized that per formance effects that are highly meaningful to the athlete might be far below the limits of detection when crude laboratory measures of performance are used (Hopkins, 2001).…”

mentioning

confidence: 99%

Development of Individual Hydration Strategies for Athletes

Maughan¹,

Shirreffs²

2008

International Journal of Sport Nutrition and Exercise Metabolism

135

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Athletes are encouraged to begin exercise well hydrated and to consume sufficient amounts of appropriate fluids during exercise to limit water and salt deficits. Available evidence suggests that many athletes begin exercise already dehydrated to some degree, and although most fail to drink enough to match sweat losses, some drink too much and a few develop hyponatremia. Some simple advice can help athletes assess their hydration status and develop a personalized hydration strategy that takes account of exercise, environment, and individual needs. Preexercise hydration status can be assessed from urine frequency and volume, with additional information from urine color, specific gravity, or osmolality. Change in hydration during exercise can be estimated from the change in body mass that occurs during a bout of exercise. Sweat rate can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses can be determined by collection and analysis of sweat samples, but athletes losing large amounts of salt are likely to be aware of the taste of salt in sweat and the development of salt crusts on skin and clothing where sweat has evaporated. An appropriate drinking strategy will take account of preexercise hydration status and of fluid, electrolyte, and substrate needs before, during, and after a period of exercise. Strategies will vary greatly between individuals and will also be influenced by environmental conditions, competition regulations, and other factors.

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mentioning

confidence: 99%

Development of Individual Hydration Strategies for Athletes

Maughan¹,

Shirreffs²

2008

International Journal of Sport Nutrition and Exercise Metabolism

135

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“…This was nicely demonstrated by Dion et al [91], who reported, in a controlled laboratory experiment with ad libitum drinking, that faster racing lead to a greater sweat rate and hypohydration at the end of a half marathon, but did not alter drink ingestion. However, the finding that endurance athletes can finish [80][81][82][83][84] and even win races in world-class times [92] with as much as 10% body mass loss is intriguing. Because of issues related to fluid availability (e.g.…”

Section: Uncomfortable and Unfamiliar Dehydration Methodsmentioning

confidence: 99%

“…This and other work [58] demonstrate that mouth rinsing water alone confers no performance benefit, suggesting fluid must be consumed to influence performance. Casa et al [81] reported a strong trend (p = 0.07) for oral rehydration to increase exercise capacity compared with intravenous rehydration in recovery from hypohydration (4% body mass). Interestingly, oral rehydration reduced rectal and skin temperatures during exercise, as well as reducing other relevant variables (blood lactate/glucose concentrations and respiration rate) compared with intravenous rehydration.…”

Section: Blinding Changes In Hydrationmentioning

confidence: 99%

Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research

et al. 2019

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The impact of alterations in hydration status on human physiology and performance responses during exercise is one of the oldest research topics in sport and exercise nutrition. This body of work has mainly focussed on the impact of reduced body water stores (i.e. hypohydration) on these outcomes, on the whole demonstrating that hypohydration impairs endurance performance, likely via detrimental effects on a number of physiological functions. However, an important consideration, that has received little attention, is the methods that have traditionally been used to investigate how hypohydration affects exercise outcomes, as those used may confound the results of many studies. There are two main methodological limitations in much of the published literature that perhaps make the results of studies investigating performance outcomes difficult to interpret. First, subjects involved in studies are generally not blinded to the intervention taking place (i.e. they know what their hydration status is), which may introduce expectancy effects. Second, most of the methods used to induce hypohydration are both uncomfortable and unfamiliar to the subjects, meaning that alterations in performance may be caused by this discomfort, rather than hypohydration per se. This review discusses these methodological considerations and provides an overview of the small body of recent work that has attempted to correct some of these methodological issues. On balance, these recent blinded hydration studies suggest hypohydration equivalent to 2-3% body mass decreases endurance cycling performance in the heat, at least when no/little fluid is ingested.

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“…The higher circulating plasma volume theoretically allows enhanced thermoregulation and attenuated cardiovascular strain. In spite of this, previous reports indicate that the rapid influx of fluid into the vasculature following IV rehydration is transient and equilibrates between the fluid compartments within 35 min during passive rehydration (Kenefick et al., ), or between 5 and 25 min when exercise begins soon after rehydration is completed (Casa et al., ; Kenefick et al., , ; Maresh et al., ), regardless of whether hypotonic or isotonic IV fluids are used (Kenefick et al., ). As a result, these studies have shown few sustained benefits with IV compared with oral rehydration.…”

mentioning

confidence: 98%

“…Despite being banned by the World Anti‐Doping Agency (WADA) in 2005 (under Section M2 of their list of prohibited substances and methods), and having risks that are not associated with oral fluid intake (e.g., infection, thrombophlebitis, air embolus, needle stick injury, bleeding, hematoma, soft tissue extravasation), the ongoing use of IV infusions is highlighted by a recent survey finding that 75% of National Football League (United States) teams reported regularly infusing 1.5 L of normal saline in up to 20 players, 2 h before games (Fitzsimmons et al., ). A major ergogenic appeal of IV fluids is the subsequent rapid enhancement of plasma volume which is achieved since the fluids bypass the gastrointestinal absorption delays associated with oral rehydration (Casa et al., ; Kenefick et al., ). The higher circulating plasma volume theoretically allows enhanced thermoregulation and attenuated cardiovascular strain.…”

mentioning

confidence: 99%

Hydration and endocrine responses to intravenous fluid and oral glycerol

Rosendal

Strobel

Osborne

et al. 2015

Scandinavian Med Sci Sports

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5 g/kg), using a randomized, crossover design. They then completed a cycling performance test. Plasma volume restoration was highest in IV with oral glycerol > IV > oral glycerol > oral. Urine volume was reduced in both IV trials compared with oral. IV and IV with oral glycerol resulted in lower aldosterone levels during rehydration and performance, and lower cortisol levels during rehydration. IV with oral glycerol resulted in the greatest fluid retention. In summary, the IV conditions resulted in greater fluid retention compared with oral and lower levels of fluid regulatory and stress hormones compared with both oral conditions.

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Intravenous Versus Oral Rehydration During a Brief Period: Responses to Subsequent Exercise in the Heat

Cited by 7 publications

References 0 publications

Development of Individual Hydration Strategies for Athletes

Development of Individual Hydration Strategies for Athletes

Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research

Hydration and endocrine responses to intravenous fluid and oral glycerol

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