Rectal temperatures, weight losses, and sweat rates in marathon running.

Pugh, L. G. C. E.; Corbett, J. L.; Johnson, Raymond H.

doi:10.1152/jappl.1967.23.3.347

Cited by 261 publications

(121 citation statements)

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“…Hyperthermia was prevented with dehydration by 4% of body weight when exercising when the environmental temperature was lowered to 58C and convective cooling was further increased by exposing the bare skin of the participants to wetting and high wind speeds (Gonzalez-Alonso, 1998). This is in line with the idea that some marathon runners competing in environmental temperatures as low as 7-188C who become dehydrated by 3-5% of body weight can still experience core temperatures of 39.0-41.78C (Pugh et al, 1967;Maron et al, 1977;Maughan, 1984Maughan, , 1985. Of course, there will be a wide range of core temperatures during exercise in a cold environment in runners with similar dehydration, based on how fast they are running towards the end of the race 41 Fluid and fuel intake during exercise (Noakes et al, 1991a).…”

supporting

confidence: 57%

“…Furthermore, Cheuvront and colleagues (Cheuvront, 2001;Cheuvront and Haymes, 2001;Cheuvront et al, 2003) point out that within the population of qualifiers for the US Olympic Trials in the marathon, that a weak relationship exists between level of dehydration and performance. The puzzling question in marathon running is how some runners perform so well despite final dehydration of 4-8% of body weight (Wyndham and Strydom, 1969;Costill, 1972) and core temperatures in excess of 408C (Pugh et al, 1967). One possibility is error in magnitude of true dehydration from the perspective that the marathon runners might have begun the race somewhat hyperhydrated at the time of pre-race body weight measurement.…”

Section: What Do Fast Marathon Runners Experience?mentioning

confidence: 99%

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Fluid and fuel intake during exercise

Coyle¹

2004

Journal of Sports Sciences

330

205

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The amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration. When possible, fluid should be ingested at rates that most closely match sweating rate. When that is not possible or practical or sufficiently ergogenic, some athletes might tolerate body water losses amounting to 2% of body weight without significant risk to physical well-being or performance when the environment is cold (e.g. 5-108C) or temperate (e.g. 21-228C). However, when exercising in a hot environment ( 4308C), dehydration by 2% of body weight impairs absolute power production and predisposes individuals to heat injury. Fluid should not be ingested at rates in excess of sweating rate and thus body water and weight should not increase during exercise. Fatigue can be reduced by adding carbohydrate to the fluids consumed so that 30-60 g of rapidly absorbed carbohydrate are ingested throughout each hour of an athletic event. Furthermore, sodium should be included in fluids consumed during exercise lasting longer than 2 h or by individuals during any event that stimulates heavy sodium loss (more than 3-4 g of sodium). Athletes do not benefit by ingesting glycerol, amino acids or alleged precursors of neurotransmitter. Ingestion of other substances during exercise, with the possible exception of caffeine, is discouraged. Athletes will benefit the most by tailoring their individual needs for water, carbohydrate and salt to the specific challenges of their sport, especially considering the environment's impact on sweating and heat stress.Keywords: carbohydrate, dehydration, fatigue, gastrointestinal function, hyperthermia, sodium. IntroductionWhen athletes exercise during training or while competing, it is clear that they sometimes benefit by ingesting various mixtures of water, carbohydrate and electrolytes (Convertino et al., 1996;Casa, 2000). The benefits can be expressed through improved performance and/or reduced physiological stress, on an athlete's cardiovascular, central nervous and muscular systems. Although ample scientific evidence exists to support the general theory for encouraging athletes to consume water, carbohydrate and electrolytes during exercise, the practical recommendations for optimally applying these general theories is not simple. This is due to the quite varied nature of the physical stresses encountered during training and competition for a wide range of sports, as well as the unique rules of each sport regarding the allowance for fluid and fuel intake during competition. Furthermore, variations in the physical intensity, duration and environment, as well as individual characteristics of a given athlete, might alter their optimal rate of water, carbohydrate and salt intake as well as the rate of gastrointestinal absorption and feelings of fullness. This task of developing consensus for general recommendations becomes less daunting when approached systematical...

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supporting

confidence: 57%

Section: What Do Fast Marathon Runners Experience?mentioning

confidence: 99%

Fluid and fuel intake during exercise

Coyle¹

2004

Journal of Sports Sciences

330

205

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“…The concentration of sodium in sweat varies widely but is usually 15 to 65 mEq/L, with highly fit athletes generally excreting sweat with sodium concentrations Ͻ40 mEq/L (38,76). The volume of sweat during exercise also varies widely, from approximately 250 ml/h to Ͼ2 L/h, again being less in more fit athletes (77,78). This loss of a substantial amount of hypotonic fluid may seem to protect against the development of hyponatremia.…”

Section: Pathophysiologymentioning

confidence: 99%

Exercise-Associated Hyponatremia

Rosner

Kirven

2007

Clinical Journal of the American Society of Nephrology

170

165

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Exercise-associated hyponatremia has been described after sustained physical exertion during marathons, triathlons, and other endurance athletic events. As these events have become more popular, the incidence of serious hyponatremia has increased and associated fatalities have occurred. The pathogenesis of this condition remains incompletely understood but largely depends on excessive water intake. Furthermore, hormonal (especially abnormalities in arginine vasopressin secretion) and renal abnormalities in water handling that predispose individuals to the development of severe, life-threatening hyponatremia may be present. This review focuses on the epidemiology, pathogenesis, and therapy of exercise-associated hyponatremia.

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“…Nevertheless, stable blood pressure regulation was not always achieved, and symptoms of syncope within three individuals in the hottest condition imply they were at the cusp of cardiovascular insufficiency (Barcroft and Edholm, 1945;Bass et al, 1955;Noakes, 2008;Taylor and Patterson, 2015). (Pugh et al, 1967;Maughan et al, 1985). However, it can have critical clinical implications in nonadapted, chronically sedentary, overweight and unhealthy individuals, and the timedependent nature of these deep-body temperature increases indicate that profound hyperthermia may become inevitable in some people during extended summer motorcycling in urban conditions.…”

Section: Discussionmentioning

confidence: 99%

Thermal and cardiovascular strain imposed by motorcycle protective clothing under Australian summer conditions

et al. 2015

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Motorcycle protective clothing can be uncomfortably hot during summer, and this experiment was designed to evaluate the physiological significance of that burden. Twelve males participated in four, 90-min trials (cycling 30 W) across three environments (25, 30, 35 °C [all 40% relative humidity]). Clothing was modified between full and minimal injury protection. Both ensembles were tested at 25 °C, with only the more protective ensemble investigated at 30 and 35 °C. At 35 °C, auditory canal temperature rose at 0.02 °C min(-1) (SD 0.005), deviating from all other trials (p < 0.05). The thresholds for moderate (>38.5 °C) and profound hyperthermia (>40.0 °C) were predicted to occur within 105 min (SD 20.6) and 180 min (SD 33.0), respectively. Profound hyperthermia might eventuate in ~10 h at 30 °C, but should not occur at 25 °C. These outcomes demonstrate a need to enhance the heat dissipation capabilities of motorcycle clothing designed for summer use in hot climates, but without compromising impact protection. Practitioner's Summary: Motorcycle protective clothing can be uncomfortably hot during summer. This experiment was designed to evaluate the physiological significance of this burden across climatic states. In the heat, moderate (>38.5 °C) and profound hyperthermia (>40.0 °C) were predicted to occur within 105 and 180 min, respectively. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences

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Rectal temperatures, weight losses, and sweat rates in marathon running.

Cited by 261 publications

References 0 publications

Fluid and fuel intake during exercise

Fluid and fuel intake during exercise

Exercise-Associated Hyponatremia

Thermal and cardiovascular strain imposed by motorcycle protective clothing under Australian summer conditions

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