Thermoregulatory and blood responses during exercise at graded hypohydration levels

Sawka, Michael N.; Young, A. J.; Francesconi, Ralph P.; Muza, Stephen R.; Pandolf, Kent B.

doi:10.1152/jappl.1985.59.5.1394

Cited by 321 publications

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“…During sauna bathing, sweating begins quickly and reaches peak levels after approximately 15 minutes, with an average total secretion of 0.5 kg [15]. The magnitude of core temperature elevation ranges from 0.1 to 0.25 o C for every percent of BML [28,39].…”

Section: Discussionmentioning

confidence: 99%

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Sauna-induced body mass loss in physically inactive young women and men

Podstawski

Boraczyński

et al. 2016

Biomedical Human Kinetics

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SummaryStudy aim: The aim of this study was to evaluate the relationship between basic somatic features (body mass and height) and body mass loss in physically inactive young women and men exposed to thermal stress in a dry sauna. Materials and methods:The research was conducted in 2015 on 685 first-year full-time students (333 women, 352 men), aged 19-20 years old. Nude body mass was measured after the students dried off before and after using the sauna.Results: An analysis of regression equations indicated that an increase in the body mass of women and men leads to a significant increase in sauna-induced body mass loss. On the other hand, body mass loss decreased with an increase in height in women and men, but to a smaller extent. From among the tested somatic features, body height and body mass, body mass had a decisive influence on body mass loss. Body height had a minimal and statistically non-significant impact on body mass loss. Conclusions:The results of this study indicate that heavier individuals have an increased risk of dehydration and hyperthermia. Therefore, they should pay close attention to replenishing fluids lost in the sauna. The determination of body mass loss values after a visit to a dry sauna has practical significance because it supports the estimation of the fluid volume required for the maintenance of correct water balance.

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Section: Discussionmentioning

confidence: 99%

“…Body water loss of 2% can reduce work capacity by 20%. Marked dehydration (5% BWL) reduces threshold and slope responses for sweating [29,39]. Dehydration in excess of 5% BWL can have serious health implications, and BWL higher than 8-10% has lethal consequences [35].…”

Section: Discussionmentioning

confidence: 99%

Sauna-induced body mass loss in physically inactive young women and men

Podstawski

Boraczyński

et al. 2016

Biomedical Human Kinetics

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“…Severe dehydration may increase the risk of heat-related illnesses, by impairing thermoregulation and augmenting thermal (Sawka et al 1985) and cardiovascular (Montain and Coyle 1992) strain, leading to a decrease in exercise-heat tolerance (Cheung and McLellan 1998a;Sawka et al 1992). Workers and medical personnel should, however, be alerted to the potential dangers of exercise-associated hyponatremia due to overdrinking during exercise in hot and humid environments (Lee et al 2011).…”

Section: Heat Mitigation Strategiesmentioning

confidence: 99%

Thermal stress, human performance, and physical employment standards

Cheung

Lee

Oksa

2016

Appl. Physiol. Nutr. Metab.

114

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Many physically demanding occupations in both developed and developing economies involve exposure to extreme thermal environments that can affect work capacity and ultimately health. Thermal extremes may be present in either an outdoor or an indoor work environment, and can be due to a combination of the natural or artificial ambient environment, the rate of metabolic heat generation from physical work, processes specific to the workplace (e.g., steel manufacturing), or through the requirement for protective clothing impairing heat dissipation. Together, thermal exposure can elicit acute impairment of work capacity and also chronic effects on health, greatly contributing to worker health risk and reduced productivity. Surprisingly, in most occupations even in developed economies, there are rarely any standards regarding enforced heat or cold safety for workers. Furthermore, specific physical employment standards or accommodations for thermal stressors are rare, with workers commonly tested under near-perfect conditions. This review surveys the major occupational impact of thermal extremes and existing employment standards, proposing guidelines for improvement and areas for future research.Key words: Heat stress, cold stress, occupational physiology, testing, work.Résumé : Plusieurs emplois physiquement exigeants dans les économies développées et en émergence s'exercent dans des milieux thermiques extrêmes qui peuvent affecter la capacité de travail et, en fin de compte, la santé. Ces milieux de condition thermique extrême se retrouvent dans des environnements de travail intérieur ou extérieur et peuvent découler d'une combinaison d'un milieu ambiant naturel ou artificiel, de la production de chaleur métabolique due au travail physique, des procédés spécifiques au milieu de travail (p. ex. fabrication de l'acier) ou du port obligatoire d'un équipement de protection s'opposant à la dissipation de la chaleur. Globalement, l'exposition à la chaleur peut diminuer ponctuellement la capacité de travail et générer des effets chroniques sur la santé, augmentant ainsi le risque de maladie chez le travailleur et la diminution de la productivité. Étonnamment, dans la plupart des emplois même dans les économies développées, il y a rarement, à propos du froid et de la chaleur, des normes de sécurité ou des règlements en vigueur à l'intention des travailleurs. De plus, rares sont les normes spécifiques aux tâches physiques ou les accommodations aux agents de stress thermique et les travailleurs sont généralement évalués dans des conditions presque parfaites. Cette analyse documentaire sonde les effets principaux des agents thermiques extrêmes sur les tâches physiques, fait le bilan des normes en vigueur en matière d'emploi, suggère des lignes directrices et des pistes pour des études ultérieures. [Traduit par la Rédaction] Mots-clés : stress thermique, stress dû au froid, physiologie du travail, évaluation, travail.

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“…6 Gonzalez-Alonso et al 7 observed an additive effect from hypohydration and heat on increasing cardiovascular strain when performing submaximal exercise. Unfortunately, inconsistent results that can be explained from the choice and subsequent interpretation of methodological designs has led to a poor understanding of the relationship between hypohydration and anaerobic performance.…”

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confidence: 99%

Influence of Hypohydration on Intermittent Sprint Performance in the Heat

Maxwell

Mackenzie

Bishop

2009

International Journal of Sports Physiology and Performance

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Purpose:To examine the effect of hypohydration on physiological strain and intermittent sprint exercise performance in the heat (35.5 ± 0.6°C, 48.7 ± 3.4% relative humidity).Methods:Eight unacclimatized males (age 23.4 ± 6.2 y, height 1.78 ± 0.04 m, mass 76.8 ± 7.7 kg) undertook three trials, each over two days. On day 1, subjects performed 90 min of exercise/heat-induced dehydration on a cycle ergometer, before following one of three rehydration strategies. On day 2, subjects completed a 36-min cycling intermittent sprint test (IST) with a -0.62 ± 0.74% (euhydrated, EUH), -1.81 (0.99)% (hypohydrated1, HYPO1), or -3.88 ± 0.89% (hypohydrated2, HYPO2) body mass defcit.Results:No difference was observed in average total work (EUH, 3790 ± 556 kJ; HYPO1, 3785 ± 628 kJ; HYPO2, 3647 ± 339 kJ, P = 0.418), or average peak power (EUH, 1315 ± 129 W; HYPO1, 1304 ± 175 W; HYPO2, 1282 ± 128 W, P = 0.356) between conditions on day 2. Total work and peak power output in the sprint immediately following an intense repeated sprint bout during the IST were lower in the HYPO2 condition. Physiological strain index was greater in the HYPO2 vs. the EUH condition, but without changes in metabolic markers.Conclusion:A greater physiological strain was observed with the greatest degree of hypohydration; however, sprint performance only diminished in the most hypohydrated state near the end of the IST, following an intense bout of repeating sprinting.

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Thermoregulatory and blood responses during exercise at graded hypohydration levels

Cited by 321 publications

References 0 publications

Sauna-induced body mass loss in physically inactive young women and men

Sauna-induced body mass loss in physically inactive young women and men

Thermal stress, human performance, and physical employment standards

Influence of Hypohydration on Intermittent Sprint Performance in the Heat

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