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Lindsay B. Baker - One of the best experts on this subject based on the ideXlab platform.
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skin interfaced microfluidic system with personalized Sweating Rate and sweat chloride analytics for sports science applications
Science Advances, 2020Co-Authors: Lindsay B. Baker, Jeffrey B Model, Kelly A Barnes, Melissa L Anderson, Stephen P Lee, Khalil A Lee, Shyretha D Brown, Adam J Reimel, Timothy J Roberts, Ryan P NuccioAbstract:Advanced capabilities in noninvasive, in situ monitoring of Sweating Rate and sweat electrolyte losses could enable real-time personalized fluid-electrolyte intake recommendations. Established sweat analysis techniques using absorbent patches require post-collection harvesting and benchtop analysis of sweat and are thus impractical for ambulatory use. Here, we introduce a skin-interfaced wearable microfluidic device and smartphone image processing platform that enable analysis of regional Sweating Rate and sweat chloride concentration ([Cl−]). Systematic studies (n = 312 athletes) establish significant correlations for regional Sweating Rate and sweat [Cl−] in a controlled environment and during competitive sports under varying environmental conditions. The regional Sweating Rate and sweat [Cl−] results serve as inputs to algorithms implemented on a smartphone software application that predicts whole-body Sweating Rate and sweat [Cl−]. This low-cost wearable sensing approach could improve the accessibility of physiological insights available to sports scientists, practitioners, and athletes to inform hydration stRategies in real-world ambulatory settings.
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Physiological mechanisms determining eccrine sweat composition
European Journal of Applied Physiology, 2020Co-Authors: Lindsay B. Baker, Anthony S. WolfeAbstract:Purpose The purpose of this paper is to review the physiological mechanisms determining eccrine sweat composition to assess the utility of sweat as a proxy for blood or as a potential biomarker of human health or nutritional/physiological status. Methods This narrative review includes the major sweat electrolytes (sodium, chloride, and potassium), other micronutrients (e.g., calcium, magnesium, iron, copper, zinc, vitamins), metabolites (e.g., glucose, lactate, ammonia, urea, bicarbonate, amino acids, ethanol), and other compounds (e.g., cytokines and cortisol). Results Ion membrane transport mechanisms for sodium and chloride are well established, but the mechanisms of secretion and/or reabsorption for most other sweat solutes are still equivocal. Correlations between sweat and blood have not been established for most constituents, with perhaps the exception of ethanol. With respect to sweat diagnostics, it is well accepted that elevated sweat sodium and chloride is a useful screening tool for cystic fibrosis. However, sweat electrolyte concentrations are not predictive of hydration status or Sweating Rate. Sweat metabolite concentrations are not a reliable biomarker for exercise intensity or other physiological stressors. To date, glucose, cytokine, and cortisol research is too limited to suggest that sweat is a useful surrogate for blood. Conclusion Final sweat composition is not only influenced by extracellular solute concentrations, but also mechanisms of secretion and/or reabsorption, sweat flow Rate, byproducts of sweat gland metabolism, skin surface contamination, and sebum secretions, among other factors related to methodology. Future research that accounts for these confounding factors is needed to address the existing gaps in the literature.
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normative data for Sweating Rate sweat sodium concentration and sweat sodium loss in athletes an update and analysis by sport
Journal of Sports Sciences, 2019Co-Authors: Kelly A Barnes, Melissa L Anderson, Adam J Reimel, Timothy J Roberts, John R. Stofan, Kortney J Dalrymple, Rebecca K Randell, Corey T Ungaro, Lindsay B. BakerAbstract:The purpose of this study was to expand our previously published sweat normative data/analysis (n = 506) to establish sport-specific normative data for whole-body Sweating Rate (WBSR), sweat [Na+],...
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body map of regional vs whole body Sweating Rate and sweat electrolyte concentrations in men and women during modeRate exercise heat stress
Journal of Applied Physiology, 2018Co-Authors: Lindsay B. Baker, Adam J Reimel, Ryan P Nuccio, John R. Stofan, Corey T Ungaro, Bridget C Sopena, James M Carter, Kelly A BarnesAbstract:This study developed a body map of regional Sweating Rate and regional (REG) sweat electrolyte concentrations and determined the effect of within-subject (bilateral and day-to-day) and between-subj...
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Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability
Sports Medicine, 2017Co-Authors: Lindsay B. BakerAbstract:Athletes lose water and electrolytes as a consequence of thermoregulatory Sweating during exercise and it is well known that the Rate and composition of sweat loss can vary considerably within and among individuals. Many scientists and practitioners conduct sweat tests to determine sweat water and electrolyte losses of athletes during practice and competition. The information gleaned from sweat testing is often used to guide personalized fluid and electrolyte replacement recommendations for athletes; however, unstandardized methodological practices and challenging field conditions can produce inconsistent/inaccuRate results. The primary objective of this paper is to provide a review of the literature regarding the effect of laboratory and field sweat-testing methodological variations on Sweating Rate (SR) and sweat composition (primarily sodium concentration [Na+]). The simplest and most accuRate method to assess whole-body SR is via changes in body mass during exercise; however, potential confounding factors to consider are non-sweat sources of mass change and trapped sweat in clothing. In addition, variability in sweat [Na+] can result from differences in the type of collection system used (whole body or localized), the timing/duration of sweat collection, skin cleaning procedure, sample storage/handling, and analytical technique. Another aim of this paper is to briefly review factors that may impact intra/interindividual variability in SR and sweat [Na+] during exercise, including exercise intensity, environmental conditions, heat acclimation, aerobic capacity, body size/composition, wearing of protective equipment, sex, maturation, aging, diet, and/or hydration status. In summary, sweat testing can be a useful tool to estimate athletes’ SR and sweat Na+ loss to help guide fluid/electrolyte replacement stRategies, provided that data are collected, analyzed, and interpreted appropriately.
Narihiko Kondo - One of the best experts on this subject based on the ideXlab platform.
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Determination of the maximum Rate of eccrine sweat glands’ ion reabsorption using the galvanic skin conductance to local sweat Rate relationship
European Journal of Applied Physiology, 2016Co-Authors: Tatsuro Amano, Yoshimitsu Inoue, Takeshi Nishiyasu, Nicola Gerrett, George Havenith, Narihiko KondoAbstract:Purpose The purpose of the present study was to develop and describe a simple method to evaluate the Rate of ion reabsorption of eccrine sweat glands in human using the measurement of galvanic skin conductance (GSC) and local Sweating Rate (SR). This purpose was investigated by comparing the SR threshold for increasing GSC with following two criteria of sweat ion reabsorption in earlier studies such as (1) the SR threshold for increasing sweat ion was at approximately 0.2–0.5 mg/cm^2/min and (2) exercise heat acclimation improved the sweat ion reabsorption ability and would increase the criteria 1. Methods Seven healthy non-heat-acclimated male subjects received passive heat treatment both before and after 7 days of cycling in hot conditions (50 % maximum oxygen uptake, 60 min/day, ambient temperature 32 °C, and 50 % relative humidity). Results Subjects became partially heat-acclimated, as evidenced by the decreased end-exercise heart Rate ( p
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determination of the maximum Rate of eccrine sweat glands ion reabsorption using the galvanic skin conductance to local sweat Rate relationship
European Journal of Applied Physiology, 2016Co-Authors: Tatsuro Amano, Yoshimitsu Inoue, Takeshi Nishiyasu, Nicola Gerrett, George Havenith, Narihiko KondoAbstract:Purpose The purpose of the present study was to develop and describe a simple method to evaluate the Rate of ion reabsorption of eccrine sweat glands in human using the measurement of galvanic skin conductance (GSC) and local Sweating Rate (SR). This purpose was investigated by comparing the SR threshold for increasing GSC with following two criteria of sweat ion reabsorption in earlier studies such as (1) the SR threshold for increasing sweat ion was at approximately 0.2–0.5 mg/cm2/min and (2) exercise heat acclimation improved the sweat ion reabsorption ability and would increase the criteria 1.
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Non-thermal modification of heat-loss responses during exercise in humans
European Journal of Applied Physiology, 2010Co-Authors: Narihiko Kondo, Yoshimitsu Inoue, Takeshi Nishiyasu, Shunsaku KogaAbstract:This review focuses on the characteristics of heat-loss responses during exercise with respect to non-thermal factors. In addition, the effects of physical training on non-thermal heat-loss responses are discussed. When a subject is already Sweating the Sweating Rate increases at the onset of dynamic exercise without changes in core temperature, while cutaneous vascular conductance (skin blood flow) is temporarily decreased. Although exercise per se does not affect the threshold for the onset of Sweating, it is possible that an increase in exercise intensity induces a higher sensitivity of the Sweating response. Exercise increases the threshold for cutaneous vasodilation, and at higher exercise intensities, the sensitivity of the skin-blood-flow response decreases. Facilitation of the Sweating response with increased exercise intensity may be due to central command, peripheral reflexes in the exercising muscle, and mental stimuli, whereas the attenuation of skin-blood-flow responses with decreased cutaneous vasodilation is related to many non-thermal factors. Most non-thermal factors have negative effects on magnitude of cutaneous vasodilation; however, several of these factors have positive effects on the Sweating response. Moreover, thermal and non-thermal factors interact in controlling heat-loss responses, with non-thermal factors having a greater impact until core temperature elevations become significant, after which core temperature primarily would control heat loss. Finally, as with thermally induced Sweating responses, physical training seems to also affect Sweating responses governed by non-thermal factors.
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Effects of physical training on heat loss responses of young women to passive heating in relation to menstrual cycle
European Journal of Applied Physiology, 2005Co-Authors: Tomoko Kuwahara, Yoshimitsu Inoue, Hiroyuki Ueda, Miyuki Taniguchi, Yukio Ogura, Narihiko KondoAbstract:To examine the effects of physical training on cutaneous vasodilation and Sweating responses of young women in the follicular and luteal phase, 11 physically trained (T group) and 13 untrained (U group) women were passively heated by lower-leg immersion into hot water of 42°C (ambient temperature of 30°C and 45%RH) for 60 min in their mid-follicular and mid-luteal phases of the menstrual cycle. Female hormones increased significantly from the mid-follicular to the mid-luteal phase in T and U groups, but the degree of increase was significantly lower in T group. Mean body temperature $$(\bar{T}_{\rm b})$$ thresholds for cutaneous vasodilation and Sweating responses were significantly lower in T group than in U group, in both the menstrual phases, and the differences between the groups were greatest during the mid-luteal phase. The slope of the relationship between frequency of sweat expulsion ( F _sw) and $$\bar{T}_{\rm b}, $$ and between local Sweating Rate and F _sw was significantly greater in T group, although the slope of the relationship between cutaneous blood flow and $$\bar{T}_{\rm b}$$ did not differ between the groups, regardless of body site or menstrual phase. These results suggest that regular physical activity enhanced Sweating and cutaneous vasodilation in young women. The enhancement of Sweating was due to both central and peripheral mechanisms, and the enhancement of cutaneous vasodilation was possibly due to a central mechanism. Enhancement of heat loss responses via central mechanisms was greater during the mid-luteal phase than in the mid-follicular phase because the elevation of female reproductive hormone levels during the mid-luteal phase was relatively low in T group.
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central command is capable of modulating Sweating from non glabrous human skin
The Journal of Physiology, 2003Co-Authors: Manabu Shibasaki, Narihiko Kondo, Niels H Secher, Christian Selmer, Craig G CrandallAbstract:Isometric handgrip exercise (IHG) increases Sweating Rate without changing core or skin temperatures. The contribution of central command resulting in increases in Sweating Rate during IHG is unknown. To investigate this question, seven subjects performed IHG (35 % maximum voluntary contraction (MVC) for 2 min) followed by 2-min of post-exercise ischaemia (PEI), with and without partial neuromuscular blockade (PNB). PNB was performed to augment central command during the IHG bout. These trials were conducted while the subject was normothermic, mildly heated, and modeRately heated. On the non-exercising arm, forearm Sweating Rate was monitored over a microdialysis membrane perfused with neostigmine (acetylcholinesterase inhibitor), and at an adjacent untreated site. In normothermia with PNB, despite reduced force production during IHG (17 ± 9 versus 157 ± 13 N; P < 0.001), the elevation in Sweating Rate at the neostigmine-treated site was greater relative to the control IHG bout (P < 0.05). During subsequent PEI, for the PNB trial mean arterial blood pressure (MAP) and Sweating Rate returned towards pre-IHG levels, while during the control trial these variables remained elevated. During IHG while mildly heated, the elevation in Sweating Rate was greater during the PNB trial relative to the control trial. In contrast, during modeRate heating Sweating increased during IHG for both trials, however the elevation in Sweating Rate during the PNB trial was not greater than during the control trial. These results suggest that central command is capable of modulating Sweating Rate in all thermal conditions, however its effect is reduced when body temperatures and/or Sweating Rate are substantially elevated.
John R. Stofan - One of the best experts on this subject based on the ideXlab platform.
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normative data for Sweating Rate sweat sodium concentration and sweat sodium loss in athletes an update and analysis by sport
Journal of Sports Sciences, 2019Co-Authors: Kelly A Barnes, Melissa L Anderson, Adam J Reimel, Timothy J Roberts, John R. Stofan, Kortney J Dalrymple, Rebecca K Randell, Corey T Ungaro, Lindsay B. BakerAbstract:The purpose of this study was to expand our previously published sweat normative data/analysis (n = 506) to establish sport-specific normative data for whole-body Sweating Rate (WBSR), sweat [Na+],...
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body map of regional vs whole body Sweating Rate and sweat electrolyte concentrations in men and women during modeRate exercise heat stress
Journal of Applied Physiology, 2018Co-Authors: Lindsay B. Baker, Adam J Reimel, Ryan P Nuccio, John R. Stofan, Corey T Ungaro, Bridget C Sopena, James M Carter, Kelly A BarnesAbstract:This study developed a body map of regional Sweating Rate and regional (REG) sweat electrolyte concentrations and determined the effect of within-subject (bilateral and day-to-day) and between-subj...
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Normative data for regional sweat sodium concentration and whole-body Sweating Rate in athletes.
Journal of sports sciences, 2015Co-Authors: Lindsay B. Baker, Kelly A Barnes, Melissa L Anderson, Dennis H. Passe, John R. StofanAbstract:AbstractThe purpose of this study was to establish normative data for regional sweat sodium concentration ([Na+]) and whole-body Sweating Rate in athletes. Data from 506 athletes (367 adults, 139 youth; 404 male, 102 female) were compiled from observational athlete testing for a retrospective analysis. The participants were skill/team-sport (including American football, baseball, basketball, soccer and tennis) and endurance (including cycling, running and triathlon) athletes exercising in cool to hot environmental conditions (15–50°C) during training or competition in the laboratory or field. A standardised regional absorbent patch technique was used to determine sweat [Na+] on the dorsal mid-forearm. Whole-body sweat [Na+] was predicted using a published regression equation (y = 0.57x+11.05). Whole-body Sweating Rate was calculated from pre- to post-exercise change in body mass, corrected for fluid/food intake (ad libitum) and urine output. Data are expressed as mean ± SD (range). Forearm sweat [Na+] and...
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serum sodium concentration changes are related to fluid balance and sweat sodium loss
Medicine and Science in Sports and Exercise, 2010Co-Authors: Matthew D Pahnke, John R. Stofan, Joel D Trinity, Jeffrey J Zachwieja, Douglas W B Hiller, Edward F CoyleAbstract:PURPOSE: This study determined if changes in serum sodium concentration are related to fluid balance as well as sweat sodium losses in triathletes competing in the Hawaii Ironman triathlon. METHODS: Endurance trained athletes (N = 46, age = 24-67 yr) were studied during 30 min of stationary cycling at 70%-75% of HRmax in a warm outdoor laboratory (26.4 degrees C +/- 1.7 degrees C wet bulb globe temperature [WBGT], 28.3 degrees C +/- 1.2 degrees C dry bulb [DB]) 3-7 d before race day. Sweat sodium concentration was measured from absorbent patches on the forearm and scapula, and Sweating Rate was derived from changes in body mass. Before and after the race, serum sodium concentration, body mass, and nutritional intake during the race were also measured (N = 46). Sweating and race day comparisons and changes in serum sodium concentration were analyzed via Student's t-test, correlation, and multiple regression. RESULTS: In men, the change in serum sodium concentration during the race was correlated with relative Sweating Rate (mL.kg.h; r = -0.49, P = 0.012), Rate of sweat sodium loss (mEq.kg.h; r = -0.44, P = 0.023), and body mass change (kg; r = -0.54, P = 0.005). Together, the Rate of sweat sodium loss and body mass change accounted for 46% of the change in serum sodium concentration in men (R = 0.46). In women, body mass change alone was significantly correlated with the change in serum sodium concentration (r = 0.31). The Rate of sodium intake (mEq.kg.h) was related to the Rate of sweat sodium loss in women (mEq.kg.h; r = 0.64, P = 0.035) but not in men (r = 0.27, P = 0.486). CONCLUSION: Changes in serum sodium concentration during an ultraendurance triathlon are significantly related to interactions of fluid balance, sweat sodium loss, and sodium ingestion.
Edward F Coyle - One of the best experts on this subject based on the ideXlab platform.
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serum sodium concentration changes are related to fluid balance and sweat sodium loss
Medicine and Science in Sports and Exercise, 2010Co-Authors: Matthew D Pahnke, John R. Stofan, Joel D Trinity, Jeffrey J Zachwieja, Douglas W B Hiller, Edward F CoyleAbstract:PURPOSE: This study determined if changes in serum sodium concentration are related to fluid balance as well as sweat sodium losses in triathletes competing in the Hawaii Ironman triathlon. METHODS: Endurance trained athletes (N = 46, age = 24-67 yr) were studied during 30 min of stationary cycling at 70%-75% of HRmax in a warm outdoor laboratory (26.4 degrees C +/- 1.7 degrees C wet bulb globe temperature [WBGT], 28.3 degrees C +/- 1.2 degrees C dry bulb [DB]) 3-7 d before race day. Sweat sodium concentration was measured from absorbent patches on the forearm and scapula, and Sweating Rate was derived from changes in body mass. Before and after the race, serum sodium concentration, body mass, and nutritional intake during the race were also measured (N = 46). Sweating and race day comparisons and changes in serum sodium concentration were analyzed via Student's t-test, correlation, and multiple regression. RESULTS: In men, the change in serum sodium concentration during the race was correlated with relative Sweating Rate (mL.kg.h; r = -0.49, P = 0.012), Rate of sweat sodium loss (mEq.kg.h; r = -0.44, P = 0.023), and body mass change (kg; r = -0.54, P = 0.005). Together, the Rate of sweat sodium loss and body mass change accounted for 46% of the change in serum sodium concentration in men (R = 0.46). In women, body mass change alone was significantly correlated with the change in serum sodium concentration (r = 0.31). The Rate of sodium intake (mEq.kg.h) was related to the Rate of sweat sodium loss in women (mEq.kg.h; r = 0.64, P = 0.035) but not in men (r = 0.27, P = 0.486). CONCLUSION: Changes in serum sodium concentration during an ultraendurance triathlon are significantly related to interactions of fluid balance, sweat sodium loss, and sodium ingestion.
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fluid and fuel intake during exercise
Journal of Sports Sciences, 2004Co-Authors: Edward F CoyleAbstract: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. 5–10°C) or tempeRate (e.g. 21–22°C). However, when exercising in a hot environment ( >30°C), 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 i...
Yoshimitsu Inoue - One of the best experts on this subject based on the ideXlab platform.
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Determination of the maximum Rate of eccrine sweat glands’ ion reabsorption using the galvanic skin conductance to local sweat Rate relationship
European Journal of Applied Physiology, 2016Co-Authors: Tatsuro Amano, Yoshimitsu Inoue, Takeshi Nishiyasu, Nicola Gerrett, George Havenith, Narihiko KondoAbstract:Purpose The purpose of the present study was to develop and describe a simple method to evaluate the Rate of ion reabsorption of eccrine sweat glands in human using the measurement of galvanic skin conductance (GSC) and local Sweating Rate (SR). This purpose was investigated by comparing the SR threshold for increasing GSC with following two criteria of sweat ion reabsorption in earlier studies such as (1) the SR threshold for increasing sweat ion was at approximately 0.2–0.5 mg/cm^2/min and (2) exercise heat acclimation improved the sweat ion reabsorption ability and would increase the criteria 1. Methods Seven healthy non-heat-acclimated male subjects received passive heat treatment both before and after 7 days of cycling in hot conditions (50 % maximum oxygen uptake, 60 min/day, ambient temperature 32 °C, and 50 % relative humidity). Results Subjects became partially heat-acclimated, as evidenced by the decreased end-exercise heart Rate ( p
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determination of the maximum Rate of eccrine sweat glands ion reabsorption using the galvanic skin conductance to local sweat Rate relationship
European Journal of Applied Physiology, 2016Co-Authors: Tatsuro Amano, Yoshimitsu Inoue, Takeshi Nishiyasu, Nicola Gerrett, George Havenith, Narihiko KondoAbstract:Purpose The purpose of the present study was to develop and describe a simple method to evaluate the Rate of ion reabsorption of eccrine sweat glands in human using the measurement of galvanic skin conductance (GSC) and local Sweating Rate (SR). This purpose was investigated by comparing the SR threshold for increasing GSC with following two criteria of sweat ion reabsorption in earlier studies such as (1) the SR threshold for increasing sweat ion was at approximately 0.2–0.5 mg/cm2/min and (2) exercise heat acclimation improved the sweat ion reabsorption ability and would increase the criteria 1.
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Non-thermal modification of heat-loss responses during exercise in humans
European Journal of Applied Physiology, 2010Co-Authors: Narihiko Kondo, Yoshimitsu Inoue, Takeshi Nishiyasu, Shunsaku KogaAbstract:This review focuses on the characteristics of heat-loss responses during exercise with respect to non-thermal factors. In addition, the effects of physical training on non-thermal heat-loss responses are discussed. When a subject is already Sweating the Sweating Rate increases at the onset of dynamic exercise without changes in core temperature, while cutaneous vascular conductance (skin blood flow) is temporarily decreased. Although exercise per se does not affect the threshold for the onset of Sweating, it is possible that an increase in exercise intensity induces a higher sensitivity of the Sweating response. Exercise increases the threshold for cutaneous vasodilation, and at higher exercise intensities, the sensitivity of the skin-blood-flow response decreases. Facilitation of the Sweating response with increased exercise intensity may be due to central command, peripheral reflexes in the exercising muscle, and mental stimuli, whereas the attenuation of skin-blood-flow responses with decreased cutaneous vasodilation is related to many non-thermal factors. Most non-thermal factors have negative effects on magnitude of cutaneous vasodilation; however, several of these factors have positive effects on the Sweating response. Moreover, thermal and non-thermal factors interact in controlling heat-loss responses, with non-thermal factors having a greater impact until core temperature elevations become significant, after which core temperature primarily would control heat loss. Finally, as with thermally induced Sweating responses, physical training seems to also affect Sweating responses governed by non-thermal factors.
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Effects of physical training on heat loss responses of young women to passive heating in relation to menstrual cycle
European Journal of Applied Physiology, 2005Co-Authors: Tomoko Kuwahara, Yoshimitsu Inoue, Hiroyuki Ueda, Miyuki Taniguchi, Yukio Ogura, Narihiko KondoAbstract:To examine the effects of physical training on cutaneous vasodilation and Sweating responses of young women in the follicular and luteal phase, 11 physically trained (T group) and 13 untrained (U group) women were passively heated by lower-leg immersion into hot water of 42°C (ambient temperature of 30°C and 45%RH) for 60 min in their mid-follicular and mid-luteal phases of the menstrual cycle. Female hormones increased significantly from the mid-follicular to the mid-luteal phase in T and U groups, but the degree of increase was significantly lower in T group. Mean body temperature $$(\bar{T}_{\rm b})$$ thresholds for cutaneous vasodilation and Sweating responses were significantly lower in T group than in U group, in both the menstrual phases, and the differences between the groups were greatest during the mid-luteal phase. The slope of the relationship between frequency of sweat expulsion ( F _sw) and $$\bar{T}_{\rm b}, $$ and between local Sweating Rate and F _sw was significantly greater in T group, although the slope of the relationship between cutaneous blood flow and $$\bar{T}_{\rm b}$$ did not differ between the groups, regardless of body site or menstrual phase. These results suggest that regular physical activity enhanced Sweating and cutaneous vasodilation in young women. The enhancement of Sweating was due to both central and peripheral mechanisms, and the enhancement of cutaneous vasodilation was possibly due to a central mechanism. Enhancement of heat loss responses via central mechanisms was greater during the mid-luteal phase than in the mid-follicular phase because the elevation of female reproductive hormone levels during the mid-luteal phase was relatively low in T group.
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relationship between skin blood flow and Sweating Rate and age related regional differences
European Journal of Applied Physiology, 1998Co-Authors: Yoshimitsu Inoue, Manabu Shibasaki, Kozo Hirata, Tsutomu ArakiAbstract:To examine the mechanisms and regional differences in the age-related decrement of skin blood flow, 11 young (age 20-25 years) and 10 older (age 64-76 years) men were exposed to a mild heat stress by immersing their feet and lower legs in water at 42 degrees C for 60 min, while they were sitting in near thermoneutral conditions [25 degrees C and 45% relative humidity (rh)]. During the equilibrium period (25 degrees C and 45% rh) before the heat test, no group differences were observed in rectal (Tre) and mean skin (Tsk) temperatures or mean arterial pressure (MAP). During passive heating, Tsk was significantly lower in the older men 20 min after commencing exposure (P<0.001), although there were similar increases in Tre in both groups. Exposure time and age did not affect MAP. The local Sweating Rate (m(sw)) and the percentage change in skin blood flow by laser Doppler flowmetry (%LDF) relative to baseline values on the chest, back, forearm and thigh were significantly lower in the older men (P<0.001), especially on the thigh. After starting the heat exposure, three temporal phases were observed in the relationship between %LDF and m(sw) at most sites in each subject. In phase A, %LDF increased but with no increase in m(sw). In phase B, m(sw) increased but with no secondary increase in %LDF. Finally, in phase C, there were proportional increases in %LDF and m(sw). The increase in %LDF in phase A was significantly lower on the forearm and thigh (P<0.05) for the older men, but not on the chest and back. In phase C, the slopes of the regression lines between %LDF and m(sw) were lower for the older men on the back (P<0.03), forearm (P = 0.08) and thigh (P<0.03), but not on the chest. These results would suggest that the age-related decrement in skin blood flow in response to passive heating may be due in part to a smaller release of vasoconstrictor tone and to less active vasodilatation once Sweating begins. Regional differences exist in the impaired vasoconstriction and active vasodilatation systems.
