Comparison of sweating components during endurance exercise under the same load in a hot environment and in a neutral thermal environment / 体力科学

Sweat contains electrolytes (minerals), therefore, it is necessary to consider its loss through sweat in the fluid replacement strategy in sports. The purpose of this study was to compare the concentration of components in sweat, such as electrolytes (minerals), when endurance exercise is performed in hot and neutral thermal environments. Eight men cycled for 60 min at 55% VO2peak under two envitonment conditions: a hot environment (WetBulb Globe Temperature (WBGT): 29.0±0.2℃; Heat) and a neutral thermal environment (WBGT: 20.5±0.2℃; Con). During exercise, sweat loss, core temperature, and heart rate (HR) were measured, and sweat from the chest, back, and thigh was collected. The core temperature, sweat loss, and HR increased significantly in Heat. The sweat electrolyte concentration was significantly higher in Heat than in Con only for Na. Regarding the amount of electrolyte loss from sweat, Na and K showed a significantly higher value than Con in Heat in comparison of each region, and the total loss amount of three regions in Cu also had a significantly higher value than Con in Heat. In addition, there was no difference in the concentration of Ca and Cu between the regions, but there was a significant difference in the amount of loss. It was concluded that even if there was no difference in the electrolyte concentration in sweat, the amount of electrolyte loss increased in K and Cu in a hot environment, and that there was a site difference in the amount of loss in Ca and Cu.

Thermophysiological Effects of Ultrafine Bubble Bathing / 日本温泉気候物理医学会雑誌

  Introduction: We examined the thermophysiological effects of ultrafine bubble (UB) bathing in comparison with microbubble (MB) and freshwater (FW) bathing.   Subjects and Methods: Seven healthy women aged 35.6±2.9 years provided informed consent to participate in the study. After a 10-min rest, each subject engaged in UB, MB, and FW bathing (on separate days) at 40°C for 10 min. During the experiment, tympanic temperature, local sweat rate, local skin temperature, heat flow, and heart rate variability were continuously recorded. Subjective assessments of thermal sensation and comfort were rated on a visual analog scale between 0 to 100.  Results: Increases in tympanic temperature and mean body temperature were highest during MB bathing, and similar increases were observed during UB and FW bathing. Local sweating was highest during MB bathing and lowest during UB bathing. A significant interaction was observed between local sweating during bathing and bathing style (P<0.001). The increase in local sweat rate relative to body temperature was lowest during UB bathing and highest during MB bathing.  Discussion: During UB bathing, UBs and MBs that were generated in high concentrations in the bathtub decreased the flow of heat to the body, thereby suppressing an increase in tympanic temperature and yielding the lowest local sweat late. However, during MB bathing, in which a moderate concentration of UBs and MBs were generated, the increase in heat flow due to the convection of hot water exceeded the decrease in heat flow due to the bubbles.  Conclusions: The results suggest that bubble properties and convection characteristics altered the balance of heat flow, leading to differences in the thermoregulatory response during and after bathing.

Thermophysiological Effects of Ultrafine Bubble Bathing / 日本温泉気候物理医学会雑誌

  Introduction: We examined the thermophysiological effects of ultrafine bubble (UB) bathing in comparison with microbubble (MB) and freshwater (FW) bathing.   Subjects and Methods: Seven healthy women aged 35.6±2.9 years provided informed consent to participate in the study. After a 10-min rest, each subject engaged in UB, MB, and FW bathing (on separate days) at 40°C for 10 min. During the experiment, tympanic temperature, local sweat rate, local skin temperature, heat flow, and heart rate variability were continuously recorded. Subjective assessments of thermal sensation and comfort were rated on a visual analog scale between 0 to 100.  Results: Increases in tympanic temperature and mean body temperature were highest during MB bathing, and similar increases were observed during UB and FW bathing. Local sweating was highest during MB bathing and lowest during UB bathing. A significant interaction was observed between local sweating during bathing and bathing style (P<0.001). The increase in local sweat rate relative to body temperature was lowest during UB bathing and highest during MB bathing.  Discussion: During UB bathing, UBs and MBs that were generated in high concentrations in the bathtub decreased the flow of heat to the body, thereby suppressing an increase in tympanic temperature and yielding the lowest local sweat late. However, during MB bathing, in which a moderate concentration of UBs and MBs were generated, the increase in heat flow due to the convection of hot water exceeded the decrease in heat flow due to the bubbles.  Conclusions: The results suggest that bubble properties and convection characteristics altered the balance of heat flow, leading to differences in the thermoregulatory response during and after bathing.

Drinking to thirst influences fluid replacement in adolescents judokas

AIM: The aim of this study was to examine the influence of the type of beverage and the use of thirst sensation to guide fluid replacement in the adolescent judokas. METHODS: Nine male judokas aged 10-16 (average age 11,8 ± 4,0 years old) were submitted to a standardized training of 90 minutes. In the first phase of the study, the athletes completed the training with ingestion ad libitum of different beverages: day 1 (water) and after 48 hours, day 2 (sports drink). In the second phase, after 7 days of first stage, the athletes completed the training with ingestion of water or sports drink, guided by thirst sensation. The total volume of liquids ingested (VI) during the training was quantified and the level of dehydration was determined by variation of body weight before and after training (∆W). At the end of each training, the athletes were asked about the training intensity to determine perceived exertion (PE). RESULTS: No differences were observed in weight loss (∆W) (range: -0,04 ± 0,4 to -0,69 ± 1,1 %) and perceived exertion (range: 3,2 to 5,0). The use of thirst sensation to guide fluid replacement reduced the total fluid intake when the beverage offered was the sports drink (no thirst vs. thirst sensation, 521,1 ± 290 vs 152,2 ± 187 mL - p=0,006). CONCLUSION: The results suggest that fluid replacement guided by thirst sensation can be influenced by the type of beverage offered.(AU)

A Method to Protect Mine Workers in Hot and Humid Environments

BACKGROUND: Work comfort studies have been extensively conducted, especially in the underground and meteorological fields resulting in an avalanche of recommendations for their evaluation. Nevertheless, no known or universally accepted model for comprehensively assessing the thermal work condition of the underground mine environment is currently available. Current literature presents several methods and techniques, but none of these can expansively assess the underground mine environment since most methods consider only one or a few defined factors and neglect others. Some are specifically formulated for the built and meteorological climates, thus making them unsuitable to accurately assess the climatic conditions in underground development and production workings. METHODS: This paper presents a series of sensitivity analyses to assess the impact of environmental parameters and metabolic rate on the thermal comfort for underground mining applications. An approach was developed in the form of a “comfort model” which applied comfort parameters to extensively assess the climatic conditions in the deep, hot, and humid underground mines. RESULTS: Simulation analysis predicted comfort limits in the form of required sweat rate and maximum skin wettedness. Tolerable worker exposure times to minimize thermal strain due to dehydration are predicted. CONCLUSION: The analysis determined the optimal air velocity for thermal comfort to be 1.5 m/s. The results also identified humidity to contribute more to deviations from thermal comfort than other comfort parameters. It is expected that this new approach will significantly help in managing heat stress issues in underground mines and thus improve productivity, safety, and health.

Sweat Potassium Decreases with Increased Sweating in Perimenopausal Women.

Objective: To investigate the relationship between rate of sweat production and sweat potassium concentration in premenopausal (PreM), perimenopausal (PeriM) and postmenopausal (PostM) women after a moderate exercise. Study Design: This is a cross-sectional study conducted in May 2012 at the Department of Physiology, University of Benin, Nigeria. Methods: Thirty healthy female volunteers comprising of PreM (aged: 22.5±0.8 yrs, n = 10), PeriM (aged: 46.5±1.1 yrs, n = 10), and PostM (aged: 52.2±0.9 yrs, n=10) participated in the study. Sweat was obtained with a sweat suction apparatus from a 120 cm2 circular area marked on the skin of the face and neck after a 15 min walk on a calibrated treadmill at a speed of 4.2 km/h at 27°C and a relative humidity of 85-95%, followed by measurement of sweat volume (SV) and [K+]. Sweat rate (SR) was determined by dividing the volume of sweat produced by the duration of exercise. Thirst perception (TP) was self-rated using the Visual Analogue Scale (VAS). Results: The PeriM women demonstrated higher SR (ml/min) (P = .01) and SV (ml) (P = .0006) compared to women in the other groups: SR (PeriM = 0.12±0.01; PreM = 0.07±0.02; PostM = 0.06±0.01), and SV (PeriM = 1.7±0.2; PostM = 0.9±0.1). However, they had lower sweat [K+] (mmol/l) (P = .04), compared to their PostM counterparts (PeriM = 19.98±1.5; PostM = 24.90±1.8). Furthermore, sweat [K+] was inversely associated with SR (r = -0.4, P = .02). Also, change in TP (cm) was highest (P = .001) in the PeriM women (PeriM = 2.5±0.2; PreM = 2.1±0.3; PostM = 0.99±0.2). Conclusion: Although excessive sweating can lead to depletion of the body's potassium concentration, the sweat potassium concentration decreases with increased sweating especially in perimenopausal women. This requires further investigation, as it could be an adaptive mechanism inhibiting excessive potassium loss.

Estrés térmico en trabajadores expuestos al área de fundición en una empresa metalmecánica, Mariara: 2004-2005 / Heat stress in workers exposed to a foundries in a metal-mechanic company, Mariara 2004-2005

Esta investigación tiene como objetivo evaluar el riesgo de estrés térmico en trabajadores expuestos al área de fundición en una Empresa Metalmecánica. El estudio realizado es de tipo transversal, descriptivo de campo. El universo estuvo integrado por veinte trabajadores y la muestra representada por ocho trabajadores del área de fundición. El análisis e interpretación de los datos se realizó a través de medida de tendencia central, desviación estándar y correlación de pearson. En conclusión, en el área de fundición existe disconfort térmico; no obstante, los trabajadores se encuentran aclimatados en dicha área. Se recomienda establecer programa preventivo de ambiente térmico.

This research aims to assess the risk of heat stress in workers exposed to foundries in Metal-mechanic Company. The study is cross-sectional, field descriptive. The universe consisted of twenty workers and the sample represented by eight workers from the foundry. The analysis and interpretation of the data was performed using the measure of central tendency, standard deviation and Pearson correlation. In conclusion, in the foundry there is heat discomfort; however, workers are acclimated in this area. It is recommended to establish thermal environment preventive program.

Perfil antropométrico e taxa de sudorese no futebol juvenil / Anthropometric profile and sweat rate in young soccer players

O futebol é um esporte cuja difusão mundial cresce a cada ano, sendo um dos eventos mais importantes no mundo esportivo. Cada vez mais crianças e adolescentes tem se engajado nesta modalidade esportiva, porém estudos sobre fatores de risco como adiposidade e impactos negativos como a desidratação e hipertermia, não são tão evidenciados.O objetivo do presente estudo foi avaliar o perfil antropométrico e determinar a taxa de sudorese e risco percentual de desidratação em atletas juvenis de futebol. Na avaliação antropométrica, coletou-se dados referentes ao peso, estatura, circunferências e dobras cutâneas e a partir destes foram calculados o índice de massa corporal e percentual de gordura. Para a obtenção da taxa de sudorese, foi realizada a pesagem antes e após treinopré-competitivo. Os atletas apresentaram, conforme determinado pelo percentual de gordura (14,4 ± 3,6%) e somatório de dobras (tríceps/subescapular) um percentual ótimo e padrão ativo provavelmente relacionado à posição de jogo. A taxa de sudorese embora baixa (8,8 ± 6,6 mL/min) variou amplamente entre os jogadores com uma redução significativa no peso final (p<0,05), porém sem risco de desidratação, mas não se pode afirmar, o mesmo, em relação à desidratação. Assim, apesar do baixo risco de desidratação não foram encontradas recomendações específicas de reidratação, devendo ainda permanecer a orientação de pesagem antes e após para monitoramento de conseqüências mais graves. Estudos futuros devem ser estimulados nesta área para estabelecer nesta faixa etária, com padrão fisicamente ativo, qual seria a estratégia mais adequada de hidratação com ênfase no monitoramento de sinais de hipertermia.

Soccer is a sport whose worldwide acceptance has been growing year after year, and is one of the most important events in the sports world. A growing number of children and teenagers are engaged in this activity, but studies regarding risk factors such as adiposity and negative impacts such as dehydration and hyperthermia are scarce. The aim of this study was to evaluate the anthropometric profile, sweat rate and risk of dehydration among young soccer players. For anthropometric assessment, weight, height, circumference measures and skinfold thickness were collected and used for the determination of body mass index and percent body fat of each player. For determination of the sweat rate, players were weighed before and after pre-competition training. Analysis of fat percentage (14.4 ± 3.6%) and the sum of skinfolds showed that the players presented an optimal percentage and activity pattern, probably related to their role in the game. Although low (8.8 ± 6.6 mL/min), the sweat rate varied widely among players, wit the observation of a significant reduction (p<0.05) in final weight. The risk of dehydration was low, but the same cannot be stated for the risk of hyperthermia. Further studies involving this population are necessary to establish an adequate hydration strategy, with emphasis on the monitoring of signs of hyperthermia.

Effects of the Foot Bathing on Hemiplegia Patients / 日本温泉気候物理医学会雑誌

The purpose of this study was to clarify effects of foot bathing at 44°C for the patients with hemiplegia. The subjects of this study were six patients with hemiplegia (average 71.6 years old) and six healthy volunteers (average 74.3 years old). Blood pressure and heart rate were measured using an autonomic spygmomanometer, tympanic temperature using a thermistor, and sweat rate using the ventrilated capsule method during the control period of 10 minutes before foot bathing, for 20 minutes during foot bathing, and for 10 minutes after foot bathing. Subjects wore a plain clothes while taking a footbath and the ambient temperature was set to 20°C. During foot bathing, heart rate was significantly increased, but blood pressure and pressure-rate product did not changed. Tympanic temperature was no significant changed in both subjects during foot bathing. But a significant increase of sweat rate was observed in patients. In healthy volunteers, in contrast, skin blood flow on the bottom of the foot was significant increased. These findings suggest that regulation system of cardiovascular is slightly declined in the patient, and patient's thermoregulatory system was difficult in healthy humans.

Effects of the Footbath on Tympanic Temperature, Sweat Rate, Blood Pressure, and Heart Rate in the Elderly Person / 日本温泉気候物理医学会雑誌

The purpose of this study was to clarify difference in heating effect of the two types of bathing for the elderly, footbathing at 44°C and full bathing at 40°C.<br>The subjects of this study were nine elderly persons for footbathing (average 73.5 years old) and 10 elderly persons for full bathing (average 77.4 years old). The tympanic temperature was measured using a thermistor, sweat rate using the ventral capsule method, and blood pressure and heart rate using an autonomic spygmomanometer during control period 10 minutes before bathing, for 20 minutes during bathing, and for 10 minutes after bathing. Subjects wore plain clothes while taking a footbath time or swimming trunks while taking a full bathing. The ambient temperature was set to 20°C during the footbath or 26°C during the full bathing.<br>During the footbath, the tympanic temperature increased to 60% that of full bathing and a significant increase of sweat rate was observed. In contrast, during full bathing, a significant rise in systolic blood pressure was observed immediately after bathing started due to hydrostatic pressure and a significant drop of diastolic pressure was observed after bathing due to heating during bathing.<br>These findings suggest that the footbath is safe, does not cause any change in blood pressure and is expected to provide mild warming for the elderly.

Effects of Fencing Uniform on Thermoregulatory Responses During Exercise in Hot Environment: Practical Field Study and Laboratory Experiment / 体力科学

The effects of fencing uniforms (U) on thermoregulatory responses were analyzed in both practical field investigation (PFI) and laboratory experiment (LE) . In PFI, six fencers (college-aged) performed regular fencing practice wearing U and wearing a short-sleeved shirt and pants (T) in summer. Rectal temperature (Tr), chest skin temperature (Tch), mask temperature (Tmk), heart rate (HR) and sweat rate (SR) were measured during fencing practice. In LE, seven male college-aged subjects performed three sessions of 20-min cycling at light intensity (250 W/m<SUP>2</SUP>) in a room temperature maintained at 28 WBGT (wet bulb globe temperature) . Esophageal temperature (Tes), mean skin temperature (Tsk), mean body temperature (Tb), HR, and SR were measured during exercise wearing U and in a semi-nude condition (N) . In both PFI and LE, increases in Tch, Tsk, Tb, Tes, Tr and SR were significantly (p<0.001) greater when wearing U than when wearing T and N. In PFI, the maximal value of Tr correlated significantly with the maximal values of Tch (r=0.513, p<0.001) and SR (r=0.635, p<0.001) during practice wearing U and T. In LE, positive correlations between Tsk and Tes (r=0.797, p<0.001), and between Tb and SR (r=0.658, p<0.02) were found at the end of exercise wearing U and N. In PFI, although the Tsk decreased within a few minutes of a decrease in Tmk, a significant relationship between the decrease in Tmk and Tsk or Tr was not observed during fencing practice. These results demonstrate that when wearing U, a higher skin temperature induces core temperature elevation, and higher skin and core temperatures are associated with increases in SR and HR during exercise in a hot environment. Thus, wearing light clothing during exercise, and taking off the fencing jacket and mask during rest periods would be recommended to reduce the heat stress during fencing practice in hot environments.

Effects of drinking on sweating and body cooling during exercise / 体力科学

To examine the effects of water replacement on sweating and body cooling during exercise, We studied the sweat rate, changes in body weight and body temperature during exercise with or with-out drinking various amounts of water. The subjects had been dehydrated or normally hydrated prior to exercise.<BR>1. Rectal temperature increased significantly with body weight loss.<BR>2. Sweat rate during exercise was constant (968-996 g/h) regardless of whether the subjects were dehydrated or hydrated.<BR>3. Body weight loss was negatively correlated with the amount of water intake, but was not correlated with the total amount of sweating.<BR>4. Total heat loss increased with increased water intake, and corresponded to 1345% of heat storage during exercise without drinking.<BR>These results suggest that although water replacement during exercise dose not affect the sweat rate, it has physiological significance in the maintenance of body fluid, and a physical effect in terms of body cooling.

A survey of ambient temperature, drinking, sweating and body temperature / 体力科学

In order to get basic data for preventing heat stroke accident during exercise in a hot environment, we analysed the relation between environmental temperature, and drinking and sweating. We also analyed the effect of water intake on body temperature regulation during exercise.<BR>The environmental temperature started to rise in April, reached the maximumin August, and then decreased. Water intake and sweating increased significantly with increase in WBGT, but there was no correlation between weight loss and WBGT. The rise in body temperature during exercise (0.52±0.080°C) was constant and independent of WBGT. The rise in oral temperature during exercise was affected by the water intake and it was significantly higher when water was not supplied than that with water supply (p<0.001) . Sweat rate was significantly greater when water was supplied than when it was not supplied (p<0.01) .<BR>The above results suggest that the amount of water intake increased with the increase in WBGT, which guarantees the increase in sweating and as a result maintenance of constant oral temperature.<BR>Therefore it is suggested that it is better to supply water during exercise to facilitate evaporative heat loss, which prevent rise in oral temperature.

The effect of environment temperature on thermal regulation during prolonged exercise. From the standpoint of individual variation / 体力科学

The purpose of this study was to investigate the possible individual difference in temperature regulating ability during identical relative exercise load under various temperature environments.<BR>Seven healthy males, aged 21 to 26 years, performed bicycle ergometer exercise of 60% VO<SUB>2</SUB>max for 60 minutes. All exercises were carried out in a climatic chamber under the conditions of 15°C (RH=70%), 25°C (RH=55%) or 35°C (RH=45%) . Herat rate, O<SUB>2</SUB> consumption, pulmonary ventilation, rectal temperature, mean skin temperature, local sweat rate at the lower part of scapula and total sweat rate were determined intermittently through the experiments. Moreover, heat loss by evaporation, radiation, convection and effective sweat rate was calculated using the heat valance equations.<BR>The results obtained are as follows :<BR>1. The increase in rectal temperature at the end of exercise was almost identical in 15°C and 25°C but significantly higher in 35°C.<BR>2. A significant positive correlation was observed between mean skin temperature (ΔTsk) at the end of exercise and effective sweat rate (r=0.468, p<0.05) during exercise.<BR>3. Inspite of the equality of relative exercise intensity (60%VO<SUB>2</SUB>max), marked individual variations were observed in rectal temperature during exercise.<BR>4. The subjects who showed marked increase in rectal temperature during exercise showed less marked increase in mean skin temperature in 15°C and 25°C and less marked increase in local sweat rate in 35°C than other subjects.<BR>It would be concluded that the main cause of individual variation in rectal temperature during exercise depends on difference in evaporative heat loss in hot environment and difference in skin temperature in mild or cold environment.