scholarly journals Evidence that transient changes in sudomotor output with cold and warm fluid ingestion are independently modulated by abdominal, but not oral thermoreceptors

2014 ◽  
Vol 116 (8) ◽  
pp. 1088-1095 ◽  
Author(s):  
Nathan B. Morris ◽  
Anthony R. Bain ◽  
Matthew N. Cramer ◽  
Ollie Jay
Keyword(s):  
Gastrointestinal Tract ◽  
Skin Temperature ◽  
Nasogastric Tube ◽  
Sweat Rate ◽  
Mean Skin Temperature ◽  
Fluid Ingestion ◽  
Local Sweat Rate ◽  
Different Temperatures ◽  
Sudomotor Activity ◽  
Skin Temperatures

Two studies were performed to 1) characterize changes in local sweat rate (LSR) following fluid ingestion of different temperatures during exercise, and 2) identify the potential location of thermoreceptors along the gastrointestinal tract that independently modify sudomotor activity. In study 1, 12 men cycled at 50% V̇o2peakfor 75 min while ingesting 3.2 ml/kg of 1.5°C, 37°C, or 50°C fluid 5 min before exercise; and after 15, 30, and 45-min of exercise. In study 2, 8 men cycled at 50% V̇o2peakfor 75 min while 3.2 ml/kg of 1.5°C or 50°C fluid was delivered directly into the stomach via a nasogastric tube (NG trials) or was mouth-swilled only (SW trials) after 15, 30, and 45 min of exercise. Rectal (Tre), aural canal (Tau), and mean skin temperature (Tsk); and LSR on the forehead, upper-back, and forearm were measured. In study 1, Tre, Tau, and Tskwere identical between trials, but after each ingestion, LSR was significantly suppressed at all sites with 1.5°C fluid and was elevated with 50°C fluid compared with 37°C fluid ( P < 0.001). The peak difference in mean LSR between 1.5°C and 50°C fluid after ingestion was 0.29 ± 0.06 mg·min−1·cm−2. In study 2, LSR was similar between 1.5°C and 50°C fluids with SW trials ( P = 0.738), but lower at all sites with 1.5°C fluid in NG trials ( P < 0.001) despite no concurrent differences in Tre, Tau, and Tsk. These data demonstrate that 1) LSR is transiently altered by cold and warm fluid ingestion despite similar core and skin temperatures; and 2) thermoreceptors that independently and acutely modulate sudomotor output during fluid ingestion probably reside within the abdominal area, but not the mouth.

Active cutaneous vasodilation in resting humans during mild heat stress

2005 ◽  
Vol 98 (3) ◽  
pp. 829-837 ◽  
Author(s):  
Yoshi-Ichiro Kamijo ◽  
Kichang Lee ◽  
Gary W. Mack
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Temperature ◽  
Skin Blood Flow ◽  
Sweat Rate ◽  
Mean Skin Temperature ◽  
Local Skin ◽  
Mild Heat ◽  
Normal Core ◽  
Local Sweat Rate

The role of skin temperature in reflex control of the active cutaneous vasodilator system was examined in six subjects during mild graded heat stress imposed by perfusing water at 34, 36, 38, and 40°C through a tube-lined garment. Skin sympathetic nerve activity (SSNA) was recorded from the peroneal nerve with microneurography. While monitoring esophageal, mean skin, and local skin temperatures, we recorded skin blood flow at bretylium-treated and untreated skin sites by using laser-Doppler velocimetry and local sweat rate by using capacitance hygrometry on the dorsal foot. Cutaneous vascular conductance (CVC) was calculated by dividing skin blood flow by mean arterial pressure. Mild heat stress increased mean skin temperature by 0.2 or 0.3°C every stage, but esophageal and local skin temperature did not change during the first three stages. CVC at the bretylium tosylate-treated site (CVCBT) and sweat expulsion number increased at 38 and 40°C compared with 34°C ( P < 0.05); however, CVC at the untreated site did not change. SSNA increased at 40°C ( P < 0.05, different from 34°C). However, SSNA burst amplitude increased ( P < 0.05), whereas SSNA burst duration decreased ( P < 0.05), at the same time as we observed the increase in CVCBT and sweat expulsion number. These data support the hypothesis that the active vasodilator system is activated by changes in mean skin temperature, even at normal core temperature, and illustrate the intricate competition between active vasodilator and the vasoconstrictor system for control of skin blood flow during mild heat stress.

Thermoregulatory responses during competitive marathon running

1977 ◽  
Vol 42 (6) ◽  
pp. 909-914 ◽  
Author(s):  
M. B. Maron ◽  
J. A. Wagner ◽  
S. M. Horvath
Keyword(s):  
Skin Temperature ◽  
Marathon Running ◽  
Heat Illness ◽  
Mean Skin Temperature ◽  
Total Water ◽  
Water Losses ◽  
Thermoregulatory Responses ◽  
Marked Disparity ◽  
Skin Temperatures ◽  
Cool Conditions

To assess thermoregulatory responses occuring under actual marathon racing conditions, rectal (Tre) and five skin temperatures were measured in two runners approximately every 9 min of a competitive marathon run under cool conditions. Race times and total water losses were: runner 1 = 162.7 min, 3.02 kg; runner 2 = 164.6 min, 2.43 kg. Mean skin temperature was similar throughout the race in the two runners, although they exhibited a marked disparity in temperature at individual skin sites. Tre plateaued after 35--45 min (runner 1 = 40.0--40.1, runner 2 = 38.9--39.2 degrees C). While runner 2 maintained a relatively constant level for the remainder of the race, runner 1 exhibited a secondary increase in Tre. Between 113 and 119 min there was a precipitous rise in Tre from 40.9 to 41.9 degrees C. Partitional calorimetric calculations suggested that a decrease in sweating was responsible for this increment. However, runner 1's ability to maintain his high Tre and running pace for the remaining 44 min of the race and exhibit no signs of heat illness indicated thermoregulation was intact.

Role of skin and of core temperatures in man's temperature regulation

1965 ◽  
Vol 20 (1) ◽  
pp. 31-36 ◽  
Author(s):  
C. H. Wyndham
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Temperature Regulation ◽  
Passive Control ◽  
Sweat Rate ◽  
Heat Conductance ◽  
Response Characteristics ◽  
Highly Nonlinear ◽  
The Right ◽  
Skin Temperatures

The response characteristics have been studied of the curves relating heat conductance and sweat rate to change in rectal temperature at different levels of skin temperature, and vice versa. The increase in these responses with deviation in rectal temperature from the “neutral” setting is highly nonlinear; the neutral point and the curve shift to the right and the slope decreases with lowering of skin temperature and vice versa when it is raised. With further deviation of rectal temperature these responses reach maximum values, i.e., become “saturated.” All of these features are analogous to servomechanisms with negative feedback, giving sensitive and stable control. Control of these responses by skin temperature is more linear, characterizing passive control systems which are insensitive and less stable. Quantitatively, the effect at skin temperature of 26 C of 1 C rise in rectal temperature on heat conductance and sweat rate is 10 times greater than the same rise in skin temperature; at a neutral skin temperature of 33–34 C, a rise of 1 C in rectal temperature is 6–7 times greater; at a high skin temperature of 36 C, a rise in rectal temperature of 1 C is 4–5 times greater. relationship between heat conductance and a change in either rectal or skin temperatures; relationship between sweat rate and a change in either rectal or skin temperatures; response characteristics of curves relating heat conductance to change in either rectal or skin temperatures; response characteristics of curves relating sweat rate to change in either rectal or skin temperatures; assessment of the contribution of skin and rectal temperatures to man's temperature regulation Submitted on October 22, 1963

scholarly journals Thermal Behavior Augments Heat Loss Following Low Intensity Exercise

2019 ◽  
Vol 17 (1) ◽  
pp. 20 ◽  
Author(s):  
Nicole T. Vargas ◽  
Christopher L. Chapman ◽  
Blair D. Johnson ◽  
Rob Gathercole ◽  
Matthew N. Cramer ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Skin Temperature ◽  
Heat Loss ◽  
Core Temperature ◽  
Sweat Rate ◽  
Upper Body ◽  
Mean Skin Temperature ◽  
Thermal Discomfort ◽  
Low Intensity ◽  
Low Intensity Exercise

We tested the hypothesis that thermal behavior alleviates thermal discomfort and accelerates core temperature recovery following low intensity exercise. Methods: In a 27 ± 0 °C, 48 ± 6% relative humidity environment, 12 healthy subjects (six females) completed 60 min of exercise followed by 90 min of seated recovery on two occasions. Subjects wore a suit top perfusing 34 ± 0 °C water during exercise. In the control trial, this water continually perfused throughout recovery. In the behavior trial, the upper body was maintained thermally comfortable by pressing a button to receive cool water (3 ± 2 °C) perfusing through the top for 2 min per button press. Results: Physiological variables (core temperature, p ≥ 0.18; mean skin temperature, p = 0.99; skin wettedness, p ≥ 0.09; forearm skin blood flow, p = 0.29 and local axilla sweat rate, p = 0.99) did not differ between trials during exercise. Following exercise, mean skin temperature decreased in the behavior trial in the first 10 min (by −0.5 ± 0.7 °C, p < 0.01) and upper body skin temperature was reduced until 70 min into recovery (by 1.8 ± 1.4 °C, p < 0.05). Core temperature recovered to pre-exercise levels 17 ± 31 min faster (p = 0.02) in the behavior trial. There were no differences in skin blood flow or local sweat rate between conditions during recovery (p ≥ 0.05). Whole-body thermal discomfort was reduced (by −0.4 ± 0.5 a.u.) in the behavior trial compared to the control trial within the first 20 min of recovery (p ≤ 0.02). Thermal behavior via upper body cooling resulted in augmented cumulative heat loss within the first 30 min of recovery (Behavior: 288 ± 92 kJ; Control: 160 ± 44 kJ, p = 0.02). Conclusions: Engaging in thermal behavior that results in large reductions in mean skin temperature following exercise accelerates the recovery of core temperature and alleviates thermal discomfort by promoting heat loss.

Influence of skin temperature on sweating and aerobic performance during severe work

1979 ◽  
Vol 47 (4) ◽  
pp. 770-777 ◽  
Author(s):  
C. T. Davies
Keyword(s):  
Standard Deviation ◽  
Skin Temperature ◽  
Sweat Rate ◽  
Work Load ◽  
Aerobic Performance ◽  
Cooling Power ◽  
Mean Skin Temperature ◽  
Submaximal Work ◽  
Power Outputs ◽  
Male Subjects

Two male subjects were measured over a range of work intensities at dry-bulb temperature (Tdb) = 21 degrees C (relative humidity, rh less than 50%) and at approximately 65 and 85% VO2max for 1 h at Tdb at 5,10,15,21, and 25 degrees C with high convective airflow (2.5–5 m/s). The results showed that mean skin temperature (Tsk) was related to Tdb and unaffected by rh over the range studied. Tsk was dependent on the relative work load and was 2.5 degrees C lower at 85% than 65% VO2max in the cooler environments. During submaximal work the relative sweat rate (Msw expressed as %Mse, max) was a linear function of rectal temperature (Tre) and Tsk for each subject and thus %Msw, max could be predicted from these two variables with a standard deviation of +/- 12%. For a given Tsk, Tre appeared to rise to meet the requirement of heat loss by stimulating set %Msw response. However, during severe work (85% VO2max) this mechanism appeared to become saturated, Tre (except for a very narrow prescriptive range) was dependent on Tdb. These results suggest that under moderate environmental conditions the maximal aerobic and evaporative (cooling) power outputs of an individual are closely matched and only during extremely hard work does thermoregulation become passive and effectively physical (rather than physiological) in nature.

Sudomotor and vasomotor responses to changing environmental temperature

1965 ◽  
Vol 20 (3) ◽  
pp. 371-378 ◽  
Author(s):  
R. D. McCook ◽  
R. D. Wurster ◽  
W. C. Randall
Keyword(s):  
Skin Temperature ◽  
Tympanic Membrane ◽  
Mean Skin Temperature ◽  
Nervous Control ◽  
Vasomotor Responses ◽  
Hot Environment ◽  
Tympanic Membrane Temperature ◽  
The Subject ◽  
Male Subjects ◽  
Skin Temperatures

Male subjects clad only in shorts were exposed in a climate chamber to a slowly rising ambient temperature while sweating, cutaneous volume pulses, and skin, tympanic membrane, and oral temperatures were simultaneously recorded. Mean skin temperature was continuously computed electronically. After sweating and vasodilatation had become well established, the copper screen bed on which the subject reclined was rapidly moved from the hot chamber into another, 20–30 C cooler. The onset of neither sweating nor vasodilatation could be accurately correlated with tympanic membrane temperature since the latter was observed to be either increasing, unchanged, or even falling during the period of recruitment. In some experiments, vasodilatation preceded sweating, while in others, it followed. When the subject was rapidly moved from the hot environment to the cold, sweating promptly stopped on all of the test areas, and profound vasoconstriction appeared on the palm. Nonpalmer areas, however, showed little or no immediate change in the amplitude of the volume pulses. Mean skin temperature invariably started to fall, but only by a few tenths of a degree when cessation of sweating and palmar constriction occurred. Tympanic membrane temperature during the same period continued to rise for 1–3 min, and thus seemed unrelated to either vasomotor or sudomotor control under these circumstances. sweating; cutaneous vasomotor responses; cutaneous vasodilatation; cutaneous vasoconstriction; tympanic membrane temperatures; mean skin temperatures; nervous control of sweating; nervous control of cutaneous vascular responses; bradykinin and sweating; bradykinin and vasodilatation Submitted on August 13, 1965

scholarly journals Skin wettedness is an important contributor to thermal behavior during exercise and recovery

2018 ◽  
Vol 315 (5) ◽  
pp. R925-R933 ◽  
Author(s):  
Nicole T. Vargas ◽  
Christopher L. Chapman ◽  
Blair D. Johnson ◽  
Rob Gathercole ◽  
Zachary J. Schlader
Keyword(s):  
Linear Regression ◽  
Thermal Behavior ◽  
Skin Temperature ◽  
Mean Skin Temperature ◽  
Independent Variables ◽  
Skin Wettedness ◽  
Custom Made ◽  
Individual Minute ◽  
Neck Temperature ◽  
Skin Temperatures

We tested the hypothesis that mean skin wettedness contributes to thermal behavior to a greater extent than core and mean skin temperatures. In a 27.0 ± 1.0°C environment, 16 young participants (8 females) cycled for 30 min at 281 ± 51 W·m2, followed by 120 min of seated recovery. Mean skin and core temperatures and mean skin wettedness were recorded continuously. Participants maintained a thermally comfortable neck temperature throughout the protocol using a custom-made device. Neck device temperature provided an index of thermal behavior. Linear regression was performed using individual minute data with mean skin wettedness and core and mean skin temperatures as independent variables and neck device temperature as the dependent variable. Standarized β-coefficients were used to determine relative contributions to thermal behavior. Mean skin temperature differed from preexercise (32.6 ± 0.5°C) to 10 min into exercise (32.3 ± 0.6°C, P < 0.01). Core temperature increased from 37.1 ± 0.3°C preexercise to 37.7 ± 0.4°C by end exercise ( P < 0.01) and remained elevated through 30 min of recovery (37.2 ± 0.3°C, P < 0.01). Mean skin wettedness increased from preexercise [0.14 ± 0.03 arbitrary units (AU)] to 20 min into exercise (0.43 ± 0.09 AU, P < 0.01) and remained elevated through 80 min of recovery (0.18 ± 0.06 AU, P ≤ 0.05). Neck device temperature decreased from 26.4 ± 1.6°C preexercise to 18.5 ± 8.7°C 10 min into exercise ( P = 0.03) and remained depressed through 20 min of recovery (14.4 ± 11.2°C, P < 0.01). Mean skin wettedness (52 ± 24%) provided a greater contribution to thermal behavior compared with core (22 ± 22%, P = 0.06) and mean skin (26 ± 16%, P = 0.04) temperatures. Skin wettedness is an important contributing factor to thermal behavior during exercise and recovery.

Heat Strain in Protective Clothing Following Hot-Wet or Hot-Dry Heat Acclimation

1996 ◽  
Vol 21 (2) ◽  
pp. 90-108 ◽  
Author(s):  
Tom M. McLellan ◽  
Yukitoshi Aoyagi
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Protective Clothing ◽  
Intermittent Exercise ◽  
Sweat Rate ◽  
Heat Acclimation ◽  
Heat Strain ◽  
Mean Skin Temperature ◽  
Time Required

The purpose of the present study was to compare the heat strain while wearing nuclear, biological, and chemical (NBC) protective clothing following a hot-wet (HW) or hot-dry (HD) heat acclimation protocol. Twenty-two males were assigned to groups HW (n = 7), HD (n = 8), or control (C, n = 7). Subjects were evaluated during continuous treadmill walking while wearing lightweight combat clothing and during intermittent exercise while wearing the NBC protective clothing. While wearing Combat clothing, greater decreases in rectal temperature (Tre), mean skin temperature [Formula: see text], and heart rate were observed for both acclimation groups. For the NBC clothing trials, lower Tre, [Formula: see text], and heart rates were observed only for group HW. The time required for Tre to increase 1.0 °C and 1.5 °C was significantly delayed for groups HW and HD. Sweat evaporation increased for HW, whereas no change was found for HD. The most significant changes in Tre, [Formula: see text], and heart rate while wearing the NBC protective clothing occur following heat acclimation that involves wearing the clothing during exercise. Key words: rectal temperature, mean skin temperature, heart rate, sweat rate

scholarly journals Two isothermal challenges yield comparable physiological and subjective responses

2020 ◽  
Vol 120 (12) ◽  
pp. 2761-2772
Author(s):  
L. Klous ◽  
A. Psikuta ◽  
K. Gijsbertse ◽  
D. Mol ◽  
M. van Schaik ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Thermal Resistance ◽  
Skin Temperature ◽  
Sweat Rate ◽  
Subjective Responses ◽  
Lower Baseline ◽  
Local Sweat Rate ◽  
Local Ventilation ◽  
Dry Thermal Resistance ◽  
Desert Climate

Abstract Purpose Ventilated vests are developed to reduce thermal stress by enhancing convective and evaporative cooling from skin tissue underneath the vest. The purpose of this study is to investigate whether thermal stress is equal when a ventilated vest is worn compared to a no-vest situation with similar dry thermal resistance. Methods Nine healthy males walked on a treadmill (7 km h−1) for 45 min in a desert climate (34 °C, 20% relative humidity) with and without ventilated vest. Gastrointestinal temperature (Tgi), heart rate (HR), and skin temperature (Tsk) were continuously monitored. Local sweat rate (LSR) was assessed two times on six skin locations. Subjective ratings were assessed every 10 min. Results Final Tgi (37.6 ± 0.1 °C for vest and 37.6 ± 0.1 °C for no-vest), HR (133 ± 7 bpm and 133 ± 9 bpm) and mean Tsk (34.8 ± 0.7 °C and 34.9 ± 0.6 °C) were not different between conditions (p ≥ 0.163). Scapula skin temperature (Tscapula) under the vest tended to be lower (baseline to final: ΔTscapula = 0.35 ± 0.37 °C) than without vest (ΔTscapula = 0.74 ± 0.62 °C, p = 0.096). LSR at locations outside the vest did not differ with and without vest (p ≥ 0.271). Likewise, subjective responses did not differ between conditions (χ2 ≥ 0.143). Conclusions We conclude that two systems with similar dry thermal resistance and, therefore, similar required evaporation, resulted in similar thermal stress during paced walking in a hot-dry environment. Local ventilation did not alter the sweating response on locations outside the vest.

Sign in / Sign up

Export Citation Format

Share Document