Regional sweat rates in humans

Exposures to hot environments and high intensity exercise provide some of the greatest challenges to the thermoregulatory system. Under such conditions evaporation is the greatest avenue of heat loss from the body. Whilst regional sweat rate variations in humans are widely recognised, most studies only measure a small number of sites using a limited surface area, and generalise this data to larger regions. A consensus in the literature indicates that the highest sweat rates are on the forehead and torso, and lowest on the extremities. However, no study has quantitatively measured regional sweat rates over large surface areas of the body. Since sweating is related to the thermal state of the body, comparison of regional sweat rates between studies is further complicated by the use of different environmental conditions, exercise modes and work rates. A good meta-analysis of existing data is therefore problematic. The aim of this thesis was to produce detailed whole body sweat maps for male and female athletes, and untrained males, during two exercise intensities in moderate environmental conditions (25°C, 50% rh) with a 2 m.s-1 air velocity. [Continues.

Upper body sweat mapping provides evidence of relative sweat redistribution towards the periphery following hot-dry heat acclimation

Purpose: Produce a detailed upper-body sweat map and evaluate changes in gross and regional sweating rates (RSR) and distribution following heat acclimation (HA). Methods: Six male participants (25±4 yrs) completed six consecutive days of HA (45°C,20% rh) requiring 90 minutes of intermittent exercise to maintain a rectal temperature (Tre) increase of 1.4°C. RSR were measured at 55% (Intensity-1; I1) and 75% V̇O2max (Intensity-2; I2) on the upper-body pre- and post-HA using a modified absorbent technique. Results: By design, work rate increased from day one to six (n.s.) of HA, and heart rate (HR), Tre, and skin temperature (Tsk) were similar between days. Gross sweat loss (GSL) increased (656±77 to 708±80g.m-2 .h-1 ; P<0.001) from day one to six. During pre- and post-acclimation experiments, relative workloads were similar for both intensities (Pre-I1 54±3, Post-I1 57±5 %VO2max; Pre-I2 73±4, Post-I2 76±7 %VO2max). GSL was significantly higher post-HA (Pre 449±90 g.m-2 .h-1 , Post 546 g.m-2 .h-1 ; P<0.01). Highest RSR were observed on the central back both pre and post acclimation at I1 (pre 854±269 post 1178±402g.m 2 .h-1 ) and I2 (pre 1221±351 post 1772±396 g.m-2 .h-1 ). Absolute RSR increased significantly in 12 (I1) to 14 (I2) of the 17 regions. Ratio data indicated significant relative RSR redistribution following HA, with the relative back contribution to whole-body sweat loss decreasing, chest staying the same and the arms increasing. Conclusions: Hot-dry HA significantly increased GSL in aerobically trained males at I2 only. Absolute RSR significantly increased in I1 and I2, with a preferential relative redistribution towards the periphery of the upper body

Body mapping of sweating patterns in athletes: a sex comparison

PURPOSE: Limited regional sweat rate (RSR) data are available for females, with only a small number of sites measured across the body. Similarly, sex differences in sweating concentrate on whole body values, with limited RSR data available. METHODS: A modified absorbent technique was used to collect sweat at two exercise intensities (60% (I1) and 75% (I2) O2 max) in 13 aerobically trained females (21±1 yrs, 59.5±10 ml.min.kg VO2max) in moderately warm conditions (25°C, 45% rh, 2 m.s air velocity). Females were compared to 9 aerobically trained males (23±3 yrs, 70.2±13 ml.min.kg VO) tested under the same conditions. RESULTS: Female I1 RSR were highest at the central upper back, heels, dorsal foot, and between the breasts (223, 161, 139 and 139 g.m.h, respectively). Lowest values were over the breasts, mid and lower outer back (<16 g.m.h). At I2 the central upper back, bra triangle, and lower back showed the highest RSR (723, 470, and 333 g.m.h, respectively). Regions of the breasts and palms had the lowest RSR at I2 (<82 g.m.h). Significantly greater GSL and thus RSR were observed in males vs. females at both exercise intensities. For the same metabolic heat production (male I1 vs. female I2) absolute and normalised RSR showed a significant region-sex interaction (p < 0.001), with a greater distribution towards the arms and hands in females vs. males. CONCLUSIONS: Despite some differences in distribution, both sexes showed highest RSR on the central upper back and lowest towards the extremities. No correlation was observed between local skin temperature and RSR, failing to explain RSR variation observed. These data have important applications for sex specific clothing design, thermophysiological modelling, and thermal manikin design

Body mapping of sweating patterns in male athletes in mild exercise-induced hyperthermia

Regional variation in sweating over the body is widely recognised. However, most studies only measured a limited number of regions, with the use of differing thermal states across studies making a good meta-analysis to obtain a whole body map problematic. A study was therefore conducted to investigate regional sweat rates (RSR) and distributions over the whole body in male athletes. A modified absorbent technique was used to collect sweat at two exercise intensities (55% (I1) and 75% (I2) V O2 max) in moderately warm conditions (25°C, 50% rh, 2 m.s-1 air velocity). At I1 and I2, highest sweat rates were observed on the central (upper and mid) and lower back, with values as high as 1197, 1148, and 856 g.m-2.h-1 respectively at I2. Lowest values were observed on the fingers, thumbs, and palms, with values of 144, 254, and 119 g.m-2.h-1 respectively at I2. Sweat mapping of the head demonstrated high sweat rates on the forehead (1710 g.m-2.h-1 at I2) compared to low values on the chin (302 g.m-2.h-1 at I2) and cheeks (279 g.m-2.h-1 at I2). Sweat rate increased significantly in all regions from the low to high exercise intensity, with exception to the feet and ankles. No significant correlation was present between RSR and regional skin temperature (Tsk), nor did RSR correspond to known patterns of regional sweat gland density. The present study has provided detailed regional sweat data over the whole body and has demonstrated large intra- and inter-segmental variation and the presence of consistent patterns of regional high versus low sweat rate areas in Caucasians male athletes. This data may have important applications for clothing design, thermophysiological modelling and thermal manikin design

Male and female upper body sweat distribution during running measured with technical absorbents

Body sweat distribution over the upper body in nine clothed male and female runners of equal 3 fitness while running at 65% V O2max and subsequent 15 minute rest in a moderate climate 4 (25ºC, 53% rh) was investigated using technical absorbent materials to collect the sweat 5 produced. No significant difference in whole body mass loss (male 474 SD 80; female 420 SD 6 114 g.m-2.h-1) nor surface weighted average of all tested zones for exercise (male 636 SD 165; 7 female 565 SD 222 g.m-2.h-1) nor rest (male 159 SD 46; female 212 SD 75 g.m-2.h-1) were 8 observed. Local sweat rate (LSR) ranges were large and overlapped substantially in most 9 areas. Males showed higher LSR for the mid-front (p<0.05), sides (p<0.05), and mid lateral 10 back (p<0.01) compare to females. Both sexes showed similar sweat distribution patterns over 11 the upper body with some exceptions. Males showed higher relative (local to overall) sweat 12 rates than females for the mid lateral back (p<0.001), while it was lower for the upper arm 13 (p<0.001), lateral lower back (p<0.05), and upper central back (p<0.05). Sweating in both 14 sexes was highest along the spine, and higher on the back as a whole than the chest as a 15 whole. Upper arm sweat rate was lowest. Males showed a higher ratio of highest to lowest 16 LSR (4.4 versus 2.8; p<0.05). The present study has provided more detailed information, 17 based on more subjects, on upper body sweat distribution than previously available, which can 18 be used in clothing design, thermo-physiological modelling, and thermal manikin design

Design data for footwear: sweating distribution on the human foot

Purpose – The purpose of this paper is to provide footwear designers, manikin builders and thermo-physiological modellers with sweat distribution information for the human foot. Design/methodology/approach – Independent research from two laboratories, using different techniques, is brought together to describe sweat production of the foot. In total, 32 individuals were studied. One laboratory used running at two intensities in males and females, and measured sweat with absorbents placed inside the shoe. The other used ventilated sweat capsules on a passive, nude foot, with sweating evaluated during passive heating and incremental exercise to fatigue. Findings – Results from both laboratories are in agreement. Males secreted more than twice the volume of sweat produced by the females (p<0.01) at the same relative work rate. Both genders demonstrated a non-uniform sweat distribution, though this was less variable in females. Highest local sweat rates were observed from the medial ankles (p<0.01). The dorsal foot sweated substantially more than the plantar (sole) areas (p<0.01). Sweating on the plantar side of the foot was uniform. Wearing shoes limited the increase in sweat production with increasing load, while the sweat rate of uncovered feet kept increasing with work and thermal load. Practical implications – The observed variation in sweat rate across the foot shows that footwear design should follow the body mapping principle. Fabrics and materials with different properties can be used to improve comfort if applied to different foot surfaces. The data also demonstrate that foot models, whether physical (manikins) or mathematical, need to incorporate the observed variation across the foot to provide realistic simulation/testing of footwear

Body sweat mapping Of male athletes following acclimation to a hot-dry environment: 660 June 1, 2: 30 PM - 2: 45 PM.

Body sweat mapping Of male athletes following acclimation to a hot-dry environment: 660 June 1, 2: 30 PM - 2: 45 PM

Body sweat mapping of untrained males during exercise-induced hyperthermia: 2506 Board #3 June 1 100 PM - 300 PM

Body sweat mapping of untrained males during exercise-induced hyperthermia: 2506 Board #3 June 1 100 PM - 300 P

Sweat mapping in humans and applications for clothing design

Sweat mapping in humans and applications for clothing desig

The skin interface - meeting point of physiology and clothing science

This paper describes the relevance of knowledge of processes that happen at the skin for sports clothing design. It looks at skin temperature distribution while cooling, relevant e.g. to outdoor winter sports and mountaineering, at sweat distribution over the body while running, relevant e.g. to clothing designed for running in general and more particularly for exercise in warm and hot climates, and finally it looks into regional skin sensitivity, relevant for all fields of sports clothing design. As these areas interact heavily, the sports clothing designer needs to be aware of their influences and their interactions in order to optimise the clothing for the specific type of sport at hand