Validity of perceived skin wettedness mapping to evaluate heat strain

Abstract

The purpose of this study was to investigate the validity of a newly developed method for quantifying perceived skin wettedness (W (p)) as an index to evaluate heat strain. Eight male subjects underwent 12 experimental conditions: activities (rest and exercise) × clothing (Control, Tyvek and Vinyl condition) × air temperatures (25 and 32°C). To quantify the W (p), a full body map with 21 demarcated regions was presented to the subject. The results showed that (1) at rest in 25°C, W (p) finally reached 4.4, 8.3 and 51.6% of the whole body surface area for Control, Tyvek, and Vinyl conditions, respectively, while W (p) at rest in 32°C rose to 35.8, 61.4 and 89.8%; (2) W (p) has a distinguishable power to detect the most wetted and the first wetted regions. The most wetted body regions were the upper back, followed by the chest, front neck, and forehead. The first perceived regions in the skin wetted map were the chest, forehead, and upper back; (3) W (p) at rest showed a significant relationship with the calculated skin wettedness (w) (r = 0.645, p < 0.01) and (4) W (p) had a significant relationship with core temperature, skin temperature, heart rate, total sweat rate, thermal comfort, and humidity sensation (p < 0.05), but these relationships were dependent on the level of activities and clothing insulation. W (p) in hot environments was more valid as a heat strain index of workers wearing normal clothing in light works, rather than wearing impermeable protective clothing in strenuous works.

Neurophysiology of Skin Thermal Sensations

“…Alternatively exploring the two main sides of the perception of skin wetness [1) perception resulting from skin's contact with wet stimuli) (1, 15, 16, 71, 98-104, 109, 120, 191, 196, 227, 284, 285) 2) perception resulting from the active production of sweat (100,109,120,191)], these studies have contributed to increase our understanding of the psychophysical bases of human skin wetness perception.…”

“…This is particularly true under conditions of sweat-induced skin wetness (16,98,103). For example, under conditions of sweat-induced skin wetness, and especially when wearing clothing, skin wetness perception has been shown to be driven primarily by tactile stimuli in the form of intermittent mechanical interaction between skin, sweat and clothing (100,109,120,191). Interestingly, these findings are in line with what observed with for the mechanisms involved in the ability to sense skin wetness when in contact with external stimuli, and have therefore led to the current view for which the integration of specific thermal and tactile sensory cues is considered critical in order to experience the perception of skin wetness, irrespectively of the modality by which wetness is experienced (i.e.…”

“…thermal and tactile) underlie the ability to perceive skin wetness, has also to led to the investigation of the potential regional variability in skin wetness sensitivity across the body, and of its relationship with what known with regards to the regional differences in sensitivity observed in other somatosensory modalities (e.g. thermal sensitivity) (1,99,100,109,120,191). As a result, we now know that, during the contact with external stimuli, as well as a result of sweating, skin wetness can be perceived to a larger extent on certain regions of hairy skin (e.g.…”

The role of decreasing contact temperatures and skin cooling in the perception of skin wetness

“…For instance, we experience the perception of "wetness" on the skin though we are not provided with specific receptors for this sensation [10,22]. This somatosensory experience is considered a result of the integration of the somatosensory sub-modalities of touch and temperature [1,3,5,7].…”

The effect of clothing fit and material of women’s Islamic sportswear on physiological and subjective responses during exercise in warm and humid environment

“…For subjective thermal measurements, each participant gave a verbal evaluation of their thermal condition using nine points rating thermal sensation (TSV, 4: very hot, 3: hot, 2: warm, 1: slightly warm, 0: neither, -1: slightly cool, -2: cool, -3: cold, and -4: very cold), seven points of thermal comfort (TCV, 3: very comfortable, 2: comfortable, 1: slightly comfortable, 0: neither, -1: slightly uncomfortable, -2: uncomfortable, and -3: very uncomfortable), Rating of Perceived Exertion (RPE) based on Borg's scale, and skin wetness sensation (SW) [9] every 10-min.…”