Human wetness perception in relation to textile water absorption parameters under static skin contact

Skin-wetness-perception (WP) greatly affects thermal and sensorial discomfort in clothing and as such is of great interest to the clothing industry. Following neurophysiological studies of WP, this study looks at textile parameters affecting WP. Twenty-four fabrics, varying in thickness, fibre-type and absorption capacity were studied. Using twelve participants (males/females), the WP induced was studied in four wetness states: 1:Dry; 2:ABS, all having the same absolute water content of 2400μl per sample (= 0.024μl·mm-2); 3:100REL, saturated with water to their individual absorption capacity; 4:50REL, to 50% of the value in 3. As total absorption capacity was highly correlated (r=0.99) to fabric thickness, condition 3 and 4 were equivalent to having the same water content per volume of textile, i.e. 0.8 and 0.4μl·mm-3 respectively. Samples were applied to the upper back, statically to minimise the contribution of surface roughness/friction. WP was highly correlated to drop in skin temperature induced by the wet fabric, and increased with application pressure of the fabric. No effect of fibre-type was observed. In REL, with equal μl·mm-3, WP showed a positive correlation to total fabric watercontent-per-area (μl·mm-2), and thus also to thickness, given the correlation between the latter two, with saturation above 1.5μl·mm-2. In ABS on the other hand, with equal μl·mm-2, and thus with relative water content (μl·mmμl·mm-3) inversely proportional to thickness, WP was also inversely proportional to thickness. Thus WP showed opposing responses depending on the wetting type, indicating that the methodology of manipulating water content should be selected in relation to the product end-use

The interaction between temperature and hypoxia on the rate of neuromuscular fatigue development

The interaction between temperature and hypoxia on the rate of neuromuscular fatigue developmen

Human wetness perception of textile materials under dynamic skin contact

Human wetness perception of textile materials under dynamic skin contac

Comfort in clothing – Determining the critical factors

Comfort is often considered in relation to a single factor causing discomfort, be it environmental, physical, physiological or perceptual. But rarely does one factor actually fully influence how comfortable an individual feels. Even within the clothing system numerous factors; fit, material, design, etc, can affect an in-dividual’s comfort perception. Currently the understanding of the impact of individual fabric properties on wear comfort is limited. This paper will consider the various interactions that occur within the clothing sys-tem that contribute to wearer comfort. The dynamic interaction of the clothing material with large areas of the skin surface changes the perception of wetness felt by the user. To understand how sensation of wetness per-ception is influenced by textile parameters, a number of textile samples with different thickness, fiber type, and surface texture, were tested. They were evaluated in Static (upper back) and Dynamic (inner forearm) contact with the skin, under both low and high application pressure. Wetness perception and stickiness sensa-tion (tactile cue) were measured with ordinal perception scales and local skin temperature (thermal cue) by thermocouples. Under Static contact, wetness perception in fabrics containing the same amount of moisture per volume was positively related to fabric thickness (r2 = 0.87). Under Dynamic, higher wetness perception was associated with greater stickiness sensation (r2 = 0.68), occurring from differences in fabric surface tex-ture. Under Dynamic fabric thickness did not correlate with wetness perception directly, however when com-bined with stickiness sensation it provided a strong predictive power (r2 = 0.86). In both Static and Dynamic conditions, greater wetness perception (p 0.05). Fabric thickness and surface texture properties trigger thermal and tactile inputs, respectively, underpinning skin wetness perception in static and dynamic clothing applications. Additionally, fabric weight and clothing fit could cause changes in fabric-to-skin pressure, which represents another tactile sensory mo-dality contributing to skin wetness perception. Consideration of these factors could aid the design of clothing and fabric products, particularly office and vehicle seating, towards optimising comfort

The interaction between environmental temperature and hypoxia on central and peripheral fatigue during high-intensity dynamic knee extension

This study investigated causative factors behind the expression of different interaction types during exposure to multi-stressor environments. Neuromuscular fatigue rates and time to exhaustion (TTE) were investigated in active males (n=9) exposed to three climates (5°C,50%-rh/23°C,50%-rh/42°C,70%-rh) at two inspired oxygen fractions (0.209/0.125 FIO2; equivalent attitude=4100 m). After 40-mins rest in the environmental conditions, participants performed constant workload (high-intensity) knee extension exercise until exhaustion, with brief assessments of neuromuscular function every 110-s. Independent exposure to cold, heat and hypoxia significantly (p0.198). In contrast, combined exposure to hypoxic-heat reduced TTE by 609-s, showing a significant antagonistic interaction (p=0.003) similarly supported by an increased rate of peripheral fatigue development (increased by 8.3%.min-1). A small decline (<0.4%.min-1) in voluntary muscle activation was only observed in thermoneutral-normoxia. In conclusion, interaction type is influenced by the impact magnitude of the individual stressors' effect on exercise capacity, whereby the greater the stressors impact, the greater the probability that one stressor will be abolished by the other. This indicates humans respond to severe and simultaneous physiological strains based on a 'worst strain takes precedence' principle

The use of optimised heating trousers and the role of the blood flow on the reduction in muscle temperature post warm up

The use of optimised heating trousers and the role of the blood flow on the reduction in muscle temperature post warm u

Measuring garment spatial sweat absorption: Gravimetric and infrared approach [Abstract]

Measuring garment spatial sweat absorption: Gravimetric and infrared approach [Abstract

T-shirt sweat absorption mapping [Abstract]

T-shirt sweat absorption mapping [Abstract

The interaction between cooling and hypoxia on the rate of peripheral and central fatigue development of the knee extensors

The interaction between cooling and hypoxia on the rate of peripheral and central fatigue development of the knee extensor

Localized and systemic variations in central motor drive at different local skin and muscle temperatures

This study investigated the ability to sustain quadriceps central motor drive while subjected to localized heat and metaboreceptive feedback from the contralateral leg. Eight active males each completed two counter-balanced trials, in which muscle temperature (Tm) of a single-leg (TEMP-LEG) was altered to 29.4 (COOL) or 37.6°C (WARM), while the contralateral leg (CL-LEG) remained thermoneutral; 35.3 and 35.2°C Tm in COOL and WARM respectively. To activate metaboreceptive feedback, participants first performed one 120-s isometric maximal voluntary contraction (MVC) of the knee extensors in the TEMP-LEG, immediately followed by post-exercise muscle ischemia (PEMI) via femoral blood flow occlusion. To assess central motor drive of a remote muscle group immediately following PEMI, another 120-s MVC was subsequently performed in the CL-LEG. Voluntary muscle activation (VA) was assessed using the twitch interpolation method. Perceived mental effort and limb discomfort were also recorded. In a cooled muscle, a significant increase in mean force output and mean VA (force, p0.68, limb discomfort, p=0.73). The present findings suggest that elevated local Tsk and Tm can increase limb discomfort and decrease central motor drive, but this does not limit systemic motor activation of a thermoneutral muscle group