Sweat distribution and perceived wetness across the human foot [Abstract]

Sweat distribution and perceived wetness across the human foot [Abstract

Sweat distribution and perceived wetness across the human foot [Abstract]

Sweat distribution and perceived wetness across the human foot [Abstract

Regional sweat distribution in young and older individuals

Regional sweat distribution in young and older individual

Shoe microclimate: An objective characterisation and subjective evaluation

Shoe microclimate (temperature and humidity) has been suggested to contribute to perceptions of foot thermal comfort. However, limited data is available for perceptual responses in relation to shoe microclimate development both over time and within different areas of the shoe. This study evaluates perceptions of foot thermal comfort for two running shoes different in terms of air permeability in relation to temporal and spatial characteristics of shoe microclimate. The temporal characteristics of shoe microclimate development were similar for both shoes assessed. However, higher temperatures and humidity were observed for the less permeable shoe. Changes to shoe microclimate over time and differences between shoes were perceivable by the users. This study provides the most detailed assessment of shoe microclimate in relation to foot thermal comfort to date, providing relevant information for footwear design and evaluation

Physiological and perceptual responses of the foot: interactions with footwear and the impact on comfort

The extremities (hands and feet) are morphologically and physiologically well suited for the dissipation of heat (Taylor et al. 2014). However, unlike the hands, the thermolytic potential of the feet is often diminished when wearing footwear. Shoes act as a barrier to heat and vapour transfer between the skin and the environment. Thus when the wearer’s dry and evaporative heat loss pathways are limited, heat and moisture may build within the air layers between the skin and the footwear (Havenith et al. 1990a; Sullivan and Mekjavic 1992; Bouskill et al. 2002). The combination of high temperatures and moisture accumulation contributes to perceptions of discomfort (Arezes et al. 2013; Irzmańska et al. 2013; West et al. 2019b), blister formation (Sulzberger et al. 1966) and encourages the growth of microorganisms which can lead to odour development and foot conditions such as tinea pedis i.e. athletes foot (Auger et al. 1993). Due to the complexities of assessing the thermal interactions within the foot-sock-shoe system, relatively little is understood as to how we subjectively evaluate this aspect of footwear comfort. Therefore, the aim of this research was to investigate the physiological and perceptual responses of the foot, the interactions within the foot-sock-shoe system and the impact on comfort. For this purpose, a multi-factorial, mixed methods approach was used to investigate regional variations in thermal sensation to warmth (Chapter 3), foot sweat production and distribution (Chapter 4), temporal and spatial characteristics of shoe microclimate (Chapter 5) and the role of the sock (Chapter 6 and 7) on perceptual responses relating to foot discomfort. The use of a thermal foot manikin as a tool for footwear evaluation and development was also examined (Chapter 8).Several findings emerged: 1) The feet play an important role in the modulation of whole body thermal sensation. 2) Foot sweat production is reduced when wearing shoes. Highest sweat rates occur at the medial ankle and dorsal regions; lowest sweat rates at the toes. 3) Shoe microclimate is significantly affected by shoe permeability. Although changes to shoe microclimate are perceivable by the wearer, thermal comfort must be considered as a function of both temperature and moisture accumulation within the shoe. 4) Although wearing/not wearing a sock does not elicit differences in thermo-physiological responses, the sock does play a role in minimising wear discomfort. 5) Tactile and mechanical inputs are important for the perception of skin wetness and discomfort within footwear. 6) The subjective evaluation of footwear does not achieve the same level of sensitivity or discriminative power observed with thermal manikin tests. Overall, this research provides a detailed insight into the physiological and perceptual responses of the feet and for the first time, provides insight into the interactions within the foot-sock-shoe system. Together, the findings from this research provide guidance for the development of thermally comfortable footwear.</div

Are running socks beneficial for comfort? The role of the sock and sock fiber type on shoe microclimate and subjective evaluations

This study evaluated the effect of socks (different in fiber type) and the effect of not wearing a sock on perceptions of thermal comfort in relation to changes in foot skin temperature and shoe microclimate (temperature and humidity) during rest and exercise. Ten females completed five trials on separate occasions. Four socks (cotton, wool, polyester, Coolmax) and no sock were evaluated. Trials were conducted at 23°C, 50% relative humidity and consisted of rest (10 min seated), treadmill running (40 min, 7.5 km·h−1) and recovery (15 min seated). Foot skin temperature and shoe microclimate were measured at seven sites on the right foot. Foot skin hydration was measured at nine foot sites. Perceptual responses were recorded. Foot thermo-physiological and foot perceptual responses were similar for all sock conditions (p > 0.05). Similar foot thermo-physiological responses were also observed between the sock and no sock conditions (p > 0.05). Interestingly, however, not wearing a sock resulted in greater perceptions of foot wetness, stickiness and discomfort (p < 0.05). As tactile interactions caused by foot movement within the shoe are strong predictors of foot wetness perception (a key contributor to wear discomfort), socks are important in reducing the tactile cues generated. The sock is therefore an important area for development and relevant for overall improvements in footwear comfort

Sweat distribution and perceived wetness across the human foot: the effect of shoes and exercise intensity

This study investigates foot sweat distribution with and without shoes and the relationship between foot sweat distribution and perceived wetness to enhance guidance for footwear design. Fourteenfemales performed low-intensity running with nude feet and low-and high-intensity running with shoes (55%VO2maxand 75%VO2max, respectively) on separate occasions. Right foot sweat rates were measured at14 regions using absorbent material applied during thelast 5 minutes of each work intensity. Perceptual responses were recorded for the body, foot and four foot regions. Foot sweat production was 22% greater nude (p<0.001) and with shoes did not increase with exercise intensity (p=0.14).Highest sweat rates were observed at the medial ankle and dorsal regions; lowest sweat rates at the toes. Perceptions of wetness and foot discomfort did not correspond with regions of high sweat production or low skin temperature but rather seemed dominated by tactile interactions caused by foot movement within the shoe

Supplementary Information Files for Body mapping of regional sweat distribution in young and older males

Supplementary Information Files for Body mapping of regional sweat distribution in young and older malesPurpose Given the pressing impact of global warming and its detrimental effect on the health of older populations, understanding age-related changes in thermoregulatory function is essential. Age differences in regional sweat distribution have been observed previously, but given the typically small measurement areas assessed, the development of whole body sweat maps for older individuals is required. Therefore, this study investigated age-related differences in regional sweat distribution in a hot environment (32 °C/50%RH) in young and older adults, using a body mapping approach. Methods Technical absorbent pads were applied to the skin of 14 young (age 24 ± 2 years) and 14 older (68 ± 5 years) males to measure regional sweat rate (RSR) at rest (30 min) and during exercise (30 min), at a fixed heat production (200 W m−2). Gastrointestinal (Tgi) and skin temperature (Tsk), heart rate, thermal sensation, and thermal comfort were also measured. Results Whole body sweat maps showed that despite equal heat production, healthy older males had significantly lower gross sweat loss (GSL) than the young and significantly lower RSR at almost all body regions at rest and at the hands, legs, ankles, and feet during exercise. The lower sweat loss in the older group coincided with a greater increase in Tgi and a consistently higher Tsk at the legs, despite subjectively feeling slightly cooler than younger individuals. Conclusion These findings support the evidence of age-related deterioration in both autonomic and subjective responses in the heat and highlight the lower extremities as the most affected body region.<br

Body mapping of regional sweat distribution in young and older males

Abstract Purpose Given the pressing impact of global warming and its detrimental effect on the health of older populations, understanding age-related changes in thermoregulatory function is essential. Age differences in regional sweat distribution have been observed previously, but given the typically small measurement areas assessed, the development of whole body sweat maps for older individuals is required. Therefore, this study investigated age-related differences in regional sweat distribution in a hot environment (32 °C/50%RH) in young and older adults, using a body mapping approach. Methods Technical absorbent pads were applied to the skin of 14 young (age 24 ± 2 years) and 14 older (68 ± 5 years) males to measure regional sweat rate (RSR) at rest (30 min) and during exercise (30 min), at a fixed heat production (200 W m−2). Gastrointestinal (Tgi) and skin temperature (Tsk), heart rate, thermal sensation, and thermal comfort were also measured. Results Whole body sweat maps showed that despite equal heat production, healthy older males had significantly lower gross sweat loss (GSL) than the young and significantly lower RSR at almost all body regions at rest and at the hands, legs, ankles, and feet during exercise. The lower sweat loss in the older group coincided with a greater increase in Tgi and a consistently higher Tsk at the legs, despite subjectively feeling slightly cooler than younger individuals. Conclusion These findings support the evidence of age-related deterioration in both autonomic and subjective responses in the heat and highlight the lower extremities as the most affected body region

Three theoretical assumptions associated with thermosensory testing [Abstract]

The goal of the study was to explore three theoretical assumptions associated with thermosensory testing, using the local application of thermal stimuli. The first assumption we addressed was that relationship between thermal sensation and physical contact temperature is linear. We also examined the assumption that local thermal discomfort is more sensitive to cold, than it is to heat. Lastly, we examined the assumption that participants exhibit high levels of confidence in repeated thermal sensation ratings, across a wide range of contact temperatures. In nine female, and eight male volunteers, thermal sensation, thermal discomfort, and the confidence in thermal sensation scores, were measured in response to seventeen physical contact temperature stimuli, ranging from 18 to 42o C, applied to the dorsal forearm. Our findings demonstrated that the first theoretical assumption, that local thermal sensations are linearly related to the stimulus temperature, is true. This indicates that the distance between the thermal sensation anchors is close to equal in terms of physical temperatures changes, across the range tested presented. On the contrary, the second assumption, that participants experience local cold as more uncomfortable than local heat stimuli, was not supported by the present data. Rather participants rated a similar thermal discomfort level to both cold and hot thermal stimuli. Indeed, the last assumption presented was also contraindicated by the present study, in which the average confidence of thermal sensation was less than 100% (87.5%). Interestingly, the similar levels uncertainty was observed across the range of physical contact temperature tested