Physiological and perceptual responses of the foot: interactions with footwear and the impact on comfort
thesisposted on 06.05.2020, 10:43 by Anna West
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.
Loughborough University, Design School. adidas AG, FUTURE Engineering Team