New approach to assessing comfort of use of protective footwear with a textile liner and its impact on foot physiology

We propose a new approach to assessing comfort of use of protective footwear with a textile liner. All-rubber footwear with wool liner and cotton/polyamide socks were evaluated in a study involving 30 firefighters. The study was designed to comprehensively assess comfort of use of textiles in the footwear using certain known and new research tools at the same time, that is, measurement of the microclimate inside the footwear (temperature and humidity), weight gain of the footwear, socks, and liner (weighing method), measurement of blood flows in the lower extremities (impedance plethysmography), as well as evaluation of user comfort (questionnaire survey). The influence of the above-mentioned parameters on the comfort of use was analyzed statistically. Following a walk, the temperature in the foot regions was found to increase by 10%, while relative humidity of the air in the plantar region rose by 50%, and the textiles absorbed 28 g/1.5 h of sweat produced by the foot. Due to the unfavorable conditions inside the footwear and as a result of physical exercise, total blood flow in the lower extremities rose significantly (by 33%). The structure and type of the fiber used in the socks and liner influenced the subjective sensations of the subjects. We found very high correlations between the subjective sensations of temperature inside the footwear and the objective measurements of temperature and humidity, blood flow, and liner weight gain. This study is the first step towards a better understanding of the influence of various parameters on the comfort of use of a textile liner and socks in protective footwear.