Effects of sock type on foot skin temperature and thermal demand during exercise

Many fabrics and clothing 'systems' have been designed to enhance heat balance and provide greater thermal comfort for the wearer. However, studies on the effects of socks have largely been ignored in clothing research. It has been suggested that the thermal state of the extremities may alter core temperature and mental stress may be a major determinant of skin blood perfusion on the foot. However, no definite conclusions have been drawn. The aim of this study was to examine the effects of two different sock types on foot skin temperature and to investigate any impact on whole body thermoregulation and energy expenditure. Sixteen subjects carried out two sessions of treadmill running exercise, one session wearing a standard running sock and one session wearing an ergonomic asymmetric fitted sock. The overall mean heart rate, core (aural) temperature, foot skin temperature, weighted mean skin temperature and sweat rate during exercise were not statistically significant between the sock conditions (p > 0.05). There was a consistent trend in all participants for the ergonomic sock to induce a higher core temperature and higher skin temperatures compared to the standard sock. Overall mean ratings of perceived exertion and ratings of thermal perception were similar for both sock conditions. Participant questionnaires highlighted a general perception that the ergonomic socks had superior cushioning but that the standard socks were comfortable to wear. Despite there being no significant physiological or thermal differences between socks, the ergonomic sock was perceived to be cooler and was the preferred sock which suggests that subjective perceptions may be more important than objective measurements when selecting a sock for wear during prolonged exercise.