Frictional Interaction between Running Sock Fabrics and Plantar Aspect of First Metatarsal Head in Different Moisture Conditions

Abstract

In a pursuit to further improve the understanding of the factors influencing friction blister formation, friction between running sock textiles and the skin at the first metatarsal head (1MTH) region was investigated in three different moisture conditions (dry, low moisture and wet).Twenty-six participants were recruited and two running sock types were selected based on the variations of their fibre composition and knit structure: 1) a predominantly nylon anti-blister sock and 2) a cotton-rich sock. All friction tests were conducted in controlled room conditions with a temperature of between 20 to 22°C and a relative humidity of 40 to 60% using a bespoke rig developed at the University of Sheffield for foot friction studies. Water was applied to the inside of the plantar region of the sock textiles to different levels using a moisture control protocol. The moisture level of both the 1MTH region and the sock fabrics were monitored throughout testing using a Corneometer® device.Increasing sock moisture above the dry condition was found to increase foot-sock sliding friction for both sock materials tested. No significant correlation was found at the level p < 0.05 between foot hydration level and sliding friction over the hydration range tested. In dry conditions, the cotton-rich sock exhibited lower levels of friction compared with the anti-blister sock. However, in both low moisture and wet conditions, the anti-blister sock showed comparatively lower levels of friction than the cotton-rich sock. This suggests that for intensive athletic events where significant perspiration is likely to occur, the anti-blister sock would provide lower friction. This study offers a new approach to friction testing of sock materials and it is hoped that its outcomes will provide new insights on the preventative measures for friction blisters.