Intra-rater reliability of footwear-related comfort assessments

Comfort is an important aspect of athletic footwear since it has been associated with health and performance benefits. Footwear comfort is also a key consideration in orthotic therapy during the prescription/fitting process of foot orthoses. However, little is known about the actual ability of individuals to reliably assess footwear-related comfort. Therefore, the main objective of this study was to determine the intra-rater reliability of footwear comfort assessments. Ninety healthy male adults completed one familiarization and two testing sessions on different days. During each session, participants performed running trials to assess comfort of six different shoe insoles using Visual Analog Scales (VASs) and Yes–No questions. For the VAS, intra-rater reliability was determined using intra-class correlation coefficients. Cronbach's alpha was calculated to obtain the intra-rater reliability based on the Yes–No questions. For 31.1% of the participants a reliable assessment based on the VAS (intra-class correlation coefficient ≥ 0.7) was obtained. Using Yes–No questions (Cronbach's alpha ≥ 0.7), 46.7% of the participants had a reliable comfort assessment. The majority of individuals did not seem able to reliably assess footwear comfort, and the reason for this poor reliability remains unclear. However, when using footwear comfort in orthotic therapy, scientific research projects, or footwear development one should account for this low reliability of comfort assessments. This may be done by (1) simplifying the measure used to assess comfort, (2) only selecting individuals that were pre-tested for reliable assessments, and/or (3) establishing mean comfort ratings for an individual across multiple testing sessions.