Do Commercially Available Insoles Meaningfully Change Reported Comfort and Biomechanics During One Day of Wear?

Abstract

Introduction: Identifying meaningful changes in comfort and any underpinning biomechanical changes is crucial to understanding differences in perceptions of footwear comfort. Research rarely considers changes in comfort, and rarely reports how meaningful these are. This study aims to utilise a portable biomechanics measurement tool to establish whether commercially available insoles make meaningful changes in comfort and identify any concurrent changes in biomechanics compared with a control whilst worn during a users' normal day.

Materials and methods: Thirty participants wore five insole conditions (participants' own shoe, and four commercially available insoles) for a typical day whilst the Runscribe inertial measurement unit (IMU) captured: Ground reaction force (GRF), GRF rate, pronation excursion, pronation velocity, impact shock, braking shock, and total shock. Comfort was measured using a 100 mm visual analogue scale. A pre-defined ± 8.28 mm minimal clinical important difference (MCID) for comfort was used as the threshold of meaningful change to group individuals into comfort classifications: 'more' (47 participants) and 'less' (36 participants). MCID was also defined for biomechanics variables from the RunScribe. Insole conditions were compared between classifications to identify significant and meaningful changes in biomechanics associated with meaningful changes in comfort from the control condition. Paired sample t-tests compared biomechanical parameters from the RunScribe between comfort classifications.

Results: Similar numbers of individuals reported 'more' and 'less' comfort across conditions. There were only significant reductions in braking shock when individuals reported meaningfully 'less comfort'. The primary result from meaningful change thresholds for biomechanics was meaningful increases in impact shock when comfort was both 'more' and 'less'.

Discussion: The measurement approach enabled identification of comfort changes, and underpinning biomechanical differences during one day of wear of insoles. Impact shock was the main contributor to comfort perception, consistent with previous literature. Highlighting impact shock as a potential variable for assessment of interventions in pathological study.