Development and evaluation of a dual density insole for people standing for long periods of time at work

Abstract

Background: Appropriate footwear is important for those who stand for prolonged periods of time at work, enabling them to remain comfortable, healthy and safe. Preferences for different footwear cushioning or hardness are often person specific and one shoe or insole will not be the choice for all. The aim of this study was to develop a range of insole options to maintain comfort during long periods of standing at work and test insole material preferences in the workplace. Methods: The study consisted of two parts. Part one evaluated 9 insoles of the same geometry that varied in hardness under 2 different plantar regions (n = 34). Insole preference, plantar pressure and selected anthropometric foot measures were taken. Three insole designs based on the most preferred options were identified from this part. In part two, these three insoles were evaluated with 22 workers immediately after trying them on (1 min) and after a working day. Foot anthropometric measures and subjective questions concerning material hardness preferences and self-reported foot characteristics were used to investigate whether either had a relationship with insole preference. Results: Part one found insole preference predominantly varied according to material hardness under the medial arch rather than the heel/forefoot. Softer material under the heel and forefoot was associated with a reduction in peak pressures in these regions (p < 0.05). The most preferred insole had lower pressures under the hallux and first metatarsal phalangeal joint, and greater pressures and contact area under the medial midfoot (p < 0.05) compared to the least preferred insole. Height and foot anthropometrics were related to insole preference. In part two, under real world conditions, insole preference changed for 65% of participants between the immediate assessment (1 min) and after a whole workday, with dorsum height related to the latter (p < 0.05). Subjective questions for self-assessed arch height and footwear feel identified 66.7% of the insole preferences after 1 day at work, compared to 36% using immediate assessment of insole preference. Conclusion: Preference for material hardness varies underneath the medial arch of the foot and is time dependent. Simple foot measures and questions about comfort can guide selection of preferred insoles.

Insoles of uniform softer material reduced plantar pressure compared to dual-material insoles during regular and loaded gait

“…More dynamic conditions that increase forefoot plantar loading could reveal differences in perceived comfort, such as running (Yang et al, 2019;Hennig et al, 1996), fatigue (Biseaux and Moretti, 2008), faster walking (Burnfield et al, 2004;Castro et al, 2015) or a greater load (Pau et al, 2015). In addition, insole materials which further increase to the relative midfoot contact area and pressure may also be subjectively perceived as more comfortable (Anderson et al, 2020;Wintana et al, 2009).…”

“…However, the effect might reduce over prolonged use, whilst alternative elastomers may retain their properties for longer (Saraswathy et al, 2009). Perceived comfort also changes over a longer wear time due to both material insole and foot properties (Anderson et al, 2020).…”

Footwear comfort: a systematic search and narrative synthesis of the literature

“…Four studies have evaluated associations between foot characteristics and comfort, specifically addressing foot alignment [ 14 , 78 , 104 ] and tactile sensitivity [ 81 ]. In relation to arch height, Zifchock et al [ 104 ] compared comfort ratings while wearing custom and semi-custom orthoses, and found that participants with high arches reported greater arch and heel comfort in the semi-custom device which provided less rearfoot control when walking, while Anderson et al [ 14 ] assessed perceptions of nine different insoles which varied according to the hardness of the heel, midfoot and forefoot in participants working in occupations that require prolonged standing, and found that those with lower arched feet preferred insoles with harder material in the midfoot. Miller et al [ 78 ] compared comfort perceptions when walking and running in three shoes that varied in relation to stiffness, cushioning and shape, and found that heel eversion angle was negatively associated with comfort in the stiffer, harder soled shoe.…”

Ergonomic evaluation and field validation of the insole padding system

“…Thus, a redesign of the arch pad shape according to the anthropometric data and foot features of the target population is one of the possible ways to improve discomfort in the arch and midfoot area. In addition, the overall preference may be affected by many factors, such as movement, fit, and density (Anderson et al, 2020; Wang et al, 2020). This might explain the slight discomfort in the arch and midfoot area, although the IPS had the highest overall preference rating.…”