Elsevier

Gait & Posture

Volume 39, Issue 1, January 2014, Pages 247-251
Gait & Posture

Effects of shoe sole hardness on plantar pressure and comfort in older people with forefoot pain

https://doi.org/10.1016/j.gaitpost.2013.07.116Get rights and content

Highlights

  • We assessed plantar pressures and comfort in shoes with soft, medium and hard soles.

  • Peak plantar pressures when walking increased as sole hardness increased.

  • No significant differences in comfort were found across the three shoes.

Abstract

Plantar forefoot pain is common in older people and is related to increased peak pressures under the foot during gait. Variations in the hardness of the shoe sole may therefore influence both the magnitude of loading under the foot and the perceived comfort of the shoe in this population. The aim of this investigation was to determine the effect of varying shoe sole hardness on plantar pressures and comfort in older people with forefoot pain. In-shoe plantar pressures under the forefoot, midfoot and rearfoot were recorded from 35 older people (mean age 73.2, SD 4.5 years) with current or previous forefoot pain using the pedar-X® system. Participants walked at their normal comfortable speed along an 8 m walkway in shoes with three different levels of sole hardness: soft (Shore A25), medium (Shore A40) and hard (Shore A58). Shoe comfort was measured on a 100 mm visual analogue scale. There were statistically significant differences in peak pressure of between 5% and 23% across the forefoot, midfoot and rearfoot (p < 0.01). The hard-soled shoe registered the highest peak pressures and the soft-soled shoe the lowest peak pressures. However, no differences in comfort scores across the three shoe conditions were observed. These findings demonstrate that as shoe sole hardness increases, plantar pressure increases, however this does not appear to have a significant effect on shoe comfort.

Introduction

Plantar forefoot pain, often referred to as metatarsalgia, is a common problem in older people, affecting at least one in four people aged over 65 years of age [1], [2]. A wide range of conditions may lead to forefoot pain, including interdigital neuroma, interdigital bursitis, tendon pathology or tears of the plantar plate [3]. Irrespective of the underlying pathology, two studies have shown that pressures under the forefoot are increased in older people with forefoot pain. In a sample of 100 people with hallux valgus, Waldecker [4] reported higher peak pressure and pressure-time integrals under the lateral forefoot in those with forefoot pain. More recently, Menz et al. [5] reported that older people with forefoot pain exhibited significantly greater peak pressure under the 3rd to 5th metatarsal heads compared to those without forefoot symptoms.

The hardness of the sole of the shoe is likely to influence the magnitude of loading under the foot when walking and the perceived comfort of the shoe, and is therefore an important consideration in older people with forefoot pain. Although previous studies have examined the pressure-relieving properties of different types of shoes in athletes [6], military personnel [7], people with diabetes [8], [9] and people with rheumatoid arthritis [10], none have evaluated older people with forefoot pain. Furthermore, previous studies have not controlled for other shoe design features, so the observed differences in plantar pressures cannot be exclusively attributed to the hardness of the sole.

Understanding the relationship between shoe sole hardness, plantar pressure and shoe comfort in older people with forefoot pain may assist in the optimum selection of shoes to alleviate pain in this population. Therefore, the aim of this study was to examine differences in in-shoe plantar pressures and perceived shoe comfort in older people with forefoot pain, using specifically manufactured test shoes that differed only by sole hardness. We hypothesised that increasing sole hardness would result in increased plantar pressures and a corresponding decrease in the perceived comfort of the shoe.

Section snippets

Participants

Thirty-seven participants were recruited from a larger randomised controlled trial [11]. To be included in the study, participants needed to be: (i) community-dwelling, (ii) aged 65 years and over, and (iii) report current or previous forefoot pain (defined as a positive response to the question “Do you have/have you ever had pain in the ball of your foot?”). Participants were excluded from the study if they: (i) were unable to walk household distances (10 m) without the use of a walking aid,

Participant characteristics

Thirty-five participants (29 women and 6 men) with a mean age of 73.2 (SD 4.5) years and mean body mass index of 29.3 (SD 4.2) kg/m2 participated in the study and provided data for the final analysis (see Table 1).

Contact time

There was no significant difference for whole foot contact time (soft-soled 698.0 [67.0], medium-soled 697.5 [60.4] and hard-soled 702.6 [63.3] ms; F2, 33 = 1.78, p = 0.185) indicating that the participants walked at a consistent speed for all conditions. Therefore, any plantar pressure

Discussion

The aim of this study was to evaluate the effect of shoe sole hardness on plantar pressure and comfort in older people with forefoot pain. As we hypothesised, the results indicate that as sole hardness increased, there was a corresponding increase in peak pressure under the heel, midfoot and forefoot. Specifically, the hard-soled shoes registered higher peak pressure than the medium-soled shoes, which in turn, registered higher peak pressures than the soft-soled shoes. However, in contrast to

Conclusion

The findings of this study indicate that as shoe sole hardness increases, there is a corresponding increase in peak plantar pressure. However, this appears to have only a minor effect on overall shoe comfort in older people with forefoot pain. This suggests that clinicians may be able to recommend harder-soled shoes to older people at risk of falling without concern that they will find them uncomfortable, although the longer term effects of the increased pressures associated with harder soles

Conflicts of interest statement

All authors declare that there are no known conflicts of interest related to this project that may have influenced this manuscript.

Acknowledgements

HBM is currently a National Health and Medical Research Council Senior Research Fellow (ID: 1020925).

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