Elsevier

Gait & Posture

Volume 41, Issue 2, February 2015, Pages 465-469
Gait & Posture

Foot posture, range of motion and plantar pressure characteristics in obese and non-obese individuals

https://doi.org/10.1016/j.gaitpost.2014.11.010Get rights and content

Highlights

  • Obese individuals exhibited flatter feet, reduced inversion–eversion range of motion, and higher peak plantar pressures.

  • Body weight is independently associated with plantar loading after accounting for foot characteristics.

  • Clinicians dealing with foot problems should consider the effect of increased bodyweight on plantar loading in obese patients.

Abstract

Obesity is a world-wide health problem and is strongly associated with musculoskeletal disorders of the lower limb. The aim of this study was to evaluate plantar loading patterns in obese and non-obese individuals, while accounting for the contribution of foot structure, range of motion and walking speed. Sixty-eight participants (mean ± SD age, 52.6 ± 8.0 years), including 47 females (69%), underwent assessments of body mass index, foot pain and foot structure. Plantar pressures were also obtained, using a floor-mounted resistive sensor mat system. Multiple regression analysis was used to determine which variables were most strongly associated with plantar loading patterns. Obese individuals exhibited flatter feet, reduced inversion–eversion range of motion, and higher peak plantar pressures when walking. After accounting for foot structure and walking speed, bodyweight was found to be significantly associated with elevated loading of the foot, particularly the forefoot and midfoot. These findings suggest that obesity increases the stresses applied to the foot directly, via increased bodyweight, and indirectly, via alterations to foot structure, which may partly explain the link between obesity and the development of foot pain. Clinicians dealing with foot problems should consider the effect of increased bodyweight on plantar loading in obese patients.

Introduction

Obesity is a world-wide health problem, and its prevalence is increasing in both developed and developing countries [1]. Previous estimates suggest that there are over 300 million people world-wide who are obese [2]. It is now well established that obesity is associated with diabetes and cardiovascular disease, however obesity is also associated with musculoskeletal disorders affecting the lower limb, such as knee and hip osteoarthritis [3]. More recent investigation has also found that the foot is not immune to the effects of obesity, with a recent systematic review of 25 studies involving 93,224 participants concluding that obesity is strongly associated with non-specific foot pain in the general population [4].

A possible explanation for the relationship between obesity and foot pain is that excess bodyweight leads to greater mechanical loading of the foot. Indeed, a link between increased force and pressure under the foot and obesity has been reported [5]. However, plantar loading patterns are affected by more than just weight. For example, variations in foot posture, joint range of motion and walking speed are also known to influence plantar loading patterns [6], [7].

Accordingly, because obesity is associated with changes in foot structure [8] and walking speed [7], it is important to take these factors into account when comparing plantar pressures in obese versus non-obese individuals. Therefore, the aim of this study was to evaluate plantar loading patterns in obese and non-obese individuals, while accounting for the contribution of foot structure and walking speed. In doing so, our objective was to provide additional insights into foot function in people that are obese, and to explore the specific anatomical regions of the foot that may be subjected to increased plantar pressure in this population. We hypothesised that both bodyweight and foot structure would influence plantar loading patterns.

Section snippets

Participants

Sixty-eight participants from a previous study [9] that assessed the relationship between obesity and musculoskeletal disease were invited to participate – all 68 agreed to participate in the present study. The aim of the previous study was to examine the relationship between body composition and foot pain, in a population ranging from healthy to obese. Initial recruitment, inclusion and exclusion criteria have been previously published [9]. The study was approved by the Alfred Health Human

Results

Sixty-eight participants completed the study (mean ± SD age, 52.6 ± 8.0 years), including 47 (69%) females. BMI ranged from underweight to morbidly obese (range, 17.6 kg/m2 to 48.1 kg/m2). There were 34 (50%) participants who had foot pain according to the MFPDI. Participant characteristics are shown in Table 1.

Discussion

The aim of this study was to examine plantar loading characteristics underneath the feet of obese adults during normal walking, while accounting for foot structure and walking speed. Our findings indicate that obese adults were more likely to have foot pain, a relatively pronated foot posture (assessed using the FPI), flatter feet (assessed using the AI), reduced ankle inversion–eversion range of motion and increased plantar loading under the foot. When the total sample was included in a

Conflicts of interest

There are no conflicts of interest to disclose.

Acknowledgements

This study was supported by the National Health and Medical Research Council (Project Grant 384233), Monash University, Shepherd Foundation, and Royal Australasian College of Physicians. Mr. Butterworth is funded by an Australian Postgraduate Award. Dr Urquhart is supported by an NHMRC Career Development Fellowship (1011975). Professor Menz is a National Health and Medical Research Council Senior Research Fellow (1020925). Associate Professor Wluka is supported by an NHMRC Career Development

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