Menz et al. BMC Geriatrics (2017) 17:212 DOI 10.1186/s12877-017-0613-2 RESEARCH ARTICLE Open Access Preliminary evaluation of prototype footwear and insoles to optimise balance and gait in older people Hylton B. Menz1,2*, Maria Auhl1 and Shannon E. Munteanu1,2 Abstract Background: Footwear has the potential to influence balance in either a detrimental or beneficial manner, and is therefore an important consideration in relation to falls prevention. The objective of this study was to evaluate balance ability and gait patterns in older women while wearing prototype footwear and insoles designed to improve balance. Methods: Older women (n = 30) aged 65 – 83 years (mean 74.4, SD 5.6) performed a series of laboratory tests of balance ability (postural sway on a foam rubber mat, limits of stability and tandem walking, measured with the Neurocom® Balance Master) and gait patterns (walking speed, cadence, step length and step width at preferred speed, measured with the GAITRite® walkway) while wearing (i) flexible footwear (Dunlop Volley™), (ii) their own footwear, and (iii) prototype footwear and insoles designed to improve dynamic balance. Perceptions of the footwear were also documented using a structured questionnaire. Results: There was no difference in postural sway, limits of stability or gait patterns between the footwear conditions. However, when performing the tandem walking test, there was a significant reduction in step width and end sway when wearing the prototype footwear compared to both the flexible footwear and participants’ own footwear. Participants perceived their own footwear to be more attractive, comfortable, well-fitted and easier to put on and off compared to the prototype footwear. Despite this, most participants (n = 18, 60%) reported that they would consider wearing the prototype footwear to reduce their risk of falling. Conclusion: The prototype footwear and insoles used in this study improve balance when performing a tandem walk test, as evidenced by a narrower step width and decreased sway at completion of the task. However, further development of the design is required to make the footwear acceptable to older women from the perspective of aesthetics and comfort. Trial registration: Australian New Zealand Clinical Trials Registry. ACTRN12617001128381, 01/08/2017 (retrospectively registered). Keywords: Ageing, Falls, Postural balance, Footwear * Correspondence: [email protected] 1Discipline of Podiatry, School of Allied Health, College of Science, Health and Engineering, La Trobe University, Bundoora, Victoria 3086, Australia 2La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria 3086, Australia © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Menz et al. BMC Geriatrics (2017) 17:212 Page 2 of 8 Background Footwear conditions Falls in older people are a major public health problem Participants performed each of the balance and gait as- [1]. By modifying the interface between the body and the sessments under three footwear conditions: (i) flexible environment during weightbearing activities, footwear has footwear, (ii) their own footwear, and (iii) the prototype the potential to influence balance in either a detrimental footwear and insoles. For the flexible and prototype foot- or beneficial manner, and is therefore an important con- wear, appropriate sizing was determined using the sideration in relation to falls prevention. Several Brannock device® [17]. The order of testing was rando- laboratory-based studies have demonstrated that elevated mised to avoid order effects. heels [2–4] and thick, soft soles [3–5] are detrimental to The flexible footwear (Dunlop Volley™, Pacific Brands, balance, while footwear with high collars [3, 6–9] and firm Australia) had a rubber sole of uniform 18 mm thick- soles [4, 7, 8] are beneficial. Prospective studies have also ness, a hardness of Shore A 35 [18], and lace fixation. shown that wearing shoes with slippery soles [10], high Across the size range, the weight of the flexible footwear heels [11, 12] and reduced sole contact area [12] increase was 280 – 420 g. The flexible footwear was selected as a the risk of falls in older people. This is of particular con- control condition as it had no features considered to be cern for older women, as many styles of female footwear either beneficial or detrimental to balance and could incorporate these potentially hazardous features. therefore be considered a ‘minimalist’ style of shoe [19]. In response to these observations, it has been sug- For the ‘own footwear’ condition, participants were gested that the ideal safe shoe for older people at risk of asked to bring to the testing session the footwear they falling should have a low, broad heel, a thin, firm mid- wore most often when outdoors. The characteristics of sole, a high collar and a textured, slip-resistant outersole the footwear were assessed and documented using [13, 14]. However, although this recommendation is a selected items from the Footwear Assessment Tool [20]. valid summary of the available literature, very few com- The prototype footwear was based on an existing mercially available footwear styles incorporate all of model and was manufactured by Dr. Comfort® Footwear these features, particularly with regard to female foot- (Mequon, WI, USA). The base model (the ‘Vigor’)was wear. Furthermore, in order for such a recommendation selected as it incorporates many of the features previ- to be widely adopted, such footwear needs to be accept- ously shown to be beneficial for balance. Specifically, the able to older people from the perspective of comfort, footwear had a firm (Shore A hardness 55 [18]) rubber ease of use and aesthetics [15]. Therefore, the objectives sole of 25 mm thickness under the heel and 18 mm of this study were to (i) evaluate balance ability and gait under the forefoot, laces plus Velcro® fastening, a high patterns in older women while wearing prototype foot- collar to support the ankle, and a firm heel counter. wear and insoles designed to improve balance, and (ii) Across the size range, the weight of the prototype foot- investigate older womens’ perceptions of the footwear. wear was 310 – 360 g. To create the prototype, the out- ersole was modified to optimise slip resistance by grinding a 10 degree bevel into the heel region [21, 22], Methods placing grooves perpendicular to the sole (1.2 mm deep Participants and assessments and 2.4 mm wide) across the heel surface area [23], and This study was conducted alongside an investigation into placing perpendicular grooves (5 mm deep and 12 mm the effects of indoor footwear on balance in community- wide) across the rest of the sole [24, 25]. A textured in- dwelling older women [16]. These studies evaluated the sole was also constructed from 4 mm thick ethyl vinyl same participants but laboratory testing was performed acetate (Shore A 25 [18]) with dome-shaped projections on two different occasions (one session for indoor foot- (3 mm high and 8 mm diameter, Shore A 85 [18]) placed wear and one session for outdoor footwear). Full details across the forefoot in a 15 mm diamond pattern and of the methods, including participant eligibility, ques- along the lateral border, extending to the heel. The tionnaires, clinical, falls risk, balance and gait assess- design of the textured insole was informed by previous ments and perceptions of footwear have been published studies reporting improvements on balance in older [16]. Apart from the footwear conditions assessed, the people when similar insoles were worn [26, 27]. Figure 2 only other methodological difference between the two shows key features of the prototype footwear. studies was that balance testing in the current study was performed when standing on a foam rubber mat rather Statistical analysis than on the floor. The balance testing protocol is shown Statistical analysis was undertaken using SPSS Version in Fig. 1. Ethical approval was granted from the La 22.0 (IBM, Armonk, NY, USA). Participants who had Trobe University Faculty of Health Sciences Human Eth- missing data because they were unable to complete the ics Committee (Reference FHEC14/254), and written in- task were given the ‘worst’ score of the remaining sam- formed consent was obtained from all participants. ple. Differences between the three footwear conditions Menz et al. BMC Geriatrics (2017) 17:212 Page 3 of 8 Fig. 1 Balance testing protocol using the NeuroCom Balance Master™ (flexible footwear, participants’ own footwear, and proto- Results type footwear) were evaluated using repeated measures Participant characteristics analysis of variance (ANOVA) with Bonferroni-adjusted Participant characteristics are shown in Table 1, and post-hoc tests for pairwise comparisons. The effect sizes characteristics of participants’ own footwear are shown in for all significant main effects were calculated using the Table 2. Two participants had missing data for the tandem eta-squared statistic (η2) and were interpreted using the walking test (due to an inability to complete the test) and following cut-offs: 0 – 0.06 (small), >0.06 – 0.14 were given the ‘worst’ score of the remaining sample. (medium) and >0.14 (large) [28]. Differences in percep- tions of participants’ own footwear versus the prototype Effects of footwear on balance footwear were evaluated using paired t-tests. Level of Results of the repeated measures ANOVAs for the significance was set at 0.05. balance tests are shown in Table 3.