Although rapid manufacturing has potential in producing personalised footwear, it is not known how best to measure feet in this context nor even whether a personalised shoe can positively affect comfort, performance and prevent risk from injury. A pilot study was conducted to define anthropometric measurement techniques for specifying personalised footwear and evaluate the most effective methods of measuring discomfort, performance and injury risk. Recreational runners were recruited and had anthropometric measurements taken as well as the plantar surface of both feet scanned. Participants then were fitted with footwear under two experimental conditions: control and personalised insole. The footwear were compared in terms of discomfort ratings, performance and injury risks. Metatarsophalangeal joint height and hallux height showed positive correlations (p< 0.05) with discomfort scores in the forefoot, whereas relative arch deformation showed significant positive correlations (p<0.05) with discomfort scores in the midfoot and arch areas. No significant differences were found between the two conditions for discomfort scores and performance. With regard to injury
risks, significant differences (p<0.05) were found between the two conditions for
midfoot peak plantar pressure. The results suggest that producing personalised insoles
from scan data and the rapid manufacturing process is feasibl

Andre S. Salles (7149296)

Diane Gyi (1247568)

English

Loughborough University Institutional Repository

   This item was submitted to Loughborough’s Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.      For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/  Submitted to 5th World Conference on Mass Customization & Personalization MCPC2009 1The specification of personalisedfootwear for rapid manufacturing: a pilotstudyAndré S. SallesLoughborough University, UK.a.s.salles@lboro.ac.ukDiane E. GyiLoughborough University, UK.Abstract. Although rapid manufacturing has potential in producing personalisedfootwear, it is not known how best to measure feet in this context nor even whether apersonalised shoe can positively affect comfort, performance and prevent risk frominjury. A pilot study was conducted to define anthropometric measurement techniquesfor specifying personalised footwear and evaluate the most effective methods ofmeasuring discomfort, performance and injury risk. Recreational runners were recruitedand had anthropometric measurements taken as well as the plantar surface of both feetscanned. Participants then were fitted with footwear under two experimental conditions:control and personalised insole. The footwear were compared in terms of discomfortratings, performance and injury risks. Metatarsophalangeal joint height and hallux heightshowed positive correlations (p ? 0.05) with discomfort scores in the forefoot, whereasrelative arch deformation showed significant positive correlations (p ? 0.05) withdiscomfort scores in the midfoot and arch areas. No significant differences were foundbetween the two conditions for discomfort scores and performance. With regard to injuryrisks, significant differences (p ? 0.05) were found between the two conditions formidfoot peak plantar pressure. The results suggest that producing personalised insolesfrom scan data and the rapid manufacturing process is feasible.Keywords. Footwear, Anthropometry, Rapid Manufacturing.Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 21. IntroductionRapid manufacturing (RM) works without any tooling and therefore cansignificantly reduce unit costs because they can be produced near the location theywill be used, minimizing transportation and stock space (Hopkinson and Dickens,2001). In addition, the fact that RM can produce unique elements with geometricfreedom allows the industry to provide low production volumes or personalisedproducts economically feasible such as footwear to the final customer.Footwear is the most important accessory for a runner. Despite aestheticoptions becoming available on the market, personalisation of the footwear ispotentially beneficial for individuals because of the following: (1) ‘perfect fit’could be achieved; (2) the preferences in terms of comfort can be met; (3) thepersonal requirements for reducing the injury risks can be provided (e.g. amount ofcushioning needed by each individual); and (4) personalised footwear could also beimportant for improving performance.In order to specify personalised footwear that is optimal to the individual, it isimportant to bear in mind that foot shape plays an important role in thedevelopment of many types of injury (James et al., 1978; McKenzie et al., 1985).Low arched (LA) individuals usually have more spread of plantar pressure and arespeculated to have more discomfort because of the lack of arch (Cheng and Perng,1999). The high arched (HA) foot is characterized by the longitudinal arch beingmore rigid and not so flexible, which makes it less efficient at absorbing impactshocks (Cavanagh, 1980; McKenzie et al., 1985).Although it appears that arch height is a crucial measurement that cancategorize individuals, other measurements can also be important in determiningindividual preferences/needs, including instep girth, bottom width, heel height, toebox space and so on (Goonetilleke et al., 1997; Cheng and Perng, 1999; Witana etal., 2004). Hence, it is not known how best to measure feet in this context noreven whether a personalised running shoe can positively (or not) affectperformance, comfort and injury risk in comparison to the generic ones currentlyavailable on the market.A pilot study was conducted in order to investigate the important measurementtechniques for specifying such personalised footwear. The aims of the study were:(1) to define anthropometric measurement techniques for specifying personalisedfootwear; (2) to evaluate the most effective methods of measuring discomfort,performance and injury risk. The data and the findings of the study will bepresented in this paper.Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 32. MethodSix recreational runners (3 males and 3 females) were recruited (age 30.5 yrs, ±3.9; mass 65.25 kg, ± 16.5; height 165.8 cm, ± 12.8). A repeated measuresexperimental design was utilized and participants were recruited using conveniencesampling and snowballing techniques.2.1. Foot measurementsDetailed anthropometric measurements were taken following Hawes and Sovak(1994), to capture dimensional aspects of the foot. The 16 measurements includedgirths, lengths, widths and heights. Additional anthropometric data was alsocollected as described by Williams and McClay (2000). Arch ratio, arch index andrelative arch deformation (RAD) were calculated from these measures followingWilliams and McClay (2000).Moreover, individuals had the plantar surface of their both feet scanned in a nonweight bearing position, using a 3 dimensional laser scanner (Model: 200; 3DDigital Corporation, Newtown, USA).2.2. Experimental conditionsOnce the scan data were taken, they were manipulated and personalised insoles fortrainers were manufactured from the scans using polyamide and utilizing selectivelaser sintering, a RM technique. The insoles were designed to match the form ofthe participants’ feet like a glove, but not to provide correction of the lower limbabnormalities. Two conditions, control (standard shoe) and personalised (shoe +personalised insole), were compared through single blind trials.2.3. Performance, discomfort and injury risks assessmentsRunning economy was used to measure performance. Participants were asked towear one of the two running shoe conditions (randomly assigned) and run on atreadmill for 6 minutes in each condition. Expired air was collected using anUltima CardiO2 (Medical Graphics Corporation, St Paul, USA) equipment.At the end of each run on the treadmill for the running economy trial,participants were given a 150 mm Visual Analog Scale (VAS) to measure self-perceived discomfort (Mundermann et al., 2002). Six aspects of the foot wereevaluated: heel, midfoot, forefoot, fit, arch height and overall. A 7-point (‘hot’ to‘cold’) thermal sensation scale was also used as described by the InternationalOrganization for Standardization (ISO 7730, 1994) to assess thermal comfort.An F-Scan Mobile (Tekscan Inc, USA) in-shoe plantar pressure distributionsensor (N/cm2) was placed in the shoe. The participants were asked to run for 5Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 4times under each condition (control and personalised) for 10 meters whilst theirplantar pressure distribution was recorded.Furthermore, participants were asked to run for 5 times under eachexperimental condition, while the Vicon MX system (250Hz; Oxford Metrics,Oxford, UK) was used to collect data. Ground reaction force was also recorded(50Hz; Type: 9281; Kistler Instrumente AG, Winterhur, Switzerland).The variables chosen to evaluate the injury risks were: peak plantar pressure,rearfoot eversion, tibial rotation and peak vertical impact forces. These variablesallowed to assess the angles of the ankle joint, pressure and force applied on theground.3. ResultsAnthropometric measures were within the range of the normal distribution of thepopulation (Hawes and Sovak, 1994).Metatarsophalangeal joint height (MPJH) showed significant (p ? 0.05) positivecorrelations with discomfort scores in the midfoot (r = 0.918) for the controlcondition and with discomfort scores in the forefoot (r = 0.824) and overalldiscomfort (r = 0.872) for the personalised condition. Hallux height showedpositive correlation with discomfort scores in the forefoot (r = 0.896) and overalldiscomfort (r = 0.836) for the personalised condition. No other significantcorrelations were found between anthropometric measurements and thediscomfort, performance and injury risk variables. There were also no significantcorrelations between arch ratio and arch index and these variables. However, RADshowed significant positive correlations (p ? 0.05) with discomfort scores in themidfoot (r = 0.910 for the control condition and r = 0.926 for the personalisedcondition), in the arch (r = 0.930 for the control condition and r = 0.906 for thepersonalised condition), and fit (r = 0.757 for the control condition and r = 0.861for the personalised condition) aspects.Student’s t-test showed no significant differences between the two conditionsfor discomfort scores. The mean ratings for foot discomfort are illustrated inFigure 1.051015Overall Forefoot Midfoot Heel Arch FitDiscomfort Rating ControlPersonalisedSalles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 5Figure 1. Mean discomfort ratings and standard error for the control and personalised conditions.No significant differences were found for peak plantar pressure under the heeland forefoot areas. The t-tests revealed significant differences for peak plantarpressure under the midfoot (p ? 0.05) between the two conditions.No statistical differences were found between the two conditions for tibialinternal rotation, rearfoot pronation and impact peak force (Table 1).Table 1. Biomechanical data.Variable Control conditionmean ± SDPersonalised condition mean± SDpRearfoot eversion (°) 2.92 ± 0.62 2.64 ± 0.97 0.374Tibial internal rotation (°) 13.4 ±  3.85 13.55 ±  3.38 0.771Vertical impact peak (bw) 1.3 ± 0.36 1.16 ± 0.23 0.381Student’s t-test showed no significant differences between the two conditionsfor the VO2 consumption (25.762 mL/kg/min, ± 5.359 for the control conditionand 26.379 mL/kg/min, ± 4.98 for the personalised condition).4. DiscussionThe research presented was a pilot study, therefore only six individuals wererecruited. This must be borne in mind when interpreting the results and thus, it wasexpected that there would be inconsistencies with the literature.Discomfort ratings were low and no significant differences were found betweenthe two conditions. This lack of significance is not consistent with the literature.For instance, Mundermann et al. (2003) reported that a molded orthotic, was morecomfortable in comparison to posting orthotics and nonmolded control conditions.In addition, Yung-Hui and Wei-Hsien (2005) showed that total contact inserts areeffective in reducing discomfort when wearing high-heeled shoes. This absence ofagreement could be anticipated due to the small sample size and the short periodof time that the insoles were worn (6 minutes) in the current study.With regard to the plantar pressure distribution, there were similarities with theliterature. Although peak pressure in the heel region was not significantly differentin the two experimental conditions, the midfoot area was significantly greater forthe personalised condition in comparison to the control. There was also a trend forhigher peak pressure (p = 0.073) in the forefoot region for the control condition.Studies have documented that total contact inserts significantly reduced peakplantar pressure in the metatarsal and heel regions and redistribute pressure to themidfoot area, in comparison to a flat insert (Chen et al., 2003; Yung-Hui and Wei-Hsien, 2005).The anthropometric measurements, arch index and arch ratio did not correlatesignificantly with: discomfort ratings, peak plantar pressure, vertical impact peak,Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 6tibial rotation and rearfoot eversion. Similarly, other studies did not find anycorrelation between arch height and running injuries (Nigg et al., 1993; Wen et al.,1997; Hreljac et al., 2000). On the other hand, Williams III et al. (2001) reportedthat LA individuals have increased rearfoot eversion excursion in comparison toHA runners. A possible explanation for this is the fact that Williams III et al.(2001) compared HA and LA runners, rather than analyse the correlation betweenarch height and injury risks. The pilot study sample was within the range of thenormal distribution of the population and as such, no LA or HA runners wererecruited. The of correlation of the anthropometric measurements MPJH, halluxheight and RAD with discomfort ratings may indicate what types of individuals(e.g. with stiff arches) can have more discomfort wearing the insoles. However,more evidence is needed to confirm or reject these correlations.The literature reports a positive correlation between arch stiffness and tibialrotation (Nigg et al., 1998), however as expected due to the small sample size, thatwas not found in the pilot study. Furthermore, individuals with stiff arches arethought to be poor shock absorbers in comparison to people with flexible feet(Butler et al., 2007), which would influence the vertical impact peak values. In thesame manner as the arch height data, the results suggest that more evidence isneeded to confirm or reject a relationship between impact peak and arch stiffness.The pilot study had limitations (i.e. the short running time on the treadmill andthe  small sample size). It also believed that the performance results may not bereliable. For practical reasons, performance tests were not duplicated to reducewithin subject variations (Williams et al., 1991). Furthermore, many variables mustbe controlled (e.g. time of the day) in order to get reliable running economy dataand differences proved difficult to be found. Nevertheless, the peak plantarpressure distribution, discomfort assessments and the anthropometricmeasurements showed promise for future studies.With regard to the rapid manufacturing, the process of capturing the plantarsurface of the foot, manipulating and manufacturing worked well. The positiveattributes of polyamide, were that the insoles did not show signs of breaking anddid not cause significant discomfort (compared to the control condition). This pilotwork is the pre-cursor for a longitudinal study involving a broader sample of thepopulation and which will commence in 2009.5. ConclusionThe anthropometric measurements MPJH, hallux height and RAD showedpotential in determining which individuals might develop discomfort wearing theglove fit personalised insoles. Similarly, the injury risks assessments indicatedpotential in identifying possible benefits of such insoles. On the other hand, theperformance test proved to be difficult to find differences.Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 7AcknowledgementsWe would like to acknowledge the IMCRC at Loughborough University who provided fundingfor this research and New Balance for providing the running shoes used in the study.ReferencesButler, R.J., Hamill, J., and Davis, I. (2007). “Effect of footwear on high and low arched runners’mechanics during a prolonged run.” Gait and Posture, vol. 26, 219-225.Cavanagh, P.R. (1980). The Running Shoe Book. Anderson World, Mountain View, California.Chen, W.P., Ju, C.W., and Tang, F.T. (2003). “Effects of total contact insoles on the plantarstress redistribution: a finite element analysis.”Clinical Biomechanics,  vol. 18, S17-S24.Cheng, F.T., and Perng, D.B. (1999). “A systematic approach for developing a foot sizeinformation system for shoe last design.”International Journal of Industrial Ergonomics,vol. 25, 171-185.Goonetilleke, R.S., Ho, E.C.F., and So, R.H.Y. (1997). Foot anthropometry in Hong Kong.Proceedings of the ASEAN 97 Conference, pp. 81-88, Kuala Lumpur, Malaysia.Hawes, M.R., and Sovak, D. (1994). “Quantitative morphology of the human foot in a NorthAmerican population.”Ergonomics, vol. 37, no. 7,  1213-1226.Hopkinson, N., and Dickens, P. (2001). “Rapid prototyping for direct manufacture.” RapidPrototyping Journal, vol. 7, no. 4, 197-202.Hreljac, A., Marshall, R.N., and Hume, P.A. (2000). “Evaluation of lower extremity overuseinjury potential in runners.”Medicine and Science in Sports and Exercise, vol. 32, no. 9,1635-1641.ISO 7730. (1994). Moderate Thermal Environments — Determination of the PMV and PPDindices and specification of the conditions for thermal comfort. International standard,International Organization Standardization, Geneva.James, S.L., Bates, B.T., and Osternig, L.R. (1978). “Injuries to runners.”The American Journalof Sports Medicine, vol. 6, no. 2, 40-50.McKenzie, D.C., Clement, D.B., and Tauton, J.E. (1985). “Running shoes, orthotics andinjuries.”Sports Medicine, vol. 2, 334-347.Mundermann, A., Nigg, B.M., Stefanyshyn, D.J., and Humble, R.N. (2002). “Development of areliable method to assess footwear comfort during running.”Gait and Posture, vol. 16, 38-45.Mundermann, A., Nigg, B.M, Humble, R.N., and Stefanyshyn, D.J. (2003). “Orthotic comfort isrelated to kinematics, kinetics and EMG in recreational runners.”Medicine and Science inSports and Exercise, vol. 35, no. 10, 1710-1719.Nigg, B.M., Cole, G.K., and Nachbauer, W. (1993). “Effects of arch height of the foot on angularmotion of the lower extremities in running.”Journal of Biomechanics, vol. 26, no. 8, 909-916.Nigg, B.M., Khan, A., Fisher, V., and Stefanyshyn, D. (1998). “Effect of shoe insert constructionon foot and leg movement.”Medicine and Science in Sports and Exercise, vol. 30, no. 4,550-555.Wen, D.Y., Puffer, J.C., and Schmalzried, T.P. (1997). “Lower extremity alignment and risk ofoveruse injuries in runners.”Medicine and Science in Sports and Exercise, vol. 29, no. 10,1291-1298.Salles and Gyi: The specification of personalised footwear for rapid manufacturing: a pilot studySubmitted to 5th World Conference on Mass Customization & Personalization MCPC2009 8Williams, T.J., Krahenbuhl, G.S., and Morgan, D.W. (1991). “Daily variation in runningeconomy of moderately trained male runners.” Medicine and Science in Sports andExercise, vol. 23, no. 8, 944-948.Williams, D.S., and McClay, I.S. (2000). “Measurements used to characterize the foot and themedial longitudinal arch: reliability and validity.”Physical Therapy, vol. 80, no. 9, 864-871.Williams III, D.S., McClay, I.S., Hamill, J., and Buchanan, T.S. (2001). “Lower extremitykinematic and kinetic differences in runners with high and low arches.”Journal of AppliedBiomechanics, vol. 17, 153-163.Witana, C.P., Feng, J., and Goonetilleke, R.S. (2004). “Dimensional differences for evaluatingthe quality of footwear fit.”Ergonomics, vol. 47, no. 12, 1301-1317.Yung-Hui, L., and Wei-Hsien, H. (2005). “Effects of shoe inserts and heel height on footpressure, impact force and perceived comfort during walking.”Applied Ergonomics, vol.36, 355-362.

The specification of personalised footwear  for rapid manufacturing: a pilot study

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The specification of personalised footwear for rapid manufacturing: a pilot study

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