Plantar foot loading patterns of healthy weight and overweight school children from South Africa and Germany

Tidbury, Gabriela Bella (2017-03)

Thesis (MScSportSc)--Stellenbosch University, 2017

Thesis

ENGLISH ABSTRACT : Background: Excessive plantar loading (peak pressures) can possibly cause deterioration of the soft tissue such as the fat pads in the foot during locomotion (Mickle, Steele & Munro, 2006). This can increase the risk for developing foot pathologies in adults and children (Yan et al., 2013). It is speculated that foot pain experienced by overweight individuals results from the higher mechanical loading of their feet because of the additional body weight they carry (Butterworth et al., 2015). Objective: The current study investigated the plantar loading differences between the healthy weight and overweight children aged 10 to 13 years from South Africa. An additional investigation was carried out to determine the plantar loading differences between children aged 10 to 13 years from Germany and South Africa of the same weight category. Methods: The current study followed a descriptive cross sectional study design. A random stratified sample of four schools were randomly selected from five regions within the Western Cape. Plantar loading measurements were obtained from 178 children (mean age 12.3 ± 1.2 years; body weight 49.2 ± 12.2kg; height 1.56 ± 0.01m; n = 178 of which 87 were girls and 91 boys) from South Africa and 139 children (mean age 12.3 ± 0.1 years; body weight 47.3 ± 1.0kg; height 1.55 ± 0.01m; n = 139 of which 61 were girls and 78 boys) from Germany with the Emed n50 pressure platform using the two-step method at a self-selected walking speed. Peak pressure, pressure-time integral, force-time integral and contact area variables were investigated for nine regions of the foot. In addition, the children were categorised into a heathy weight category or overweight category according to their body mass index (BMI) (Cole & Lobstein, 2012). A mixed model linear regression was used to analyse the data. The level of significance was adjusted from p = 0.05 by using a Šidák correction to: p = 0.0057. Results: The overweight category of children from South Africa had statistically significantly higher peak pressure, pressure-time integral, force-time integral and contact area for most of the foot regions than the healthy weight children from South Africa. The German children had significantly higher peak pressure, pressure-time integral and force-time integral values than the South African children of the same weight category. Interestingly, the healthy weight South African children had significantly greater contact area for most regions of the foot compared to the healthy weight German children. Conclusion: Body weight is a primary factor influencing plantar loading values (of overweight children). It is possible that the significant differences found in the midfoot region of the overweight children compared to healthy weight children could have been influenced by structural foot differences such as additional fat mass of the medial longitudinal arch or structurally lowered medial longitudinal arch of the foot. It is possible that the plantar loading differences between the German and South African children are a result of structural foot differences.

AFRIKAANSE OPSOMMING : Agtergrond: Oormatige plantaarlading (piekdruk) kan moontlik lei tot agteruitgang van die sagteweefsels soos die vetsak in die voet gedurende voortbeweging (Mickle, Steele & Munro, 2006). Dit kan die risiko vir die ontwikkeling van voetpatologieë in volwassenes en kinders verhoog (Yan et al., 2013). Daar word gespekuleer dat voetpyn wat deur oorgewig individue ondervind word, die gevolg kan wees van hoër meganiese lading van die voete as gevolg van die addisionele liggaamsgewig (Butterworth et al., 2015). Doel: Die huidige studie het die verskille in plantaarlading tussen gesonde-gewig en oorgewig kinders tussen die ouderdomme van 10 en 13 in Suid-Afrika bestudeer. ‘n Addisionele ondersoek is gedoen om te bepaal of daar verskille is in die plantaarladings by kinders tussen die ouderdomme van 10 en 13, in die dieselfde gewigskategorieë, van SuidAfrika en Duitsland. Metodes: Die huidige studie het ‘n beskrywende deursnee studie ontwerp gevolg. Vier skole is op ‘n lukrake gestratifiseerde manier uit die vyf streke van die Wes-Kaap gekies. Plantaarladingsmetings is verkry van 178 kinders (gem ouderdom12.3 ± 1.2 jaar; liggaamsgewig 49.2 ± 12.2kg; lengte 1.56 ± 0.01m; n = 178; 87 meisies en 91 seuns) uit Suid-Afrika en 139 kinders (gem ouderdom 12.3 ± 0.1 jaar; liggaamsgewig 47.3 ± 1.0kg; lengte 1.55 ± 0.01m; n = 139 met 61 meisies en 78 seuns) van Duitsland. Die Emed n50 drukplatform en ‘n twee-tree stapmetode teen ‘n selfgeselekteerde stapspoed is gebruik. Piekdruk, druk-tyd intervalle, krag-tyd intervalle en kontakarea veranderlikes is vir nege areas van die voet ondersoek. Kinders is ingedeel in gesonde enoorgewigkategorieë op grond van hulle liggaamsmassa indeks (LMI) (Cole & Lobstein, 2012). . ‘n Gemengde model lineêre regressie is gebruik om die data te analiseer. Die vlak van beduidenheid is aangepas van p = 0.05 tot p = 0.0057 deur middel van ‘n Šidák regstelling. Resultate: Oorgewig kinders van Suid-Afrika het statisties beduidende hoër piekdruk, druktyd intervalle, krag-tyd intervalle en kontakarea vir die meeste dele van die voet gehad in vergelyking met die gesonde-gewig kinders van Suid-Afrika. Vir dieselfde gewigskategorieë het die Duitse kinders statisties beduidende hoër piekdruk, druk-tyd intervalle, krag-tyd intervalle as die Suid-Afrikaanse kinders gehad. Die gesonde-gewig kinders van Suid-Afrika het beduidend groter kontakareas vir die meeste dele van die voet gehad in vergelyking met hul Duitse ewekenieë Gevolgtrekking: Liggaamsgewig is ‘n primêre faktor wat die plantaarladings waardes van oorgewigkinders beïnvloed. Daar word vermoed dat die beduidende verskille wat tussen die middelvoet-area van oorgewig kinders teenoor gesonde-gewig kinders gevind is, moontlik deur strukturele voetverskille kan wees, soos bykomende vetmassa van die mediale langboog of ‘n strukturele laer mediale boog van die voet. Dit is moontlik dat die plantaarladingsverskille tussen Duitse en Suid-Afrikaanse kinders die gevolg kan wees van strukturele voetverskille.

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