Ergonomic chair design for school computer laboratories in the Cape Metropole, Western Cape, South Africa

Van Niekerk, Sjan-Mari (2013-03)

Thesis (PhD)--Stellenbosch University, 2013.

Thesis

ENGLISH SUMMARY : Background: Computers have become increasingly accessible in developing countries. Such increased computer usage is also noted in the Western Cape, South Africa. Prolonged posture whilst using computers and a learner‐chair mismatch is associated with spinal pain in adolescents. In South Africa, the prevalence of spinal pain among high school learners has been reported as being about 70%. Consideration of learner anthropometrics and school furniture design is essential to evolving strategies to be adopted to promote adolescent spinal health. Aim: The aim of this project is to determine whether the school computer laboratory chair or a commercially‐available chair matches the anthropometric profile of high school learners and, if not, to develop and test a prototype chair that will also facilitate postural changes, whilst the sitter is using a desktop computer. Methods: This study consisted of two phases. Phase one dealt with the anthropometric match of the learners to their school chair and to commercially‐available chairs. The following body dimensions were measured: stature; popliteal height (PH); buttock‐topopliteal length (BPL) and hip width (HW). These body dimensions were matched with the corresponding chair seat dimensions; and height, depth and width, using standard matching criteria. During Phase two, a prototype chair was designed according to the anthropometric profile of the learners concerned. The chair’s ability to reduce static sitting postures by facilitating postural changes in sitters whilst they are seated at a desktop computer was evaluated. The three‐dimensional (3D) sitting posture of twelve learners was evaluated while they were sitting on the school and the prototype chairs. The anthropometric and 3D data were analysed using descriptive statistics, including means (and standard deviations), medians (and interquartile ranges (IQR)) and ratios. To determine the difference in the number of postural changes between chairs, the Wilcoxon match pair test was used. Results: The sample consisted of 689 male and female learners aged 13 to 18 years, for the anthropometric study (phase 1). Of the learners, 65% to 80% did not match the school chairs’ dimensions. Five commercial chairs offered a good match for the seat height, but neither the seat depth nor the seat width matched 50% of the learners. The prototype chair matched 97% for height, 65% for depth and 60% for seat width. The prototype chair was associated with more postural changes in the frontal and transverse planes for the pelvis (ρ <0.05). Conclusions: This thesis is the first to report on the lower body anthropometric size of high school learners in the Cape Metropole area, Western Cape, South Africa. Neither the school computer laboratory chair nor commercially‐available adjustable computer chairs offered an acceptable fit for the anthropometric profile of the learners. The prototype “Dynamic” chair was consequently developed and provided the best match for the anthropometric profile. The prototype chair was also associated with an increased number of postural changes, particularly of the pelvis. The promising results obtained warrant further exploration of the prototype chair to determine the effect on the musculoskeletal pain experienced by school learners in South Africa.

AFRIKAANSE OPSOMMING : Agtergrond: Rekenaars is toenemend in ontwikkelende lande beskikbaar. Hierdie toename in rekenaargebruik is ook in die Wes‐Kaap, Suid‐Afrika, sigbaar. Gebrek aan postuurafwisseling tydens rekenaargebruik en ’n stoel wat nie die fisiese afmetings van die leerder pas nie, kan tot spinale pyn in adolessente lei. ’n Deursnee‐studie in Suid‐Afrika toon dat rugpyn onder meer as 70% van hoërskoolleerlinge in die Wes‐Kaap voorkom. Die antropometrie van leerders en die ontwerp van skoolmeubels is bepalende faktore in die ontwikkeling van strategieë om die spinale gesondheid van adolessente te bevorder. Doel: Om te bepaal of die afmetings van rekenaarstoele wat in skole gebruik word en in die handel beskikbaar is met die antropometriese afmetings van hoërskoolleerlinge ooreenstem; en, indien nie, om ’n prototipe te ontwikkel van ʼn stoel wat posturale beweging tydens rekenaargebruik aanmoedig. Metode: Hierdie studie is in twee fases uitgevoer. In fase 1 is leerders se antropometrie vergelyk met die afmetings van hulle skoolstoele en stoele wat in die handel beskikbaar is. Die volgende liggaamsafmetings is geneem: lengte, popliteale lengte, boud‐tot‐popliteale lengte en heupomtrek. Hierdie afmetings is vergelyk met die volgende ooreenstemmende stoelafmetings: sitplekhoogte, ‐diepte en ‐breedte. Die verhouding tussen die fisiese afmetings van leerlinge en dié van hulle stoele is met behulp van standaarddefinisies bepaal. Tydens fase 2 is 'n prototipe van ʼn stoel wat volgens die optimale afmetings wat in fase 1 verkry is, ontwerp is. Die stoel se vermoë om meer beweging tydens rekenaargebruik aan te moedig, is ondersoek. Twaalf leerders se drie‐dimensionele sitposisie terwyl hulle dieselfde rekenaarverwante taak uitgevoer het, is ontleed. Die meting het 15 minute lank geduur in die skoolstoel, gevolg deur 15 minute in die prototipe. Die driedimensionele antropometriese profiel is beskryf aan die hand van beskrywende statistiek wat die gemiddeld (standaardafwykings), mediaan (en interkwartiel reeks (IKR)) en onderlinge verhoudings insluit. Die verskil in sitpostuurgedrag tussen die meting met die skoolstoel en dié met die prototipe is deur middel van die Wilcoxon‐vergelykende pare ontleed. Resultate: Die steekproef vir fase 1 het uit 689 leerders tussen 13 en 18 jaar bestaan. Uit dié groep het 65% tot 80% nie met die skoolstoele se afmetings ooreengestem nie. Vyf stoele wat in die handel beskikbaar is, se hoogte het goed met die leerders se afmetings vergelyk, maar 50% van die leerders kon op nie een van die stoele in hierdie groep se sitplekdiepte en ‐breedte inpas nie. Die prototipe se hoogte het met 97% van die leerders ooreengestem, en die sitplek se diepte en breedte met onderskeidelik 65% en 60% van die leerders. Gevolgtrekkings: Hierdie navorsing het vir die eerste keer die onderlyf‐antropometrie van veelrassige hoërskoolleerders in die Kaapse Metropool (Wes‐Kaap, Suid‐Afrika) ondersoek. Nóg die stoele wat in die skool se rekenaarlaboratorium gebruik word nóg verstelbare stoele wat in die handel te kry is, toon ’n aanvaarbare ooreenkoms met die antropometriese profiel van die groep plaaslike hoërskoolleerders. Die prototipe is gevolglik ontwikkel, en dít het die naaste met die leerders se antropometrie ooreengestem. Met die prototipe is ’n toename in posturale bewegings aangeteken, vir veral in die pelvis. Hierdie belowende resultate verg verdere navorsing om die effek van hierdie prototipe van ʼn stoel op muskuloskeletale pyn in leerders te bepaal.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/79811
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