Contrary to common belief, back pain amongst young people is a frequent phenomenon. Epidemiological studies have found high prevalence rates of back pain amongst schoolchildren. The investigation reported here aims to validate children's self-reporting and the observation of sitting postures to establish the intensity, duration and frequency of exposure in the classroom. The sitting postures of 18 children were recorded using three methods, the portable ergonomic observation method (PEO), video analysis and self-report. The three methods were compared. PEO was significantly correlated with video analysis of the sitting postures after development of the method. Self-report was not significantly correlated with video analysis of the sitting postures. Therefore PEO was selected as the main observation tool in further analysis of children's sitting posture in schools in South-East England as part of a large research programme investigating back pain amongst schoolchildren.
Back pain is a significant burden on industrialised countries. If the symptoms and causes of back pain could be identified at an early stage, the opportunity for remedial action would be improved. It has been shown that a strong predictor of having future back pain is a previous history of such symptoms (Troup et al., 1987). A large portion of adult sufferers report a first onset of back pain in their early teenage years or in their 20s (Papageorgiou et al., 1996). It is commonly perceived that back pain amongst young people is uncommon (Turner et al., 1989). However, epidemiological studies have found high prevalence rates of back pain (Brattberg and Wickman, 1992; Troussier et al., 1994). Mandal (1994) suggests that a seated person has a hip joint flexion of about 60° and the pelvis has a sloping axis, so that the lumbar region then exhibits a convexity, or kyphosis. This is supported by Schoberth (1962), who found from X-ray examinations of 25 people sitting upright, an average 60° hip flexion and 30° lumbar flexion. Storr-Paulsen and Aagaard-Hansen (1994) found that in one school, children remained seated between 19 and 90 min during a 90 min double lesson, with older children sitting for longer periods of time and most of the children sitting on average for more than 60 min. Of the time spent seated, 57% was spent leaning forward (e.g. writing or painting) with 43% spent doing backward leaning activities (e.g. looking at blackboard or reading). School chairs and desks are designed for children to sit and work with a 90° flexion of the hip joint and a preserved lumbar lordosis, as recommended by Snorrason (1968). It seems that children do not use school furniture in this way.
The study reported in this paper is part of a large research programme investigating back pain amongst children in schools in two areas of England (i.e. Surrey and Manchester). Aims of the whole study are to:
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identify the extent of back pain experienced by schoolchildren, aged 11–14;
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establish any physical risk factors, which may be present in schools; and
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provide advice to prevent problems arising in the future,
in association with the Arthritis Research Campaigns’ Epidemiology Unit University of Manchester.
As a sub-section of this, the aims of the study reported here are:
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validation of methods to record the sitting posture of schoolchildren in the classroom; and
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minimising disruption in normal lessons during posture recording.
Direct observation of children in the classroom was considered the most suitable method to use in schools to record posture (Murphy and Buckle, 2000). This paper describes the calibration of the observer and the development of the portable ergonomic observation method (PEO) (Fransson-Hall et al., 1995), for use in the classroom to observe the sitting posture of schoolchildren. PEO was used in the study as the method records the posture of the children in real time in the classroom. Time-sampled observations such as Posturegram (Priel, 1974) and OWAS (Karhu et al., 1977) only provide an estimate of this information whereas real-time observations provide information about the intensity, duration and frequency of the posture.
1.1. Ethics
Permission was granted from the Director of Education for Surrey schools, The Ethics Committee of the University of Surrey and the head teacher of the school involved. The parents and children were each sent a consent letter informing them of the study with the option to withdraw at any stage.
PEO meets the requirements set out at the start of this paper. The method provides a valid method to record the sitting posture of school children in the classroom, without disruption as a result of using a video camera in lessons. PEO can be used to record the intensity, duration and frequency of sitting posture in the classroom and will be used in the next stage of the study to identify different sitting behaviours.
