The impact of standing desks within the school classroom on sedentary behaviour, physical activity, health and development

Internationally, children spend most of their waking hours sedentary. Growing evidence indicates that sedentary behaviour tracks and continually increases from childhood through to adulthood. This is of public health concern because in adulthood excessive sedentary time is clearly associated with an increased risk of morbidity and mortality. Consequently, early intervention is essential before sedentary habits become entrenched and years of potentially harmful exposure are endured. Standing desks within the school classroom have emerged as one of the most promising strategies for reducing total sedentary time in children. This thesis focuses on sedentary behaviour in children and the implementation of standing desks in the school environment and the influence of standing desks on reducing sedentary time.

Chapter 2 describes a systematic review of the impact of standing desks within the school classroom. Systematic reviews are an essential component of evidence-based practice and provided vital information and direction for the research described in later chapters. The systematic review demonstrated that standing desk interventions implemented within the school classroom is a rapidly emerging area of research. There were promising early findings from pilot studies on important outcomes related to health, feasibility and development. However, more long-term studies and studies specifically measuring sitting behaviour as an outcome are needed.

Chapter 3 outlines and critically evaluates the methods and data reduction decisions made for both the activPAL and ActiGraph measurement devices relating to the research reported in Chapters 4 and 5. Many decisions made for data reduction procedures were standard practice and recommended within sedentary behaviour and physical activity research. However, with small initial samples in Chapters 4 and 5, there was a conflict between retaining as much of these samples as possible while also gaining the most valid and representative data of behaviour. Data compliance was modest in Chapter 4 and somewhat poor within intervention groups in Chapter 5, which is a limitation of the evidence presented within these chapters.

Chapter 4 describes a cross-sectional surveillance study that was designed to fill gaps in the literature about children’s objectively-measured levels and patterns of sedentary time and physical activity accumulation, and to gain a greater insight into times of the day and week where interventions could be best targeted. Children in Year 5 of primary

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school and of South Asian and White British ethnicity of lower socio-economic position were the population of interest. The results demonstrated that children were highly sedentary during different periods of the week; over 10 hours/day on school days and 11 hours/day on weekend days was spent sitting. This also included high proportions of waking hours spent in prolonged sitting bouts (30+ mins), particularly after school and on weekends, which has not been observed in European children previously. To inform interventions, further longitudinal research is required, with larger sample sizes spread across multiple UK areas, to better understand the levels and patterns of sitting accumulated at and away from school in children.

Chapters 5 describe the impact of the Stand Out In Class intervention pilot, the first longer-term standing desk study based in the primary school classroom in Europe. The Stand Out In Class intervention was underpinned by the Behaviour Change Wheel framework, COM-B model and Behavioural Change Taxonomy (v1). This chapter describes the impact of two different intervention designs; full desk allocation (FDA) (one per child) and partial desk allocation (PDA) (children rotated between sit-stand desks and traditional seated desks) on objectively measured classroom sitting time and physical activity in Year 5 children based in a school in Bradford, UK. Changes in sitting time and physical activity in these two classes were compared to a control class located within a nearby school. Sitting time (activPAL data) and physical activity (activPAL and ActiGraph data) were measured during a 7-day period at baseline (autumn/winter) 4 months (spring) and 8 months (summer) of desk exposure. Children were not rotated on a regular basis (as planned) within the PDA group and therefore the intervention was not implemented sufficiently. Consequently, data from this group were difficult to interpret with any clarity. Large reductions were observed in the proportion of wear time spent sitting during class time and during a total week day in the FDA group compared to the control group at both 4 months (class time -25.3%, full week day -7.7%) and 8 months (class time -19.9%, full week day -5.5%). Chapter 5 also describes the impact of the Stand Out In Class intervention on adiposity, cognitive function, musculoskeletal discomfort and behaviour-related mental health at 4 months and 8 months of intervention exposure in FDA and PDA groups. The intervention demonstrated no influence on adiposity outcomes. The sit-stand desks appeared to have a negative influence on behaviour related mental health over time in both intervention groups. No changes were observed in musculoskeletal discomfort scores or in cognitive function

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scores. Chapters 5 together suggest sit-stand desks in the classroom may influence reductions in sitting time over the longer-term within an FDA system although careful consideration are needed for day-to-day teaching practicalities.

Chapter 6 evaluated the implementation of the Stand Out In Class intervention within the FDA and PDA classes using focus groups with pupils and interviews with teachers. Within the FDA class, standing classes were delivered by the lead teacher, however, acceptance of sufficient intervention delivery was based on the word of the teacher and a single classroom observation only, with no other evidence available. Within the PDA class, insufficient child rotation appeared to be due to a lack of motivation from the teacher, a behaviourally challenging group of pupils, curriculum pressures, lack of space, lack of time and the distracting nature of the desks. Overall this intervention encountered many barriers to effective implementation which should be considered in future standing desk interventions adopting a PDA system. Evaluation in this study would have benefitted from daily or weekly implementation logs for teachers in both FDA and PDA classes. Future qualitative research should attempt to explore barriers and solutions to effective PDA intervention implementation as this is the more economically feasible system.

This thesis found that sit-stand desks in the classroom may influence a reduction in children’s sitting time using a full allocation approach and provides important evidence for sedentary behaviour patterns, intervention design and public health and education policy for UK children. The evidence provided in this thesis is pertinent in children of South Asian and White British ethnicity of lower socio-economic position. The utilisation of standing desks in the classroom environment holds potential for reducing children’s sitting time