Sedentary behaviour (SB) is prevalent across all ages, but particularly in older adults aged 50 years and above. Given that older adults spend more than 60% of waking hours sedentary, enhancing our understanding of the correlates of SB will be important to inform the development of interventions to reduce SB in mid-age and older adults. This thesis provides five studies focusing on the correlates of SB in mid-age and older adults. Firstly, Chapter 2 presents a literature review using behaviour epidemiology framework to examine the existing evidence on sedentary behaviour in general adults in order to identify the gap of current knowledge in sedentary behaviour. Chapter 3 presents a systematic review which included the existing evidence on correlates of SB in mid-age and older adults and provides evidence-based conclusions on the topic. Chapter 4 presents a study examining the association of demographics and physical activity (PA) with daily sitting time in mid-age and older adults, and found behavioural correlates of SB and PA in mid-age and older adults. Chapter 5 presents a secondary data analysis using the data of the older office worker from the Stormont study. This chapter uses the results from the cross-sectional and longitudinal data to examine the association of demographics and behaviours with domain-specific sitting time among the older office workers. In this study, differences were found in demographic and behavioural correlates according to the studied domain of sitting. Chapter 6 presents a 6-month longitudinal study, which was designed to fill the gaps of our understanding of the associations between demographics, health and PA with SB in older adults aged 65 years and above. This chapter also looked into the changes of sitting time and its correlates. Together, these four studies provide adequate evidence on the demographics and behavioural correlates of SB and also identified the determinants of SB in mid-age and older adults. This thesis found that demographics had limited associations with SB, and sociodemographics were associated with work-related sitting time. Health behaviour was generally inversely associated with SB. These findings provide information to the correlates and determinants of mid-age and older adults SB and will inform further research on behaviour change strategies.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.