Physical Activity: Measurement and Health Outcomes for People of Advanced Age in New Zealand

Abstract

The overall aim of this thesis was to better understand the impact of physical activity on the health and well-being of people in advanced age. The first aim was to investigate the relationships between physical activity and health outcomes by examining the epidemiology of physical activity among older adults, with particular focus on the “oldest old” (80 years and over). The health outcomes of interest were depression, health related quality of life, and functional status. The inception cohort of a longitudinal study, LiLACS NZ, was examined (n=664). Non-Māori aged 85 years and Māori aged 80–90 years completed an interviewer administered, self-reported questionnaire of physical activity, depression, health related quality of life (relating to both mental health and physical health), and function. Secondly, given the nature of older people, it has been recognised that more detailed measures of physical activity (whether incidental, daily living, or planned) were needed, in order to better understand the types and patterns of activity in which older people engage and the benefits of such activity. Hence, the second aim of this thesis was to validate a use-of-time measure known as the MARCA (Multimedia Activity Recall for Children and Adults) in the oldest old. A subsample (n=45) of the LiLACS NZ cohort was administered the MARCA at repeated times and activity levels were compared using the Actigraph accelerometer. Findings of Study 1 indicated that physical activity was strongly related to functional status and physical health related quality of life in people of advanced age. Physical activity was related to mental health related quality of life only in non-Māori men and physical activity was related to depression in the non-Māori men and women in the cohort. Collectively these findings suggest that physical activity is an important factor for the health of the oldest old, but greater understanding of mental health in older Māori is required. Study 2 demonstrated that the MARCA was a valid and reliable self-reported measure of physical activity that can provide useful descriptive information about the way older adults use their time. Findings from Study 2 will be useful for furthering research on the relationship of physical activity to health outcomes in older people, as well as improving the quality and precision of future studies.