Temporal relationships among physical activity levels and stationary time in preschool-aged children and adolescents: An investigation of the ActivityStat hypothesis
Creators: Lamboglia, Carminda
Publisher: name: University of Alberta Library
Year: 2023

<p>The ActivityStat hypothesis suggests that movement can be internally regulated by a biological control center. Specifically, humans maintain their total physical activity (PA) at a constant level by triggering behavioural and/or energy compensatory responses. However, there is considerable debate about the possibility of a compensation mechanism. Thus, the original intent of this dissertation was to test the hypothesis in an intervention involving adults living with liver disease. For Study 1, a scoping review was conducted addressing the following objectives: (1) to assess whether individuals living with liver disease display behavioural (i.e., PA, sedentary-related behaviour, and sleep) and/or energy (i.e., total energy expenditure [EE], basal EE, resting EE, and activity EE) compensation throughout the day and/or days; and (2) to examine whether a prescribed PA intervention triggers compensatory responses. Findings revealed insufficient evidence to support the ActivityStat hypothesis throughout the day and/or across days in people living with liver disease. Additionally, findings related to the effects of a PA intervention on behavioural and energy responses do not support the hypothesis. Due to interruptions related to the COVID-19 pandemic, I switched the focus of my dissertation to children and adolescents. These studies investigated the ActivityStat hypothesis by examining the presence of continuous-time multivariate relationships and the timeframe during which the multivariate relationships existed between light PA (LPA), moderate-to-vigorous PA (MVPA), and stationary time (ST). In Study 2, a secondary analysis was performed on data from the Parent-Child Movement Behaviours and Pre-School Children’s Development project involving preschool-aged children (3 to 5 years old) in Edmonton (Canada). Participants wore accelerometers to assess PA levels (i.e., LPA and MVPA) and ST. Though positive continuous-time relationships were found within LPA, MVPA, and ST, no relationships were observed between the behaviours after accounting for all other dynamic relationships (e.g., within-behavioural) examined. The timeframe at which LPA, MVPA, and ST predicted their later behaviours was about 0.5 days later. In conclusion, findings do not support the behavioural compensation component of ActivityStat hypothesis in preschool-aged children when simultaneously taking into account all dynamic relationships among LPA, MVPA and ST. In Study 3, a secondary analysis was performed on data from the Built Environment and Active Transport to School (BEATS) study involving adolescents (13 to 18 years old) in Dunedin (New Zealand). Participants wore accelerometers to assess PA levels and ST. Increases in LPA, MVPA, and ST were positively associated with their later behaviours until 1.7 to 2.5 days. A cross-behavioural reciprocal and negative relationship between LPA and ST was demonstrated 0.4 days later. A positive relationship between ST and MVPA was observed until about 0.4 day later. Though behavioural compensation was not observed for LPA and MVPA, evidence of compensation was noted for ST. Thus, findings from this study support evidence of the hypothesis in adolescents. Overall, this dissertation provides novel insights on examining the continuous-time multivariate relationships among PA levels and ST to investigate the ActivityStat hypothesis in different populations.</p>