PhD Thesis

2/4/2021 4-minute read


My PhD thesis is focusing on the area of short bouts of physical activity. Short bouts of physical activity (defined as lasting less than 10 minutes in duration) have been increasingly investigated within physical activity research over the last decade. This research has shown performing short bouts of physical activity leads to comparable health benefits as performing the same volume as bouted physical activity (activity lasting 10 minutes or more). This evidence has led to changes in the physical activity guidelines produced by the United States, the United Kingdom, Canada and the World Health Organisation. Due to these changes, it is now possible for individuals to achieve the physical activity guidelines by performing many short bouts of physical activity rather than fewer longer bouts.

Due to the benefits of short bouts of physical activity, it is logical to promote performing such activity to those that are currently inactive. My PhD forms part of one of these programmes called Snacktivity. Snacktivity looks to encourage individuals to perform several “activity snacks” over the course of a day in order to accumulate the necessary volume of physical activity to achieve the current physical activity guidelines. To do this, participants will be given an activity tracker along with an accompanying mobile application (the SnackApp). An overview of the project can be found on this webpage.

To keep this page a reasonable length, a brief outline of each paper will be provided along with links to publications, external sources and other more detailed blog posts as appropriate. I hope this will provide a concise overview of my Thesis whilst allowing those who are interested to further explore given areas.

Study 1 - Accelerometer Physical Activity Datasets: A cross-country Scoping review

Due to the miniturisation and ever reducing price of accelerometric devices their use has become widespread for the measurement of physical activity. Studies that utilise such devices regularly collect a range of health outcomes allowing the relationship between these variables and the volume of physical activity individuals are performing to be assessed. Due to the large number of such datasets, this is the opportune time to begin the creation of a library of datasets. To create this library, a systematic search of the literature will be conducted to identify papers which have used accelerometric devices and simultaneously collected a range of health outcomes. From these papers, the key characteristics of the datasets will be extracted.

For a more detailed methodology, the study protocol for this review has been published on Open Science Framework. Results and discussion will be added as the study progresses.

As of the 1st April 2021, the searches have been conducted and are currently being screened.

A more comprehensive summary of this study can in the following blog post.

Study 2 - A harmonised data and compositional isotemporal substitution analysis to examine the impact of short bouts of physical activity on cardiometabolic health outcomes

The large number of datasets that have used accelerometers to measure physical activity and simultaneously collected a range of health outcomes presents a bolus of data. Much of this data is analysed individually by each study. However, in the last decade several studies have looked to harmonise data across a number of studies. By doing this, the statistical power of the data analysis increases as well as increasing the ability of researchers to detect more nuanced associations within their data. Due to these benefits, the use of harmonisation with multiple datasets has become more frequent. From our scoping review (discussed above) we will select a sample of datasets based on inclusion criteria which will be determined a priori. From this harmonised dataset, we will perform compositional isotemporal substitution analysis to determine the impact of substituting a given amount of time of one physical behaviour (such as sedentary behaviour) with the same amount of another behaviour (such as activity snacking).

A protocol for this study is currently being written, will be published on Open Science Framework, and a link will be provided here shortly.

A more comprehensive summary of this study can in the following blog post.

Study 3 - The acute health impacts of activity snacks in a highly controlled setting

Study 4 - The longer term impacts of activity snacks on cardiometabolic health outcomes