Title: Self-reported and accelerometer-recorded physical activity and cross-sectional associations with the gut microbiome: a Coronary Risk Development in Young Adults study
Thesis Supervisor: Dr. Eli Puterman
Committee members: Dr. Michael Koehle, Dr. Katie Meyer
Defence Chair: Dr. Daniel Gamu
Abstract: The role of the gut microbiome in host physiology and its association with various diseases is a developing field of research and there is limited knowledge the impact of physical activity on the gut microbiome, particularly in diverse population-based cohorts. This study examines the associations between physical activity with gut microbial diversity, composition, and function. Utilizing data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, we evaluated the relationship between physical activity and the gut microbiome in participants aged 47-61. Physical activity was assessed through self-reported measures (n = 581) and accelerometer data (n= 362), while gut microbiome composition was analyzed from stool samples using whole genome shotgun (WGS) sequencing. We employed regression models for cross-sectional analyses, adjusting for sociodemographic and behavioural covariates, such as diet and smoking, as well as body mass index (BMI). Self-reported physical activity showed significant positive associations with microbial beta diversity and negative associations with species richness, a measure of alpha diversity, which persisted even after adjusting for other behavioural factors and BMI, but no change in Shannon Diversity Index. Identification of associations with specific bacterial species, metabolic pathways and enzyme families revealed both positive and negative associations with self-reported physical activity levels, highlighting complex associations between physical activity and gut microbiota. Similar to self-reported physical activity, accelerometer data revealed significant positive associations between beta diversity and MVPA, with no associations with alpha diversity measures, such as richness and Shannon Diversity Index, or specific species, metabolic pathways and enzyme families. The study underscores the intricate association between physical activity and the gut microbiome in a middle-aged, racially diverse cohort. Our findings support the notion that regular physical activity is associated with a change in gut microbial composition associated pathways and species which promote improved host health, and negatively associated with metabolic functions that have been implicated in pathological states. While these insights enhance our understanding of the multifactorial nature of gut microbiome dynamics, physical activity interventions are required to determine whether it is in fact a modifiable factor in promoting gut health. The study’s diverse demographic and robust methodology strengthen its external validity and contribute to a growing body of evidence on lifestyle factors that are associated with the gut microbiome. Future studies should employ longitudinal and interventional designs with integrated methodologies for physical activity assessment, using the most up-to-date methods of DNA analysis.