The Exercise Microbiome Project: An 8 week Cardiovascular Intervention on the Human Gut Microbiome

Abstract

INTRODUCTION: The effects of diet and exercise are well studied in connection with human health. However, the relationship between the human gut microbiome (HGM) and exercise is not well understood. PURPOSE: The purpose of this study was to examine possible changes to the HGM diversity and composition resulting from an 8-week intervention of cardiovascular exercise (CVE). METHODS: Twenty-seven participants (20 F and 7 M) aged 18-25 years were recruited. Inclusion/exclusion criteria were determined using the AHA/ACSM pre-screening questionnaire along with screening for historical factors that might impact the microbiome. Fecal samples for HGM profiling were collected weekly, during three phases of the project: baseline (4 wks; no CVE), intervention (8 wks; CVE 3x wk), and washout (4 wks; no CVE). Pre/post VO2 max and body composition analyses were conducted. Heart rate ranges for the CVE intervention were pre-determined by the subject’s VO2 max test. Gut microbiota were profiled using 16S rRNA gene sequencing. Microbiome sequence data were analyzed with the QIIME 2 bioinformatics platform. RESULTS: To track changes in each subject’s HGM, community richness and composition were compared to the week 1 (baseline) values for each subject. One week after the CVE began there was a significant change (p = 0.0001) in the HGM composition. This change persisted through week 11, when the CVE program stopped and microbial compositions abruptly returned to baseline values. Interestingly, in week 8, some individuals seem to have returned to a composition similar to baseline. Reasons for this anomaly are unclear. Additionally, each individual’s community richness and compositions were compared to the prior week to understand week-to-week changes, demonstrating a significant shift (p = 0.0002) in composition at week 8, indicating settlement into a novel HGM composition. The week to prior week community richness showed significant decreases in weeks 7-9 (p = 0.02). This was followed by a significant increase in week 12 (p = 0.017). CONCLUSION: The CVE intervention showed significant changes in HGM richness and composition that correlated with the beginning and the end of the CVE intervention. These changes indicate that exercise has a clear impact on the HGM and further studies are needed to uncover the underlying mechanism.