Relationship between Cardiorespiratory Fitness and Relative Gut Microbiota Composition in Healthy Adults

Abstract

PURPOSE: Bacteria residing in the human gastrointestinal tract has a symbiotic relationship with its host. Animal models have demonstrated a relationship between exercise and gut microbiota composition. The purpose of this study was to explore the relationship between cardiorespiratory fitness and relative gut microbiota composition, measured by the ratio of Firmicutes to Bacteroidetes (F/B ratio) in healthy adults. METHODS: Twenty-one males and 19 females (Age=26.1 ± 2.8 y; BMI=24.0 ± 4.2 kg/ m2), who did not take antibiotics in the last 6 months, volunteered for this study. Participants completed a 3-month exercise recall, tracked their nutritional intake for 7 days (via MyFitnessPal), and collected their stool sample with an OMNIGENE Gut home stool collection kit. Body composition and maximal cardiorespiratory fitness (VO2max), were measured via air displacement plethysmography using the Bod Pod and a symptom-limited graded treadmill test, respectively. Relative microbiota composition was determined by analyzing DNA extracted from stool samples using a Quantitative Polymerase Chain Reaction (qPCR) approach that specifically measured the amount of a target gene (16s RNA) found in Firmicutes and Bacteroidetes. Relationships between F/B ratio and potentially related dietary, anthropometric, and fitness variables were assessed using correlation analyses with appropriate Bonferroni adjustment (p<0.004). RESULTS: Average F/B ratio in all participants was 0.94 and average VO2max was 45.8 ± 8.8 ml/ kg/min. F/B ratio was significantly correlated to VO2max (r=0.45, p<0.004), but no other fitness, nutritional intake, or anthropometric variables (p>0.004). CONCLUSIONS: VO2max was responsible for ~20% of the variance of an individual’s relative gut bacteria as determined by F/B ratio. These data support animal findings by demonstrating a relationship between relative human gut microbiota composition and cardiorespiratory fitness in healthy adults. Future investigations should confirm this relationship in heterogenous populations and investigate the utility of exercise training as medium to promote beneficial changes in gut microbiota.