The Effect of High-intensity Interval Training (HIT) on Gut Microbiota in Humans

Abstract

In the light of rising obesity rates and the increasing incidence of metabolic disease which contributes significantly to both global and local health problems, novel approaches to reduce the burden of disease must be explored. It is now widely acknowledged that gut microbiota can affect host metabolism, and its composition and activity are an important influence on overall health. Whilst exercise and physical activity have long been recognised as a way to prevent or delay numerous chronic conditions, emerging evidence from rodent studies, supported by limited research in humans suggests that modulation of gut microbiota may be one of the potential mechanisms that exercise improves health. The purpose of this study was to investigate the effect of a high-intensity exercise intervention on the gut microbiota of lean and overweight/obese, healthy adult males in Auckland, New Zealand. Participants were recruited to either lean (BMI < 25) or overweight/obese (BMI >28) groups for nine high-intensity interval training (HIT) sessions over 3 weeks. Gut microbiota composition, cardiorespiratory fitness, blood and fecal biomarkers of metabolic and inflammatory health were measured pre and post intervention with the ultimate goal of increasing the understanding of how possible exercise mediated changes in gut microbiota may improve metabolic health. Overall results demonstrate that while a short term HIT intervention is limited in its capacity to modify the composition of gut microbiota in healthy young men, and did not change the body composition of participants or blood or fecal biomarkers of metabolic and inflammatory health, it is an effective exercise protocol for improving cardiorespiratory fitness irrespective of BMI. Changes in fecal pH observed indicate HIT can bring about modifications in the gut, dependent on BMI status. Our analysis of gut microbiota revealed limited compositional differences between BMI groups at baseline line and as a consequence of HIT. We did not demonstrate any significant changes in gut microbiota, apart from an increase in Faecalibacterium prausnitzii in lean participants. Inter- and intra-subject variation presents vast challenges in determining the effect of HIT on gut microbiota composition and it remains unclear whether HIT is a useful strategy in this regard.