Exercise Alters Gut Microbiota Composition and Function in Lean and Obese Humans

PURPOSE Exercise is associated with altered gut microbial composition, but studies have not investigated whether the gut microbiota and associated metabolites are modulated by exercise training in humans. We explored the impact of six weeks of endurance exercise on the composition, functional capacity, and metabolic output of the gut microbiota in lean and obese adults with multiple-day dietary controls prior to outcome variable collection. METHODS Thirty-two lean (n=18 [9 female]) and obese (n=14 [11 female]), previously sedentary subjects participated in six weeks of supervised, endurance-based exercise training (3 days/wk) that progressed from 30 to 60 minutes/day and from moderate (60% of heart rate reserve [HRR]) to vigorous intensity (75% HRR). Subsequently, participants subsequently returned to a sedentary lifestyle activity for a six week washout period. Fecal samples were collected before and after six weeks of exercise, as well as after the sedentary washout period, with 3-day dietary controls in place prior to each collection. RESULTS β-diversity analysis revealed that exercise-induced alterations of the gut microbiota were dependent on obesity status. Exercise increased fecal concentrations of short chain fatty acids (SCFAs) in lean, but not obese, participants. Exercise-induced shifts in metabolic output of the microbiota paralleled changes in bacterial genes and taxa capable of SCFA production. Lastly, exercise-induced changes in the microbiota were largely reversed once exercise training ceased. CONCLUSION These findings suggest that exercise training induces compositional and functional changes in the human gut microbiota that are dependent on obesity status, independent of diet and contingent on the sustainment of exercise. Corresponding Author: Jeffrey A. Woods, PhD, 906 S. Goodwin Ave., 348 Louise Freer Hall, University of Illinois at Urbana-Champaign, Urbana IL 61801, Woods1@illinois.edu, 217-244-8815 This work was partially funded by a doctoral student research grant from the American College of Sports Medicine (ACSM). Authors have no professional relationships with companies or manufacturers who will benefit from the results of the present study. Results of the present study do not constitute endorsement by ACSM. Results of the study are presented clearly, honestly and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 6 November 2017 © 2017 American College of Sports Medicine

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