Gut microbiota responses to aerobic exercise training are intensity-dependent and associated with individual improvements in V.O2max
Abstract
BackgroundExercise intensity is a key determinant of physiological adaptations to training, yet its influence on the gut microbiota remains poorly understood. Furthermore, considerable interindividual variability in aerobic training adaptations exists, but factors associated with this variability are still unclear. We investigated how six weeks of cycling in the moderate, heavy, and severe exercise intensity domains influenced V.O2max and the gut microbiota in healthy adults.MethodsSixty-five healthy young adults were randomized to one of five cycling intervention groups according to exercise intensity domains (MOD: n = 11; HVY1: n = 10; HVY2: n = 13; HIIT: n = 11; SIT: n = 12), or a non-intervention control group (CON: n = 8). For analysis, groups were combined at the domain level into moderate (MOD: n = 11), heavy (HVY; HVY1 + HVY2: n = 23), and severe (SVR; HIIT + SIT: n = 23). All groups except SIT were work matched. Participants performed 3 training sessions weekly for 6 weeks. Stool samples, serum, and a 3-day dietary food log were collected before (PRE) and after (POST) the 6-week intervention.ResultsHVY and SVR exercise significantly increased V.O2max and gut microbiota alpha diversity, whereas changes in the MOD group were not statistically significant. Participants with larger improvements in V.O2max (responders) exhibited distinct gut microbiota profiles differing from those with limited improvements (non-responders), and proxy markers of gut permeability and inflammation further distinguished non-responders. Holdemanella was consistently associated with non-response and was the primary discriminating feature in a decision-tree classification model.ConclusionSix weeks of HVY and SVR intensity cycling was associated with improvements in V.O2max and detectable changes in the gut microbiota under the conditions of this intervention; the dose–response relationship and any physiological threshold remain to be determined. Distinct gut microbiota profiles were associated with the magnitude of improvement in V.O2max across intensity domains, raising the possibility that the gut microbiota contributes to interindividual differences in aerobic training response.
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BibTeX
@article{sales2026microbiota,
title = {{Gut microbiota responses to aerobic exercise training are intensity-dependent and associated with individual improvements in V.O2max}},
author = {Kate M. Sales and Jared Schlechte and Erin Calaine Inglis and Weilan Wang and Nicole A. Cho and Dana E. Lowry and Martin J. MacInnis and Juan M. Murias and Raylene A. Reimer},
journal = {Frontiers in Microbiology},
year = {2026},
month = nov,
doi = {10.3389/fmicb.2026.1981808},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1981808},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Gut microbiota responses to aerobic exercise training are intensity-dependent and associated with individual improvements in V.O2max
AU - Kate M. Sales
AU - Jared Schlechte
AU - Erin Calaine Inglis
AU - Weilan Wang
AU - Nicole A. Cho
AU - Dana E. Lowry
AU - Martin J. MacInnis
AU - Juan M. Murias
AU - Raylene A. Reimer
PY - 2026
DA - 2026/11/04
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1981808
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1981808
AB - BackgroundExercise intensity is a key determinant of physiological adaptations to training, yet its influence on the gut microbiota remains poorly understood. Furthermore, considerable interindividual variability in aerobic training adaptations exists, but factors associated with this variability are still unclear. We investigated how six weeks of cycling in the moderate, heavy, and severe exercise intensity domains influenced V.O2max and the gut microbiota in healthy adults.MethodsSixty-five healthy young adults were randomized to one of five cycling intervention groups according to exercise intensity domains (MOD: n = 11; HVY1: n = 10; HVY2: n = 13; HIIT: n = 11; SIT: n = 12), or a non-intervention control group (CON: n = 8). For analysis, groups were combined at the domain level into moderate (MOD: n = 11), heavy (HVY; HVY1 + HVY2: n = 23), and severe (SVR; HIIT + SIT: n = 23). All groups except SIT were work matched. Participants performed 3 training sessions weekly for 6 weeks. Stool samples, serum, and a 3-day dietary food log were collected before (PRE) and after (POST) the 6-week intervention.ResultsHVY and SVR exercise significantly increased V.O2max and gut microbiota alpha diversity, whereas changes in the MOD group were not statistically significant. Participants with larger improvements in V.O2max (responders) exhibited distinct gut microbiota profiles differing from those with limited improvements (non-responders), and proxy markers of gut permeability and inflammation further distinguished non-responders. Holdemanella was consistently associated with non-response and was the primary discriminating feature in a decision-tree classification model.ConclusionSix weeks of HVY and SVR intensity cycling was associated with improvements in V.O2max and detectable changes in the gut microbiota under the conditions of this intervention; the dose–response relationship and any physiological threshold remain to be determined. Distinct gut microbiota profiles were associated with the magnitude of improvement in V.O2max across intensity domains, raising the possibility that the gut microbiota contributes to interindividual differences in aerobic training response.
SN - 1664-302X
ER -