Objective: Population-based studies investigating the relationship between physical activity and the gut microbiota composition have mainly relied on self-reported activity, potentially influenced by reporting bias. Here, we investigated associations of accelerometer-based sedentary behaviour and physical activity with the gut microbiota composition and functional profile in the large Swedish CArdioPulmonary bioImage Study. Methods: In 8507 participants aged 50-65, the proportion of time in sedentary (SED), moderate-intensity (MPA), and vigorous-intensity (VPA) physical activity were estimated with hip-worn accelerometer. The gut microbiota was profiled using shotgun metagenomics of fecal samples. We fitted multivariable regression models, and adjusted for sociodemographic, lifestyle, and technical covariates while also accounting for multiple testing. Results: Overall, SED and MPA were associated with microbiota species in opposite directions. For example, the strongest positive regression coefficient for MPA and the strongest negative for SED were with Prevotella copri, a plant-polysaccharide-degrading bacteria. Species associated with VPA aligned with the MPA associations, although with clear discrepancies. For instance, Phocaeicola vulgatus was negatively associated with MPA, while the association with VPA was non-significant and in the positive direction. Additional adjustment for dietary variables or adiposity attenuated some of the associations. For the functional profile, MPA and VPA were generally associated with lower capacity for amino acid degradation. Conclusion: Our findings suggest that sedentary behaviour and physical activity are associated with a similar set of gut microbiota species and functions, but in opposite directions. Furthermore, the intensity of physical activity may have specific effects on certain species of the gut microbiota.

J.Ä. has served on the advisory boards for Astella, AstraZeneca and Boehringer Ingelheim and has received lecturing fees from AstraZeneca and Novartis, all unrelated to the present work. Remaining authors declare no competing interests.

Financial support was obtained in the form of grants from the European Research Council [ERC-STG-2018-801965 (TF); ERC-CoG-2014-649021 (MO-M); ERC-STG-2015-679242 (JGS)], the Swedish Heart-Lung Foundation [Hjärt-Lungfonden, 2019-0505 (TF); 2018-0343 (JÄ); 2020-0711 (MO-M); 2020-0173 (GE); 2019-0526 (JGS)], the Swedish Research Council [VR, 2019-01471 (TF), 2018-02784 (MO-M), 2019-01015 (JÄ), 2020-00243 (JÄ), 2019-01236 (GE), 2021-02273 (JGS), 2018-02837 ( EXODIAB 2009-1039)], the Swedish Research Council for Sustainable Development [FORMAS, 2020-00989 (SA)], EASD/Novo Nordisk (SA), Göran Gustafsson foundation [2016 (TF)], Axel and Signe Lagerman's foundation (TF), the A.L.F. governmental grant 2018-0148 (MO-M), The Novo Nordic Foundation NNF20OC0063886 (MO-M), The Swedish Diabetes Foundation DIA 2018-375 (MO-M), the Skandia Risk&Hälsa, 2023 (ÖE, EEB), and governmental funding of clinical research within the Swedish National Health Service (JGS). The study was also supported by the Swedish Foundation for Strategic Research (LUDC-IRC 15-0067). Funding for the SCAPIS study was provided by the Swedish Heart-Lung Foundation, the Knut and Alice Wallenberg Foundation, the Swedish Research Council and VINNOVA (Sweden's Innovation agency), the University of Gothenburg and Sahlgrenska University Hospital, Karolinska Institutet and Stockholm County council, Linköping University and University Hospital, Lund University and Skåne University Hospital, Umeå University and University Hospital, Uppsala University and University Hospital.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Swedish Ethical Review Authority approved the Swedish CardioPulmonary bioImage Study (DNR 2010-228-31M) and the present study (DNR 2018-315 with amendment 2020-06597). All participants provided written informed consent.

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The de-identified metagenomic sequences can be found in the European Nucleotide Archive under the accession code PRJEB51353. The statistical analyses R codes can be found at https://github.com/MolEpicUU/physicalactivity_gut. The individual-level data underlying this article were provided by the SCAPIS study and are not shared publicly due to confidentiality. Data will be shared upon reasonable request to the corresponding author only after permission by the Swedish Ethical Review Authority (https://etikprovningsmyndigheten.se) and by the SCAPIS Data access board (https://www.scapis.org/data-access/).

https://github.com/MolEpicUU/physicalactivity_gut