To the Editor, He et al present a prospective cohort study using wrist-worn accelerometry to examine the association between moderate-to-vigorous physical activity (MVPA) and long-term outcomes among individuals with inflammatory bowel disease (IBD) in the UK Biobank1. By leveraging objective activity measurement and extended follow-up, the authors demonstrate that higher MVPA levels are associated with a reduced risk of bowel resection and all-cause mortality, with evidence of a nonlinear dose–response relationship1. This work advances prior literature largely reliant on self-reported physical activity and provides an important signal supporting lifestyle-oriented risk modification in IBD. The biological plausibility of these findings is supported by emerging mechanistic and epidemiological evidence. Regular physical activity has been shown to exert systemic anti-inflammatory effects, modulate immune responses, and improve gut barrier integrity – mechanisms highly relevant to IBD pathophysiology2,3. Observational studies in IBD cohorts have previously linked higher physical activity levels to lower flare risk and improved quality of life, although most relied on questionnaires with inherent recall bias4. The use of accelerometry in the present study therefore represents a meaningful methodological advance. Nevertheless, several issues merit careful consideration. First, residual confounding and reverse causation cannot be fully excluded. Individuals capable of sustained MVPA may have milder disease, lower inflammatory burden, or fewer extraintestinal manifestations – factors not completely captured by baseline covariates. Although sensitivity analyses excluding early events were performed, physical activity may decline long before clinical deterioration or surgical indication, complicating causal inference. Second, exposure assessment was based on a single 7-day measurement. In a relapsing–remitting disease such as IBD, physical activity patterns may vary substantially over time in response to flares, treatment changes, or fatigue. While regression dilution bias was addressed analytically, repeated or longitudinal activity assessments would better reflect clinically relevant behavior. Third, the relatively small number of outcome events and the predominantly White study population limit statistical power and generalizability. Whether similar associations exist in younger patients, ethnically diverse populations, or those with more severe disease remains uncertain. From a clinical perspective, these findings should be viewed as hypothesis-generating rather than prescriptive. Randomized trials and pragmatic intervention studies are needed to define safe, individualized MVPA prescriptions across disease states, incorporating outcomes such as flare frequency, inflammatory biomarkers, hospitalization, and patient-reported symptoms. Such trials would complement broader evidence supporting lifestyle modification as an adjunct to medical therapy in IBD5,6. In summary, this study provides compelling objective evidence linking higher MVPA with favorable long-term outcomes in IBD. Translating these associations into actionable clinical guidance now represents an important research priority. We prepared this commentary in line with the principles of the TITAN 2025 guidelines, aiming to provide a transparent and responsible appraisal of evidence and its clinical implications7.
Xiaohong Xu (Wed,) studied this question.