Among 2,785 US adults with fatty liver disease (MASLD, defined by Hepatic Steatosis Index) followed a median 14.7 years, each additional 10 minutes of accelerometer-measured moderate-to-vigorous physical activity (MVPA) was associated with 20% lower all-cause mortality (HR 0.80, 95% CI 0.71-0.91) and 28% lower cardiovascular mortality (HR 0.72, 95% CI 0.53-0.99). Both relationships were nonlinear. Total activity showed substantially weaker associations, sedentary time showed none, and an alternative liver-fat index produced attenuated but directionally similar results.
The pattern matters because cardiovascular disease, not liver failure, is the leading cause of death in MASLD, so exercise advice here is really cardiac risk reduction. Intensity appeared to outperform sheer movement volume, echoing broader accelerometer cohorts such as UK Biobank, where vigorous minutes carry outsized mortality benefit. The nonlinear curve usually signals steepest gains at the low end, meaning the least active patients stand to gain most from adding even brief bouts of brisk walking or cycling. Caveats are real: this is observational, so reverse causation is plausible, since sicker people move less. Only about 200 cardiovascular deaths occurred, and the cardiovascular confidence interval nearly touches 1.0. A single week of accelerometry in 2003-2006 cannot capture later habit changes, and HSI is a surrogate for imaging- or biopsy-confirmed steatosis. The attenuated sensitivity results also suggest definition-dependent effects. Overall, this is a confirmatory finding that extends known exercise-mortality links into a high-risk population, supporting intensity-focused prescriptions without overturning existing guidance.