In 96,408 UK Biobank adults wearing wrist accelerometers, a higher proportion of activity spent vigorous (%VPA) tracked with lower incidence of eight chronic diseases and all-cause mortality, even after adjusting for total activity volume. Those above 4% VPA had 29-61% lower risk than those at 0%. Population attributable fractions favored intensity over volume for dementia (32.3% vs 8.1%), chronic respiratory disease, atrial fibrillation, cardiovascular events and immune-mediated inflammatory disease; type 2 diabetes, fatty liver and kidney disease showed more balanced contributions. A 375,730-person self-report analysis supplied corroboration.
The practical message extends the vigorous-activity literature, including the 2022 Nature Medicine work on vigorous intermittent lifestyle physical activity: short, hard efforts appear to carry disproportionate protection, and the dementia and inflammatory-disease signals are the novel contribution. Caution is warranted. This is observational, so reverse causation is plausible, since fitter and healthier people do more vigorous activity and early disease can suppress it, though the average follow-up and exclusion of early events may mitigate this. Accelerometer data come from a single week in a healthier-than-average volunteer cohort, and %VPA is correlated with total volume and fitness, so attributable fractions assume causality that trials have not shown. Wrist-based intensity thresholds are also imperfect. Still, the consistency across diseases and volume strata is notable. For adults who already move regularly, swapping some moderate minutes for brief hard efforts is a reasonable step, taken gradually and after medical advice for those with heart disease or high risk. Confirmatory in direction, incremental in breadth.