A major UK Biobank study published on Mar. 31 suggests that increasing the proportion of vigorous physical activity, while keeping total exercise time the same, is linked to lower risks of heart disease, diabetes, dementia, and other chronic conditions.
The research addresses how different intensities of physical activity affect health outcomes beyond just overall exercise volume. This is important as public health guidelines often focus on both moderate and vigorous activities but do not always clarify their relative benefits.
Researchers used data from over 500,000 participants in the UK Biobank cohort. Physical activity was measured through self-reported questionnaires and accelerometers worn by a subset of participants. The study tracked eight chronic diseases—major adverse cardiovascular events (MACE), atrial fibrillation (AFib), type 2 diabetes (T2D), chronic kidney disease (CKD), chronic respiratory disease (CRD), dementia, metabolic dysfunction-associated steatotic liver disease (MASLD), and immune-mediated inflammatory diseases (IMIDs)—as well as all-cause mortality.
Participants were grouped by the percentage of their weekly activity performed at vigorous intensity (%VPA). Those with more than 4% VPA had between 29% and 61% lower risk for these conditions compared to those with no vigorous activity when adjusting for demographic and lifestyle factors. Even after further adjustments for medical history and biomarkers, these associations remained significant though somewhat reduced. For example, the five-year risk for MACE dropped from 10.16% in those with no VPA to 6.42% in those exceeding 4%. The findings were consistent across both device-measured and self-reported data sets.
The study found that any amount of vigorous activity could potentially prevent up to one-third of dementia cases compared to none at all. IMIDs showed strong dependence on exercise intensity specifically, while other conditions like CKD or T2D were influenced by both how much people exercised overall and how intensely they did so.
Researchers concluded that higher-intensity activities may offer greater preventive benefits against several chronic diseases than simply increasing total exercise time alone. However, they caution that because this was an observational study it cannot prove cause-and-effect relationships.
