Enough exercise could prevent two thirds of new chronic disease cases, a model finds

Insufficient physical activity has been associated with a higher risk of several non-communicable diseases and with death from all causes, yet public health planning needs more than a general warning: it needs numbers. Knowing how many actual cases of cancer, heart disease, stroke and diabetes could be avoided if a population moved more helps governments decide where prevention money goes. This study set out to produce those estimates for Chile, a country with its own national survey data on how active its adults really are. The result is a picture of the prevention opportunity sitting inside one nation's activity habits.

The researchers ran a comparative risk assessment model using data from 5834 participants aged 20 and over in the Chilean National Survey of 2016 to 2017. Physical activity was measured with the Global Physical Activity Questionnaire and converted into MET minutes reflecting intensity. Estimated new cases of five diseases in Chile in 2019, breast cancer, colon cancer, ischaemic heart disease, diabetes and stroke, were taken from the Global Burden of Disease study. Relative risks from a published pooled analysis were then applied to the prevalence of insufficient activity to calculate how many cases each activity scenario could prevent.

In the most ambitious scenario, where the population reached high activity levels of at least 8000 MET minutes a week, more than 22,000 new cases of the five diseases could be avoided, 64.6% of the total. That ranged from 498 preventable breast cancer cases (10.1%) to 5629 diabetes cases (14.7%). More modest scenarios still helped but delivered much less: if everyone at least met the activity recommendation, 6522 cases would be prevented (18.7%), and a 10% relative reduction in insufficient activity would prevent just 651 cases (1.8%). Every scenario reduced cases of all five diseases to some degree.

The study fits a wider body of work quantifying the disease burden attributable to inactivity, and it echoes the familiar dose pattern: more movement, more prevention. Its strength is putting country-specific numbers on the opportunity; its weakness is that a model is only as good as its inputs. Activity was self-reported by questionnaire, the risk figures came from other populations, and no intervention was actually tested. Whether comparable numbers would hold in other countries, or whether real programmes could shift activity enough to realise them, remains open.

For an individual, this is a vivid illustration of scale rather than a personal prescription: in this model, a substantial share of new diabetes, stroke, heart disease and two common cancers simply would not happen in a highly active population. It is also honest about the flip side, since small shifts in population activity produced correspondingly small returns. The broad message is that physical activity is not just fitness maintenance but one of the larger levers on chronic disease risk that this kind of modelling can find.