Structural physical activity restriction, cerebrovascular and diabetes mortality, and long-term care intensity in Japan: An ecological panel study across 47 prefectures (2013-2022) with a COVID-19 counterfactual analysis

Physical inactivity is an established cardiovascular risk factor at the individual level, but the population-level mortality cost attributable to modifiable, built-environment constraints on daily physical activity - rather than to individual behaviour - has lacked an empirical benchmark, leaving investment in walkable urban design without a clear health-economic case. We asked whether structurally constrained population physical activity is associated with cause-specific mortality, and used the 2020 COVID-19 mobility restriction - a society-wide curtailment that could never be imposed experimentally - to estimate the effect size of an acute collective PA shock on cardiovascular and metabolic deaths.

10-year ecological panel of Japan's 47 prefectures (2013-2022; N = 470). We modelled cerebrovascular (CVD), diabetes (DM), and heat-illness deaths with age-sex-standardized CRE Mundlak Poisson regression and the severe long-term-care ratio (SHR) with a fractional logit, applying stepwise confounder adjustment (M0-M5: medical resources, income, education, age structure, birth rate). 2020 excess was estimated against a counterfactual trend trained on 2013-2019.

Higher car-only commuting (range 8.5-79.0%) was associated with greater CVD (IRR per SD = 1.064; 95% CI 1.037-1.093; +29% across the observed range) and DM mortality (IRR = 1.030; 1.000-1.060), and with greater long-term-care severity (SHR OR = 1.39; 1.18-1.64). CVD persisted across all five adjustment models; DM attenuated to non-significance after consumption-expenditure adjustment, consistent with a correlated socioeconomic cluster rather than an independent driver. In 2020, the most car-dependent tertile recorded +8.3% excess CVD deaths (95% CI +2.8% to +14.0%) versus near-zero excess elsewhere - a quantifiable effect of acute collective PA restriction on cardiovascular mortality.

A modifiable feature of modern life - car dependence - carries a measurable population-level cardiovascular mortality cost that amplifies when behavioural PA is acutely curtailed. The effect size justifies treating walkable urban design and public transit as primary NCD prevention in super-ageing societies, not as ancillary transport policy.

None declared.