Future health gain from increasing physical activity in Australia, including multiple physiological effects of physical activity, and falls and injury risk: A simulation study

Abstract Background: Previous physical activity simulation studies only account for the effects of cardiovascular diseases, diabetes, dementia, and some cancers, which neglects many of its costs and benefits. We estimate the health and economic impacts of increased physical activity in Australia, including those on mental health, increased injury rate, and conditions mediated by other risk factors, commencing 2021, over 20 years. Methods: We used a Proportional Multistate Lifetable Model specified with disease rate and risk factor forecasts, and causal associations, derived from the Global Burden of Disease study and other sources. Findings: If all Australians shifted to the maximum physical activity level of 4200+ MET-min/week, there would be: 653,000 (230,000 - 1,210,000) or 0.16% more HALYs lived; 9,720 (7,400 to 12,700) or 1.33% fewer deaths before age 75; increased working age income of AUD$16.8 billion ($12.8 - $22.2 billion); and decreased health expenditure of $748 million (-$4.46 billion - $6.98 billion) or 0.02%. Net health gains diminish for each additional 600 MET-min/week increase in physical activity, and above 4,200 MET-min/week the health costs from injuries outweigh the reduction in health costs from avoided disease. Because of injuries, increasing physical activity in the lowest activity group to meet the physical activity guidelines reduces health expenditure more ($1.86 billion; 896 million - 3.13 billion) than shifting to maximum activity levels. Interpretation: Increasing physical activity levels in Australia would improve population health (even allowing for injuries due to participation), reduce health spending, and increase income. Funding: Australian Sports Commission. TB is funded by NHMRC Investigator Grant (2023) #2026992