Rising temperatures are making physical activity undesirable and even dangerous in many parts of the world, and as global heating worsens, it will further affect how much people are able to move.
Researchers analysed data from 156 countries between 2000 and 2022 and modelled how rising temperatures may affect physical activity globally by 2050.
They found that each additional month with an average temperature above 27.8C would increase physical inactivity by an average of 1.5 percentage points globally, with an even higher increase of 1.85 points in low and middle-income countries.
Physical inactivity increases the risk of cardiovascular disease, type 2 diabetes, certain cancers and mental health disorders, all of which shorten life expectancy, said the study’s lead author, Christian García-Witulski, a research fellow at the Lancet Countdown Latin America and a professor at the Pontifical Catholic University of Argentina.
Reduced physical activity is already a big global health problem and is responsible for an estimated 5% of all adult deaths, according to the study, which was published in the Lancet Global Health journal. About a third of the world’s population fails to meet World Health Organization guidelines for weekly exercise.
The study projects that the increase in physical inactivity could contribute to about half a million additional premature deaths annually and $2.4bn – $3.68bn in productivity losses by 2050.
The biggest increases in inactivity are projected to be in hotter regions such as Central America, the Caribbean, eastern sub-Saharan Africa, and equatorial south-east Asia, where inactivity could rise by more than four percentage points a month.
“This is not just a climate story, it is also an inequality story. The places expected to face the greatest increases in climate-driven inactivity are often the same places with fewer resources to adapt,” said García-Witulski.
“In settings where people have less access to cooling, fewer safe indoor alternatives, and less flexibility in their daily schedules, heat appears more likely to translate into reduced physical activity.”
The model also predicted a bigger increase in inactivity among women, which could reflect physiological differences as well as social factors, such as less time and access to cool places for exercise, said García-Witulski.
The findings are modelled projections based on self-reported activity surveys and don’t account for other climate impacts such as extreme rainfall, flooding and tropical cyclones.
The authors say the results show that physical activity should be treated as a climate-sensitive public health issue, not just an individual lifestyle choice.
“Staying active in a warming world depends not only on personal motivation, but also on urban design, infrastructure and access to reliable information. In practical terms, climate-resilient physical activity policies are those that help people remain active safely even under hotter conditions,” said García-Witulski.
That includes designing cooler cities by expanding the tree cover and shade networks in streets and parks, providing affordable air-conditioned places to exercise, and giving clear advice on how to stay safe in extreme heat, as well as ambitious emissions reductions.
