As the planet warms, increasing heat is expected to limit people’s ability to remain physically active. Physical inactivity is already a major global health concern, with nearly one in three adults failing to meet the World Health Organization (WHO) guidelines for weekly exercise.

The study analysed data from 156 countries between 2000 and 2022 to project how rising temperatures may influence physical activity levels through 2050.

Findings suggest that for every additional month with an average temperature above 27.8°C, physical inactivity could increase by 1.5 percentage points globally and 1.85 percentage points in low- and middle-income countries, while showing no significant impact in high-income nations.

This rise in inactivity is projected to result in an estimated 470,000 to 700,000 additional premature deaths annually, along with $2.40–$3.68 billion in global productivity losses.

The impact is expected to be most severe in already hot regions, including Central America, the Caribbean, Eastern Sub-Saharan Africa, and Equatorial Southeast Asia, where inactivity levels could rise by more than 4 percentage points for each additional month of extreme heat.

However, researchers caution that these findings are based on modelling and self-reported physical activity data, and only account for temperature changes. As such, there remains uncertainty about the precise real-world effects.

The authors stress the need for urgent action to mitigate the health impacts of rising temperatures.

Recommended measures include designing cooler, climate-resilient cities, improving access to affordable air-conditioned spaces for exercise, and providing clear public guidance on staying safe during extreme heat. They also emphasise the importance of reducing greenhouse gas emissions to limit long-term risks.