Analysing data from 156 countries, researchers say each additional month of extreme heat could significantly increase global inactivity levels, especially in lower-income regions.
Stepping outside for a walk or run may become increasingly more difficult as the planet warms, with a new study warning that rising temperatures could drive a global surge in inactivity, leading to hundreds of thousands of additional premature deaths each year by 2050.
ADVERTISEMENT
ADVERTISEMENT
Researchers analysed data from 156 countries between 2000 and 2022 and modelled how higher temperatures could shape global activity levels in decades to come.
They found that each additional month with an average temperature above 27.8°C was linked to a 1.5 percentage point rise in physical inactivity worldwide. The increase was steeper – at 1.85 points – in low- and middle-income countries.
The study published in The Lancet Global Health, said that "heat elevates skin blood flow and sweating, increasing cardiovascular strain, dehydration risk, and perceived exertion”.
Physical inactivity is already a major risk factor for cardiovascular disease, type 2 diabetes, certain cancers, and mental health conditions, all of which can reduce life expectancy, said the study’s lead author, Christian García-Witulski.
The growing health risks of a less active world
The study estimates that inactivity already accounts for around 5 percent of all adult deaths globally.
"Physical inactivity represents a major global health challenge. Recent findings indicate that approximately one-third of the global adult population does not adhere to WHO guidelines, which stipulate a minimum of 150 min of moderate intensity or 75 min of vigorous intensity physical activity on a weekly basis,” the study said.
By 2050, rising inactivity linked to heat could contribute to roughly 500,000 additional premature deaths each year, alongside productivity losses of between $2.4 billion and $3.68 billion (€2.18 billion to €3.35 billion), the study warned.
The sharpest increases are expected in already hot regions, including Central America, the Caribbean, eastern sub-Saharan Africa, and equatorial south-east Asia, where inactivity could rise by more than four percentage points per month.
Inactivity could rise more among women, the study suggests.
"Women and adolescents often lack access to climate-controlled recreational spaces; and public health budgets in these settings are least able to absorb downstream cardiometabolic costs," the study said.
Researchers say the results highlight the need to treat physical activity as a climate-sensitive public health issue, rather than solely an individual lifestyle choice.
The study also highlights how cities can be designed more effectively to allow for more activity - such as connected shade networks, reflective surfaces, water features, and climate-sheltered public spaces.
"Beyond heat-comfort gains, such designs can yield co-benefits that standard damage models rarely monetise - mitigating heat-related sleep loss, preserving cognitive performance, and protecting labour productivity," the study read.
Can keeping active really lower risk of mortality?
Yes. A separate study from last year found that adults who shift from inactive to active lifestyles can lower their mortality risk by 22 percent.
Another study published last year showed that reaching just 7,000 steps a day is associated with a significantly reduced risk of a wide range of conditions, including dementia, heart disease, depression, type 2 diabetes, and cancer.
According to that research - also published in_The Lancet Public Health_ - the benefits vary by condition, ranging from a 6 percent reduction in cancer risk to as much as a 38 percent decrease in dementia risk.
