A sedentary lifestyle—defined as low-energy activities performed while sitting, reclining, or lying down for at least 30 consecutive minutes—is associated with a range of adverse health outcomes.
People who accumulated the longest uninterrupted periods of sitting had a higher risk of cancer mortality, overall cancer incidence, obesity-related cancers, and cancers associated with type 2 diabetes, according to a study published in PLOS Medicine.
The researchers found that each additional hour of prolonged uninterrupted sitting was associated with a 10% increase in the risk of death from cancer.
The good news is that even modest amounts of physical activity can help reduce this risk. Replacing one hour of sitting with light physical activity—such as walking, washing dishes, or ironing—was associated with a 12% lower risk of cancer death. Replacing 30 minutes of sitting with moderate-intensity activities, such as mopping the floor or brisk walking, reduced the risk by 8%, while just five minutes of vigorous activity, such as running or playing basketball, was linked to a 22% reduction in cancer mortality.
"Our findings suggest that the health effects of sedentary behavior may depend not only on the total amount of time spent sitting, but also on whether that time is accumulated in long, uninterrupted bouts or broken up by periods of activity," the authors wrote.
They noted that previous experimental studies have shown that interrupting prolonged sitting with brief periods of movement improves metabolic health compared with remaining seated continuously.
"Current public health recommendations place strong emphasis on moderate- and vigorous-intensity physical activity. However, our findings indicate that light-intensity activity should not be overlooked," the researchers added.
According to participants' self-reports, sedentary behavior accounts for approximately 55% of waking hours in both children and adults.
At the World Health Assembly in 2018, countries adopted a global target to reduce physical inactivity by 15% by 2030, compared with 2010 levels.
However, the World Health Organization (WHO) has warned that progress is off track, with millions of adults worldwide still failing to meet recommended levels of physical activity.
In 2024, the WHO cautioned that if current trends continue, the global prevalence of physical inactivity could reach 35% by 2030.
Physical inactivity is more common among women than men, affecting 34% of women globally compared with 29% of men. Adults aged 60 years and older are also less physically active than younger adults, underscoring the importance of promoting regular movement and exercise throughout later life.
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