Reducing Time Spent Sitting Has Impact on Premature Mortality

Reducing the amount of time spent sitting plays an important role in promoting an active lifestyle, which is an important aspect of preventing premature mortality worldwide, according to a new analysis of data from 54 countries. The study was published in the American Journal of Preventive Medicine.

Brazilian and Spanish researchers led by Leandro Fornias Machado de Rezende, MSc, found that sitting time was responsible for 3.8% of all-cause mortality (about 433,000 deaths per year in these countries), and they concluded that eliminating sitting time would increase life expectancy by 0.20 years in those nations. The researchers believe their new estimates about reducing sitting time might be helpful to policy makers considering the impact of sedentary behavior on public health.

All-cause mortality due to sitting time was higher in the countries from the Western Pacific region, followed by European, Eastern Mediterranean, American, and Southeast Asian countries.

The burden of disease attributable to inactivity has been estimated to be responsible for 6% to 9% of total deaths worldwide. Some researchers argue that excessive time spent sitting may be harmful to health regardless of whether people meet recommended guidelines of moderate-to-vigorous physical activity. They suggest that rather than focusing only on activities of at least moderate intensity, replacing sitting time with standing or light physical activity may also provide significant public health benefits.

This study’s goal was to estimate the population attributable factor (PAF) for all-cause mortality associated with time spent sitting. PAF is a measure epidemiologists use to quantify and summarize the public health burden related to one factor—in this case, time spent sitting—and how much a certain outcome (in this study, all-cause mortality) can be reduced by eliminating that factor.

The researchers found that for the adults in the 54 countries studied, the weighted mean sitting time across countries was 4.7 hours/day. Even modest reductions in sitting time, such as a 10% reduction in mean sitting time or a 30-minute absolute decrease in daily sitting time, could have an instant impact in all-cause mortality (0.6%) in the countries that were evaluated. Bigger changes, such as a 50% decrease or 2 fewer hours of sitting, would mean at least 3 times fewer deaths than the 10% or 30-minute sitting time reduction.