A harmonized meta-analysis concluded that longer sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30–40min of moderate-to-vigorous-intensity physical activity (MVPA) per day attenuate the association between sedentary time and risk of death. The analysis included 44370 middle-aged and older men and women followed for 4.0 to 14.5 years in 9 prospective cohort studies from 4 countries with 7.8% mortality rate. Associations between different combinations of MVPA and sedentary time were analyzed at study level using Cox proportional hazards regression analysis and summarized using random effects meta-analysis. Across cohorts, the average time spent sedentary ranged from 8.5 hours/day to 10.5 hours/day and 8 min/day to 35 min/day for MVPA. Compared with the referent group (highest physical activity/lowest sedentary time), the risk of death increased with lower levels of MVPA and greater amounts of sedentary time. Among those in the highest third of MVPA, the risk of death was not statistically different from the referent for those in the middle (16% higher) and highest (40% higher) thirds of sedentary time. Those in the lowest third of MVPA had a greater risk of death in all combinations with sedentary time; 65%, 65% and 263% higher with low, medium and high sedentary time, respectively. The findings suggest that a higher risk of premature death associated with sedentary time may be attenuated by 30–40 min of MVPA per day. Source: https://bjsm.bmj.com/
