Sedentary time increases the risk of adverse health conditions

Sedentary time is associated with many adverse health conditions. Replacing vigorous physical activity (VPA) instead of moderate physical activity (MPA) and light physical activity (LPA) may reduce the risk of non-communicable diseases (NCDs), according to a study published in electronic clinical medicine.1

“Sedentary time is a serious public health problem, given its high prevalence and health costs,” said researchers. “In the UK, every adult spends an average of 5 hours a day on sedentary activities, 30% of adults are sedentary for at least 6 hours a day during the week, up to 37% on weekends.

Patients (N = 360,047, aged 37-73 years) at the UK Biobank without 45 common NCDs were included in this prospective, population-based cohort study conducted between April 2006 and December 2010. Information reported by itself on sedentary life, including the amount of time spent watching TV, using a computer and driving, as well as physical activity, measured by the International Physical Activity Questionnaire, were collected at the beginning. The follow-up period analyzes the diagnosis of common NCDs, according to ICD-10, by 2020. Covariations include age, gender, ethnicity, employment status, socioeconomic status, alcohol intake, body mass index and smoking. Isotemporal substitution models determine differences in sedentary time replacement with LPA, MPA, and VPA, after adjustment for confusing factors.

The mean age of the patients was 55.8 years and 54.5% were women. Patients who self-reported> 6 hours per day (n = 67034, 18.6%), compared with ≤ 2 hours per day of sedentary period, were more likely to have a higher risk of 12 of 45 NCDs (26.7 %, P<0.0011). According to an analysis of the population fraction (PAF) for individual NCDs significantly associated with sedentary periods, 3.7% -22.1% of NCDs may not occur if sedentary life time is reduced to less than 6 hours per day.

Replacing sedentary time with LPA, MPA and VPA is associated with risk reduction of 4, 6 and 10 types of NCDs, respectively. For patients with> 6 hours of sedentary life, replacement of 1 hour per day with VPA is associated with a greater risk reduction (11% -31%) in diabetes, depression, diverticular disease, sleep disturbance and chronic liver disease. .

The study was limited by his design for observation. In addition, sedentary life and physical activity were subjectively measured, which may have led to a deviation in measurement. However, in recent years UK Biobank has implemented objective measurement of activity levels using 7-day accelerometers for certain participants. Sedentary behavior is assessed only through leisure activities, such as watching TV and computer time, without taking into account professional sedentary behavior. Therefore, the sedentary time calculated in the study cannot be summarized to the total sedentary time. Further research can be used to expand ongoing analysis. The diet was not included as covariate, which may have affected some NCDs. Finally, the results do not take into account changes in sedentary habits at the beginning and during the follow-up period.

“Our findings provide evidence of the harmful effects of prolonged sedentary time,” the researchers concluded. “Recommendations for sedentary time may show that any reduction in sedentary behavior coincides with an increase in time spent in healthier alternatives to ensure the positive effects of substitution. Further studies are needed to investigate the causal relationship through experimental intervention. “


Cao Z, Xu C, Zhang P, Wang Y. Associations of sedentary time and physical activity with adverse health conditions: Analysis of the whole result using a model of isotemporal substitution. EClinicalMedicine. 2022; 48: 101424. Published on April 28, 2022 doi: 10.1016 / j.eclinm.2022.101424

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