Physical inactivity versus sedentariness: Analysis of the chilean national health survey 2016-2017

Background: Physical inactivity and sedentariness are independent risk factors for mortality. Physical inactivity is defined as engaging in insufficient moderate/vigorous physical activity (i.e. not meeting the WHO's recommendations). Sedentariness is defined according to sedentary behavior; evidence suggests that > 8 h/d could serve to consider a person as sedentary. The Chilean National Health Survey 2016-2017 (NHS), using a single question (Question-NHS), considered as "sedentary" those who did not engage in sports or physical activity for ≥ 30 min, ≥ 3 times/wk. Thus, it attempted to estimate sedentariness without considering sedentary behavior. Aim: To determine the prevalence of physical inactivity and sedentariness in Chile, and to contrast such results with the Question-NHS. Material and Methods: We analyzed data from 5564 participants of the 2016-2017 NHS, aged ≥ 18 years. The Global Physical Activity Questionnaire was used to determine moderate/vigorous physical activity and sedentary behavior. We defined physical inactivity as having < 600 MET × min/ wk of moderate/vigorous physical activity, and sedentariness as having > 8 h/d of sedentary behavior. Results: The prevalences [95% confidence intervals] of physical inactivity and sedentariness were 32% [29-34] and 6% [5-7] respectively, while 3% [2-4] were both physically inactive and sedentary. The Question-NHS classified 88% [86-89] as "sedentary", but among them, 35% were physically inactive and 6% were sedentary. Conclusions: One third of adults are inactive, one out of ten is sedentary, and one out of twenty is inactive and sedentary. The Question-NHS overestimates the population at risk.