CE: Too Much Sitting: A Newly Recognized Health Risk

Abstract

: While moderate-to-vigorous physical activity (MVPA) has been widely accepted as a major factor in promoting optimal health, emerging research specific to sedentary behavior suggests that MVPA alone may not be enough. This integrative literature review examines the evidence on sedentary behavior as an independent health risk for cardiometabolic health conditions, certain cancers, and all-cause mortality. In so doing, it reveals new insights into high-volume sitting and prolonged uninterrupted sitting and their relationship to adverse health conditions in order to increase awareness of sedentary behavior as an independent health risk factor, examine the potential effects of displacing sedentary time with light-intensity physical activity, and encourage nurses to advance the overall reduction of sedentary behavior.

Can Replacing Sitting Time with Standing Time Improve Adolescents’ Cardiometabolic Health?

“…Our findings indicated that replacement of 30, 60, or 120 min of sitting time with standing promotes a reduction of 2.4%, 4.8%, and 9.7% for TC; 3.6%, 7.0%, and 14.3% for non-HDL-c; and 3.1%, 6.3%, and 16.2% for LDL-c. These findings are consistent with previous epidemiological and experimental studies [7,9,20,21,39,40,41], which show that reducing daily sitting time by approximately 60 min may probably be the minimum necessary to obtain clinical benefits, with further reductions resulting in greater health gain. Therefore, along with messages related to the accumulation of at least 60 min·day −1 of MVPA, adolescents should also be encouraged to sit less and stand more.…”

“…In the TG analysis, it was observed that the replacement of sitting time with standing led to an increase in serum TG level. This result was somewhat unexpected, since the presumed hypothesis was that the enzymatic actions triggered by the muscular contractions necessary to assume the standing posture would cause a reduction of TG levels [9,38]. Therefore, it should be noted that the TG baseline was labeled as borderline, and this may have influenced this outcome.…”

“…A possible explanation for this divergence is that the samples used in the two aforementioned studies [7,20] were composed of people at high risk for type 2 diabetes and therefore had high baseline levels of carbohydrate-related biomarkers. Other potential physiological mechanisms that may explain the standing time benefits on biomarkers linked to lipid metabolism exist [9,15,38]. Studies have suggested that increased activity of lipoprotein lipase and hormone-sensitive lipase, enzymes responsible for the hydrolysis of triglyceride-rich lipoproteins during muscle contractions, promote the breakdown of TGs into free fatty acids, reducing TGs in circulation [9,38].…”

“…Other potential physiological mechanisms that may explain the standing time benefits on biomarkers linked to lipid metabolism exist [9,15,38]. Studies have suggested that increased activity of lipoprotein lipase and hormone-sensitive lipase, enzymes responsible for the hydrolysis of triglyceride-rich lipoproteins during muscle contractions, promote the breakdown of TGs into free fatty acids, reducing TGs in circulation [9,38]. This fact may also explain the decrease observed for TG when the replacement time was elevated from 15 min to up to 120 min.…”

“…Recently, accumulating evidence has suggested that sitting time is associated with poor cardiometabolic health outcomes [6,7,8,9,10,11,12], and an increase in all-cause mortality rates and cardiovascular diseases [8,9,13,14], even after adjusting for moderate-to-vigorous physical activity (MVPA) and leisure-time physical activity [7,8,13]. However, these studies were mostly conducted in adults; for children and adolescents, such associations require further evidence [7,8,9,10,11]. Given the ubiquitous nature of sitting in our modern society, recent studies have focused on seeking alternatives to reduce the daily sitting time [2,15,16].…”