Replacement Effects of Sedentary Time on Metabolic Outcomes

Introduction Sedentary time has been associated with detrimental health effects, so in some countries, guidelines to reduce sedentary time have been developed. As reducing sedentary time inevitably results in more nonsedentary time, effects of this reduction may depend on the activity with which it is replaced. Purpose This study aimed to examine associations of theoretical reallocations of sedentary time to standing or stepping with cardiometabolic outcomes and type 2 diabetes. Methods We included 2213 participants (51% men, mean ± SD age = 60.0 ± 8.1 yr) of the Maastricht Study who were asked to wear an accelerometer 24 h·d−1 for a week. We calculated daily sedentary, standing, and stepping time. An isotemporal substitution modeling approach was applied to examine effects on waist circumference; body mass index; cholesterol, triacylglycerol, glucose, and insulin levels; metabolic syndrome; and type 2 diabetes. Results Replacement of sedentary time (30 min·d−1) with stepping was associated with lower odds for metabolic syndrome (odds ratio [OR] = 0.72, 95% confidence interval [CI] = 0.66–0.78) and type 2 diabetes (OR = 0.79, 95% CI = 0.72–0.87), more favorable waist circumference (B = −1.42, 95% CI = −1.78 to −1.06), and body mass index (B = −0.48, 95% CI = −0.62 to −0.35) and improved cholesterol, triacylglycerol, glucose, and insulin levels. Replacing sedentary time with standing was associated with lower odds for metabolic syndrome and type 2 diabetes and favorable outcomes in waist circumference, cholesterol, triacylglycerol, and insulin levels. Conclusion Theoretical replacements of sedentary time with nonsedentary time (both standing and stepping) were associated with lower odds for metabolic syndrome, type 2 diabetes, and beneficial metabolic outcomes. These results could be important for the general population, including those who cannot meet physical activity guidelines. Consideration should be given to developing recommendations for daily reallocating sedentary time.