Effects of a sedentary behavior reduction intervention on common cardiometabolic risk factors in metabolic syndrome patients : a three-month randomized controlled trial

Abstract

Sedentary behavior is associated with metabolic disorders, cardiovascular disease, type 2 diabetes, and premature mortality. However, evidence regarding the health effects of sedentary behavior relies mainly on findings from observational epidemiological studies, experimental trials, or interventions of a short duration, and the understanding of causal cardiometabolic benefits of sitting time reductions in long term is lacking. The purpose of this three-month intervention study was therefore to investigate whether reducing sedentary behavior could improve the cardiometabolic health in subjects at high risk for cardiometabolic diseases.

Sixty-four metabolic syndrome patients (mean age 58, standard deviation (SD) 7; 57 % women) were randomized into the intervention (n = 33) and the control group (n = 31). The intervention group was guided to limit their daily sitting time by one hour through increased standing and light physical activity, without increasing moderate-to-vigorous physical activity. The control group was guided to maintain their normal sedentary behavior and physical activity habits. At baseline and after the intervention cardiometabolic risk markers were assessed via fasting blood sample analyses and measurements of anthropometrics, body composition and blood pressure. A linear mixed model was used to estimate intervention effects and changes within groups over time, and differences between groups were tested with independent samples t-test.

At three months statistically significant intervention effects in favor of the intervention group were observed in fasting insulin, insulin sensitivity, glycated hemoglobin, triglycerides, and liver enzymes alanine and aspartate aminotransferase. The intervention effects occurred mainly due to worsening of these biomarkers over time in the control group. Statistically significant favorable within-group changes in waist circumference, body fat percentage, fat free mass, blood pressure and HDL cholesterol were observed in both groups as well. However, the intervention was not effective in preventing the worsening occurring over time in fasting glucose, LDL and total cholesterol.

In conclusion, an intervention aiming to reduce sedentary behavior can produce beneficial effects on cardiometabolic health in high-risk individuals by attenuating the worsening in several important risk biomarkers. Sedentary behavior reduction alone may not be strong enough stimulus to improve biomarkers, but preventing or delaying sedentary-induced worsening in risk biomarker levels in high-risk population may be an important public health implication.