Effects of reducing sedentary behaviour on cardiac structure and function in adults with metabolic syndrome: a six-month randomised controlled trial

Background The effects of reducing sedentary behaviour (SB) on cardiac structure and function remain unknown, yet reducing SB may have potential for heart failure prevention. Purpose The aim of this study was to investigate whether reducing SB could lead to healthy cardiac remodelling. Methods Sixty-four physically inactive adults with metabolic syndrome were randomised into an intervention (n=33) or a control (n=31) group. The intervention group aimed at reducing SB by 1 h/day for six months and increasing non-exercise activities or standing and the control group was advised to continue as usual. All participants wore accelerometers for SB and physical activity (PA) assessment during the whole study. Conventional echocardiographic measurements of cardiac structure and (resting) function were taken before and after the study. Results The intervention resulted in a 40 min/day reduction in SB and a concomitant 20 min/day increase in moderate-to-vigorous PA. In the main analyses, no intervention effects on any echocardiographic variable were observed. However, when the participants were re-grouped according to the measured change in SB (i.e., less sedentary group: SB reduction at least 3 %-points [~27 min/day] vs. continuously sedentary group: SB reduction <3 %-points or increase in SB), left ventricular (LV) mass index and LV end-diastolic diameter decreased statistically significantly more in the less sedentary group (group x time p=0.045 and 0.020, respectively; Figure 1). In the whole study group, the change in light PA correlated inversely with the change in LV mass index (r=-0.32, p=0.026). Furthermore, the change in standing correlated with the change in E/e’ ratio (r=0.28, p=0.048). Conclusion An intervention aimed at reducing SB by 1 h/day was not sufficient at affecting cardiac structure or function. However, successfully reducing SB may lead to healthy LV remodelling. Figure 1