Optimizing physical activity bouts to interrupt sedentary behaviour for cardiometabolic health: a systematic review and meta-analyses of randomized controlled trials

AIMS: Chronic diseases such as type 2 diabetes mellitus and cardiovascular diseases are leading causes of mortality worldwide, with sedentary behaviour (SB) and physical inactivity recognized as major interrelated risk factors. Prolonged SB, particularly when combined with insufficient physical activity, adversely affects cardiometabolic health. This systematic review aimed to evaluate which characteristics of physical activity (PA) bouts, in terms of frequency, duration, and intensity, are associated with improvements in cardiometabolic outcomes. METHODS AND RESULTS: Studies assessing physical activity interventions compared with sedentary control conditions were included. Eligible studies involved adults aged 18-65 years, with or without cardiometabolic conditions. PubMed, Cochrane Central, Embase, and Web of Science were searched to February 2025. Random-effects models were used to calculate pooled standardized mean differences (SMD) with 95% confidence interval (CI). Subgroup and meta-regression analyses explored potential moderators. A total of 144 studies (247 intervention arms; 2216 participants) were included. Frequent PA bouts reduced blood glucose [SMD -0.22 (95% CI -0.27 to -0.16)]. Longer and/or more intense PA bouts decreased triglycerides [SMD -0.27 (-0.34 to -0.19)], with significant duration × intensity interactions for glucose (P = 0.032) and triglycerides (P < 0.001). Moderate-to-vigorous PA bouts improved endothelial function [flow-mediated dilation SMD 0.88 (0.47-2.24); shear rate SMD 0.54 (0.31-0.78)]. PA bouts also lowered insulin [SMD -0.26 (-0.32 to -0.19)], systolic BP [SMD -0.29 (-0.39 to -0.19)], and diastolic BP [SMD -0.16 (-0.26 to -0.05)]. CONCLUSION: In acute experimental settings, glucose regulation appears to benefit more from frequent PA bouts, while triglyceride responses are more closely related to greater duration and/or intensity. Blood pressure shows favourable acute responses across PA types, whereas higher PA intensity is associated with improved endothelial function. Tailoring strategies to interrupt SB with PA bouts may help inform approaches to improve cardiometabolic health.