1 Research Center of Sainte Justine University Hospital, Université de Montréal, Montreal, Quebec, Canada.
2 Department of Mathematics and Statistics, Concordia University, Montreal, Quebec, Canada.
3 Department of Family Medicine, McGill University, Montreal, Quebec, Canada.
4 School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.
5 Ingram School of Nursing, McGill University, Montreal, Quebec, Canada.
6 Department of Pediatrics, University of Montréal, Montreal, Quebec, Canada.
7 PERFORM Centre, Concordia University, Montreal, Quebec, Canada.
8 School of Public Health, Department of Social and Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada.

Objectives: Obesity is the most prevalent risk factor for cardiovascular disease (CVD) in children. We developed a 2-year lifestyle intervention for youth at risk of CVD. We assessed changes in body mass index z-scores (zBMI) and key cardiometabolic risk factors, physical fitness, and capacity among those who completed the program.

Methods: The CIRCUIT program is a multidisciplinary lifestyle intervention for children aged 4 to 18 years at risk of CVD, based on a personalized plan to improve cardiometabolic outcomes by increasing physical activity and reducing sedentary behaviours. Both at baseline and 2-year follow-up, we measured zBMI, blood pressure z-scores (zBP), adiposity (%body and %trunk fat), fasting blood glucose and lipid profile, aerobic (VO₂max) and anaerobic (5×5 m shuttle run test) fitness, and physical capacity indicators. Differences between baseline and follow-up were examined using paired t-tests (for age-sex standardized outcomes) and multivariable mixed effect models, adjusted for age and sex (for other outcomes).

Results: Among the 106 participants (53 males) who completed the 2-year program, mean age at baseline was 10.9 years (SD=3.2). After 2 years, zBMI and diastolic zBP decreased by 0.30SD (95% CI: -0.44; -0.16) and 0.43SD (95% CI: -0.65; -0.23), respectively. Participants improved %body and %trunk fat, lipid profile, aerobic and anaerobic fitness levels, and physical capacity (p<0.02). No changes in systolic zBP nor in fasting plasma glucose were observed.

Conclusion: Our findings showed improved zBMI, cardiometabolic outcomes, physical fitness, and capacity among children at risk of CVD, suggesting that CIRCUIT is a promising intervention.