In a recent article published in Jama Network Open, researchers performed a secondary analysis of the ActiveBrains randomized clinical trial (RCT) in Granada, Spain, between November 1, 2014, and June 30, 2016, with two primary goals.
First, they evaluated whether a 20-week exercise program improved the cardiometabolic and mental health of children with obesity. Second, they explored how the observed effects changed for each child participant.
The ActiveBrains RCT evaluated the effects of exercise on the mental health of eight-to-11-year-olds with obesity. These children did not suffer from attention deficit, hyperactivity, or physical issues. Due to more than 90% of participants being categorized as White, race or ethnicity were not considered to be important covariates. Participants were recruited mainly at the hospitals.
By offering physical, psychological, and cognitive benefits, exercise has become an essential component of obesity treatment programs, which is a leading cause of type 2 diabetes and cardiovascular disease (CVD) in pediatric populations worldwide.
A systematic review and meta-analysis of previous trials in children with obesity has demonstrated that measuring cardiometabolic risk as a composite measure of adiposity, blood lipid levels, blood pressure (BP), and metabolism during childhood is an early predictor of CVD in adolescents than the presence of metabolic syndrome.
Exercise improves visceral fat, high- and low-density lipoprotein (HDL\LDL) cholesterol levels, insulin resistance (IR), BP, body composition, cardiorespiratory fitness (CRF), and self-worth. Yet, data on the holistic benefits of exercise and the exercise response variability in obese children is limited.
About the study
In the present study, researchers randomly assigned all children to the exercise program of 20 weeks duration or the control group in a 3:1 ratio after the baseline evaluation.
During this evaluation, they collected sociodemographic data and cardiometabolic health-related measurements, e.g., systolic and diastolic BP, blood lipid biomarkers, body weight and height, whole-body fat mass, lean mass, visceral adipose tissue, physical fitness components, e.g., CRF, etc.
The participants in both groups also received a pamphlet with information regarding a healthy diet and recommended physical activities. The team again measured all these cardiometabolic health outcomes immediately after the exercise intervention program ended.
The 20-week exercise program covered resistance exercises, like aerobic and muscle-bone–strengthening activities. The team instructed all the exercise group participants to attend at least three supervised 90-minute sessions per week.
They tracked each participant’s exercise intensity during sessions. Then, the team classified children with poor cardiometabolic health based on age- and gender-specific internationally accepted reference values for CRF, a cardiometabolic health biomarker proposed by the American Heart Association.
Further, the researchers computed a cardiometabolic risk score, i.e., the median age- and gender-specific z scores for triglyceride, inverted HDL cholesterol, glucose levels, BP, and waist circumference.
A z score of at least 0.39 indicated that a child was at risk of metabolic syndrome. Likewise, they computed a composite standardized score for psychological ill-and well-being, overall mental health, and the risk of depression and anxiety.
Furthermore, the team used accelerometers to determine how much time each child spent in physical activity, being sedentary, and sleeping daily during the intervention and the daily changes induced by the exercise intervention.
Before statistical analyses, the team winsorized raw scores from each cardiometabolic health outcome. Next, they computed baseline z scores of these outcomes by subtracting their mean and then dividing them by their standard deviation (SD), representing the characteristics of the study participants.
They also computed postexercise z scores relative to the baseline SD as a standardized effect size measure.
The team had confirmed via a posteriori power analysis that a sample size of 92 children was enough to detect up to medium effect sizes, assuming an α error of 0.05 and 80% statistical power.
Notably, the researchers conducted the outcome analyses under the per-protocol (PP) and the intention-to-treat (ITT), i.e., with participants attending ≥70% and all the sessions, respectively.
Finally, the team examined the within-individual change distribution, where they considered changes >0.2 Cohen d as meaningful. They also compared the rate of change in both study groups using χ2 tests.
Results and conclusion
The current study demonstrated a noticeable reduction of ~0.38 SDs in cardiometabolic risk. After exercise interventions, more participants at risk of metabolic syndrome at baseline were no longer at risk. The researchers suggested that this was mainly a result of improved blood lipid levels, total and visceral adiposity, and CRF.
Specifically, the exercise group participants reduced their fasting LDL cholesterol levels and visceral adipose tissue by 7 mg/dL and 31.44 g, respectively, compared to children in the control group.
However, the exercise program did not change their lean mass index, speed agility, or muscular fitness. Intriguingly, these children improved their CRF performance in the test (laps) and the estimated maximum oxygen consumption (V̇o2max).
The lack of sensitivity of mental health measures used in this study and the ceiling effect experienced by the cohort justified the null findings for exercise-induced improvements in mental health.
Overall, the study findings demonstrated the potential of exercise programs to promote cardiometabolic health in children with obesity. However, more work is needed to examine these interventions in parallel with other health behaviors (e.g., a healthy diet).