Associations of Cardiorespiratory Fitness and Adiposity With Arterial Stiffness and Arterial Dilatation Capacity in Response to a Bout of Exercise in Children

Longitudinal Mediating Effect of Fat Mass and Lipids on Sedentary Time, Light PA, and MVPA with Inflammation in Youth

CONTEXT

Inflammation has been associated with atherosclerosis and metabolic disorders in youth. Preventing inflammation through exposure to different accelerometer-based movement behaviors has not been longitudinally examined.

OBJECTIVE

This work aimed to examine the mediating role of fat mass, lipids, and insulin resistance on the associations of cumulative sedentary time (ST), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with inflammation.

METHODS

From the Avon Longitudinal Study of Parents and Children, United Kingdom, 792 children with data on at least 2 time-point measures of accelerometer-based ST, LPA, and MVPA during age 11, 15, and 24 years follow-up clinic visits with complete high-sensitivity C-reactive protein (hsCRP) measures at age 15, 17, and 24 years were studied. Mediating associations were examined using structural equation models. When the magnitude of the association between the exposure and outcome is increased after including a third variable, suppression occurred but mediation if decreased.

RESULTS

Among 792 (58% female; mean [SD] age at baseline, 11.7 [0.2] years), ST increased, LPA decreased, and MVPA had a U-shaped increase while hsCRP increased during 13-year follow-up. Insulin resistance partly suppressed (23.5% suppression) the positive associations of ST with hsCRP among participants who were overweight/obese. Fat mass partly mediated (30% mediation) the negative associations of LPA with hsCRP. Fat mass had a 77% mediation effect on the negative associations of MVPA with hsCRP.

CONCLUSION

ST worsens inflammation, but increased LPA had a 2-fold inflammatory-lowering effect and was more resistant to the attenuating effect of fat mass compared with MVPA, and hence should be targeted in future interventions.

A Systematic Review of the Associations of Adiposity and Cardiorespiratory Fitness With Arterial Structure and Function in Nonclinical Children and Adolescents

PURPOSE

To summarize the evidence on associations of adiposity and cardiorespiratory fitness (CRF) with arterial structure and function in nonclinical children and adolescents.

METHODS

Two researchers conducted a search in 5 electronic databases in April 2022 to find studies in nonclinical youth (age 5-17.9 y) reporting multivariable associations. Studies were eligible if adiposity and/or CRF were used as the predictor and arterial structure and/or function was the outcome. The Quality Assessment Tool for Quantitative Studies was used to assess methodological quality for experimental studies, and a modified version was used for observational studies.

RESULTS

Ninety-nine studies (72.7% cross-sectional) were included. Ninety-four assessed associations between adiposity and arterial outcomes, most using overall body proportion (n = 71), abdominal (n = 52), or whole-body adiposity (n = 40). Most evidence was inconsistent or nonsignificant, but 59 studies suggested higher abdominal adiposity and worse body proportion were associated with adverse arterial outcomes. Twenty-one assessed associations between CRF and arterial outcomes, with findings inconsistent. Most evidence was rated weak in quality.

CONCLUSION

While high adiposity may contribute to poor arterial outcomes, evidence is limited regarding CRF. Future studies should disentangle these associations by studying youth with healthy adiposity but poor CRF, or vice versa, using longitudinal or experimental study designs.

Cardiorespiratory Fitness, Fat Mass, and Cardiometabolic Health with Endothelial Function, Arterial Elasticity, and Stiffness

PURPOSE

This study aimed to determine whether estimated cardiorespiratory fitness (CRF), fat mass (FM), lean mass (LM), and adiponectin bidirectionally associate with arterial function and structure and if CRF mediates the relationship between cardiometabolic health and arterial outcomes in 9- to 11-yr-old children drawn from the Avon Longitudinal Study of Parents and Children birth cohort, United Kingdom.

METHODS

Brachial artery flow-mediated dilation (FMD), distensibility coefficient (DC), and carotid-radial pulse wave velocity (PWV) were measured by ultrasonography; CRF was measured during the submaximal ergometer test; total FM, trunk FM, and LM were measured by dual-energy x-ray absorptiometry; plasma adiponectin was measured by enzyme assay; and cardiometabolic health was computed based on the International Diabetes Federation criteria for diagnosing metabolic syndrome. We tested bidirectionality by including CRF, FM, LM, and adiponectin as exposures and FMD, DC, and PWV as outcomes, alternatively.

RESULTS

Among 5566 participants (2816 (51%) girls; median age, 9.75 yr), CRF per body mass0.21 was directly related to DC (β (95% confidence interval) = 0.004 (<0.0001 to 0.008); P = 0.046), whereas CRF per LM0.54 was inversely associated with PWV (-0.034 (-0.063 to -0.003); 0.032) after adjusting for covariates. These associations remained in bidirectional analyses. Total FM, trunk FM, and LM were bidirectionally and positively associated with FMD and DC. Total FM and trunk FM but not LM had bidirectional and inverse associations with PWV. Adiponectin was not related to FMD, DC, or PWV. CRF partially mediated the associations of cardiometabolic health with FMD (1.5% mediation), DC (12.1% mediation), and PWV (3.5% mediation).

CONCLUSIONS

Associations of poor cardiometabolic health with adverse arterial structure and function in childhood may be mitigated by increasing CRF. Higher CRF was associated with better arterial structure whereas higher total FM and trunk FM were associated with better arterial function and structure. In the reverse analysis, healthy arterial structure and function were independently associated with increased total FM and trunk FM, suggesting an "arterial paradox."

Longitudinal associations of physical activity, sedentary time, and cardiorespiratory fitness with arterial health in children - the PANIC study

We investigated the longitudinal associations of physical activity (PA), sedentary time (ST), and cardiorespiratory fitness (CRF) with arterial health among children. In our primary analyses, we investigated 245 children (girls 51.8%) aged 6-9 years participating in the baseline examinations who had data on arterial health at 2-year follow-up. We also utilized a subsample of 90 children who had a complete arterial health data at baseline and 2-year follow-up. ST (≤1.5 METs), light PA (>1.5-4 METs), moderate PA (>4-7 METs), vigorous PA (>7METs), and moderate-to-vigorous PA (MVPA, >4 METs) were assessed by combined movement and heart rate monitoring and CRF by maximal exercise testing on a cycle ergometer at baseline and 2-year follow-up. Stiffness index (SI) as a measure of arterial stiffness and change in reflection index during exercise test (DRI) as a measure of arterial dilation capacity were assessed by pulse contour analysis. Two-year change in vigorous PA was associated with DRI in boys but not in girls (p=0.021 for interaction). In a subsample analyses, 2-year changes in MPA, VPA, and MVPA were inversely associated with 2-year change in SI. In conclusion, promoting PA at higher intensities may confer larger benefits on arterial health than reducing ST and increasing LPA.

Vascular Structure and Function in Children and Adolescents: What Impact Do Physical Activity, Health-Related Physical Fitness, and Exercise Have?

A physically active lifestyle can prevent cardiovascular disease. Exercise intervention studies in children and adolescents that aim to increase physical activity have resulted in reduced vascular wall thickening and improve cardiovascular function. Here we review the literature that explores the correlations between physical activity, health-related physical fitness, and exercise interventions with various measures of vascular structure and function in children and adolescents. While several of these studies identified improvements in vascular structure in response to physical activity, these associations were limited to studies that relied on questionnaires. Of concern, these findings were not replicated in studies featuring quantitative assessment of physical activity with accelerometers. Half of the studies reviewed reported improved vascular function with increased physical activity, with the type of vascular measurement and the way physical activity was assessed having an influence on the reported relationships. Similary, most of the studies identified in the literature report a beneficial association of health-related physical fitness with vascular structure and function. Overall, it was difficult to compare the results of these studies to one another as different methodologies were used to measure both, health-related physical fitness and vascular function. Likewise, exercise interventions may reduce both arterial wall thickness and increased vascular stiffness in pediatric populations at risk, but the impact clearly depends on the duration of the intervention and varies depending on the target groups. We identified only one study that examined vascular structure and function in young athletes, a group of particular interest with respect to understanding of cardiovascular adaptation to exercise. In conclusion, future studies will be needed that address the use of wall:diameter or wall:lumen-ratio as part of the evaluation of arterial wall thickness. Furthermore, it will be critical to introduce specific and quantitative measurements of physical activity, as intensity and duration of participation likely influence the effectiveness of exercise interventions.