Association of body composition and blood pressure categories with retinal vessel diameters in primary school children

Vascular biomarkers in the prevention of childhood cardiovascular risk: From concept to clinical implementation

Vascular biomarkers allow for non-invasive assessment of vascular structure and function and have been shown to be surrogates for cardiovascular (CV) outcome in adults. They reflect the cumulative risk of a plethora of single CV risk factors, such as obesity and hypertension, on the arterial wall. The process of atherosclerosis oftentimes has its origin in childhood and tracks into adulthood. Obesity-related CV risk in childhood is a main determinant of manifest CV disease and adverse outcome in adulthood. To date, prevention strategies are directed toward the detection and reduction of CV disease in adulthood. This review updates and puts into perspective the potential use of vascular biomarkers in children. With reference to the concept of early vascular aging in adults, it elaborates on the role of vascular biomarkers for CV risk stratification in children. The concept of primordial vascular aging implies that young children be screened for vascular health, in an attempt to timely detect subclinical atherosclerosis and initiate treatment strategies to reverse vascular damage in a period of life with high probability for risk regression. The evidence for the validity of macro- and microvascular candidate biomarkers as screening tools of CV risk in children is reviewed, and limitations as well as remaining research gaps are highlighted. Furthermore, an overview on the effects of exercise treatment on vascular biomarkers is given. Vascular biomarkers susceptible to lifestyle or drug treatment have the potential to qualify as monitoring tools to guide clinicians. This review discusses evidence for vascular biomarkers to optimize screening of childhood CV risk from initial concepts to potential future clinical implementation in cardiovascular prevention.

Retinal vessel diameters and function in cardiovascular risk and disease

In the last two decades evidence has gradually accumulated suggesting that the eye may be a unique window for cardiovascular risk stratification based on the assessment of subclinical damage of retinal microvascular structure and function. This can be facilitated by non-invasive analysis of static retinal vessel diameters and dynamic recording of flicker light-induced and endothelial function-related dilation of both retinal arterioles and venules. Recent new findings have made retinal microvascular biomarkers strong candidates for clinical implementation as reliable risk predictors. Beyond a review of the current evidence and state of research, the article aims to discuss the methodological benefits and pitfalls and to identify research gaps and future directions. Above all, the potential use for screening and treatment monitoring of cardiovascular disease risk are highlighted. The article provides fundamental comprehension of retinal vessel imaging by explaining anatomical and physiological essentials of the retinal microcirculation leading to a detailed description of the methodological approach. This allows for better understanding of the underlying retinal microvascular pathology associated with the prevalence and development of cardiovascular disease. A body of new evidence is presented on the clinical validity and predictive value of retinal vessel diameters and function for incidence cardiovascular disease and outcome. Findings in children indicate the potential for utility in childhood cardiovascular disease prevention, and the efficacy of exercise interventions highlight the treatment sensitivity of retinal microvascular biomarkers. Finally, coming from the availability of normative data, solutions for diagnostic challenges are discussed and conceptual steps towards clinical implementation are put into perspective.

Association of Parental Socioeconomic Status and Physical Activity with Development of Arterial Stiffness in Prepubertal Children

The present study examined the prospective association of parental household income, education level, migration background, and physical activity (PA) behavior with the development of pulse wave velocity (PWV) in prepubertal children. A total of 223 children (initial age 6–8 years) were included in this prospective school-based cohort study from 2014 to 2018. Parental socioeconomic status, migration background, and PA behavior were assessed by the use of questionnaires at both times points. PWV was measured by an oscillometric device at follow-up (2018). No significant association of household income, education level, and parental migration background with PWV in children after four years was found. However, a high level of maternal PA was related to a lower childhood PWV at follow-up (mean (95% CI) 4.6 (4.54–4.66) m/s) compared to children of mothers with a low PA behavior (mean (95% CI) 4.7 (4.64–4.77) m/s) (p = 0.049). Children of mothers with a high PA level revealed a beneficial arterial stiffness after four years. Little evidence for an association of socioeconomic status and migration background with childhood arterial stiffness was found. Increased parental PA seems to support the development of childhood vascular health and should be considered in the generation of future primary prevention strategies of childhood cardiovascular health.

Remodeling of Retinal Microcirculation Is Associated With Subclinical Arterial Injury in Hypertensive Children

[Figure: see text].

Independent and Synergistic Effects of High Blood Pressure and Obesity on Retinal Vasculature in Young Children: The Hong Kong Children Eye Study

Background High blood pressure (BP) and obesity are becoming increasingly prevalent among children globally. Although prior studies have shown their adverse impacts on macrovascular health, less is known about their effects on microvascular heath. This study aims to evaluate the independent and synergistic effects of hypertensive BP and obesity on retinal vasculature in young children. Method and Results 1006 children aged 6 to 8 years were recruited from the Hong Kong Children Eye Study. Quantitative retinal vascular parameters, including central retinal arteriolar and venular equivalents and retinal arteriolar and venular fractal dimensions, were measured from retinal photographs following a standardized protocol. BP and body mass index were categorized according to reference values from American Academy of Pediatrics and International Obesity Task Force guidelines respectively. Children with hypertensive systolic BP had the narrowest central retinal arteriolar equivalents compared with children with either elevated or normotensive systolic BP (162.4, 164.6, and 167.1 µm; P-trend <0.001). Increased standardized systolic BP was associated with narrower central retinal arteriolar equivalents (β=-2.276 µm, P<0.001), wider central retinal venular equivalents (1.177, P=0.007), and decreased arteriolar fractal dimensions (β=-0.004, P=0.034). Children with obesity had the smallest arteriolar fractal dimensions compared with children with overweightness and normal weight (1.211, 1.234, and 1.240; P-trend=0.004). Children with both hypertensive BP and either overweightness or obesity had the narrowest central retinal arteriolar equivalents and smallest arteriolar D_f (P-trend<0.001 and P-trend=0.007). Conclusions Our findings demonstrate the potential synergistic or additive effects for both hypertensive BP and obesity on retinal vasculature in children.

Systematic review on retinal microvasculature, physical activity, sedentary behaviour and adiposity in children and adolescents

AIM

As retinal microvasculature (RMV) can be assessed non-invasively, it presents an opportunity to examine the health and disease of the human microcirculation, as RMV alterations have been recognised as one of the earliest signs of cardiovascular risk. This review summarises current literature on the associations between physical activity (PA), sedentary behaviour (SB) and/or adiposity and RMV in children and adolescents aged 0-18 years.

METHODS

Six databases were searched (MEDLINE, Scopus, Web of Science, ScienceDirect, PsycINFO and CINAHL), through to December 11, 2019. English, Portuguese, French, Spanish or Dutch were the languages searched. Meta-analyses were performed using the meta-analyst software.

RESULTS

A total of 6796 studies were screened, and 26 studies were included, representing 24 448 participants, from 12 different countries. Studies reporting results on weight status were twenty-three, PA was assessed in six studies, and SB was assessed in three studies. Four studies examined weight status and PA/SB. Meta-analysis was performed for two studies and showed that children with obesity have smaller retinal arterioles (-2.38 µm difference, 95% CI 0.62, 4.15 µm) and larger retinal venules (2.74 µm difference, 95% CI -4.78, -0.72 µm) than children without obesity.

CONCLUSION

Results showed that adiposity was associated with microvascular alterations in children and adolescents. Increased adiposity, lack of PA and high levels of SB were negatively correlated with vessel width parameters.

Retinal Vessel Diameters and Blood Pressure Progression in Children

The prevalence of high childhood blood pressure (BP) is rising globally and has been associated with subclinical vascular impairments in children. Longitudinal data on the association of microvascular alterations with the development of high BP in children are lacking. We aimed to analyze the association of central retinal arteriolar (CRAE) and venular (CRVE) diameters with development of higher BP over 4 years in young school children. In 2014, 391 children aged 6 to 8 years were screened for BP and retinal vessel diameters using standardized protocols. Retinal vessel analysis was performed using a retinal vessel analyzer to determine CRAE and central retinal venular equivalent. In the follow-up of 2018, all parameters were assessed in 262 children using the same standardized protocols. During follow-up, systolic and diastolic BP increased significantly (Δ 3.965±8.25 and 1.733±7.63 mm Hg, respectively), while CRAE decreased by Δ -6.325±8.55 µm without significant changes in central retinal venular equivalent (Δ -0.163±7.94 µm). Children with narrower CRAE at baseline developed higher systolic BP after four years (β [95% CI] 0.78 [0.170-1.398] mm Hg per 10 µm decrease, P=0.012). Children with increased systolic or diastolic BP at baseline developed narrower CRAE (β [95% CI] -0.154 [-0.294 to -0.014] µm per 1mmHg, P=0.031 and β [95% CI] -0.02 [-0.344 to -0.057] µm per 1 mmHg, P=0.006, respectively) at follow-up. Narrowing of retinal arterioles predicted evolution of systolic BP. In turn, higher initial systolic and diastolic BP was associated with subsequent development of microvascular impairments. Our results give good evidence for a bivariate temporal relationship between BP and microvascular health in children.

Microvascular function and oxidative stress in adult individuals with early onset of cardiovascular disease

The current study aims to investigate retinal vascular function and its relationship with systemic anti-oxidative defence capacity in normal individuals versus those with early hypertensive changes according to the current ESC/ESH guidelines. Retinal microvascular function was assessed in 201 participants by means of dynamic retinal vessel analysis. Blood pressure, lipid panel, oxidized (GSH) & reduced glutathione (GSSG) were also evaluated for each participant. Individuals classed as grade 1 hypertension demonstrated higher retinal arterial baseline diameter fluctuation (p = 0.0012), maximum dilation percentage (p = 0.0007), time to maximum constriction (p = 0.0003) and lower arterial constriction slope (p = 0.0131). Individuals classed as high normal and grade 1 hypertension also demonstrated higher time to maximum dilation than individuals classed as optimal or normal. GSH levels correlated negatively with SBP, DBP and MBP values in all participants (p = 0.0010; p = 0.0350 and p = 0.0050) as well as with MBP values in high normal and grade 1 hypertension (p = 0.0290). The levels of GSSG correlated positively with SBP, DBP and MBP values in all participants (p = 0.0410; p = 0.0330 and, p = 0.0220). Our results point to the fact that microvascular alterations can be identifiable at BP values still considered within normal values and go in parallel with the changes observed in the level of oxidative stress.

Obesity, High Blood Pressure, and Physical Activity Determine Vascular Phenotype in Young Children

Cardiovascular disease often develops during childhood, but the determinants of vascular health and disease in young children remain unclear. The study aimed to investigate the association of obesity and hypertension, as well as physical fitness with retinal microvascular health and large artery stiffness, in children. In this cross-sectional study, 1171 primary school children (aged 7.2±0.4 years) were screened for central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) diameters, pulse wave velocity (PWV), body mass index, blood pressure (BP), and cardiorespiratory fitness by standardized procedures for children. BP was categorized according to the reference values of the population-based German KiGGS study (Kinder- und Jugendgesundheitssurvey [Children- and Adolescents Health Survey]) and the American Academy of Pediatrics guidelines. Overweight (mean [95% CI]: CRAE, 200.5 [197.9-203.2] µm; CRVE, 231.4 [228.6-234.2] µm; PWV, 4.46 [4.41-4.52] m/s) and obese children (CRAE, 200.5 [196.4-204.7] µm; CRVE, 233.3 [229.0-237.7] µm; PWV, 4.51 [4.43-4.60] m/s) had narrower CRAE, wider CRVE, and higher PWV compared with normal-weight children (CRAE: 203.3 [202.5-204.1] µm, P<0.001; CRVE: 230.1 [229.1-230.9] µm, P=0.07; PWV: 4.33 [4.31-4.35] m/s, P<0.001). Children with high-normal BP (CRAE, 202.5 [200.0-205.0] µm; PWV, 4.44 [4.39-4.49] m/s) and BP in the hypertensive range (CRAE, 198.8 [196.7-201.0] µm; PWV, 4.56 [4.51-4.60] m/s) showed narrower CRAE, as well as higher PWV, compared with normotensive peers (CRAE: 203.7 [202.9-204.6] µm, P<0.001; PWV: 4.30 [4.28-4.32] m/s, P<0.001). With each unit increase of body mass index and systolic BP, CRAE decreased and PWV increased significantly. Children with the highest cardiorespiratory fitness had wider CRAE, narrower CRVE, and lower PWV compared with least fit children. Childhood obesity and hypertension, even at preclinical stages, are associated with microvascular and macrovascular impairments in young children. Primary prevention programs targeting physical activity behavior may have the potential to counteract development of small and large vessel disease early in life. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02853747.

Hemoglobin A1c and retinal arteriolar narrowing in children with type 1 diabetes: the diagnostics of early atherosclerosis risk in kids study

BACKGROUND/OBJECTIVE

Microvascular alterations play a key role in the development of diabetes complications. Retinal vessel analysis is a unique method to examine microvascular changes in brain-derived vessels.

METHODS

Sixty-seven pediatric and adolescent type 1 diabetes patients and 58 healthy control persons (mean age 12.4 ± 2.9 years) underwent non-mydriatic retinal photography of both eyes. Central retinal arteriolar and central retinal venular (CRVE) diameter equivalents as well as the arteriolar-to-venular ratio were calculated using a semiautomated software. All anthropometric and laboratory parameters were measured according to standardized procedures for children.

RESULTS

Retinal vessel diameter did not differ between type 1 diabetic children and healthy controls. However, there was an independent association of higher hemoglobin A1c (HbA1c) levels with arteriolar narrowing. Arteriolar narrowing of 5.4 μm was observed with each percent increase in HbA1c. Longer duration of diabetes was associated with wider retinal arterioles. CRVE was not associated with diabetes duration or HbA1c.

CONCLUSIONS

Microvascular arteriolar alterations are already present in childhood and may indicate subclinical atherosclerosis and increased risk of diabetes complications later in life. Future research will have to investigate the potential use of retinal vessel diameters for treatment monitoring and guidance of therapy in children.

Characteristics of the retinal microvasculature in association with cardiovascular risk markers in children with overweight, obesity and morbid obesity

To aim of this study was to evaluate characteristics of the retinal microvasculature, but particularly potential associations with classic and novel (endothelial function and low-grade inflammation)markers for cardiovascular risk, in a cohort of children with overweight and (morbid) obesity. Central retinal arteriolar equivalent(CRAE) and central retinal venular equivalent(CRVE) were assessed. CRAE was significantly lower and AVR significantly higher in children with morbid obesity than in children with overweight and normal weight(p < 0.01). CRVE did not differ significantly between the four weight categories. A multiple linear regression model with CRAE as dependent variable showed that only DBP z-score(β = −2.848,p = 0.029) and plasma glucose concentrations(β = 6.029,p = 0.019) contributed significantly to the variation in CRAE. Remarkably, despite a correlation between CRAE and circulating concentrations of the adhesion molecules VCAM-1 or ICAM-1, markers for inflammation and endothelial function did not contribute to the variation in CRAE. This is the first study showing in population of children with overweight and obesity that the retinal arteriolar microvasculature, but not venular diameter is aberrant, with increasing BMI z-score. CRAE was significantly associated with several cardiovascular risk markers, and multiple linear regression showed that a higher diastolic blood pressure z-score and lower fasting plasma glucose concentrations significantly contributed to the variance in CRAE.

Childhood Fat and Lean Mass: Differing Relations to Vascular Structure and Function at Age 8 to 9 Years

Objective- Childhood body mass index (BMI) has been related to vascular structure and function. However, little is known about the differing contributions of fat and lean mass to this relationship. Our objectives were to relate the fat and lean mass (bone excluded) components of BMI (fat mass index and lean mass index; mass [kg]/height [m]2) to vascular measures in prepubertal children. Approach and Results- In the UK Southampton Women's Survey mother-offspring cohort, 983 children had dual x-ray absorptiometry and vascular measurements at 8 to 9 years. Using linear regression analyses, we found that most vascular measures were related to BMI, but fat and lean mass contributed differently. Systolic blood pressure was positively associated with both fat mass index (β=0.91 [95% CI, 0.52-1.30] mm Hg) and lean mass index (β=2.16 [95% CI, 1.47-2.85] mm Hg), whereas pulse rate was positively associated with fat mass index (β=0.93 [95% CI, 0.48-1.38] b/min) but negatively associated with lean mass index (β=-1.79 [95% CI, -2.59 to -0.99] b/min). The positive relation between BMI and carotid intima-media thickness was mainly due to a positive association with lean mass index (β=0.013 [95% CI, 0.008-0.019] mm). Carotid-femoral pulse wave velocity, but not carotid-radial pulse wave velocity, was positively associated with fat mass index (β=0.06 [95% CI, 0.03-0.09] m/s). For systolic blood pressure, carotid-femoral pulse wave velocity and reactive hyperemia significant interactions indicated that the association with fat mass depended on the amount of lean mass. Conclusions- In prepubertal children, differences in vascular structure and function in relation to BMI probably represent combinations of adverse effects of fat mass, adaptive effects of body size, and relatively protective effects of lean mass.

Association between blood pressure and retinal arteriolar and venular diameters in Chinese early adolescent children, and whether the association has gender difference: a cross-sectional study

Background

To establish the independent association between blood pressure (BP) and retinal vascular caliber, especially the retinal venular caliber, in a population of 12-year-old Chinese children.

Methods

We have examined 1501 students in the 7th grade with mean age of 12.7 years. A non-mydriatic fundus camera (Canon CR-2, Tokyo, Japan) was used to capture 45⁰ fundus images of the right eyes. Retinal vascular caliber was measured using a computer-based program (IVAN). BP was measured using an automated sphygmomanometer (HEM-907, Omron, Kyoto, Japan).

Results

The mean retinal arteriolar caliber was 145.3 μm (95% confidence interval [CI], 110.6–189.6 μm) and the mean venular caliber was 212.7 μm (95% CI, 170.6–271.3 μm). After controlling for age, sex, axial length, BMI, waist, spherical equivalent, birth weight, gestational age and fellow retinal vessel caliber, children in the highest quartile of BP had significantly narrower retinal arteriolar caliber than those with lower quartiles (P for trend< 0.05). Each 10-mmHg increase in BP was associated with narrowing of the retinal arterioles by 3.00 μm (multivariable-adjusted P < 0.001), and the results were consist in three BP measurements. The association between BP measures and retinal venular caliber did not persist after adjusting for fellow arteriolar caliber. And there was no significant interaction between BP and sex, age, BMI, and birth status.

Conclusions

In a large population of adolescent Chinese children, higher BP was found to be associated with narrower retinal arterioles, but not with retinal venules. Sex and other confounding factors had no effect on the relationship of BP and retinal vessel diameter.

Obesity, Blood Pressure, and Retinal Vessels: A Meta-analysis

CONTEXT

Retinal vessel imaging is a noninvasive diagnostic tool used to evaluate cardiovascular risk. Childhood obesity and elevated blood pressure (BP) are associated with retinal microvascular alterations.

OBJECTIVE

To systematically review and meta-analyze associations between obesity, BP, and physical activity with retinal vessel diameters in children.

DATA SOURCES

We conducted a literature search through the databases of PubMed, Embase, Ovid, Web of Science, and the Cochrane Register of Controlled Trials.

STUDY SELECTION

School- and population-based cross-sectional data.

DATA EXTRACTION

General information, study design, participants, exposure, and outcomes.

RESULTS

A total of 1751 studies were found, and 30 full-text articles were analyzed for eligibility. Twenty-two articles (18 865 children and adolescents) were used for further assessment and reflection. Eleven articles were finally included in the meta-analysis. We found that a higher BMI is associated with narrower retinal arteriolar (pooled estimate effect size -0.37 [95% confidence interval (CI): -0.50 to -0.24]) and wider venular diameters (0.35 [95% CI: 0.07 to 0.63]). Systolic and diastolic BP are associated with retinal arteriolar narrowing (systolic BP: -0.63 [95% CI: -0.92 to -0.34]; diastolic BP: -0.60 [95% CI -0.95 to -0.25]). Increased physical activity and fitness are associated with favorable retinal vessel diameters.

LIMITATIONS

Long-term studies are needed to substantiate the prognostic relevance of retinal vessel diameters for cardiovascular risk in children.

CONCLUSIONS

Our results indicate that childhood obesity, BP, and physical inactivity are associated with retinal microvascular abnormalities. Retinal vessel diameters seem to be sensitive microvascular biomarkers for cardiovascular risk stratification in children.

Retinal Vessel Diameters and Physical Activity in Patients With Mild to Moderate Rheumatic Disease Without Cardiovascular Comorbidities

Objectives: Low-grade systemic inflammation is responsible for atherosclerotic lesions in patients with rheumatic diseases. Vascular dysfunction is a precursor of atherosclerosis and can be improved by physical activity (PA). Our aim was to asses micro- and macrovascular function as well as PA and cardiorespiratory fitness (CRF) in patients with rheumatic diseases in the absence of cardiovascular (CV) comorbidities compared to controls. Methods: Fifty-one patients without CV comorbidities were compared to 35 controls. Retinal microvascular diameters were assessed using a Retinal Vessel Analyzer. Arterial stiffness (AST) was measured by applanation tonometry. CRF was assessed as peak oxygen consumption and PA was assessed with a questionnaire. Results: Retinal venular diameters were significantly wider in patients [median 221 μm (interquartile range (IQR) 211, 231)] compared to controls [median 215 μm (IQR 196, 223); p = 0.01]. One hour increase of PA per week led to a venular constriction of -0.56 μm (95%CI -1.09, -0.03; p = 0.04). In our patients with low disease activity (median DAS28 1.9; median BASDAI 2.8), no differences in AST were evident compared to controls. The association of PA and CRF with AST was not independent of blood pressure. Conclusions: Patients with rheumatic disease and mild-to-moderate disease activity show an impairment of the retinal microvasculature but not of large artery stiffness. Retinal vessel analysis seems to be a sensitive biomarker to unmask vascular impairments even in the absence of classic CV risk factors. PA may have the potential to counteract the development of small artery disease at early stages of rheumatic disease.

Ocular Signs Related to Overweight and Arterial Hypertension in Children: A Systematic Review

Background:

The ocular effects of obesity and hypertension need to be established and can be used as prognostic markers.

Objective:

To estimate the prevalence of ophthalmological alterations in children and adolescents who are overweight and/or have SAH.

Methods:

The database for this study included all observational studies (CS, cohort, case-control and “baseline” description of randomized clinical trials) with children and/or adolescents who were overweight, obese or had SAH and that measured ophthalmological alterations.

Results:

Comparative studies with healthy children demonstrated positive association between body adiposity with retinal venular dilation, and SAH with retinal arteriolar narrowing. Different retinal fundus cameras and computer-assisted programs to evaluate the retinal vessels, variations in the methods of analysis, adjustments, populations, were the main arguments against formal meta-analysis. The heterogeneity was too high (I² >90%, in fixed or randomized effects), and the lack of linearity, normal distribution and homoscedasticity did not recommend meta-regression.

Conclusion:

Obesity and SAH show associations with ophthalmological alterations, especially with retinal vessel diameter. Lack of standardization does not allow a quantitative evaluation.

In 6- to 8-year-old children, hair cortisol is associated with body mass index and somatic complaints, but not with stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness

OBJECTIVES

Hair cortisol measurement has become an increasingly accepted approach in endocrinology and biopsychology. However, while in adult research hair cortisol has been proposed as a relevant biomarker for chronic stress (and its adverse consequences), studies with children are scarce. Therefore, the goal of the present exploratory study was to examine the associations between hair cortisol concentrations (HCCs), stress, and a series of health-related outcomes in a sample of Swiss first grade schoolchildren.

METHODS

The sample consisted of 318 children (53% girls, M_age=7.26, SD=0.35). Hair strands were taken near the scalp from a posterior vertex position, and HCCs were tested for the first 3-cm hair segment. Parents provided information about their children's age, gender, parental education, children's stress (recent critical life events, daily hassles), health-related quality of life, and psychosomatic complaints. Body composition, blood pressure, retinal vessel diameters, and cardiorespiratory fitness were measured with established methods.

RESULTS

In multiple regression analyses, higher HCCs were weakly associated with increased BMI in girls (β=0.22, p<0.001), whereas higher HCCs were associated with increased somatic complaints in boys (β=0.20, p<0.05). No significant relationships were found between HCCs and parental reports of stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness.

CONCLUSIONS

Although small significant relationships were found between HCCs, BMI and somatic complaints, the findings of this exploratory study challenge the view that HCCs can be used as a reliable biomarker of recent critical life events, daily hassles, health-related quality of life, and cardiovascular health indicators in non-clinical young children.

Relationship between cardiorespiratory fitness and blood pressure in young adults: a mediation analysis of body composition

High blood pressure levels are among the most important cardiovascular disease risk factors and are influenced by physical fitness and body composition. However, the degree to which obesity may attenuate or modify the beneficial effects of physical fitness on blood pressure levels in young adults is uncertain. Thus, the aim of this study was to analyze whether body composition is a mediator between cardiorespiratory fitness (CRF) and blood pressure levels in young adults. This work was a cross-sectional study involving first-year college students (n=386) at the University Campus of Cuenca (Spain). We measured weight, height, waist circumference, fat mass percentage (by densitometry), systolic and diastolic blood pressure and CRF levels (by a 20 m shuttle run test). Partial correlation coefficients were estimated to examine the relationships among adiposity variables, CRF and blood pressure variables, controlling for age and sex. ANCOVA models were conducted to explore differences in blood pressure levels across adiposity and CRF categories. Hayes's PROCESS macro was used for the simple mediation analysis. The indirect effect and Sobel test were significant (P<0.001), confirming that all body composition variables mediate between CRF and all of the included blood pressure variables. All body composition variables acted as mediators between CRF and blood pressure. These results highlight the importance of maintaining a healthy body composition to prevent hypertension in young adults.

In 6- to 8-year-old children, cardiorespiratory fitness moderates the relationship between severity of life events and health-related quality of life

PURPOSE

In children, the pathways by which physical activity and fitness are associated with physical and psychological wellbeing are still not fully understood. The present study examines for the first time in young children whether high levels of cardiorespiratory fitness and physical activity moderate the relationship between severity of life events and health-related quality of life.

METHODS

Three hundred and seventy-eight children (188 girls, 190 boys, M _age = 7.27 years) participated in this cross-sectional study. Parental education, gender, age, severity of life events, health-related quality of life and physical activity were assessed via parental questionnaires. Cardiorespiratory fitness was assessed with the 20 m shuttle run test. Hierarchical regression analyses were used to test whether physical activity and fitness interacted with critical life events to explain health-related quality of life.

RESULTS

When exposed to critical life events, children with higher fitness levels experienced higher levels of psychological wellbeing, relative to their less fit peers. On the other hand, children with higher fitness levels experienced higher physical wellbeing and more positive friendship relationships when severity of life events was low. A similar moderation effect was found for physical activity with overall quality of life as outcome.

CONCLUSIONS

Recent stressful experiences alone were not sufficient to explain negative health outcomes in young children. Children with low cardiorespiratory fitness levels experienced lower psychological wellbeing when they were exposed to critical life events. More research is needed to find out whether similar findings emerge with objective physical activity measurements and when critical life events are assessed over longer periods of time.

Does Physical Fitness Buffer the Relationship between Psychosocial Stress, Retinal Vessel Diameters, and Blood Pressure among Primary Schoolchildren?

Background. Strong evidence exists showing that psychosocial stress plays an important part in the development of cardiovascular diseases. Because physical inactivity is associated with less favourable retinal vessel diameter and blood pressure profiles, this study explores whether physical fitness is able to buffer the negative effects of psychosocial stress on retinal vessel diameters and blood pressure in young children. Methods. 325 primary schoolchildren (51% girls, M_age = 7.28 years) took part in this cross-sectional research project. Retinal arteriolar diameters, retinal venular diameters, arteriolar to venular ratio, and systolic and diastolic blood pressure were assessed in all children. Interactions terms between physical fitness (performance in the 20 m shuttle run test) and four indicators of psychosocial stress (parental reports of critical life events, family, peer and school stress) were tested in a series of hierarchical regression analyses. Results. Critical life events and family, peer, and school-related stress were only weakly associated with retinal vessel diameters and blood pressure. No support was found for a stress-buffering effect of physical fitness. Conclusion. More research is needed with different age groups to find out if and from what age physical fitness can protect against arteriolar vessel narrowing and the occurrence of other cardiovascular disease risk factors.