Endothelial wall thickness, cardiorespiratory fitness and inflammatory markers in obese and non-obese adolescents

Lower adiponectin is associated with higher anthropometry and insulin resistance but not with low cardiorespiratory fitness in adolescents

PURPOSE

The aim of this study was to analyze the relationship between adiposity, cardiometabolic risk and cardiorespiratory fitness (CRF) according to different groups of adiponectin concentration.

METHODS

255 adolescents of both sexes, aged 11-17 years old, participated. Anthropometric and biochemical parameters such as body mass, height, abdominal circumference (AC), waist circumference (WC), fat mass, fat-free mass, total cholesterol (TC), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c), triglycerides (TG), glucose, insulin, adiponectin, blood pressure, peak oxygen consumption (VO2peak) were measured. Body mass index (BMI), z-score BMI (BMI-z), triponderal mass index (TMI), waist-to-height ratio (WHtR), homeostasis model to assessment insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were calculated. Adiponectin was categorized: low adiponectin concentration (LAC  ≤ 5.18 µg/mL-1), intermediate (IAC = 5.18 and 7.63 µg/mL-1) and high (HAC ≥ 7.63 µg/ml-1).

RESULTS

LAC showed higher BMI, BMI-z and TMI than the other groups (p < 0.05) and higher AC, WC and WHtR that the HAC (p < 0.05). IAC showed lower values of TC, LDL-c and TG, and the LAC presented the highest values of insulin, HOMA-IR and QUICKI (p < 0.05) to the IAC and HAC. HAC presented the lower VO2peak than the other groups (p < 0.01). BMI, TMI, glucose, insulin, HOMA-IR showed inverse, and QUICKI a direct and weak correlation with adiponectin (p < 0.05). No significant association was found between adiponectin and VO2peak (p > 0.05).

CONCLUSION

The LAC group had higher means in the anthropometric variables and the worst results related to insulin resistance and sensitivity. Thus, adiponectin may play an important role in obesity and reduced concentration may be a factor in the development of obesity-associated morbidities.

Effect of adiposity and physical fitness on cardiometabolic risk factors in adolescents: A 2-year longitudinal study

Although risk factors for cardiometabolic diseases begin to present in young people, the association between physical fitness and adiposity with traditional and novel risk factors for cardiometabolic diseases across adolescence remains relatively unknown. Following ethical approval, fifty-two adolescents (age 11.6 ± 0.6 years; 32 girls) were recruited for a 2-years longitudinal study. Adiposity was assessed based on sum of skinfolds, waist circumference and body mass index, and physical fitness as distance run on the multi-stage fitness test (MSFT). Risk factors for cardiometabolic diseases (pro- and anti-inflammatory cytokines, plasma insulin, Homeostatic Model Assessment of Insulin Resistance - HOMA-IR, blood pressure) were measured following an overnight fast. Relationships between independent and response variables were analysed using multi-level modelling (final combined models were created using the stepwise backward elimination method). Plasma insulin concentration and HOMA-IR were positively associated with adiposity and inversely associated with distance run on the MSFT (all p < 0.05). The final combined models for plasma insulin concentration and HOMA-IR contained main effects for age, skinfolds and distance run on the MSFT. Levels of the anti-inflammatory cytokine IL-10 were inversely related to the sum of skinfolds (p = 0.046), whereas there was a trend for levels of the pro-inflammatory cytokine TNF-α to be positively related to the sum of skinfolds (p = 0.056). Adiposity and physical fitness are important, independent, determinants of metabolic health in adolescents. Furthermore, adiposity influences levels of pro- and anti-inflammatory cytokines in adolescence, with greater adiposity associated with a poorer inflammatory profile. The present study demonstrates an independent effect of physical fitness on metabolic health longitudinally across adolescence. It is therefore recommended that future work develops therapeutic interventions that reduce adiposity and enhance physical fitness in adolescents, to promote lifelong health.

Predictors of postprandial glycaemia, insulinaemia and insulin resistance in adolescents

Postprandial glycaemia and insulinaemia are important risk factors for type 2 diabetes. The prevalence of insulin resistance in adolescents is increasing, but it is unknown how adolescent participant characteristics such as BMI, waist circumference, fitness and maturity offset may explain responses to a standard meal. The aim of the present study was to examine how such participant characteristics affect the postprandial glycaemic and insulinaemic responses to an ecologically valid mixed meal. Data from the control trials of three separate randomised, crossover experiments were pooled, resulting in a total of 108 participants (fifty-two boys, fifty-six girls; aged 12·5 (SD 0·6) years; BMI 19·05 (SD 2·66) kg/m2). A fasting blood sample was taken for the calculation of fasting insulin resistance, using the homoeostatic model assessment of insulin resistance (HOMA-IR). Further capillary blood samples were taken before and 30, 60 and 120 min after a standardised lunch, providing 1·5 g/kg body mass of carbohydrate, for the quantification of blood glucose and plasma insulin total AUC (tAUC). Hierarchical multiple linear regression demonstrated significant predictors for plasma insulin tAUC were waist circumference, physical fitness and HOMA-IR (F(3,98) = 36·78, P < 0·001, adjusted R2 = 0·515). The variance in blood glucose tAUC was not significantly explained by the predictors used (F(7,94) = 1·44, P = 0·198). Significant predictors for HOMA-IR were BMI and maturity offset (F(2,102) = 14·06, P < 0·001, adjusted R2 = 0·021). In summary, the key findings of the study are that waist circumference, followed by physical fitness, best explained the insulinaemic response to an ecologically valid standardised meal in adolescents. This has important behavioural consequences because these variables can be modified.

Separate and combined relationships for cardiorespiratory fitness and muscular strength with visceral fat and insulin sensitivity in adolescents with obesity

We examined the separate and combined associations for cardiorespiratory fitness (CRF) and muscular strength (MS) with total and regional fat, and insulin sensitivity (IS) in 204 adolescents (BMI ≥85th percentile, 12-18 years) at UPMC Children's Hospital of Pittsburgh. CRF was measured by maximum oxygen consumption during a graded treadmill test. MS was quantified by combining 1-repetition maximum test for the leg and bench press. Participants were stratified as having either high or low CRF and MS based on sex-specific median split. Both high CRF and high MS groups had lower (P < 0.05) total fat after adjustment for sex, Tanner stage and ethnicity than the low CRF and MS groups (Difference: 6.6, 2.6-9.6% and 5.4, 2.4-8.3%, respectively). High CRF, but not high MS, had lower visceral (67.5 versus 77.9 cm², P < 0.01) and intermuscular fat (3.6 versus 4.0 kg, P = 0.01) than the low CRF groups. Differences by CRF remained significant after adjustment for MS. High CRF, but not high MS, was associated (P < 0.05) with lower fasting glucose and higher IS after accounting for sex, Tanner stage and ethnicity than the low CRF group, and high CRF remained associated with these markers after adjustment for MS. High CRF is associated with lower total and regional fat, and higher IS after adjustment for MS. Novelty: CRF is associated with lower total fat, visceral and intermuscular fat, and higher insulin sensitivity adjusting for muscular strength. Muscular strength is not associated with regional body fat and insulin sensitivity after accounting for CRF.

Oxidative Stress and Inflammation, Key Targets of Atherosclerotic Plaque Progression and Vulnerability: Potential Impact of Physical Activity

Atherosclerosis, a complex cardiovascular disease, is a leading cause of mortality and morbidity worldwide. Oxidative stress and inflammation are both involved in the development of atherosclerotic plaque as they increase the biological processes associated with this pathology, such as endothelial dysfunction and macrophage recruitment and adhesion. Atherosclerotic plaque rupture leading to major ischemic events is the result of vulnerable plaque progression, which is a result of the detrimental effect of oxidative stress and inflammation on risk factors for atherosclerotic plaque rupture, such as intraplaque hemorrhage, neovascularization, and fibrous cap thickness. Thus, both are key targets for primary and secondary interventions. It is well recognized that chronic physical activity attenuates oxidative stress in healthy subjects via the improvement of antioxidant enzyme capacities and inflammation via the enhancement of anti-inflammatory molecules. Moreover, it was recently shown that chronic physical activity could decrease oxidative stress and inflammation in atherosclerotic patients. The aim of this review is to summarize the role of oxidative stress and inflammation in atherosclerosis and the results of therapeutic interventions targeting them in both preclinical and clinical studies. The effects of chronic physical activity on these two key processes are then reviewed in vulnerable atherosclerotic plaques in both coronary and carotid arteries.

Multi-Stage Fitness Test Performance, V ˙ O2 Peak and Adiposity: Effect on Risk Factors for Cardio-Metabolic Disease in Adolescents

The role of physical activity in determining the metabolic health of adolescents is poorly understood, particularly concerning the effect on low-grade chronic inflammation (chronic elevation of pro-inflammatory cytokines IL-1β, IL-6, TNF-α and acute phase protein CRP, which is implicated in the etiology of atherosclerosis) and anti-inflammatory mediators such as IL-10. Furthermore, there is limited information on the mediating effects of performance on the multi-stage fitness test (MSFT), V˙O₂ peak and adiposity on risk factors for cardio-metabolic disease in adolescents.

Purpose: To examine the effect of performance on the MSFT, V˙O₂ peak and adiposity on risk factors for cardio-metabolic diseases in adolescents.

Methods: Following ethical approval, 121 adolescents (11.3 ± 0.8 year) completed the study. Risk factors for cardio-metabolic disease (circulating inflammatory cytokines, blood glucose and plasma insulin concentrations) was assessed using a fasted capillary blood sample. Participants were separated into quartiles based upon distance ran during the MSFT, the blood lactate response to submaximal exercise, V˙O₂ peak (determined during an uphill graded treadmill test), and adiposity (determined as the sum of four skinfolds). The blood lactate response to submaximal exercise and V0₂ peak were measured in a sub-group of participants. Data were analyzed using two-way between-subjects ANCOVA and multiple linear regression.

Results: Participants with the lowest performance on the MSFT had higher blood concentrations of IL-6 (3.25 ± 0.25 pg mL^-1) and IL-1β (4.78 ± 0.54 pg mL^-1) and lower concentrations of IL-10 (1.80 ± 0.27 pg mL^-1) when compared with all other quartiles (all p < 0.05). Yet, when categorized into V˙O₂ peak quartiles, no differences existed in any of the inflammatory mediators (all p > 0.05). Performance on the MSFT was the only predictor of IL-6 (β = -0.291, p = 0.031), IL-1β (β = -0.405, p = 0.005), IL-10 (β = 0.325, p = 0.021) and fasted blood glucose (β = -0.545, p < 0.001) concentrations. Adiposity was the only predictor of plasma insulin concentration (β = 0.515, p < 0.001) and blood pressure (diastolic: β = 0.259, p = 0.042; mean arterial pressure: β = 0.322, p = 0.011).

Conclusion: Enhanced performance on the MSFT, but not V˙O₂ peak, was associated with a favorable inflammatory profile in adolescents; whilst adiposity adversely affected plasma insulin, diastolic and mean arterial blood pressure. These findings demonstrate that enhancing performance on the MSFT and maintaining a healthy body composition are a potential therapeutic intervention for the attenuation of risk factors for cardio-metabolic diseases in adolescents.

LOCALIZED FAT-FREE MASS DOES NOT INFLUENCE MUSCLE STRENGTH IN OBESE AND NON-OBESE BOYS

ABSTRACT Introduction: Obesity in adolescents has increased worldwide, and is generally associated with poor eating habits and physical inactivity. Objective: To compare absolute and relative muscle strength with body mass (BM), fat-free mass (FFM) and localized FFM of upper and lower limbs among obese and non-obese adolescents. Methods: BM, height and body mass index (BMI) were verified in 39 male adolescents (aged 13-17 years). Body composition was measured by dual-energy X-ray absorptiometry (DXA) and maximal strength of upper and lower limbs was estimated by a one-repetition maximum (1RM) test. Participants were divided into three groups: eutrophic (normal weight) (n=11), overweight (n=14), and obese (n=14). One-way ANOVA was used to compare the variables, followed by a Bonferroni post-hoc test for multiple comparisons. Pearson's correlation coefficient was used for relevant correlations and multiple linear regression to verify the influence of anthropometric variables, body composition and muscle strength of upper and lower limbs. Results: Obese and overweight adolescents had absolute muscle strength values similar to those of the eutrophic adolescents, which were lower when corrected by BM (p<0.001). However, muscle strength related to FFM and localized FFM were similar between groups in both upper and lower limbs. Linear regression showed that BMI explained 59% of the variation in absolute muscle strength of the lower limbs (β=0.59, p<0.05), FFM explained 84% of the variation in absolute muscle strength of the upper limbs (β=0.84, p<0.01) and 68% of the lower limbs (β=0.68; p<0.01), while localized FM was inversely associated in the lower limbs (β=−0.53, p<0.05). Conclusion: Muscle strength of lower and upper limbs, when corrected by localized FFM, does not distinguish between overweight and normal weight adolescents, indicating that obesity does not have a negative effect on generation of muscle strength in obese boys. Level of Evidence III; Case-control study.

Sport-based physical activity recommendations and modifications in C-reactive protein and arterial thickness

We analyzed the effects of 1 year of engagement in ≥ 300 min/week of organized sports on inflammatory levels and vascular structure in adolescents. The sample was composed of 89 adolescents (11.6 ± 0.7 years old [43 boys and 46 girls]), stratified according to engagement in ≥ 300 min/week of sport practice during at least 12 months of follow-up (n = 15, sport practice; n = 74, non-sport practice). Arterial thickness (carotid and femoral) was assessed by ultrasound scan, while high sensitive C-reactive protein levels were used to assess inflammatory status. Trunk fatness (densitometry scanner), biological maturation (age at peak height velocity), blood pressure, and skipping breakfast were treated as covariates. Independently of body fatness and biological maturation, the group engaged in sports presented a higher reduction in C-reactive protein (mean difference -1.559 mg/L [95%CI -2.539 to -0.579]) than the non-sport group (mean difference -0.414 mg/L [95%CI -0.846 to 0.017]) (p = 0.040). There was a significant relationship between changes in C-reactive protein and changes in femoral intima-media thickness in the non-sport group (r = 0.311 [95%CI 0.026 to 0.549]).

CONCLUSION

Inflammation decreased in adolescents engaged in organized sports, independently of trunk fatness and biological maturation. Moreover, inflammation was related to arterial thickening only in adolescents not engaged in sports. What is Known: • Intima media thickness is a relevant marker of cardiovascular disease in pediatric groups, being affected by obesity and inflammation. • The importance of monitoring inflammatory markers from childhood is enhanced by the fact that alterations in these inflammatory markers in early life predict inflammation and alterations in carotid IMT in adulthood. What is New: • Anti-inflammatory properties related to physical exercise performed at moderate intensity, on inflammation and alterations in IMT are not clear in pediatric groups. • Due to the importance that sport participation has assumed as a promoter of improvements in health and quality of life, it is necessary to understand its potential benefits for cardiovascular health during human growth.

Analysis of different anthropometric indicators in the detection of high blood pressure in school adolescents: a cross-sectional study with 8295 adolescents

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Overweight adolescents classified in any of three anthropometric indices have more HBP.

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The sensitivity of the indicators was low and the specificity was high in detecting HBP.

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Parents must be aware that high BMI, WC or WTHR are highly associated with HBP.

Background

High blood pressure is strongly associated with obesity in different populations. However, it is unclear whether different anthropometric indicators of obesity can satisfactorily predict high blood pressure in the school setting.

Objectives

This study evaluated the sensitivity and specificity of body mass index, waist circumference, and waist to height ratio in the detection of high blood pressure in adolescents.

Methods

The sample consisted of 8295 adolescents aged 10–17 years. Weight was measured using a digital scale, height with a stadiometer, and waist circumference using a tape measure. Blood pressure was measured by an automatic blood pressure measuring device. ROC curves were used for the analysis of sensitivity and specificity of the three anthropometric indices in identifying high blood pressure. Binary Logistic Regression was used to assess the association of body mass index, waist circumference, and waist to height ratio with high blood pressure.

Results

Low values of sensitivity were observed for body mass index (0.35), waist circumference (0.37), and waist to height ratio (0.31) and high values of specificity for body mass index (0.86), waist circumference (0.82), and waist to height ratio (0.83) in the detection of high blood pressure. An association was observed between adolescents classified with high body mass index (OR = 3.57 [95% CI = 3.10–4.10]), waist cirumference (OR = 3.24 [95% CI = 2.83–3.72]), and waist to height ratio (OR = 2.94 [95% CI = 2.54–3.40]) with high blood pressure.

Conclusions

Body mass index, waist circumference, and waist to height ratio presented low sensitivity to identify adolescents with high blood pressure. However, adolescents classified with high body mass index, waist circumference, and waist to height ratio demonstrated a high association of presenting high blood pressure.

MMP-9 Levels and IMT of Carotid Arteries are Elevated in Obese Children and Adolescents Compared to Non-Obese

BACKGROUND

Childhood obesity is associated with increased risk of atherosclerosis and cardiovascular disease in adulthood. Increased intima-media thickness (IMT) of the carotid artery is linked to the initiation and progression of the chronic inflammatory processes implicated in cardiovascular disease. Matrix metalloproteinase-9 (MMP-9) plays an important role in the degradation of the extracellular matrix and, consequently, in the development, morphogenesis, repair and remodeling of connective tissues.

OBJECTIVES

(i) to determine and compare the concentrations of MMP-9, tissue inhibitor of metalloproteinase -1 (TIMP-1), and MMP-9/TIMP-1 ratio in obese and non-obese children and adolescents; (ii) to investigate the association of these markers with common and internal IMT of carotid arteries.

METHODS

Cross-sectional study involving 32 obese and 32 non-obese (control) individuals between 8 - 18 years of age.

RESULTS

Significantly (p < 0.05) higher values of MMP-9 concentration, as well as a higher MMP-9/TIMP-1 ratio were detected in the obese group compared to control counterparts. Common and internal carotid IMT values were significantly higher (p < 0.001) in the obese group compared to the control group. Positive correlations were observed between the common carotid IMT values and MMP-9 concentrations as well as MMP-9/TIMP-1 ratio.

CONCLUSIONS

Our data demonstrate that obese children and adolescents present higher mean IMT values, plasma MMP-9 and MMP-9/TIMP-1 ratio compared to the non-obese. Thus, these findings indicate that this group presents a risk profile for early atherosclerosis.

Insulin Sensitivity and Inflammation Mediate the Impact of Fitness on Cerebrovascular Health in Adolescents

BACKGROUND/OBJECTIVES

To investigate in adolescents the relationships between retinal vessel diameter, physical fitness, insulin sensitivity, and systemic inflammation.

METHODS

We evaluated 157 adolescents, 112 with excessive weight and 45 lean, all without type 2 diabetes mellitus. All received detailed evaluations, including measurements of retinal vessel diameter, insulin sensitivity, levels of inflammation, and physical fitness.

RESULTS

Overweight/obese adolescents had significantly narrower retinal arteriolar and wider venular diameters, significantly lower insulin sensitivity, and physical fitness. They also had decreased levels of anti-inflammatory and increased levels of proinflammatory markers as well as an overall higher inflammation balance score. Fitness was associated with larger retinal arteriolar and narrower venular diameters and these relationships were mediated by insulin sensitivity. We demonstrate that inflammation also mediates the relationship between fitness and retinal venular, but not arterial diameter; insulin sensitivity and inflammation balance score jointly mediate this relationship with little overlap in their effects.

CONCLUSIONS

Increasing fitness and insulin sensitivity and reducing inflammation among adolescents carrying excess weight may improve microvascular integrity. Interventions to improve physical fitness and insulin function and reduce inflammation in adolescents, a group likely to benefit from such interventions, may reduce not only cardiovascular disease in middle age, but also improve cerebrovascular function later in life.

The mediating role of physical inactivity on the relationship between inflammation and artery thickness in prepubertal adolescents

OBJECTIVE

To analyze the relationship between inflammatory markers and the lipid profile, blood flow, and artery structure in prepubertal adolescents stratified according to sports practice.

STUDY DESIGN

The sample was composed of 120 adolescents (57 boys and 63 girls) with a mean age of 11.7 ± 0.7 years (ranging from 11 to 13 years). Intima-media thickness (IMT) and blood flow were measured with ultrasonography. The lipid profile and high-sensitivity C-reactive protein were measured after the subjects had fasted for 12 hours overnight. Trunk fatness was measured by dual-energy x-ray absorptiometry. Organized sports participation was analyzed as a categorical variable. Biological maturation was determined via the age at peak height velocity.

RESULTS

In the adjusted model, high-sensitivity C-reactive protein was significantly related to high-density lipoprotein-cholesterol (β = -5.797 [-11.500 to -0.093]), femoral IMT (β = 0.062 [0.008-0.116]), and the sum of femoral and carotid IMT (β = 1.107 [0.223-1.919]), but only in the group without sports participation. Slopes of the crude linear regression were greater in the group without sports participation for femoral IMT (t = 2.621; P = .009) and the sum of femoral and carotid IMT (t = 2.876; P = .004) when compared with the group with sports participation.

CONCLUSION

Independent of body fatness and biological maturation, inflammatory status was related to artery IMT and dyslipidemia in prepubertal adolescents, modulated by sport participation.

Early and current physical activity: relationship with intima-media thickness and metabolic variables in adulthood

BACKGROUND

It is unclear whether early physical activity has a greater influence on intima-media thickness and metabolic variables than current physical activity.

OBJECTIVE

To analyze the relationship between current and early physical activity, metabolic variables, and intima-media thickness measures in adults.

METHOD

The sample was composed of 55 healthy subjects of both sexes (33 men and 22 women). Total body fat and trunk fat were estimated by dual-energy X-ray absorptiometry. Carotid and femoral intima-media thickness were measured using a Doppler ultrasound device. A 12-hour fasting blood sample collection was taken (fasting glucose and lipid profile). Early physical activity was assessed through face-to-face interview, and the current physical activity was assessed by pedometer (Digi-Walker Yamax, SW200), which was used for a period of seven days.

RESULTS

Current physical activity was negatively related to total cholesterol (rho=-0.31), while early physical activity was negatively related to triglycerides (rho=-0.42), total cholesterol (rho=-0.28), very low density lipoprotein (rho=-0.44), and carotid intima-media thickness (rho=-0.50). In the multivariate model, subjects engaged in sports activities during early life had lower values of very low density lipoprotein (b=-8.74 [b95%CI=-16.1; -1.47]) and carotid intima-media thickness (b=-0.17 [95%CI: -0.28; -0.05]).

CONCLUSION

Early 95%CI physical activity has a significant influence on carotid intima-media thickness, regardless of the current physical activity.