Ability of Measures of Adiposity in Identifying Adverse Levels of Inflammatory and Metabolic Markers in Adolescents

Cardiovascular health behavior and blood pressure in adolescents: A longitudinal analysis

BACKGROUND

The ideal cardiovascular health behaviors (ICHB) have been associated with a subsequent positive health status in adults. However, evidence regarding blood pressure (BP) and ICHB in adolescents is scarce. The aim of this prospective cohort was to evaluate the impact of accumulation of ICHB on BP values in adolescents over two years.

METHODS

This is a longitudinal analysis with 445 adolescents (232 girls) aged 12-18 years old. Resting blood pressure was measured at baseline and 2 years later, and ICHBs at baseline according to standard procedures. Based on the American Heart Association definition, the ICHB index was defined as a sum of meeting the ICHBs (from 0 to 4, where 4 would be the healthiest profile of all ICHBs) for a healthy diet, physical activity, smoking status and body mass index.

RESULTS

Adjusted means values (ANCOVA) of BP parameters through achievement of a greater number of (between 1-4) the ICHBs (adjusting for potential confounders, age, sex, pubertal stage and socioeconomic status) showed that, as increase the number of ICHB accumulated as a lower the BP levels [ICHB and SBP (F_3.435) = 4.501, p = 0.004), DBP (F_(3.435) = 2.725, p = 0.044), pulse pressure (F_(3.435) = 4.004, p = 0.008), and rate pressure product (F_(3.435) = 2.866, p = 0.036)] over two years.

CONCLUSION

A lower number of ICHB (smoking status, body mass index, physical activity, and diet) during adolescence play a key role on blood pressure over two years. A higher number of ICHB is seen to be associated with a lower risk of short-term, hypertension.

Cardiovascular health behavior and cardiorespiratory fitness in adolescents: a longitudinal study

Cardiorespiratory fitness has been substantially associated with health status. However, longitudinal studies on cardiorespiratory fitness and ideal cardiovascular health behavior (ICHB) in adolescents are scarce. The aim of this study was to evaluate the longitudinal association between ICHB (at baseline) and cardiorespiratory fitness (at follow-up). This is a 2-year prospective analysis of 445 adolescents (232 girls) aged 12-18 years. The ICHB was developed by the American Heart Association as meeting the ideal health behaviors for a healthy diet, physical activity, smoking status, and body mass index. ANCOVAS adjusted by age, sex, pubertal stage, socioeconomic status, and cardiorespiratory fitness showed that the higher the number of ICHB metrics accumulated at baseline (from 1 to 4), the higher the cardiorespiratory fitness levels over a 2-year period (p = 0.038). In logistic regressions, after adjusting for potential confounders, the odds ratios for having high cardiorespiratory fitness at follow-up was 4.9 (95% CI, 1.2-20.1, p = 0.02) for those who accumulated all four metrics of ICHB, when compared to those with 1 or less metrics of ICHB. In addition, the higher the number of ICHB metrics accumulated, the higher the likelihood of having a high cardiorespiratory fitness level over a 2-year period (p for trend = 0.01).

CONCLUSION

 We identified a significant association between ICBH and cardiorespiratory fitness in adolescents. Therefore, improving ICBH in adolescence is likely to benefit the cardiorespiratory fitness.

WHAT IS KNOWN

• Smoking status, body mass index, physical activity, and diet are associated to cardiorespiratory fitness in adulthood. • Lifestyle behaviors such as physical activity, smoking, body weight, and healthy diet are individually linked with cardiorespiratory fitness and, however, have not been examined jointly, as combined health behaviors.

WHAT IS NEW

• Accumulation of cardiovascular health behavior metrics was positively associated with cardiorespiratory fitness at a 2-year follow-up, in adolescents. • Meeting all the four metrics of ideal cardiovascular health behavior seems important for healthy cardiorespiratory fitness during adolescence.

Prevalence, patterns and socio-demographic correlates of sleep duration in adolescents: results from the LabMed study

OBJECTIVE

The aim of this study was to report the prevalence of adequate sleep and the correlates of sleep duration in Portuguese adolescents aged 12-18 years.

METHODS

Cross-sectional analysis with 1017 adolescents (471 girls) aged 14.6 ± 1.8 years. Adolescents self-reported their sleep duration.

RESULTS

The percentage of adolescents meeting the guidelines was 72.7%, 60.7% and 51.3%, during a whole week, on weekdays and on weekends, respectively. Boys were always more compliant with the guidelines than girls, for all week categories. A significant difference was found on sleep duration on weekends, between boys and girls (p < 0.001). During weekdays, more adolescents were classified as short sleepers when compared to long sleepers. Younger adolescents were more likely to meet the guidelines over the whole week and on weekdays (OR = 2.23, OR = 2.13, respectively; p < 0.05) and being long sleepers on weekends (OR = 1.49, p < 0.05). Those of medium and low SES were less likely to meet the sleep guidelines for all week categories (p_trend<0.001). Girls were more likely than boys to meet the guidelines or being long sleepers on weekends (OR = 1.78, OR = 2.85, respectively; p < 0.05).

CONCLUSIONS

During weekends, the percentage of girls sleeping more than recommended is high, indicating a clear compensation of low sleep duration during weekdays. Those of low SES and older adolescents were less likely to meet the sleep guidelines. Policy makers and researchers should consider the potential effects that SES, gender and age might have on sleep duration, when designing targeted interventions to promote adequate sleep duration.

Association of Adipocytokines and Inflammatory Biomarkers with Blood Pressure in Adolescents: A Longitudinal Analysis

BACKGROUND AND AIMS

Several cross-sectional, but few prospective, studies suggest that inflammation may be involved in the development of high blood pressure. We examined markers of inflammation for their associations with blood pressure levels over a two-year period in healthy adolescents.

METHODS AND RESULTS

The sample comprised 406 adolescents (209 girls) aged 12-18 years in the LabMed Physical Activity Study were followed-up for 2 years. Anthropometric (weigh, height, BMI), markers of inflammation (high sensitivity C-reactive protein, complement factors C3 and C4, fibrinogen, leptin and adiponectin) and ambulatory blood pressure (BP) were collected. Socioeconomic status, pubertal development, adherence to Mediterranean diet and cardiorespiratory fitness were measured for adjustment for potential confounders. Adjusted linear regression models revealed a significant association of Leptin/Adiponectin (L/A) Ratio (baseline) with systolic BP (β = 0.120; p < 0.034) and with diastolic BP (β = 0.125; p < 0.036) at follow-up (full adjusted model). Leptin was associated with systolic BP at follow-up (β = 0.102; p < 0.038) after adjustment for systolic BP at baseline, height, pubertal stage, socioeconomic status, adherence to Mediterranean diet, cardiorespiratory fitness, however, not independently of BMI.

CONCLUSION

L/A ratio was positively associated with systolic BP and diastolic BP even after adjusting confounding variables. Therefore, a higher misbalance between leptin and adiponectin (higher L/A ratio) early adolescence may exert a negative effect BP levels in late adolescence regardless of several confounders factors.

Associations Between Anthropometric Indicators in Early Life and Cardiorespiratory Fitness, Physical Activity, and Sedentary Time in Adolescence

BACKGROUND

To explore the associations between birth weight and body mass index (BMI) from 6 months to 6 years of age, with cardiorespiratory fitness (CRF), physical activity, and sedentary time in adolescence.

METHODS

Retrospective school-based study with 539 adolescents (292 girls), mean age of 13.94 (1.62) years. Anthropometric data from birth up to 6 years were extracted from individual child health booklets. CRF was estimated by 20-m shuttle run test. Physical activity and sedentary time were assessed with accelerometers.

RESULTS

Birth weight was not associated with any outcome measured in adolescence. From the age of 6 months onwards in girls, and from 3 years in boys, BMI associated inversely with CRF in adolescence. In girls, BMI (at 12 mo and at 3 y of age) associated positively with sedentary time in adolescence, but not with physical activity. In boys, positive associations between BMI at the ages of 3, 5, and 6 years old and time spent in some intensities of physical activity in adolescence were found.

CONCLUSIONS

BMI during the early years was negatively associated with CRF in adolescence, in a consistent way, for both genders, but with physical activity and sedentary time the associations were scarce and inconsistent, depending on the gender.

Prevalence of idiopathically elevated ESR and CRP in patients undergoing primary total knee arthroplasty as a function of body mass index

BACKGROUND

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are commonly used inflammatory markers utilized to aid in the diagnosis of periprosthetic infection (PJI). Patients with obesity, however, are known to have elevated baseline levels of these inflammatory markers. Therefore, this retrospective study aimed to determine the relationship between elevated ESR and CRP and body mass index (BMI) in patients undergoing total knee arthroplasty (TKA). In doing so, physicians can better determine whether BMI should be taken into account when evaluating the prognostic value of elevated preoperative ESR and CRP levels for risk of PJI in primary TKA patients.

METHODS

This is a retrospective case series of 181 patients who had undergone primary TKA at a single institution. Patients undergoing primary unilateral TKA were eligible unless they had undergone previous TKA, contralateral knee symptoms, or elevated white blood cell (WBC) count. A linear regression model was utilized to demonstrate the relationship between proportions of patients with elevated biomarker values and categories of BMI. Analysis of variance and independent two-sample t-tests were utilized to assess differences in mean ESR, CRP, and WBC levels between the "healthy patients" and "patients with comorbidities" subgroups within each BMI category.

RESULTS

Eligible patients (n = 181) were stratified by BMI category. Elevated ESR was associated significantly with BMI (ESR: r2 = 0.89, P < 0.001) unlike elevated CRP (r2 = 0.82, P = 0.133) and WBC count (r2 = .01; P = .626). No statistically significant differences in ESR values and WBC count between the "healthy patients" versus "patients with comorbidities" were demonstrated within any BMI category. In patients of normal weight (BMI 20-25 kg/m2), "healthy patients" had a statistically significantly higher mean CRP level than "patients with comorbidities" (1.73 mg/L vs. 0.70 mg/L, P < 0.001). There were no other statistically significant differences in mean CRP levels by health status.

CONCLUSION

Caution is advised when utilizing ESR and CRP to diagnose periprosthetic joint infection without considering BMI given that increasing preoperative levels of ESR and CRP are correlated with higher BMI.

High levels of adiponectin attenuate the detrimental association of adiposity with insulin resistance in adolescents

BACKGROUND AND AIM

This study aimed to: i) examine the differences in insulin resistance (IR) across adiposity levels; and ii) ascertain whether high levels of adiponectin attenuate the detrimental association of adiposity with IR in adolescents.

METHODS AND RESULTS

A total of 529 adolescents aged 12-18 years participated in this cross-sectional study (267 girls). Anthropometry and body adiposity parameters [body mass index (BMI), sum of skinfolds, body fat percentage (BF %) by bio-impedance analysis and waist circumference (WC)], were measured according to standardized procedures and categorized into age- and sex-specific quartiles. Socioeconomic status, pubertal stage and lifestyle determinants (Mediterranean diet adherence and cardiorespiratory fitness) were gathered and used as confounders. Serum adiponectin and IR (homeostasis model assessment of insulin resistance [HOMA-IR] estimated from fasting serum insulin and glucose were assessed. Analysis of covariance (ANCOVA) showed that HOMA-IR increased in a linear fashion throughout the quartiles of all adiposity measures (p < 0.001 for all), independently of age, sex, pubertal stage, socioeconomic status, adherence to the Mediterranean diet and cardiorespiratory fitness. Two-way ANCOVA showed that adolescents in the higher quartile of adiposity for BF%, BMI, WC and skinfolds sum (Q4) presented the highest adiponectin levels, and had 0.77 Standard Deviation (SD), 0.8 SD, 0.85 SD and 0.8 SD lower HOMA-IR, respectively (p < 0.01) than their low adiponectin group counterparts, after adjustments for potential confounders.

CONCLUSION

Higher adiponectin levels may attenuate the detrimental association between adiposity and IR, particularly in subjects with higher adiposity.

Marked Influence of Adiposity on Laboratory Biomarkers in a Healthy Cohort of Children and Adolescents

BACKGROUND

The prevalence of pediatric obesity is increasing worldwide and strongly associates with metabolic abnormalities, including inflammation, insulin resistance, and dyslipidemia. This study assessed the influence of 3 measures of adiposity on levels of routinely assessed biochemical markers in apparently healthy children and adolescents.

METHODS

The influence of adiposity on 35 biochemical markers was examined in the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort of healthy children and adolescents by comparing serum biomarker levels between subjects with a normal weight, overweight, and obese body mass index (BMI). The cohort comprised 1332 subjects 5.1 to 19.0 years of age with a BMI ranging from 13.4 to 65.0 kg/m2. The association between each biochemical marker and BMI, waist circumference, and waist-to-height ratio z-scores was assessed, while adjusting for age and sex. Reference intervals were established for all biochemical markers before and after removing overweight/obese subjects.

RESULTS

In children and adolescents, levels of 13 routinely assessed biochemical markers, including alanine aminotransferase, apolipoprotein B, complement components 3 and 4, cholinesterase, high sensitivity C-reactive protein, gamma-glutamyl transferase, haptoglobin, high-density lipoprotein cholesterol, iron, transferrin, triglycerides, and uric acid, were significantly different between BMI categories. BMI, waist circumference, and/or waist-to-height ratio were significantly associated with the serum concentration of 24 of the 35 markers examined, after adjusting for age and sex.

CONCLUSIONS

Excess adiposity significantly influences circulating levels of routinely assessed laboratory markers, most notably liver enzymes, lipids/lipoproteins, inflammatory markers, and uric acid in children and adolescents. Although it is unknown whether altered biochemical marker levels in subjects with overweight/obesity reflect health or indolent disease, clinicians should be aware of the effect of weight status on several laboratory tests.

Ability of 2 estimation methods of body fat percentage in identifying unfavorable levels of cardiometabolic biomarkers in adolescents: Results from the LabMed study

Background:

To assess and compare the ability of body fat percentage (BF%) estimated by 2 methods, bioelectrical impedance analysis (BIA) and by the Slaughter et al equations for triceps and subscapular skinfold thickness (SKF), in identifying unfavorable levels of several biomarkers of cardiometabolic risk.

Methods:

Cross-sectional school-based study with 529 apparently healthy adolescents (267 girls), aged 14.3 ± 1.7 years.

Results:

BF% estimated by both methods always showed higher areas under the curve (AUC) for each biomarker in girls than in boys (with the exception of BIA for leptin). BF% estimated by BIA and by SKF presented a discriminatory ability in identifying unfavorable levels in all biomarkers of cardiometabolic risk in girls; however, BF% estimated by BIA displayed the highest AUC (except for C-reactive protein). In boys, BF% estimated by SKF presented higher AUC for C-reactive protein, fibrinogen and erythrocyte sedimentation rate; and BF% estimated by BIA for complement C3 and leptin. Positive and significant associations between BIA and SKF with all biomarkers (P < .05) were found (except for SKF and complement C4 in girls, and SKF and fibrinogen and erythrocyte sedimentation rate in boys), after adjustments for pubertal stage, cardiorespiratory fitness, adherence to the Mediterranean diet and socioeconomic status.

Conclusions:

Overall, diagnostic performance was more accurate in girls. BF% estimated by BIA presented a slightly better overall discriminatory ability for each biomarker than BF% estimated by SKF in girls, while in boys no method clearly prevailed over the other.

Cardiorespiratory fitness and health-related quality of life in adolescents: A longitudinal analysis from the LabMed Physical Activity Study

OBJECTIVE

The purpose of this study was to examine the longitudinal associations between cardiorespiratory fitness and health-related quality of life (HRQoL) in a sample of adolescents, and to determine whether changes in cardiorespiratory fitness were associated with HRQoL over a 2-year follow-up.

METHODS

This is a longitudinal analysis with 571 Portuguese adolescents (274 boys and 297 girls) aged 12-18 years. HRQoL was measured with the Kidscreen-10 questionnaire; the 20 m shuttle-run was used to estimate cardiorespiratory fitness; socioeconomic status was assessed with the Family Affluence Scale; and pubertal stage was assessed with Tanner stages. Linear regression and analysis of covariance (ancovas) were used to examine the associations between cardiorespiratory fitness and HRQoL.

RESULTS

HRQoL decreased over a 2-year period both in boys and girls (P < .05). Moreover, girls at baseline and at follow-up reported significantly lower HRQoL values than boys (between subjects P < .001). After adjustments for potential confounders, regression analyses showed significant cross-sectional associations between cardiorespiratory fitness and HRQoL both at baseline (B = 0.095; P = .023) and at follow-up (B = 0.090; P = .012). ancova showed that adolescents whose cardiorespiratory fitness decreased over time exhibited lower scores of HRQoL at follow-up, compared to those with persistent high cardiorespiratory fitness; this held after adjustments for age, sex, socioeconomic status, and pubertal stage.

CONCLUSIONS

Changes in cardiorespiratory fitness during adolescence were associated with HRQoL over a 2-year period. This study suggests that improving cardiorespiratory fitness could be an important strategy in improving the HRQoL of adolescents.

Associations between anthropometric indicators in early life and low-grade inflammation, insulin resistance and lipid profile in adolescence

BACKGROUND AND AIMS

The long-term relations between excessive adiposity in early childhood and unfavourable cardiometabolic profiles in later ages are not yet completely understood. We aimed to assess the associations between birth weight (BW) and BMI from 6 months to 6 years of age, with biomarkers indicative of low-grade inflammation, insulin resistance and lipid profiles in adolescence.

METHODS AND RESULTS

Retrospective school-based study with 415 Portuguese adolescents (220 girls), mean age of 14.08 ± 1.6 years old. Anthropometric data from birth to 6 years old was extracted from individual child health book records. Actual weight and height were measured and BMI calculated. Participants were classified at each time point as normal weight or overweight according to WHO reference values. Biomarkers were obtained from venous blood samples. Linear regressions were used to explore the associations between the biomarkers and early life anthropometric indicators. From 2 years onwards, BMI associated positively with the inflammatory score and HOMA-IR in adolescence. Children who were overweight/obese from 2 to 6 years of age presented significantly higher inflammatory score and HOMA-IR later in adolescence. TC/HDL ratio was also positively associated with BMI from the age of 5 years onwards. The associations between BMI and cardiometabolic outcomes remained positive in adolescence, with overweight adolescents presenting a higher inflammatory score, HOMA-IR and TC/HDL than normal weight adolescents.

CONCLUSION

A high BMI from an early age was consistently associated with worse inflammatory and lipid profiles and insulin resistance in adolescence. No associations were found between BW and the same studied outcomes.

Ability of adiposity indicators to identify elevated high-sensitivity C-reactive protein in young adults

OBJECTIVE

The aim of the present study was to compare the discriminatory ability of different adiposity indicators in distinguishing subclinical inflammatory levels in individuals 21 y of age.

METHODS

Data from the EPITeen (Epidemiological Health Investigation of Teenagers in Porto) population-based cohort (N = 1547) was analyzed. Body mass index (BMI), body fat percentage (BF%), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) were ascertained to assess their relationship to high-sensitivity C-reactive protein (hs-CRP). Logistic regression models were fitted to examine the association of each adiposity indicator with elevated hs-CRP (≥75th sex-specific percentile). The areas under the curve (AUCs) of the receiver operating characteristic curves were calculated for all adiposity indicators to compare their relative ability to correctly classify individuals with elevated hs-CRP.

RESULTS

After adjustment, all adiposity indicators were significantly associated with high hs-CRP in both sexes, except WHR in women (odds ratio, 1.15; 95% confidence interval [CI], 0.98-1.36). The magnitude of the associations was stronger in women. BMI presented the best discriminatory ability in women (AUC = 0.675; 95% CI, 0.632-0.717; cutoff values >22.6 kg/m²). In men, both BF% (AUC = 0.604; 95% CI, 0.557-0.651; cutoff values >18%) and WHtR (AUC = 0.604; 95% CI, 0.557-0.651; cutoff values >0.5) showed the best discriminatory ability. On the contrary, WHR showed the least ability to discriminate high hs-CRP in both sexes (AUC = 0.539; 95% CI, 0.489-0.584 for women and AUC = 0.574; 95% CI, 0.528-0.620 for men).

CONCLUSION

WHR showed the least discriminatory ability for correctly identifying individuals with elevated hs-CRP. The small differences observed among the adiposity indices hinder the recommendation of a single best adiposity measure as predictor of low-grade inflammatory levels.

Adiposity and adipocytokines: the moderator role of cardiorespiratory fitness and pubertal stage in girls

Background Cardiorespiratory fitness (CRF) and pubertal stages have been related to many health outcomes, including obesity and adipocytokines. Thus, the present study aimed to analyze the moderator role of CRF and pubertal stage in the relationship between adiposity and adipocytokines in girls. Method This cross-sectional study was performed with 42 pre-pubertal girls aged from 7 to 11 years and 54 post-pubertal girls aged from 13 to 17 years. Blood samples were collected to determine the serum levels of leptin and adiponectin, and then the leptin/adiponectin ratio (L/A ratio) was calculated. CRF, anthropometric and body composition indicators were assessed. For statistical analysis, descriptive statistics and several linear regression models were used. The moderation analysis was tested using the PROCESS macro. Results An interaction between body mass index (BMI) and CRF (β: -0.70; confidence interval [CI]: -1.29, -0.12), as well as between BMI and pubertal stage (β: 0.79; CI: 0.28, 1.30) with leptin, was found. Regarding the L/A ratio, an interaction was found only in BMI × CRF (β: -0.56; CI: -1.06, -0.06). Using a combined interaction (CRF and pubertal stage), the results showed a positive association between BMI with leptin and L/A ratio only in low CRF, pre-pubertal and post-pubertal stages. Conclusion This study suggests a protective role of high levels of CRF in the relationship between BMI and adipocytokines. Despite the effect of pubertal stage, the results suggest that youth should be engaged in physical activity in order to improve CRF levels and consequently improve cardiometabolic health.

Lifestyle patterns and endocrine, metabolic, and immunological biomarkers in European adolescents: The HELENA study

OBJECTIVE

To evaluate the association of lifestyle patterns related to physical activity (PA), sedentariness, and sleep with endocrine, metabolic, and immunological health biomarkers in European adolescents.

METHODS

The present cross-sectional study comprised 3528 adolescents (1845 girls) (12.5-17.5 years) enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence Study. Cluster analysis was performed by including body composition, PA by accelerometry, self-reported sedentary behaviors, and sleep duration. We also measured endocrine, metabolic, and immunological biomarkers.

RESULTS

Three-cluster solutions were identified: (a) light-PA time, moderate-vigorous-PA time and sedentary time, (b) light-PA time, moderate-vigorous-PA time, sedentary time and sleep time, (c) light-PA time, moderate-vigorous-PA time, sedentary time and body composition. In addition, each cluster solution was defined as: "healthy," "medium healthy," and "unhealthy" according to the presented rating. Analysis of variance showed that overall the healthiest groups from the three clusters analyzed presented a better metabolic profile. A decision tree analysis showed that leptin had a strong association with cluster 3 in both boys and girls, high-density lipoprotein cholesterol had the strongest association with clusters 1 and 3 in boys. Cortisol had the strongest association with cluster 1. HOMA index (homeostatic model assessment) and C3 showed a strong association with cluster 3 in girls.

CONCLUSIONS

Our results support the existence of different interactions between metabolic health and lifestyle patterns related to PA, sedentariness, and sleep, with some gender-specific findings. These results highlight the importance to consider multiple lifestyle-related health factors in the assessment of adolescents' health to plan favorable strategies.

Muscular fitness and cardiorespiratory fitness are associated with health-related quality of life: Results from labmed physical activity study

BACKGROUND

Adolescents' physical fitness levels are an important indicator of their lifestyle and seem to have positive consequences in health-related quality of life (HRQoL).

OBJECTIVE

The purpose of this study is to analyse the combined associations of cardiorespiratory fitness and muscular fitness with HRQoL and to assess the differences between HRQoL scores across groups of cardiorespiratory fitness and muscular fitness in Portuguese adolescents.

DESIGN

This is a cross-sectional analysis with 567 Portuguese adolescents aged 12-18 years-old.

METHODS

HRQoL was measured using the Kidscreen-10 questionnaire. Cardiorespiratory fitness was estimated with the 20-m shuttle-run test. Muscular fitness was evaluated using the handgrip and the standing long jump tests and a muscular fitness index was computed by means of standardized measures of both tests. Socioeconomic status was assessed using the Family Affluence Scale. Body composition (body mass and height) was measured according to standard protocols. Accelerometers were used to obtain objective physical activity time. Pubertal stage was assessed using Tanner stages. Adherence to the Mediterranean diet was assessed using the KIDMED index. Participants were divided into four groups based on low or high values of both cardiorespiratory and muscular fitness. Regression analysis, mediation analysis and ANCOVA were performed.

RESULTS

HRQoL was positively associated with cardiorespiratory fitness (B = 0.112; p < 0.05) and muscular fitness score (B = 0.328 p < 0.05), after controlling for potential confounders. However, when both fitness variables were entered in the same model only cardiorespiratory fitness remained significantly associated with HRQoL (B = 0.093 p < 0.05). Cardiorespiratory fitness acted as a full mediator variable on the relationship between muscular fitness and HRQoL in adolescents (p < 0.05). ANCOVA showed that adolescents with high cardiorespiratory fitness/high muscular fitness exhibit better HRQoL scores when compared to those with low muscular fitness/low cardiorespiratory fitness and with those with low muscular fitness/high cardiorespiratory fitness (p < 0.05).

CONCLUSIONS

In adolescents, the combination of high cardiorespiratory fitness and high muscular fitness was positively associated with a better HRQoL.

Longitudinal association between ideal cardiovascular health status and muscular fitness in adolescents: The LabMed Physical Activity Study

BACKGROUND AND AIMS

Muscular fitness is an emerging predictor for cardiovascular disease mortality. The ideal cardiovascular health metrics has been inversely related to a subsequent cardiometabolic health in adulthood. However, evidence regarding muscular fitness and ideal cardiovascular health in adolescents is scarce. This study aimed to examine the longitudinal association between ideal cardiovascular health index and muscular fitness.

METHODS AND RESULTS

This study cohort consisted of 331 adolescents (183 girls) from the LabMed Physical Activity Study who were followed from 2011 to 2013. Ideal cardiovascular health, as defined by the American Heart Association, was determined as meeting ideal health factors (total cholesterol, blood pressure, and glucose) and behaviors (smoking status, body mass index, physical activity, and diet). Handgrip strength and standing long jump tests assessed muscular fitness and were transformed into standardized values according to age and sex. ANCOVA showed a significant association between the accumulation of ideal cardiovascular health metrics at baseline and muscular fitness indices at follow-up (F_{(4, 322)} = 2.280, p = 0.04). In addition, the higher the number of ideal cardiovascular health metrics accumulated, the higher the likelihood of having a high muscular fitness over a two-year period (p for trend = 0.01), after adjustments for age, sex, pubertal stage and socioeconomic status and muscular fitness at baseline.

CONCLUSION

The ideal cardiovascular health status during adolescence was associated with high muscular fitness levels over a two-year period.

Assessing truncal obesity in predicting cardiometabolic risk in children: clinical measures versus dual-energy X-ray absorptiometry

AIM

The objectives of this study were to 1) compare the accuracy of waist:hip ratio (WHR) and waist:height ratio (WHtR) by determining their association with reference-standard measures derived from dual-energy X-ray absorptiometry (DXA) and 2) assess the relationship of DXA, WHR and WHtR to measures of dyslipidemia, insulin resistance and inflammation in children.

METHODS

Subjects aged four to 21 were prospectively recruited. Truncal obesity by DXA was defined as the trunk fat:height ratio and trunk fat:nontrunk fat ratio. Three hundred and eight subjects were studied, and 246 (80%) were obese.

RESULTS

There was a strong correlation between WHtR and trunk fat:height (r = 0.84, p < 0.01). DXA measures of truncal obesity had stronger correlations with measures of cardiometabolic risk than WHR and WHtR. Upon multivariable regression, only WHtR had independent associations with cholesterol/HDL, HOMA-IR and high-sensitivity c-reactive protein.

CONCLUSION

WHtR is an accurate measure of truncal obesity. WHtR showed stronger associations with measures of insulin resistance and truncal obesity than WHR.

Low-grade inflammation and muscular fitness on insulin resistance in adolescents: Results from LabMed Physical Activity Study

BACKGROUND

Low muscular fitness (MF) and low-grade inflammation has been linked to insulin resistance (IR).

OBJECTIVE

To evaluate the associations between MF and a clustered score of inflammatory biomarkers on IR and to investigate the combined impact of MF and inflammation on IR in adolescents.

METHODS

This is a cross-sectional analysis with 529 adolescents (267 girls) aged 12 to 18 years. Pubertal stage, socioeconomic status, adherence to the Mediterranean diet, cardiorespiratory fitness, and waist circumference were assessed. Standing long-jump and isometric handgrip dynamometry were used as indicators of MF. Continuous score of clustered inflammatory biomarkers (InflaScore) (sum of Z-scores of C-reactive protein, C3, C4, fibrinogen, and leptin) and IR (homeostasis model assessment of insulin resistance [HOMA-IR] estimated from fasting serum insulin and glucose) were assessed.

RESULTS

HOMA-IR and fasting insulin were positively associated with InflaScore and negatively associated with MF, independently of age, sex, pubertal stage, socioeconomic status, adherence to the Mediterranean diet, cardiorespiratory fitness, and waist circumference. Adolescents classified as High InflaScore/Unfit showed significantly higher HOMA-IR when compared than those with High InflaScore/Fit and those with Low InflaScore/Fit (F_(3,519)  = 4.761, P < .003), after adjustments for potential confounders. Unfit adolescents with high InflaScore had the highest odds of expressing high HOMA-IR (odds ratio, OR = 2.40, 95% confidence interval [CI]: 1.2-5.6) and insulin risk (2.53 95% CI, 1.5-5.9) when compared to those of the Low InflaScore/Fit group, after adjustments for potential confounders.

CONCLUSION

Higher levels of MF seem to minimize the deleterious effect of inflammation on IR.

Associations between health-related quality of life and body mass index in Portuguese adolescents: LabMed physical activity study

Background In adolescence there are several biological and physiological changes associated with overweight and obesity. Objective The purpose of this study was to analyze the associations between health-related quality of life (HRQoL) and body mass index (BMI) in adolescents. Methods This is a cross-sectional analysis of 957 Portuguese adolescents (446 girls and 511 boys) aged 12-18 years. A series of variables were collected: (a) HRQoL was assessed using the KIDSCREEN-10 questionnaire; (b) socioeconomic status (SES) was measured using the Family Affluence Scale; (c) body composition (weigh, height) were measured and BMI was calculated and, (d) pubertal stage was assessed with Tanner stages; (e) the 20-m shuttle-run was used to estimate cardiorespiratory fitness. Regression models and mediation analysis were performed to assess the association between HRQoL and BMI. Results HRQoL was significantly higher in boys than girls (p < 0.05). The prevalence of overweight and obesity was 23.5% and 6.7% in girls, and 21.3% and 5% in boys, respectively. HRQoL was inversely and significantly associated with BMI in boys (B = -0.130; p < 0.05) and girls (B = -0.148; p < 0.05) after controlling for age, pubertal stage and SES. Cardiorespiratory fitness act as a full mediator variable on the relationship between BMI and HRQoL in adolescents (p < 0.05). Conclusion Our results suggest that cardiorespiratory fitness acted as a full mediator in the relationship between BMI and HRQoL, in adolescents. Public health policies targeting a wealthy weight and an improved physical fitness level could be a strategy of particular interest for improving the HRQoL of adolescents.

Cardiorespiratory Fitness and Blood Pressure: A Longitudinal Analysis

OBJECTIVES

To examine the association between cardiorespiratory fitness and cardiovascular indices 2 years later, and to determine whether changes in cardiorespiratory fitness are associated with cardiovascular indices at a 2-year follow-up in adolescents.

STUDY DESIGN

The sample comprised 734 adolescents (349 girls) aged 12-18 years followed for 3 years from the LabMed Physical Activity Study. Cardiorespiratory fitness was assessed by the 20-meter shuttle run test. Height, weight, waist circumference, and resting blood pressure (BP) were measured according to standard procedures.

RESULTS

Regression analyses showed a significant inverse association between cardiorespiratory fitness at baseline and systolic BP (B = -0.126; P = .047) and rate pressure product (B = -29.94; P = .016), at follow-up after adjustments for age, sex, height, pubertal stage, socioeconomic status, and waist circumference. Significant differences were found between cardiorespiratory fitness groups (fit vs unfit) at baseline and systolic BP and rate pressure product at follow-up (P < .05 for all). Analysis of covariance showed a significant association between cardiorespiratory fitness changes and systolic BP (P = .024) and rate pressure product (P = .014), after adjustment for age, sex, height, pubertal status, socioeconomic status, and waist circumference.

CONCLUSIONS

Changes in cardiorespiratory fitness during adolescence were associated with cardiovascular indices over a 2-year period. Adolescents with persistently low levels of cardiorespiratory fitness exhibited the highest levels of systolic BP and rate pressure product.

Association between Leptin, Adiponectin, and Leptin/Adiponectin Ratio with Clustered Metabolic Risk Factors in Portuguese Adolescents: The LabMed Physical Activity Study

Introduction: Circulating leptin and adiponectin levels have been associated with impaired vascular function, insulin resistance, and acute cardiovascular evens. This study aimed to evaluate the associations of leptin, adiponectin, and the leptin/adiponectin (L/A) ratio with a clustering of metabolic risk factors (MRF) in adolescents aged 12-18 years. Methods: This is a cross-sectional analysis with 529 Portuguese adolescents aged 12-18 years. Blood samples were taken to analyze total cholesterol (TC) and high-density lipoprotein (HDL) cholesterol (HDL-c), triglycerides glucose, insulin, leptin, and adiponectin levels. A continuous variable of clustered MRF score (sum of Z-scores of body fat percentage, systolic blood pressure, ratio TC/HDL, triglycerides, homeostatic model assessment insulin resistance, and cardiorespiratory fitness*[-1]) was computed. Results: Regression analyses showed that adiponectin was a significant and negative predictor of MRF score (boys: β = -0.199; p < 0.001; girls: β = -0.200; p < 0.001); whereas leptin was a significant positive predictor of MRF score (boys: β = 0.553; p < 0.001; girls: β = 0.399; p < 0.001). The L/A ratio was also a significant positive predictor of MRF score in both sexes (boys: β = 0.593; p < 0.001; girls: β = 0.461; p < 0.001), after adjustments for age, pubertal stage, adherence to the Mediterranean diet, and socioeconomic status. In addition, adiponectin, leptin, and L/A ratio were accurate to predict MRF among adolescents, but L/A ratio showed the highest area under receiver operating characteristic curve. Conclusion: Leptin, adiponectin, and L/A ratio are associated with the clustering of MRF in adolescents after adjustments for age, sex, pubertal stage, adherence to the Mediterranean diet, and socioeconomic status. L/A ratio was more strongly associated with MRF score than adiponectin or leptin.