Role of muscle mass in the association between handgrip strength and blood pressure in children and adolescents.

Studies have reported conflicting results on the association between handgrip strength (HGS) and blood pressure during childhood and adolescence. High multicollinearity involving somatic components that influence both HGS and blood pressure might be an important source of bias. This study sought to investigate the independent effects of HGS and muscle mass on blood pressure levels in children and adolescents. Muscle mass and fat mass (Multifrequency Electrical Bioimpedance) and systolic (SBP) and diastolic (DBP) blood pressure (Automatic oscillometric device) were assessed in 833 volunteers aged 6-18 years, of both sexes. Handgrip strength-for-age quartiles were calculated and participants were assigned to groups by HGS quartiles. Analysis of covariance was conducted to address the linear association between HGS and SBP adjusted for height, muscle mass, and fat mass. To test for linear trend, contrast analysis was conducted. Partial eta-squared was used to confirm or rule out a small significant effect of the independent variables on SBP. The effect size of HGS on SBP was not significant in both sexes. In girls, 1.7% of the between-groups variance in SBP was accounted for by muscle mass (P = 0.016). In boys, 2.3% and 1.8% of the between-groups variance in SBP was accounted for by muscle mass (P = 0.001) and height (P = 0.005), respectively. In conclusion, children with a more advanced physical maturity for their age, that is, who are taller, stronger, and have greater fat-free mass, may be nearly reaching the physiological parameters of adulthood, and consequently have higher systolic blood pressure.

Establishing international optimal cut-offs of waist-to-height ratio for predicting cardiometabolic risk in children and adolescents aged 6-18 years.

BACKGROUND: Waist-to-height ratio (WHtR) has been proposed as a simple and effective screening tool for assessing central obesity and cardiometabolic risk in both adult and pediatric populations. However, evidence suggests that the use of a uniform WHtR cut-off of 0.50 may not be universally optimal for pediatric populations globally. We aimed to determine the optimal cut-offs of WHtR in children and adolescents with increased cardiometabolic risk across different countries worldwide. METHODS: We used ten population-based cross-sectional data on 24,605 children and adolescents aged 6-18 years from Brazil, China, Greece, Iran, Italy, Korea, South Africa, Spain, the UK, and the USA for establishing optimal WHtR cut-offs. We performed an external independent test (9,619 children and adolescents aged 6-18 years who came from other six countries) to validate the optimal WHtR cut-offs based on the predicting performance for at least two or three cardiometabolic risk factors. RESULTS: Based on receiver operator characteristic curve analyses of various WHtR cut-offs to discriminate those with ≥ 2 cardiometabolic risk factors, the relatively optimal percentile cut-offs of WHtR in the normal weight subsample population in each country did not always coincide with a single fixed percentile, but varied from the 75th to 95th percentiles across the ten countries. However, these relatively optimal percentile values tended to cluster irrespective of sex, metabolic syndrome (MetS) criteria used, and WC measurement position. In general, using ≥ 2 cardiometabolic risk factors as the predictive outcome, the relatively optimal WHtR cut-off was around 0.50 in European and the US youths but was lower, around 0.46, in Asian, African, and South American youths. Secondary analyses that directly tested WHtR values ranging from 0.42 to 0.56 at 0.01 increments largely confirmed the results of the main analyses. In addition, the proposed cut-offs of 0.50 and 0.46 for two specific pediatric populations, respectively, showed a good performance in predicting ≥ 2 or ≥ 3 cardiometabolic risk factors in external independent test populations from six countries (Brazil, China, Germany, Italy, Korea, and the USA). CONCLUSIONS: The proposed international WHtR cut-offs are easy and useful to identify central obesity and cardiometabolic risk in children and adolescents globally, thus allowing international comparison across populations.

Association of sun exposure and seasonality with vitamin D levels in Brazilian children and adolescents.

OBJECTIVE: This study aimed to verify vitamin D concentration in children and adolescents during the seasons of the year and to compare vitamin D concentration between children engaged in outdoor activities and those engaged in indoor activities. METHODS: This is a cross-sectional study with a sample of 708 children and adolescents (aged 6-18 years), excluding 109 (16 were over 19 years old; 39 had a disease that required continuous treatment; 20 were on continuous medication; and 34 had no vitamin D data), ending with 599. The plasma concentration of 25-hydroxyvitamin D2 was measured with commercial kits following manufacturer instructions. RESULTS: Participants who engaged in outdoor activities, as well as those who had data collected during summer and spring, had higher levels of vitamin D. According to the Poisson regression, the proportion of participants with inadequate levels of vitamin D was greater in the participants whose vitamin D was measured during spring (PR 1.15, 95%CI 1.03-1.29) and winter (PR 1.18, 95%CI 1.05-1.32). Also, a greater proportion of inadequate vitamin D was observed for those engaged in indoor activities (PR 1.08, 95%CI 1.01-1.15). CONCLUSIONS: Participants who measured the vitamin during the summer and autumn had a lower prevalence of hypovitaminosis D. Even in regions with high solar incidence throughout the year, vitamin D levels can vary significantly during the period's seasons.

Pediatric dyslipidemia is associated with increased urinary ACE activity, blood pressure values, and carotidal-femoral pulse wave velocity.

This study aimed to evaluate the enzymatic activity of the angiotensin-converting enzyme (ACE) in children and adolescents to investigate their relationship with dyslipidemia and other cardiometabolic alterations. Anthropometric measurements, blood pressure (BP), and fasting lipid concentrations were taken from 360 subjects. Categorization was done according to the levels of each lipoprotein (total cholesterol, triglycerides (TG), LDL-C, HDL-C, and non-HDL-C) into three groups: normolipidemic (NL), borderline (BL), and dyslipidemic (DL). Enzymatic activity in urine was measured using the substrates Z-FHL-OH and hippuryl-HL-OH (h-HL-OH) and the ACE activity ratio (Z-FHL-OH/h-HL-OH) was calculated. Dyslipidemic levels of HDL-C, TG, and LDL-C were observed in 23%, 9%, and 3% of the participants, respectively, and were more frequent in obese children (Chi-square, p < 0.001). ACE activity ratio was augmented in BL(HDL-C) when compared to NL(HDL-C) (5.06 vs. 2.39, p < 0.01), in DL(LDL-C) in comparison to BL(LDL-C) and NL(LDL-C) (8.7 vs. 1.8 vs. 3.0, p < 0.01), and in DL(non-HDL-C) than in BL(non-HDL-C) and in NL(non-HDL-C) (6.3 vs. 2.1 vs. 2.9, p = 0.02). The groups with impaired HDL-C and TG levels presented an increased diastolic BP percentile, and a higher systolic BP percentile was observed in BL(TG) and DL(TG). The carotidal-femoral pulse wave velocity (cfPWV) was higher in the groups with DL levels of TG and LDL-C than in NL groups. Hypertriglyceridemia was associated with higher cfPWV. No direct impact of the ACE activity on BP values was observed in this cohort, however, there was an association between hyperlipidemia and ACE upregulation which can trigger mechanisms driving to early onset of hypertension and cardiovascular disease. Graphical abstract exemplifying the cohort, categorization of subjects into the groups NL normolipidemic, BL borderline, DL dyslipidemic, methods, and main findings. Pediatric dyslipidemia was consistent with dyslipidemia secondary to obesity (DSO), associated with higher urinary angiotensin-converting enzyme (ACE) activity ratio, BP blood pressure values, and carotidal-femoral pulse wave velocity (cfPWV).

Sedentary Behavior, Dietary Habits, and Cardiometabolic Risk in Physically Active Children and Adolescents. / Comportamento Sedentário, Hábitos Alimentares e Risco Cardiometabólico em Crianças e Adolescentes Fisicamente Ativos.

BACKGROUND: Sedentary behavior has been associated with several cardiometabolic risk factors during childhood. However, little is known about the impact of sedentary behavior on the health and eating habits of physically active children and adolescents. OBJECTIVE: To evaluate the association between sedentary behavior and cardiometabolic risk factors and eating habits in physically active children and adolescents. METHODS: This cross-sectional study was conducted, including 516 physically active children and adolescents (10 to 18 years old; both sexes) enrolled in the social project "Estação Conhecimento-Vale" were evaluated. Biochemical and lifestyle variables (questionnaire) were collected. Sedentary behavior was determined indirectly (questionnaire), by using sitting time ≥ 3 hours per day as a cutoff point. A p-value < 0.05 was considered statistically significant for all tests. RESULTS: Sedentary behavior was not associated with overweight/obesity (odds ratio = 0.72 [95% confidence interval (CI): 0.325-1.389]), hypertriglyceridemia (odds ratio = 0.63 [95% CI: 0.306-1.297]), low HDL cholesterol (odds ratio = 0.57 [95% CI: 0.323-1.019]), or high non-HDL cholesterol (odds ratio = 0.63 [95% CI: 0.283-1.389]). However, children and adolescents with sedentary behavior were more likely to regularly consume food in front of the television (odds ratio = 1.96 [95% CI: 1.114-3.456]) and to consume at least one ultra-processed food per day (odds ratio = 2.42 [95% CI: 1.381-4.241]). In addition, they were less likely to consume fruit regularly (odds ratio = 0.52 [95% CI: 0.278-0.967]). CONCLUSION: There was no association between sedentary behavior and cardiometabolic risk factors in physically active children and adolescents. However, sedentary behavior was associated with inadequate eating habits. Thus, we may suggest that the regular engagement in physical activity may attenuate the deleterious effects of sedentary behavior on the cardiometabolic parameters of children and adolescents.

FUNDAMENTO: O comportamento sedentário tem sido associado a diversos fatores de risco cardiometabólicos durante a infância. No entanto, pouco se sabe sobre o impacto do comportamento sedentário na saúde e nos hábitos alimentares de crianças e adolescentes fisicamente ativos. OBJETIVO: Avaliar a associação entre comportamento sedentário e fatores de risco cardiometabólicos e hábitos alimentares em crianças e adolescentes fisicamente ativos. MÉTODOS: Esse estudo transversal avaliou 516 crianças e adolescentes (10 a 18 anos; ambos os sexos) fisicamente ativos integrados no projeto social "Estação Conhecimento-Vale". O comportamento sedentário foi determinado de maneira indireta (questionário), utilizando como ponto de corte o tempo sentado ≥ 3 h/dia. Foram estatisticamente significantes as análises com p-valor < 0,05. RESULTADOS: O comportamento sedentário não foi associado ao excesso de peso (odds ratio = 0,72 [intervalo de confiança (IC) de 95%: 0,325-1,389]), hipertrigliceridemia ( odds ratio = 0,63 [IC95%: 0,306-1,297]), HDL colesterol baixo ( odds ratio = 0,57 [IC95%: 0,323-1,019]) e HDL não colesterol alto ( odds ratio = 0,63 [IC95%: 0,283-1,389]). Contudo, crianças e adolescentes que adotavam comportamento sedentário apresentaram maior chance de consumir regularmente alimentos em frente à televisão ( odds ratio =1,96 [IC95%: 1,114-3,456]) e de consumir pelo menos um alimento ultraprocessado por dia ( odds ratio =2,42 [IC95%: 1,381-4,241]). Além disso, apresentaram menor chance de consumir frutas regularmente (OR=0,52 [IC95%: 0,278-0,967]). CONCLUSÃO: Não houve associação entre comportamento sedentário e fatores de risco cardiometabólicos em crianças e adolescentes fisicamente ativos. Contudo, o comportamento sedentário foi associado a hábitos alimentares inadequados. Dessa forma, podemos sugerir que a prática regular de atividade física pode atenuar os efeitos deletérios do comportamento sedentário nos parâmetros cardiometabólicos de crianças e adolescentes.

The association between salt intake and blood pressure is mediated by body mass index but modified by hypertension: The ELSA-Brasil study.

High salt intake has been linked to both obesity and high blood pressure (BP). Part of the variability of BP attributed to salt intake might be BMI-mediated. To investigate whether hypertension would be an effect modifier in the complex network including salt intake, obesity, and BP, we tested the hypothesis that salt intake has direct and BMI-mediated effects on systolic (SBP) and diastolic blood pressure (DBP). Data from 9,028 participants (aged 34-75 years, 53.6% women) were analyzed. A validated formula was used to estimate daily salt intake from the sodium excretion (12 h urine collection). A path model adjusted for covariates was designed in which salt intake has both a direct and a BMI-mediated effect on BP. In normotensives, standardized beta coefficients showed significant direct (Men: 0.058 and 0.052, Women: 0.072 and 0,061, P < 0.05) and BMI-mediated (Men: 0.040 and 0.065, Women: 0.038 and 0.067, P < 0.05) effect of salt intake on the SBP and DBP, respectively. However, in hypertensive individuals, neither the direct (Men: 0.006 and 0.056, Women: 0.048 and 0.017) nor the indirect effect (Men: -0.044 and 0.014, Women: 0.011 and 0.050) of salt intake on the SBP and DBP were significant. These data suggest that cardiovascular risk stratification should consider the complex interaction between salt intake and weight gain, and their effects on BP of normotensive and hypertensive individuals.

Association of sun exposure and seasonality with vitamin D levels in Brazilian children and adolescents / Associação da exposição solar e da sazonalidade com os níveis de vitamina D em crianças e adolescentes brasileiros

Abstract Objective: This study aimed to verify vitamin D concentration in children and adolescents during the seasons of the year and to compare vitamin D concentration between children engaged in outdoor activities and those engaged in indoor activities. Methods: This is a cross-sectional study with a sample of 708 children and adolescents (aged 6-18 years), excluding 109 (16 were over 19 years old; 39 had a disease that required continuous treatment; 20 were on continuous medication; and 34 had no vitamin D data), ending with 599. The plasma concentration of 25-hydroxyvitamin D2 was measured with commercial kits following manufacturer instructions. Results: Participants who engaged in outdoor activities, as well as those who had data collected during summer and spring, had higher levels of vitamin D. According to the Poisson regression, the proportion of participants with inadequate levels of vitamin D was greater in the participants whose vitamin D was measured during spring (PR 1.15, 95%CI 1.03-1.29) and winter (PR 1.18, 95%CI 1.05-1.32). Also, a greater proportion of inadequate vitamin D was observed for those engaged in indoor activities (PR 1.08, 95%CI 1.01-1.15). Conclusions: Participants who measured the vitamin during the summer and autumn had a lower prevalence of hypovitaminosis D. Even in regions with high solar incidence throughout the year, vitamin D levels can vary significantly during the period's seasons.

Resumo Objetivo: Verificar a concentração de vitamina D em crianças e adolescentes durante as estações do ano e comparar essa concentração entre crianças praticantes de atividades ao ar livre e aquelas praticantes de atividades em ambiente fechado. Métodos: Trata-se de estudo transversal com amostra de 708 crianças e adolescentes (seis a 18 anos), excluindo-se 109, pois 16 eram maiores de 19 anos; 39 tinham doença que exigia tratamento contínuo; 20 estavam em uso de medicação contínua; e 34 não tinham dados de vitamina D. Terminou-se, assim, com 599 pacientes. A concentração plasmática de 25-hidroxivitamina D2 foi medida com kits comerciais, seguindo as instruções do fabricante. Resultados: Os participantes que realizaram atividades ao ar livre, assim como aqueles que tiveram dados coletados durante o verão e a primavera, apresentaram níveis mais elevados de vitamina D. De acordo com a regressão de Poisson, a proporção de participantes com níveis inadequados de vitamina D foi maior naqueles cuja medição foi realizada durante a primavera (razão de prevalência — RP 1,15, intervalo de confiança — IC95% 1,03-1,29) e o inverno (RP 1,18, IC95% 1,05-1,32). Além disso, maior proporção de vitamina D inadequada foi observada para aqueles envolvidos em atividades internas (RP 1,08, IC95% 1,01-1,15). Conclusões: Participantes que mediram a vitamina durante o verão e o outono tiveram menor prevalência para hipovitaminose D. Mesmo em regiões com alta incidência solar ao longo do ano os níveis de vitamina D podem variar significativamente durante as estações.

Comportamento Sedentário, Hábitos Alimentares e Risco Cardiometabólico em Crianças e Adolescentes Fisicamente Ativos / Sedentary Behavior, Dietary Habits, and Cardiometabolic Risk in Physically Active Children and Adolescents

Resumo Fundamento O comportamento sedentário tem sido associado a diversos fatores de risco cardiometabólicos durante a infância. No entanto, pouco se sabe sobre o impacto do comportamento sedentário na saúde e nos hábitos alimentares de crianças e adolescentes fisicamente ativos. Objetivo Avaliar a associação entre comportamento sedentário e fatores de risco cardiometabólicos e hábitos alimentares em crianças e adolescentes fisicamente ativos. Métodos Esse estudo transversal avaliou 516 crianças e adolescentes (10 a 18 anos; ambos os sexos) fisicamente ativos integrados no projeto social "Estação Conhecimento-Vale". O comportamento sedentário foi determinado de maneira indireta (questionário), utilizando como ponto de corte o tempo sentado ≥ 3 h/dia. Foram estatisticamente significantes as análises com p-valor < 0,05. Resultados O comportamento sedentário não foi associado ao excesso de peso (odds ratio = 0,72 [intervalo de confiança (IC) de 95%: 0,325-1,389]), hipertrigliceridemia ( odds ratio = 0,63 [IC95%: 0,306-1,297]), HDL colesterol baixo ( odds ratio = 0,57 [IC95%: 0,323-1,019]) e HDL não colesterol alto ( odds ratio = 0,63 [IC95%: 0,283-1,389]). Contudo, crianças e adolescentes que adotavam comportamento sedentário apresentaram maior chance de consumir regularmente alimentos em frente à televisão ( odds ratio =1,96 [IC95%: 1,114-3,456]) e de consumir pelo menos um alimento ultraprocessado por dia ( odds ratio =2,42 [IC95%: 1,381-4,241]). Além disso, apresentaram menor chance de consumir frutas regularmente (OR=0,52 [IC95%: 0,278-0,967]). Conclusão Não houve associação entre comportamento sedentário e fatores de risco cardiometabólicos em crianças e adolescentes fisicamente ativos. Contudo, o comportamento sedentário foi associado a hábitos alimentares inadequados. Dessa forma, podemos sugerir que a prática regular de atividade física pode atenuar os efeitos deletérios do comportamento sedentário nos parâmetros cardiometabólicos de crianças e adolescentes.

Abstract Background Sedentary behavior has been associated with several cardiometabolic risk factors during childhood. However, little is known about the impact of sedentary behavior on the health and eating habits of physically active children and adolescents. Objective To evaluate the association between sedentary behavior and cardiometabolic risk factors and eating habits in physically active children and adolescents. Methods This cross-sectional study was conducted, including 516 physically active children and adolescents (10 to 18 years old; both sexes) enrolled in the social project "Estação Conhecimento-Vale" were evaluated. Biochemical and lifestyle variables (questionnaire) were collected. Sedentary behavior was determined indirectly (questionnaire), by using sitting time ≥ 3 hours per day as a cutoff point. A p-value < 0.05 was considered statistically significant for all tests. Results Sedentary behavior was not associated with overweight/obesity (odds ratio = 0.72 [95% confidence interval (CI): 0.325-1.389]), hypertriglyceridemia (odds ratio = 0.63 [95% CI: 0.306-1.297]), low HDL cholesterol (odds ratio = 0.57 [95% CI: 0.323-1.019]), or high non-HDL cholesterol (odds ratio = 0.63 [95% CI: 0.283-1.389]). However, children and adolescents with sedentary behavior were more likely to regularly consume food in front of the television (odds ratio = 1.96 [95% CI: 1.114-3.456]) and to consume at least one ultra-processed food per day (odds ratio = 2.42 [95% CI: 1.381-4.241]). In addition, they were less likely to consume fruit regularly (odds ratio = 0.52 [95% CI: 0.278-0.967]). Conclusion There was no association between sedentary behavior and cardiometabolic risk factors in physically active children and adolescents. However, sedentary behavior was associated with inadequate eating habits. Thus, we may suggest that the regular engagement in physical activity may attenuate the deleterious effects of sedentary behavior on the cardiometabolic parameters of children and adolescents.

Reference values for the tri-ponderal mass index and its association with cardiovascular risk factors in Brazilian adolescents aged 12 to 17 years.

OBJECTIVES: The aims of this study was to determine the cutoff values for tri-ponderal mass index (TMI) and investigate the association between overweight/obesity as classified by TMI and cardiometabolic risk factors in Brazilian adolescents aged 12 to 17 y. METHODS: This was a cross-sectional study comprising 37 815 adolescents (40 % boys; 12-17 y) enrolled in the Study of Cardiovascular Risks in Adolescents. TMI was calculated as weight divided by cubed height (kg/m3). Overweight (TMI-for-age ≥85th percentile to <95th percentile) and obesity (TMI-for-age ≥95th percentile) were determined for both sexes. Poisson regression model analyses were used to test associations. RESULTS: TMI was stable across the age span (12-17 y) in both sexes. Boys and girls classified by TMI as obese had higher prevalence ratios (PR) for hypertension (PR, 4.98; 95% confidence interval [CI], 3.26-7.61 for boys; PR, 6.88; 95% CI, 3.70-12.78 for girls), insulin resistance (PR, 19.72; 95% CI, 13.56-28.69 for boys; PR, 10.04; 95% CI, 7.47-13.50 for girls), hypercholesterolemia (PR,5.05; 95% CI, 3.68-6.94 for boys; PR, 1.44; 95% CI, 1.00-2.11 for girls), and hypertriacylglycerolemia (PR,7.36; 95% CI, 5.16-10.50 for boys; PR, 3.37; 95% CI, 2.52-4.51 for girls) when compared with normal weight counterparts. CONCLUSIONS: Obesity, as classified by TMI, was strongly associated with several cardiovascular risk factors. Our data showed that TMI was stable across the age span. Therefore, a fixed cutoff value to determine weight status in Brazilian adolescents seems appropriate.

A sex-related mediating effect of uric acid in the association between body composition and blood pressure in children and adolescents.

The increase in blood pressure (BP) during somatic growth might have direct determinants but also mediating factors. We investigated whether uric acid (UA) and other metabolic factors would mediate the association between body composition components and BP. A cross-sectional study was conducted in 928 children and adolescents (aged 6-18 years), in which body composition and blood biochemistry were evaluated. Structural equation modeling was performed to test the direct and indirect pathways between systolic blood pressure (SBP) and body composition parameters. Muscle mass (MM) showed a strong direct effect on BP, regardless of sex. In girls, a mediating pathway through UA was not significant, but the association between fat mass (FM) and MM with SBP was mediated by the cluster of metabolic factors. In boys, both MM and FM were associated with SBP through a mediating pathway via UA, but not via the cluster of metabolic factors. The association between body composition and BP in children and adolescents has a complex design and also has a sex-specific mediating component. The increase in the UA levels may affect BP levels early in boys. Also, metabolic changes elicited by FM contribute to the increase in BP at an early age in girls. Novelty: MM showed a strong direct effect on BP, regardless of sex. In girls, the association between FM and MM with SBP was mediated by the cluster of metabolic factors. In boys, both MM and FM were associated with SBP through a mediating pathway via UA.

Uric acid reference values: report on 1750 healthy Brazilian children and adolescents.

BACKGROUND: Our purpose was to determine reference values and determinants of serum uric acid (SUA) in children and adolescents. METHODS: A fasting blood sample was collected from 1750 schoolchildren and adolescents (6-17 years). Puberty was defined according to the Tanner scale. Bodyweight, muscle mass, and body fat percentage were determined by bioimpedance. Data are given as cut-offs and mean ± standard deviation. RESULTS: SUA level was higher in children that had already entered puberty (4.2 ± 1.1 mg/dL) than among prepubescent (3.6 ± 0.8 mg/dL; p < 0.01). Considering the 90 percentile (p90) as the upper reference value, the following values are proposed for boys and girls, respectively: <10 years or prepubescent: ≤4.5 mg/dL and ≤4.8 mg/dL; from 10 to 13 years: ≤5.7 mg/dL and ≤5.2 mg/dL; from 14 to 17 years: ≤6.4 mg/dL and ≤5.3 mg/dL. Muscle mass explained part of the variability in SUA after pubescence, acting as an independent variable for higher levels of SUA. CONCLUSIONS: The sex, age, and phase of puberty influence SUA reference levels, and part of this influence could be explained by the higher muscle mass, mainly after the adolescence onset. IMPACT: The key message of this study is that high levels of uric acid in the blood are associated with metabolic syndrome and cardiovascular risk factors. These diseases should be prevented since the infancy However, it is necessary to establish reference values of uric acid (SUA) for children and adolescents. The Brazilian population is highly admixed and these values were not determined so far. We studied a robust sample of Brazilian schoolchildren and adolescents (6-17 years) and defined the 90th percentile of uric acid as the upper limit of normality for sex, age, and pubertal stage. These values can be used as a reference for other populations with similar characteristics.

Insulin resistance may be misdiagnosed by HOMA-IR in adults with greater fat-free mass: the ELSA-Brasil Study.

AIMS: Conflicting results have been reported on the association of fat-free mass (FFM) and insulin resistance (IR). This study sought to test the association of FFM and IR by indexing FFM to avoid collinearity with fat mass. METHODS: This cross-sectional study comprised 11,284 volunteers, aged 38-79 years. Body composition was assessed by multi-frequency bioelectrical impedance. FFM indexed to body surface area (FFMbsa) was calculated. IR and impaired glucose tolerance (IGT) were estimated with homeostatic model assessment of insulin resistance index (HOMA-IR) and 2-h oral glucose tolerance test (2h-OGTT), respectively. RESULTS: Percent body fat decreased from the 1st to the 5th quintile of FFMbsa in both women (Eta2 = 0.166) and men (Eta2 = 0.133). In women, fasting insulin (Eta2 = 0.002), glucose (Eta2 = 0.006), and HOMA-IR (Eta2 = 0.007) increased slightly, but 2-h plasma glucose (2-h PG) was similar across the quintiles of FFMbsa. In men, fasting insulin and HOMA-IR were similar across the quintiles of FFMbsa, whereas fasting glucose increased slightly (Eta2 = 0.002) and 2-h PG decreased (Eta2 = 0.005) toward the highest quintile of FFMbsa. The higher the odds ratio for IR, the greater the FFMbsa in both sexes. Differently, FFMbsa did not affect the odds of IGT in women, while in men the odds ratio for IGT was lower in the 5th quintile compared with the 1st quintile of FFMbsa. CONCLUSIONS: Higher odds of IR associated with greater FFMbsa contrasted with lower odds of IGT associated with greater FFMbsa. IR may be misdiagnosed by HOMA-IR in adults with greater fat-free mass.

Arterial stiffness in black adults from Angola and Brazil.

Ethnicity is an important determinant of blood pressure levels, being black individuals affected more than any other ethnic group. Arterial stiffening, an independent risk factor for hypertension, is also influenced by ethnicity. However, whether black individuals from different continents would have different patterns of arterial stiffening is still unknown. Thus, the authors aimed to compare pulse wave velocity (PWV) in black subjects living in Angola and Brazil. A total of 677 black individuals from two independent cross-sectional studies conducted in Brazil and Angola were included in this analysis. Carotid-to-femoral PWV was measured following the same protocols for both studies, as well as clinical and anthropometric variables. Adjusted PWV was higher in Brazilian blacks than in Angolans, regardless of sex (men from Brazil: 10.7 ± 1.8 vs men from Angola: 9.9 ± 1.8 m/s, P < .001; women from Brazil: 10.3 ± 1.5 vs women from Angola: 9.2 ± 1.3 m/s, P < .001). Although the cf-PWV was higher in Brazilian blacks, the age-related increase in cf-PWV was higher in Angolan men compared to Brazilians, but not in women. SBP showed the strongest association with cf-PWV, regardless of sex and country. However, age was associated with cf-PWV in all groups, except in Brazilian men. Our results clearly show a difference in PWV between two black populations, and highlight for sex differences in the hemodynamic parameters that might affect blood pressure levels in these populations.

Muscle mass is the main somatic growth indicator associated with increasing blood pressure with age in children and adolescents.

Studies have shown that lean mass must be an important determinant of blood pressure value in children and adolescents. The absence of adjustment for the collinearity between lean and fat mass (FM), restricted age span, and lack of separate analysis by sex leave a gap in the literature. This study determined direct and indirect effects of the somatic growth indicators linked to the association between age and systolic blood pressure (SBP) in boys and girls. This is a cross-sectional study comprising 1,510 participants (6-18 years). Path analysis was used to test a model in which the association between age and SBP would have a direct and independent component, but also indirect mediating paths through muscle mass (MM), FM, and height. There was no significant association between age and SBP (unstandardized ß ± SE) for both girls (0.072 ± 0.236, P = .761) and boys (0.238 ± 0.264, P = .368). Height was not a mediator for the association between age and SBP in both girls (-0.291 ± 0.156, P = .062) and boys (-0.015 ± 0.187, P = .935). Mediating effect of MM was significant for both girls (0.909 ± 0.137, P < .001) and boys (1.341 ± 0.161, P < .001), whereas mediating path through FM was significant only for boys (0.069 ± 0.023, P = .003). In conclusion, muscle mass was the strongest somatic growth indicator associated with the blood pressure value in children and adolescents. Further increase in body fat mass may affect systolic blood pressure more in boys than in girls.

Longitudinal study of the sympathovagal balance in women submitted to bariatric surgery.

Studies have shown improvement of the cardiac autonomic balance in post-bariatric patients. Most of these studies included patients using drugs interfering in the autonomic nervous system. This study assessed the time course of changes in the sympathovagal balance after bariatric surgery (Roux-en-Y gastric bypass) in 26 women free from drugs. A 10-min electrocardiographic recording was obtained at baseline and at 3 and 6 months after surgery. Temporal and spectral domains of heart rate variability were analysed. The time domain components of cardiac vagal modulation increased progressively after surgery. In the frequency domain, high frequency power increased from 24.9 at baseline (18.0 to 46.3) to 44.5 at 3 months (23.4 to 65.6), and 54.1 at 6 months after surgery (37.6 to 64.0) (median and IQR in normalized units). Low frequency spectral power decreased from 56.2 at baseline (39.6 to 74.4) to 36.8 at 6 months after surgery (24.9 to 53.9) (P= 0.036). Low frequency/high frequency ratio decreased from 2.3 at baseline (1.0 to 4.2) to 0.8 at 6 months after surgery (0.4 to 1.3) (P= 0.038). Progressive shift towards predominance of vagal tonus was detected in the follow-up. Most of the patients recovered low frequency/high frequency at 6 months after surgery.

TRI-PONDERAL MASS INDEX IS USEFUL FOR SCREENING CHILDREN AND ADOLESCENTS WITH INSULIN RESISTANCE.

OBJECTIVE: To investigate whether tri-ponderal mass index and body mass index Z scores are equivalent for screening children and adolescents with insulin resistance. METHODS: Cross-sectional study with 296 children and adolescents enrolled at public schools of Vitória, Espírito Santo, Brazil, aged eight to 14 years. The tri-ponderal mass index was calculated as the ratio between weight and height cubed. The body mass index was calculated as the ratio between weight and height squared. Insulin resistance was defined with the homeostatic model assessment (HOMA-IR). RESULTS: The HOMA-IR was higher in the 4th quartile of body mass index Z scores and tri-ponderal mass index compared to 1st and 2nd quartiles for both girls and boys. The areas under the age-adjusted receiver operating characteristic curves were similar between the indices for girls (body mass index Z scores=0.756; tri-ponderal mass index=0.763) and boys (body mass index Z scores=0.831; tri-ponderal mass index=0.843). In addition, according to the simple linear regression analyses estimations, both body mass index Z scores and tri-ponderal mass index explained a significant fraction of the homeostatic model assessment variability for girls (body mass index Z scores: R2=0.269; tri-ponderal mass index: R2=0.289; p<0.001) and boys (body mass index Z scores: R2=0.175; tri-ponderal mass index: R2=0.210; p<0.001). CONCLUSIONS: The tri-ponderal mass index and body mass index Z scores were similar to discriminate children and adolescents with insulin resistance. It is noteworthy that the use of tri-ponderal mass index is clearly advantageous, because it can be calculated with no concerns on adjustments for the age, a fact that makes it very applicable in the clinical practice.

Influence of muscle mass on the serum uric acid levels in children and adolescents.

BACKGROUND AND AIM: Uric acid (UA) is an end-product of purine catabolism and its increase in blood is a risk factor for several diseases. UA levels in men are usually higher than in women. This difference is partially due to sex hormones. We sought to investigate the onset of sexual difference in UA levels during pubertal development and the determinants of UA levels in children and adolescents. METHODS AND RESULTS: The muscle mass and fat mass were measured by multi-frequency bioelectrical impedance in a cross-sectional study involving 823 children and adolescents (both sexes; 6-18 years). Serum UA was determined using a commercially available kit. UA levels started to become higher in boys (5.0 ± 1.0 mg/dL) than in girls (4.1 ± 0.9 mg/dL) around 13 years. Boys in the highest quartile of muscle mass presented higher UA levels (5.2 ± 0.7 mg/dL) when compared with the third (4.2 ± 0.7 mg/dL), second (3.7 ± 0.9 mg/dL) and first (3.4 ± 0.9 mg/dL). Similarly, girls in the highest quartile of muscle mass presented higher UA levels (4.2 ± 0.7 mg/dL) when compared with the second (3.8 ± 0.9 mg/dL) and first (3.3 ± 0.9 mg/dL). Muscle mass explained 43.0% and 7.7% of the variability of UA in boys and girls, respectively. CONCLUSION: Sexual differences in serum UA levels begin at puberty and partially result from a direct influence of muscle mass.

Tri-ponderal mass index is useful for screening children and adolescents with insulin resistance / O índice de massa tri-ponderal é útil na triagem de crianças e adolescentes com resistência à insulina

ABSTRACT Objective: To investigate whether tri-ponderal mass index and body mass index Z scores are equivalent for screening children and adolescents with insulin resistance. Methods: Cross-sectional study with 296 children and adolescents enrolled at public schools of Vitória, Espírito Santo, Brazil, aged eight to 14 years. The tri-ponderal mass index was calculated as the ratio between weight and height cubed. The body mass index was calculated as the ratio between weight and height squared. Insulin resistance was defined with the homeostatic model assessment (HOMA-IR). Results: The HOMA-IR was higher in the 4th quartile of body mass index Z scores and tri-ponderal mass index compared to 1st and 2nd quartiles for both girls and boys. The areas under the age-adjusted receiver operating characteristic curves were similar between the indices for girls (body mass index Z scores=0.756; tri-ponderal mass index=0.763) and boys (body mass index Z scores=0.831; tri-ponderal mass index=0.843). In addition, according to the simple linear regression analyses estimations, both body mass index Z scores and tri-ponderal mass index explained a significant fraction of the homeostatic model assessment variability for girls (body mass index Z scores: R2=0.269; tri-ponderal mass index: R2=0.289; p<0.001) and boys (body mass index Z scores: R2=0.175; tri-ponderal mass index: R2=0.210; p<0.001). Conclusions: The tri-ponderal mass index and body mass index Z scores were similar to discriminate children and adolescents with insulin resistance. It is noteworthy that the use of tri-ponderal mass index is clearly advantageous, because it can be calculated with no concerns on adjustments for the age, a fact that makes it very applicable in the clinical practice.

RESUMO Objetivo: Investigar se o índice de massa tri-ponderal e os escores-z do índice de massa corporal são equivalentes na triagem de crianças e adolescentes com resistência à insulina. Métodos: Estudo transversal com 296 crianças e adolescentes matriculados em escolas públicas de Vitória, Espírito Santo, Brasil, com idades entre oito e 14 anos. O índice de massa tri-ponderal foi calculado como a razão entre o peso e a altura ao cubo. O índice de massa corporal foi calculado como a razão entre o peso e a altura ao quadrado. A resistência à insulina foi definida pelo modelo de avaliação da homeostase para resistência à insulina (HOMA-IR). Resultados: O HOMA-IR foi maior no 4º quartil dos escores-z do índice de massa corporal e do índice de massa tri-ponderal, em relação ao 1º e 2º quartis em ambos os sexos. As áreas sob as curvas receiver operating characteristic ajustadas por idade foram semelhantes em meninas (escores-z do índice de massa corporal=0,756; índice de massa tri-ponderal=0,763) e meninos (escores-z do índice de massa corporal=0,831; índice de massa tri-ponderal=0,843). Além disso, de acordo com as estimativas das análises de regressão linear simples, os escores-z do índice de massa corporal e o índice de massa tri-ponderal explicaram uma fração significativa da variabilidade do modelo de avaliação da homeostase para meninas (escores-z do índice de massa corporal: R2=0,269; índice de massa tri-ponderal: R2=0,289; p<0,001) e meninos (escores-z do índice de massa corporal: R2=0,175; índice de massa tri-ponderal: R2=0,210; p<0,001). Conclusões: O índice de massa tri-ponderal e os escores-z do índice de massa corporal foram semelhantes na triagem de crianças e adolescentes com resistência à insulina. É importante ressaltar que o uso do índice de massa tri-ponderal é claramente vantajoso, pois pode ser calculado sem ajustes por idade, fato que o torna muito aplicável à prática clínica.

Relationship between body composition and dyslipidemia in children and adolescentes. / Relação entre composição corporal e dislipidemias em crianças e adolescentes.

We studied the relationship between different anthropometric indexes and plasma lipids. Data were collected from 2014 to 2016 in 854 schoolchildren (6-18 years). Waist circumference (WC), body fat percentage (BFP) by bioimpedance, body mass index (BMI), and waist-to-height ratio (WHtR) were measured. Total cholesterol (TC), HDLc, and triglycerides were measured in fasting blood samples and Non-HDL cholesterol (Non-HDLc) was calculated. Data are presented as mean ± standard deviation, with percentages. Means were compared using the t test or ANOVA followed by Tukey's test. The association between variables was tested by linear regression. The study was approved by the Research Ethics Committee of the Universidade Federal do Espírito Santo. Obese boys had higher TC, non-HDLc, and LDLc than eutrophic boys (p < 0.05). In girls this difference was found only for non-HDLc (p < 0.05). Children with inappropriate BFP and WHtR presented higher LDLc and non-HDLc concentrations (p < 0.001), which showed positive association (p<0.001) with lipid fractions (TC and non-HDLc). Excess body fat increased the probability of cholesterol above the reference value (170 mg/dL) by 21%. Excess body fat was associated with an atherogenic lipid profile (higher non-HDLc), especially in boys.

Verificou-se a relação entre diferentes índices antropométricos e os lipídios plasmáticos. Os dados foram coletados de 2014 a 2016 em 854 escolares (6-18 anos). Foram aferidas a circunferência da cintura (CC), o percentual de gordura corporal (%G) por bioimpedância, o índice de massa corporal (IMC) e relação da cintura/estatura (RCE). Em sangue coletado em jejum mediu-se o colesterol total (CT), HDLc, e triglicerídeos e calculou-se o colesterol não HDL (Não HDLc). Os dados são apresentados por média ± desvio padrão, porcentagens. A comparação de médias foi feita pelo teste t ou ANOVA seguida de teste de Tukey. A associação entre variáveis foi testada por regressão linear. O estudo foi aprovado pelo Comitê de Ética da Universidade Federal do Espírito Santo. Meninos obesos tinham CT, Não HDLc e LDLc mais elevados do que os eutróficos. Em meninas este achado foi apenas para o Não HDLc. Crianças com o %G e RCE inadequados apresentaram LDLc e Não HDLc maiores (p < 0,001), os quais associaram-se positivamente (p < 0,001) com as frações lipídicas (CT e Não HDLc). O excesso de gordura corporal elevou em 21% a probabilidade de ocorrência de colesterol acima da referência (170 mg/dL). O excesso de gordura corporal associou-se com o perfil lipídico aterogênico (maior Não HDLc), principalmente em meninos.

Relação entre composição corporal e dislipidemias em crianças e adolescentes / Relationship between body composition and dyslipidemia in children and adolescentes

Resumo Verificou-se a relação entre diferentes índices antropométricos e os lipídios plasmáticos. Os dados foram coletados de 2014 a 2016 em 854 escolares (6-18 anos). Foram aferidas a circunferência da cintura (CC), o percentual de gordura corporal (%G) por bioimpedância, o índice de massa corporal (IMC) e relação da cintura/estatura (RCE). Em sangue coletado em jejum mediu-se o colesterol total (CT), HDLc, e triglicerídeos e calculou-se o colesterol não HDL (Não HDLc). Os dados são apresentados por média ± desvio padrão, porcentagens. A comparação de médias foi feita pelo teste t ou ANOVA seguida de teste de Tukey. A associação entre variáveis foi testada por regressão linear. O estudo foi aprovado pelo Comitê de Ética da Universidade Federal do Espírito Santo. Meninos obesos tinham CT, Não HDLc e LDLc mais elevados do que os eutróficos. Em meninas este achado foi apenas para o Não HDLc. Crianças com o %G e RCE inadequados apresentaram LDLc e Não HDLc maiores (p < 0,001), os quais associaram-se positivamente (p < 0,001) com as frações lipídicas (CT e Não HDLc). O excesso de gordura corporal elevou em 21% a probabilidade de ocorrência de colesterol acima da referência (170 mg/dL). O excesso de gordura corporal associou-se com o perfil lipídico aterogênico (maior Não HDLc), principalmente em meninos.

Abstract We studied the relationship between different anthropometric indexes and plasma lipids. Data were collected from 2014 to 2016 in 854 schoolchildren (6-18 years). Waist circumference (WC), body fat percentage (BFP) by bioimpedance, body mass index (BMI), and waist-to-height ratio (WHtR) were measured. Total cholesterol (TC), HDLc, and triglycerides were measured in fasting blood samples and Non-HDL cholesterol (Non-HDLc) was calculated. Data are presented as mean ± standard deviation, with percentages. Means were compared using the t test or ANOVA followed by Tukey's test. The association between variables was tested by linear regression. The study was approved by the Research Ethics Committee of the Universidade Federal do Espírito Santo. Obese boys had higher TC, non-HDLc, and LDLc than eutrophic boys (p < 0.05). In girls this difference was found only for non-HDLc (p < 0.05). Children with inappropriate BFP and WHtR presented higher LDLc and non-HDLc concentrations (p < 0.001), which showed positive association (p<0.001) with lipid fractions (TC and non-HDLc). Excess body fat increased the probability of cholesterol above the reference value (170 mg/dL) by 21%. Excess body fat was associated with an atherogenic lipid profile (higher non-HDLc), especially in boys.