Relationship between the body mass index and the ponderal index with physical fitness in adolescent students.

BACKGROUND: The relationship between the Body Mass Index (BMI) with physical fitness in children and adolescent populations from diverse regions are consistent. However, the relationship between the Ponderal Index (PI) with physical fitness, based on what is known to date, has not been examined in depth. The objective was to evaluate the relationships between BMI and PI with three physical fitness tests of students living at moderate altitudes in Peru. METHODS: A descriptive correlational study was carried out with 385 adolescents, between the ages of 10.0 to 15.9 years old, from the province of Arequipa, Peru. Weight, height, and three physical fitness tests (horizontal jump, agility, and abdominal muscle resistance) were evaluated. BMI and PI were calculated, and they were, then, categorized into three strata (low, normal, and excessive weight). Specific regressions were calculated for sex, using a non-lineal quadratic model for each item adjusted for BMI and PI. RESULTS: The relationship between BMI and PI with the physical tests reflected parabolic curves that varied in both sexes. The regression values for BMI in males oscillated between R2 = 0.029 and 0.073 and for females between R2 = 0.008 and 0.091. For PI, for males, it varied from R2 = 0.044 to 0.82 and for females, from R2 = 0.011 to 0.103. No differences occurred between the three nutritional categories for BMI as well as for PI for both sexes (p range between 0.18 to 0.38), as well as for low weight (BMI vs PI), normal weight (BMI vs PI), and excessive weight (BMI vs PI) (p range between 0.35 to 0.64). CONCLUSIONS: BMI showed inferior quadratic regressions with respect to the PI. In addition, physical performance was slightly unfavorable when it was analyzed by BMI. PI could be a useful tool for analyzing and predicting physical fitness for adolescents living at a moderate altitude since it corrects for the notable differences for weight between adolescents.

Establishing percentiles for blood pressure based on absolute height for children and adolescents.

BACKGROUND: Evaluating blood pressure (BP) is one element for diagnosing and preventing disease in student populations. The objectives of this research were to (a) identify the range of height for measuring BP adjusted for student populations and (b) propose percentiles for evaluating BP based on height. METHODS: A cross-sectional study was carried out with 3,013 students. Weight, height, and diastolic (DBP) and systolic (SBP) blood pressure were evaluated. Body Mass Index (BMI) was calculated. Height ranges of 5 and 10 cm were generated. RESULTS: R2 values for height ranges of 5 cm consisted of [normotensive: DBP (R2 = 10 to 13%) and SBP (R2 = 14 to 20%), and for hypertensive: DBP (R2 = 0.07 to 15%) and for SBP (R2 = 29 to 32%)]. For height ranges of 10 cm, values included: [normotensive: DBP (R2 = 10 to 15%), and SBP (R2 = 15 to 21%) and for hypertensive: DBP (R2 = 0.07 to 16%) and SBP (R2 = 29 to 35%)]. For 5 cm height ranges, diferences occurred between both sexes for DBP (in 5 height ranges from 123 to 148 cm and 158 to 168 cm) and for the SBP (in 6 height ranges from 128 to 148 cm and from 158 to 168 cm). In the 10 cm categories, diferences appeared in DBP (from 138 to 148 cm) and in the SBP (from 158 to 168 cm). CONCLUSIONS: Height is a determinant for evaluating blood pressure, and height ranges of 10 cm are more suitable for children and adolescents. The proposed percentiles based on height ranges allowed assessment of the DBP and SBP suggest their use in epidemiological and educational contexts.

Referencial values for the physical growth of school children and adolescents in Campinas, Brazil.

AIMS: To compare the values of weight, height and IMC with the regional curve (Cariri); to compare with the international references of the CDC-2000; and to construct references that will measure physical growth from childhood to adolescence. SUBJECTS AND METHODS: The sample consists of 6531 individuals with an age range of 6.0-17.9 years. Comparisons (weight, height and BMI) between the means of the group were made with the regional reference Cariri and the international reference CDC-2000. RESULTS: The students of both sexes from Campinas were taller, heavier and presented more IMC than those from Cariri. With respect to CDC-2000, the girls were heavier until 12 years old and the boys were heavier until 15 years old. For height, the students of both sexes from Campinas were taller until age 10. In IMC, the students from Campinas showed superior qualities in relation to the reference in both sexes (for girls until age 14 and boys until 16 years old). CONCLUSION: Patterns of physical growth of children in Campinas are different in relation to the regional and international reference curve. The regional standards proposed are a possibility to assess the trajectory of physical growth of school children of Campinas in clinical or epidemiological settings.

Physical Growth, Biological Age, and Nutritional Transitions of Adolescents Living at Moderate Altitudes in Peru.

BACKGROUND: Peru is experiencing a stage of nutritional transition where the principal characteristics are typical of countries undergoing development. OBJECTIVES: The objectives of this study were the following: (a) compare physical growth patterns with an international standard; (b) determine biological age; and (c) analyze the double nutritional burden of adolescents living at a moderate altitude in Peru. DESIGN: Weight, standing height, and sitting height were measured in 551 adolescents of both sexes (12.0 to 17.9 years old) from an urban area of Arequipa, Peru (2328 m). Physical growth was compared with the international standard of the CDC-2000. Biological age was determined by using a non-invasive transversal technique based on years from age at peak height velocity (APHV). Nutritional state was determined by means of weight for age and height for age. Z scores were calculated using international standards from the CDC-2000. RESULTS: Body weight for both sexes was similar to the CDC-2000 international standards. At all ages, the girls' height (p < 0.05) was below the standards. However, the boys' height (p < 0.05) was less at ages, 15, 16, and 17. Biological age showed up in girls at age 12.7 years and for boys at 15.2 years. Stunted growth (8.7% boys and 18.0% girls) and over weight (11.3% boys and 8.8% girls) occurred in both groups. A relationship existed in both sexes between the categories of weight for the age and stunted growth by sex. CONCLUSIONS: Adolescents living at a moderate altitude exhibited stunted linear growth and biological maturation. Furthermore, adolescents of both sexes showed the presence of the double nutritional burden (stunted growth and excessive weight).

Efectos de la suplementación de carnitina sobre el nivel de fatiga muscular del gastrocnemio de ratas entrenadas y sedentarias / Effect of carnitine supplementation on fatigue level in the gastrocnemius muscle of trained and sedentary rats

La L-carnitina tiene un gran valor en procesos metabólicos al cumplir un papel importante en el proceso de β -oxidación mitocondrial, por lo cual, podría ser usada para mejorar el rendimiento atlético y mantener una carga de trabajo. Este trabajo tuvo por objetivo evaluar los efectos de la suplementación de L-carnitina y del entrenamiento en el tiempo necesario a la inducción de la fatiga muscular en preparaciones in situ del nervio ciático y músculo gastronemio en ratas. Cuatro grupos de animales fueron constituidos: sedentario no suplementado (SNS), sedentario suplementado (SS), entrenado no suplementado (ENS) y entrenado suplementado (ES). El entrenamiento fue realizado en sesiones diarias (1h/5dias/semana) y con suplementación oral crónica de L-Carnitina (1mg/ml) por 4 semanas. La fatiga muscular fue obtenida mediante estimulación supra-maximal tetánica del nervio ciático (50 Hz). Los valores del tiempo para la reducción de fuerza fueron significativamente diferentes (p< 0,05) entre los grupos SNS vs SS y ENS vs ES, respectivamente. Sin embargo, no hubo diferencias significativas entre los grupos ES vs SS y ENS vs SNS. Estos resultados demuestran que la L-carnitina prolongo el tiempo necesario para la reducción de fuerza a nivel del músculo gastrocnemio.

L-carnitine, considered to be of great value in metabolic processes, plays an important role in the mitochondrial β -oxidation process. It may be used to improve athletic performance and to maintain a higher workload during exercise. This study aimed to investigate the effect of L-carnitine supplementation on muscle fatigue in sciatic nerve-gastrocnemius muscle preparations in sedentary and trained rats. The animals were divided into 4 groups: non-supplemented sedentary (NSS), supplemented sedentary (SS), non-supplemented trained (NST), and supplemented trained (ST) rats. The animals were trained in daily 1-h sessions (5 days/week) and received chronic oral L-carnitine supplementation (1 mg/mL) for 4 weeks. Muscle fatigue was determined by supramaximal tetanic stimulation of the sciatic nerve (50 Hz). Time values for strength reduction were significantly different (p< 0.05) between NSS vs. SS and NST vs. ST rats. No significant differences were observed between SS vs. ST and NST vs. NSS rats. These findings demonstrate that L-carnitine lengthen the time required for induction of muscle fatigue.

O uso das curvas de crescimento da Organização Mundial da Saúde em crianças e adolescentes que vivem em regiões de altitude moderada / The use of World Health Organization growth curves in children and adolescents that live in regions of moderate altitude / El uso de curvas de crecimiento de la Organización Mundial de la Salud en niños y adolescentes que viven en regiones de altitud moderada

OBJETIVO: Determinar a aplicabilidade do uso das curvas de crescimento da Organização Mundial da Saúde (OMS) em escolares que vivem em regiões de altitude moderada. MÉTODOS: Estudo transversal cuja população foi constituída por uma amostra probabilística estratificada com 955 crianças e adolescentes de seis a 12 anos, sendo 473 meninos e 482 meninas que frequentavam escolas públicas da área urbana da Região de Arequipa (Peru). As variáveis avaliadas envolveram medidas de massa corpórea (kg) e estatura (m) e índice de massa corporal. Para as comparações, utilizou-se o escore Z e o teste t para medidas pareadas. RESULTADOS: Os meninos apresentaram valores similares de massa corpórea quando comparados com a referência. No entanto, as meninas mostraram valores superiores à referência nas idades de seis, sete e dez anos (p<0,001). No caso da estatura e do índice de massa corporal, houve diferenças (p<0,001) entre a referência e os escolares de moderada altitude em todas as idades e em ambos os sexos, com estatura inferior à referência e, consequentemente, maior índice de massa corporal, sendo o escore Z para os meninos: 1,0 (seis anos), 0,69 (sete anos), 0,50 (oito anos), 1,20 (nove anos), 0,75 (dez anos) 0,41 (11 anos) e 0,82 (12 anos); para as meninas, 0,36 (seis anos), 0,53 (sete e oito anos), 0,48 (nove anos), 0,89 (dez anos), 0,55 (11 anos) e 0,43 (12 anos). CONCLUSÕES: O índice de massa corporal não deve ser aplicado a crianças e adolescentes de moderada altitude devido ao retardo no crescimento linear, o que compromete o resultado final deste índice.

OBJECTIVE: To determine the applicability of the World Health Organization growth curves in school children that live in areas of moderate altitude. METHODS: A cross-sectional study, using a stratified random sample of 955 children and adolescents aged 6 to 12 years-old (473 boys and 482 girls) attending public schools in the urban area of Arequipa (Peru). The evaluated variables included body mass (kg) and height (m) values and the body mass index. Z score and the t test for paired measurements were applied for statistical analysis. RESULTS: The boys had similar values of body mass when compared with the reference. However, girls showed higher values than the reference at ages six, seven, and ten years-old (p<0.001). For height and body mass index, differences (p<0.001) were noted between the reference and the school children living in areas of moderate altitude for all ages and genders, being the height lower than the reference and the body mass index higher than the reference. Z scores for the body mass index were: boys - 1.0 (six years-old), 0.69 (seven years-old), 0.50 (eight years-old), 1.20 (nine years-old), 0.75 (ten years-old), 0.41 (11 years-old) and 0.82 (12 years-old); girls - 0.36 (six years-old), 0.53 (seven and eight years-old), 0.48 (nine years-old), 0.89 (10 years-old), 0.55 (11 years-old), and 0.43 (12 years-old). CONCLUSIONS: The body mass index should not be applied to children and adolescents that live in regions of moderate altitude. The linear growth retardation presented by this population directly compromises the results of this index.

OBJETIVO: Determinar la aplicabilidad del uso de curvas de crecimiento de la Organización Mundial de la Salud en escolares que viven en regiones de altitud moderada. MÉTODOS: Estudio transversal, cuya población fue constituida por una muestra probabilística estratificada con 955 niños y adolescentes de seis a 12 años de edad, siendo 473 muchachos y 482 muchachas, que frecuentaban escuelas públicas de área urbana de la Región de Arequipa (Perú). Las variables evaluadas implicaron medidas de masa corporal (kg) y estatura (m) y el índice de masa corporal. Para las comparaciones, se utilizó el escore Z y la prueba t para medidas pareadas. RESULTADOS: Los muchachos presentaron valores similares de masa corporal cuando comparados con la referencia. Sin embargo, las muchachas mostraron valores superiores a la referencia en las edades de seis, siete y diez años (p<0,001). En el caso de la estatura y del índice de masa corporal, hubo diferencias (p<0,001) entre la referencia de los escolares de moderada altitud en todas las edades y en ambos sexos, con estatura inferior a la referencia y, como consecuencia, mayor índice de masa corporal, siendo el escore Z para los muchachos: 1,0 (seis años), 0,69 (siete años), 0,50 (ocho años), 1,20 (nueve años), 0,75 (diez años), 0,41 (11 años) y 0,82 (12 años) y, para las muchachas, 0,36 (seis años), 0,53 (siete y ocho años), 0,48 (nueve años), 0,89 (diez años), 0,55 (11 años) y 0,43 (12 años). CONCLUSIONES: El índice de masa corporal no debe ser aplicado a niños y adolescentes de moderada altitud debido al retraso en el crecimiento lineal, lo que compromete el resultado final de este índice.