Resumo Objetivo: Desenvolver e validar equações para estimar o percentual de gordura corporal (%GC) de crianças e adolescentes do México com medidas antropométricas. Métodos: Foi feito um estudo transversal com 601 crianças e adolescentes do México cinco e 19 anos. Os participantes foram divididos aleatoriamente nos seguintes dois grupos: a amostra de desenvolvimento (n = 398) e a amostra de validação (n = 203). A validade das equações publicadas anteriormente (por exemplo, Slaughter) também foi avaliada. O %GC foi estimado por absorciometria de dupla energia de raios X (raios X de dupla energia [DXA]). As medidas antropométricas incluíram estatura, altura sentado, peso, circunferências da cintura e do braço, dobras cutâneas (tríceps, bíceps, subescapular, suprailíaca e panturrilha) e larguras do cotovelo e bitrocantérica. Os modelos de regressão linear foram estimados com o %GC, a variável dependente e as medidas antropométricas como as variáveis independentes. Resultados: As equações foram criadas com base nas combinações de seis a nove variáveis antropométricas e apresentaram coeficientes de determinação (r2) iguais ou superiores a 92,4% para meninos e 85,8% para meninas. Na amostra de validação, as equações desenvolvidas apresentaram altos valores de r2 (≥ 85,6% em meninos e ≥ 78,1% em meninas) em todos os grupos, baixo nível de erros padrão (EP ≤ 3,05% em meninos e ≤ 3,52% em meninas) e os interceptos não foram diferentes da origem (p > 0,050). Com as equações publicadas anteriormente, os coeficientes de determinação foram menores e/ou os interceptos foram diferentes da origem. Conclusões: As equações desenvolvidas neste estudo podem ser usadas para avaliar o %GC das crianças em idade escolar e adolescentes mexicanos, pois têm uma maior validade e menor erro em comparação com as equações publicadas anteriormente.

Abstract Objective: To develop and validate equations to estimate the percentage of body fat of children and adolescents from Mexico using anthropometric measurements. Methods: A cross-sectional study was carried out with 601 children and adolescents from Mexico aged 5-19 years. The participants were randomly divided into the following two groups: the development sample (n = 398) and the validation sample (n = 203). The validity of previously published equations (e.g., Slaughter) was also assessed. The percentage of body fat was estimated by dual-energy X-ray absorptiometry. The anthropometric measurements included height, sitting height, weight, waist and arm circumferences, skinfolds (triceps, biceps, subscapular, supra-iliac, and calf), and elbow and bitrochanteric breadth. Linear regression models were estimated with the percentage of body fat as the dependent variable and the anthropometric measurements as the independent variables. Results: Equations were created based on combinations of six to nine anthropometric variables and had coefficients of determination (r2) equal to or higher than 92.4% for boys and 85.8% for girls. In the validation sample, the developed equations had high r2 values (≥85.6% in boys and ≥78.1% in girls) in all age groups, low standard errors (SE ≤ 3.05% in boys and ≤3.52% in girls), and the intercepts were not different from the origin (p > 0.050). Using the previously published equations, the coefficients of determination were lower, and/or the intercepts were different from the origin. Conclusions: The equations developed in this study can be used to assess the percentage of body fat of Mexican schoolchildren and adolescents, as they demonstrate greater validity and lower error compared with previously published equations.

Abstract: Background: An accurate assessment of physical activity in schoolchildren is necessary to implement strategies that promote active lifestyles. The objective of this study was to validate a self-administered questionnaire to assess physical activity and sedentary behaviors and to analyze differences in the validity according to nutritional status in Mexican schoolchildren. Methods: Schoolchildren of 8-12 years of age answered a self-report physical activity and sedentary behaviors questionnaire to evaluate sedentary and light physical activity (SLPA) and moderate to vigorous physical activity (MVPA). The data of children who wore a triaxial accelerometer days was analyzed. Concordance between both methods to determine the time schoolchildren spend watching television was assessed using intraclass correlation coefficients and Bland-Altman method. Results: The estimation of MVPA by questionnaires was higher than that of accelerometers by 117.6 minutes per week, and the estimation of SLPA was lower by 1,924.7 minutes per week. No correlation between the time assessed by accelerometers and the time reported in the questionnaires for SLPA and MVPA was detected. In normal-weighted children, a low correlation between the time dedicated to play videogames with sedentary activities (ric =0.29, p=0.031) assessed by accelerometers was observed. Conclusions: Schoolchildren over-estimate MVPA and under-estimate SLPA. Body weight can be a factor influencing such bias.

Resumen: Introducción: La evaluación precisa de la actividad física (AF) en escolares es necesaria para implementar estrategias que favorezcan estilos de vida activos. El objetivo del presente estudio fue evaluar la validez de un cuestionario autoadministrado de AF y actividades sedentarias y ligeras (ASL) desarrollado para escolares mexicanos, analizando las diferencias en la validez de acuerdo con el estado de nutrición. Métodos: Escolares de 8-12 años de edad contestaron un cuestionario autoaplicable en el cual se evaluaron las ASL y AF moderada y vigorosa (AFMV). Se determinaron los minutos a la semana dedicados a ASL y AFMV en niños que portaron un acelerómetro triaxial. La concordancia entre los dos métodos para detectar el tiempo que los niños invierten en ver televisión se evaluó mediante coeficientes de correlación intraclase y el método de Bland-Altman. Resultados: La estimación de AFMV por cuestionarios fue mayor que la de acelerometría por 117.6 min/semana, mientras que la estimación de ASL fue menor por 1,924.7 min/semana. No se detectó correlación entre el tiempo evaluado con acelerómetros y el reportado en el cuestionario para las ASL y AFMV. En niños con índice de masa corporal normal, se detectó una correlación baja entre el tiempo reportado y el medido por acelerometría para jugar videojuegos con las actividades sedentarias (ric = 0.29, p = 0.031). Conclusiones: Los escolares sobreestiman las AFMV y subestiman las ASL. El peso corporal puede ser un factor que influya en dichos sesgos.

Introduction: There are different prediction equations for estimating resting energy expenditure (REE) in children. However, there is not consensus on which it is the most appropriate for use in Mexican pediatric population. Objective: To know the correlation of REE measured by indirect calorimetry with different estimates from prediction equations in a group of school children from Mexico City. Material and method: A cross-sectional study with schoolchildren aged 6 to 12 years (n = 63) was carried out. REE was measured by indirect calorimetry, which was used as reference to assess the accuracy of the prediction equations of Schofield, FAO/WHO, Tverskaya and Harris-Benedict. To assess the agreement between measured TEE and prediction equations, intra-class correlation coefficients (r) were estimated. Results: In the total population the four equations overestimated REE, average differences were from 12.1 a 97.5 kcal. The equations that had the highest agreement with the measured TEE were Schofield and FAO/WHO (r = 0.74), whereas Tverskaya and Harris-Benedict had the lowest (r = 0.64). Agreement was lower in younger children, especially with the equations of Harris-Benedict (r = 0.33) and Tverskaya (r = 0.47). Conclusions: Although it is required more research on the convenience of using prediction equations of TEE in the Mexican pediatric population, our results showed that the equations of FAO/WHO or Schofield are more appropriate.

Introducción: existen diferentes ecuaciones de predicción para estimar el gasto de energía en reposo en niños; sin embargo, no hay consenso de cuál es la más adecuada para usarse en población pediátrica mexicana. Objetivo: conocer la concordancia del gasto de energía en reposo medido por calorimetría indirecta con el estimado con diferentes ecuaciones de predicción en un grupo de escolares de la Ciudad de México. Material y método: se realizó un estudio transversal en escolares de 6 a 12 años de edad (n = 63). El gasto de energía en reposo fue medido mediante calorimetría indirecta, se usó como referencia para conocer la exactitud de las ecuaciones de predicción de Schofield, de FAO/OMS, de Tverskaya y de Harris-Benedict. Para conocer la concordancia entre las ecuaciones y el gasto de energía en reposo se estimaron coeficientes de correlación intraclase (r). Resultados: en esta población las cuatro ecuaciones sobrestimaron el gasto de energía en reposo; en promedio, las diferencias fueron de 12.1 a 97.5 kcal/día. Las ecuaciones que tuvieron la mayor concordancia con el gasto de energía en reposo medido fueron las de Schofield y las de FAO/OMS (r = 0.74), mientras que las de Tverskaya y de Harris-Benedict tuvieron la menor (r = 0.64). La concordancia fue menor en los niños más pequeños, especialmente con las ecuaciones de Harris-Benedict (r = 0.33) y Tverskaya (r = 0.47). Conclusiones: aunque se requiere más investigación sobre la conveniencia de usar ecuaciones de predicción del gasto de energía en reposo en población pediátrica de México, nuestros resultados muestran que las ecuaciones de FAO/OMS o las de Schofield son las más adecuadas.

Background. At any age, physical activity (PA) is critical to maintaining health. Different PA guidelines have been formulated to improve the health of children and adolescents. We undertook this study to analyze the difference in physical activity levels in school children during the day and week and to determine whether two recommendations of physical activity (frequency and duration vs. accumulated duration) in school children identify difference in physical fitness and fatness. Methods. Seventy-one school children participated. A tri-axis accelerometer (ActiGraph) was used for 7 consecutive days. Minutes spent on moderate or vigorous physical activity (MVPA) were estimated. Two criteria were used to define whether a child is active: ≥60 min of MVPA/day and 300 min of MVPA/week. Nutritional status was assessed using the body mass index (BMI) and physical fitness with the FITNESSGRAM® protocol. Results. It was shown that 12.5% of school children were active according to 60 min MVPF/day criterion and 55.5% with 300 min MVPF/week criteria. School children were more active during school recess and afternoons on weekdays and afternoons and nights on weekends. Boys were more actives than girls. The time spent on vigorous and moderate activities was positively correlated with aerobic fitness (r =0.23, p =0.057 and r =0.32, p =0.007, respectively). There was a positive correlation between the time spent on sedentary activities and body fat (r =0.343, p =0.003) and negative with light and moderate activities (r =-0.249, p =0.003; r =-0.249, p =0.013, respectively). School children classified as active according to 300 min of MVPA/week criteria showed better aerobic capacity. Conclusions. The proportion of active school children differs according to the physical activity criterion. It was shown that physical activity varied according to gender and time of day. The time spent on high intensity activities appears to have an influence on aerobic fitness of school children.

Introducción. A cualquier edad, la actividad física (AF) es fundamental para mantener la salud. Se han formulado diferentes directrices de AF para mejorar la salud de niños y adolescentes. Los objetivos de este trabajo fueron analizar las diferencias que existen en los niveles de AF en escolares a lo largo del día y por los días de la semana y conocer si las dos formas de implementar las recomendaciones de AF (frecuencia y duración versus duración acumulada) permiten identificar diferencias en condición física y adiposidad. Métodos. Participaron 71 escolares que portaron un acelerómetro triaxial por siete días consecutivos. Se estimaron los minutos dedicados a la actividad física moderada o vigorosa (AFMV). Se utilizaron dos criterios para definir si un niño era activo: ≥60 minutos de AFMV/día y 300 minutos de AFMV/semana. El estado de nutrición fue evaluado con el índice de masa corporal (IMC) y la condición física según el protocolo FITNESSGRAM®. Resultados. El 12.5% de los escolares fueron activos de acuerdo al criterio de 60 min AFMV/día y 55.5% con el criterio de 300 min AFMV/semana. Los escolares fueron más activos en el recreo y en la tarde entre semana y en la tarde y noche los fines de semana. Los hombres fueron más activos que las mujeres. El tiempo dedicado a AF vigorosa y moderada se correlacionó positivamente con la condición aeróbica. Existió correlación positiva entre el tiempo dedicado a las actividades sedentarias y la grasa corporal, y negativa con la AF ligera y moderada. Los niños clasificados como activos según el criterio de 300 minutos de AFMV/semana mostraron mejor capacidad aeróbica. Conclusiones. La proporción de niños activos difiere según el criterio de AF. Se mostró que la AF varió por sexo y hora del día. El tiempo dedicado a actividades de mayor intensidad parece influir en la capacidad aeróbica de los escolares.

OBJECTIVE: To determine in a population-based sample of smokers the level exposure to tobacco industry marketing through different channels before and after their restriction through the General Tobacco Control Law of 2008. MATERIALS AND METHODS: Data were analyzed from a cohort of adult smokers from four Mexican cities who were surveyed in 2007 and 2008. GEE models were estimated for each indicator of advertising and promotion exposure. RESULTS: Increases were found in report of receiving free samples of tobacco (3.7-8.1%), branded clothing (3.6-6.4%), noticing tobacco industry sponsored events (1.9-4.7%) and noticing ads in bars (21.4-28%). Noticing outdoor advertising decreased over this time (54.7 a 47.2%). CONCLUSIONS: Our findings confirm tobacco industry shifting of marketing efforts when advertising and promotion bans are not comprehensive. There is a need to monitor compliance with marketing bans while working to make them comprehensive.

OBJETIVO: Determinar en población fumadora el nivel de exposición a la mercadotecnia de la industria tabacalera (IT), a través de diferentes métodos de promocionar sus productos, antes y durante la publicación de la Ley General para el Control del Tabaco (LGCT) en 2008. MATERIAL Y MÉTODOS: Estudio de cohorte en fumadores adultos (n=941 pre-LGCT y n=1 051 post-LGCT) de cuatro ciudades mexicanas. Se realizaron análisis multivariados mediante modelos de ecuaciones de estimación generalizada (GEE). RESULTADOS: Se incrementó el autorreporte de recepción de muestras gratis de cigarros (3.7 a 8.1%), ropa o artículos con marcas o logos (3.6 a 6.4%), haber visto información sobre eventos especiales (1.9 a 4.7%), y publicidad en bares y discotecas para mayores de edad (21.4 a 28%). Se observaron decrementos de publicidad en exteriores (54.7 a 47.2%). CONCLUSIÓN: Es necesaria una política integral con prohibiciones totales de la publicidad y promoción de los productos de tabaco que integre mayor vigilancia y sanciones para lograr la disminución y prevención del consumo de tabaco.

OBJECTIVE: To determine in a population-based sample of smokers the level exposure to tobacco industry marketing through different channels before and after their restriction through the General Tobacco Control Law of 2008. MATERIALS AND METHODS: Data were analyzed from a cohort of adult smokers from four Mexican cities who were surveyed in 2007 and 2008. GEE models were estimated for each indicator of advertising and promotion exposure. RESULTS: Increases were found in report of receiving free samples of tobacco (3.7-8.1%), branded clothing (3.6-6.4%), noticing tobacco industry sponsored events (1.9-4.7%) and noticing ads in bars (21.4-28%). Noticing outdoor advertising decreased over this time (54.7 a 47.2%). CONCLUSIONS: Our findings confirm tobacco industry shifting of marketing efforts when advertising and promotion bans are not comprehensive. There is a need to monitor compliance with marketing bans while working to make them comprehensive.

OBJETIVO: Determinar en población fumadora el nivel de exposición a la mercadotecnia de la industria tabacalera (IT), a través de diferentes métodos de promocionar sus productos, antes y durante la publicación de la Ley General para el Control del Tabaco (LGCT) en 2008. MATERIAL Y MÉTODOS: Estudio de cohorte en fumadores adultos (n=941 pre-LGCT y n=1 051 post-LGCT) de cuatro ciudades mexicanas. Se realizaron análisis multivariados mediante modelos de ecuaciones de estimación generalizada (GEE). RESULTADOS: Se incrementó el autorreporte de recepción de muestras gratis de cigarros (3.7 a 8.1%), ropa o artículos con marcas o logos (3.6 a 6.4%), haber visto información sobre eventos especiales (1.9 a 4.7%), y publicidad en bares y discotecas para mayores de edad (21.4 a 28%). Se observaron decrementos de publicidad en exteriores (54.7 a 47.2%). CONCLUSIÓN: Es necesaria una política integral con prohibiciones totales de la publicidad y promoción de los productos de tabaco que integre mayor vigilancia y sanciones para lograr la disminución y prevención del consumo de tabaco.

According to WHO, tobacco is responsible of almost five million deaths annually and around 13 thousand daily deaths in the world. Mexico has 60 thousand deaths per year and 165 per day for smoking, 25.6% of the population are passive smokers and the initiated age in tobacco consumption has diminished to 11 either 12 years or less. Two decades ago the fight against tobacco began in Mexico, and recently it combined administrative actions and legislative related to tributary matter and sanitary regulation. Mexico was the first country in America in signing the FCTC in August 12, 2003 and in April 14, 2004 ratified it, which means it is part of our legislation. At present, Federal Government prevention and tobacco treatment are focus actions integrated in an Strategy, which is looking to articulate synergy of all public, private and social actors involved in the subject, to give fulfillment to the Framework Convention on Tobacco Control (WHO) specially in the contracted obligations and in 2008 they must show results.

Según la Organización Mundial de la Salud (OMS), el tabaquismo causa en todo el mundo cerca de cinco millones de muertes al año, es decir, alrededor de 13 mil muertes diarias. En México, cerca de 60 000 defunciones por año y 165 diarias se atribuyen a esa causa, 25.6% de la población es fumador pasivo y se estima que la edad de inicio de consumo disminuyó a 12 años de edad o menos. México inició la lucha contra el tabaquismo hace dos decenios y en años recientes se combinaron acciones administrativas y legislativas relacionadas con aspectos tributarios y de regulación sanitaria. México fue el primer país en América en adherirse al Convenio Marco para el Control del Tabaco (CMCT, de la OMS, firmado por México el 12 de agosto de 2003 y ratificado el 14 de abril del año siguiente). Para el gobierno federal, la prevención y el tratamiento del tabaquismo son parte de una estrategia que busca la sinergia de los actores públicos, privados y sociales involucrados en el tema; los resultados de ese esfuerzo deberán presentarse en 2008.

According to WHO, tobacco is responsible of almost five million deaths annually and around 13 thousand daily deaths in the world. Mexico has 60 thousand deaths per year and 165 per day for smoking, 25.6% of the population are passive smokers and the initiated age in tobacco consumption has diminished to 11 either 12 years or less. Two decades ago the fight against tobacco began in Mexico, and recently it combined administrative actions and legislative related to tributary matter and sanitary regulation. Mexico was the first country in America in signing the FCTC in August 12, 2003 and in April 14, 2004 ratified it, which means it is part of our legislation. At present, Federal Government prevention and tobacco treatment are focus actions integrated in an Strategy, which is looking to articulate synergy of all public, private and social actors involved in the subject, to give fulfillment to the Framework Convention on Tobacco Control (WHO) specially in the contracted obligations and in 2008 they must show results.

Según la Organización Mundial de la Salud (OMS), el tabaquismo causa en todo el mundo cerca de cinco millones de muertes al año, es decir, alrededor de 13 mil muertes diarias. En México, cerca de 60 000 defunciones por año y 165 diarias se atribuyen a esa causa, 25.6% de la población es fumador pasivo y se estima que la edad de inicio de consumo disminuyó a 12 años de edad o menos. México inició la lucha contra el tabaquismo hace dos decenios y en años recientes se combinaron acciones administrativas y legislativas relacionadas con aspectos tributarios y de regulación sanitaria. México fue el primer país en América en adherirse al Convenio Marco para el Control del Tabaco (CMCT, de la OMS, firmado por México el 12 de agosto de 2003 y ratificado el 14 de abril del año siguiente). Para el gobierno federal, la prevención y el tratamiento del tabaquismo son parte de una estrategia que busca la sinergia de los actores públicos, privados y sociales involucrados en el tema; los resultados de ese esfuerzo deberán presentarse en 2008.