AVENA Study Research Articles

STRAIGHT-A STUDENTS DISLIKE PHYSICAL EDUCATION IN ADOLESCENCE: MYTH OR TRUTH? THE AVENA, AFINOS AND UP&DOWN STUDIES.

to examine if those adolescents who dislike physical education classes get better results on academic and cognitive performance than their peers. participants included 4 226 adolescents from the AVENA, AFINOS and UP&DOWN studies. Physical education enjoyment was assessed with a 7-point Likert scale. Cognitive performance in the AVENA study was assessed using the Spanish version of the SRA Test of Educational Ability. Academic performance in the AFINOS and UP&DOWN studies was assessed through Mathematics and Language grades and the average of both subjects. in the AVENA study we found differences in verbal ability among girls who dislike physical education and their peers (P = 0.033). In the AFINOS study, boys who dislike physical education had higher scores in Language than their peers (P = 0.024). In the UP&DOWN study girls who disliked physical education had higher scores in Language and in the average of Language and Mathematics than their peers (P < 0.001). in the AVENA and AFINOS studies adolescents who disliked physical education had similar results in cognitive and academic performance than their peers, but in the UP&DOWN study girls who disliked physical education showed higher results in academic performance than their peers.

Nutrient intake in Spanish adolescents SCOFF high-scorers: the AVENA study.

To evaluate whether adolescents with a positive score in a screening tool for possible eating disorders (ED) have a different diet intake in comparison with those with a negative score. Cross-sectional study performed in 235 adolescents (37.9% boys) from Zaragoza (Spain). Age, gender, BMI, maternal education, nutrient intake (7-day record) and screening tool for detecting ED [sick control on fat food test (SCOFF)] were assessed. ANCOVA test was used to determine nutrient intake differences (namely energy, macronutrients and micronutrients) according to the SCOFF total score (SCOFF ≥2 indicates a possible case of ED). ANCOVA test was adjusted by age, maternal education and BMI. This research was based on data from the cross-sectional multicenter Alimentación y Valoración del Estado Nutricional en Adolescentes españoles (Feeding and Assessment of Nutritional status of Spanish Adolescents) study. The proportion of adolescents with possible symptoms of ED was 21.7%. Girls SCOFF high-scorers (SCOFF+) mean daily energy intake was significantly lower than in those SCOFF low-scorers (SCOFF-) (P<0.001); however, in boys there was no difference. Both in girls and boys, there were no statistically significant differences according to SCOFF questionnaire for macronutrient intake, adjusted by daily energy intake. Concerning micronutrients, in girls with SCOFF+ sodium, potassium, phosphorus, iron, zinc, vitamin B2 and niacin intakes were significantly lower than in those with SCOFF-; however, in boys, there were no differences. Adolescent girls with current possible symptoms of ED presented lower total energy intake and several micronutrients intake compared with their peers without ED.

Television viewing time and risk of eating disorders in Spanish adolescents: AVENA and AFINOS studies.

Effective preventive interventions for both eating disorders and obesity in adolescence should be focused on shared risk factors. We analyzed the association between television (TV) viewing time and the risk of eating disorders, as well as the potential role of obesity in this association. The sample consisted of a total of 3458 Spanish adolescents, aged 13-18.5 years, from the Food and Assessment of the Nutritional Status of Adolescents (AVENA) and Physical Activity as a Preventive Measure of the Development of Overweight, Obesity, Allergies, Infections, and Cardiovascular Risk Factors in Adolescents (AFINOS) studies. Adolescents' TV time was assessed by self-report. Body mass index was calculated and the adolescents were classified into non-overweight and overweight-obesity. The risk of eating disorders was evaluated using the SCOFF questionnaire. Adolescents who watched TV >1 h/day had a higher risk for eating disorders, compared with those adolescents who watch TV <1 h/day. Also, overweight-obese adolescents had a higher risk for eating disorders than those who were non-overweight. Analyses across groups of TV viewing time and weight status showed similar trends, so that the higher the time spent in TV viewing, the higher the risk of eating disorders, regardless of weight status. TV viewing time might be a focal point for prevention of both eating disorders and obesity in adolescence.

Actitudes hacia la práctica de actividad físico-deportiva orientada a la salud en adolescentes españoles: Estudio AVENA (Attitudes toward the physical activity and sport practice in Spanish adolescents: the AVENA study)

El objetivo del estudio se centra en conocer las actitudes hacia la práctica de actividad físico deportiva orientada a la salud en una muestra representativa de adolescentes españoles. Para ello, se ha efectuado un estudio descriptivo de corte transversal, empleando la encuesta sobre comportamientos, actitudes y valores sobre actividad física y deportiva del Grupo AVENA. El análisis descriptivo e inferencial, nos permite obtener la opinión de 2.859 estudiantes, procedentes tanto de centros públicos como privados de cinco ciudades españolas: Granada, Madrid, Murcia, Santander y Zaragoza. Los principales resultados verifican que tanto chicos como chicas presentan una mayor orientación hacia actitudes relacionadas con el proceso (AP) de la actividad físico-deportiva que hacia actitudes referidas al resultado (AR) de dicha práctica. En ambos sexos, se produce una disminución progresiva en dicha orientación, tanto en las AP como en las AR, conforme aumenta la edad. En aquellos adolescentes que practican actividad física, la orientación hacia las actitudes es mayor que en adolescentes no practicantes. Como conclusión, las AP adquieren mayor importancia que las AR en los jóvenes adolescentes, siendo ambas mayores en chicos respecto a chicas y disminuyendo los valores de ambas conforme aumenta la edad. El conocimiento facilitado en este trabajo podría servir de apoyo para perfeccionar las diversas estrategias de promoción de la salud sobre las que asentar la adquisición de nuevos estilos de vida entre la población joven de una forma estable y duraderaPalabras clave: Actitudes; Actividad física; Adolescente.Abstract: the aim of this study was to know the attitudes toward the physical activity and sport practice oriented to health in a representative sample of Spanish adolescents. A descriptive cross-sectional study was implemented and the survey about behaviours, attitudes and values related to physical activity and sport practice developed in the AVENA study was used. The sample size was 2859 Spanish students from public and private secondary schools in 5 Spanish cities: Granada, Madrid, Murcia, Santander and Zaragoza. The main results verify that both boys and girls have a greater orientation towards process-related attitudes (PA) of physical activity and sport that outcome-related attitudes (AR) of the practice. In boys and girls, both AP and AR both genders, there is a progressive decrease when increasing the age. Adolescents who engaged in physical activity had higher levels of attitudes than non-practitioners. In conclusion, AP became more important than AR in young adolescents; both AP and AR were higher in boys than in girls and attitude values decreased with increasing age. The knowledge of attitudes might allow to develop effective and long-term successful intervention programmes for adopting healthy lifestyles in the current young people Key words: Attitudes; Physical activity; Adolescent.

Cognition and the risk of eating disorders in Spanish adolescents: the AVENA and AFINOS studies.

Eating disorders (ED) can arise from a combination of biological and psychological factors. Some studies suggest that intellectual factors might be important in the development of ED, although the evidence is still scarce. The aim of this study was to examine the association between cognition measurements (cognitive performance and academic achievement) and the risk of developing ED in adolescents considering their weight status. The sample consisted of 3,307 adolescents (1,756 girls), aged 13-18.5 years, who participated in the AVENA (n = 1,430; 783 girls) and AFINOS (n = 1,877; 973 girls) studies. Cognitive performance was measured by the TEA test in the AVENA study, and academic achievement was self-reported in the AFINOS study. ED risk was evaluated in both studies by using the SCOFF questionnaire. Body mass index was calculated to classify adolescents as non-overweight or overweight (including obesity). Overweight adolescents showed a higher risk of developing ED than non-overweight ones in both studies. In the AVENA study, overweight boys with low performance in reasoning ability showed increased risk of ED (p = 0.05). In the AFINOS study, overweight boys with low academic performance in physical education and non-overweight girls with low academic achievement in all the areas analyzed showed higher risk of ED than their peers (all p < 0.05). No association between cognitive performance and ED risk was found in adolescents, while academic achievement was associated with ED risk, especially in non-overweight girls. The non-cognitive traits that accompany academic achievement could influence the likelihood of developing ED in these girls.

Characteristics of extracurricular physical activity and cognitive performance in adolescents. The AVENA study

The aim of this report was to examine the associations between some characteristics (i.e., structure and number) of extracurricular physical activity (EPA) and cognitive performance in adolescents. A total of 1662 adolescents (880 girls; 13.0–18.5 years) from 5 Spanish cities (Granada, Madrid, Murcia, Santander and Zaragoza) were included in this study. Structure (organised and non-organised) and number of EPAs, and participation at vigorous intensity during EPA were self-reported. Cognitive performance (verbal, numeric and reasoning abilities, and an overall score) was measured with the “SRA-Test of Educational Ability”. Results showed that vigorous EPA was positively associated with all cognitive variables. Adolescents who practiced an organised EPA had higher scores in 3 of the 4 cognitive variables than those who practiced a non-organised EPA (all P < 0.05). Likewise, the group who participated in more than one EPA had higher cognitive performance in all variables than the group who participated in only one EPA (all P < 0.05). Regardless of potential confounder variables, including vigorous EPA, both structure and number of EPAs were each other independently associated with cognitive performance. Therefore, structure and number of EPAs may positively influence cognitive performance in adolescents. Participating in multiple, organised EPA may have benefits for cognitive performance.

Physical fitness, overweight and the risk of eating disorders in adolescents. The AVENA and AFINOS studies

What is already known about this subject Eating disorders are among the public health issues facing adolescents. An excess of body fat has been associated with an increased risk of these disorders. The association of physical fitness with eating disorders has not yet been analysed in adolescents. What this study adds This study confirms that the overweight and obesity increase the risk of developing eating disorders. The present study shows that there is an inverse association between physical fitness levels and the risk of eating disorders. This study suggests that physical fitness might attenuate the influence of overweight on the development of eating disorders in adolescents. Eating disorders together with the overweight and obesity are important health concerns in adolescents. To analyse the individual and combined influence of overweight and physical fitness on the risk of developing eating disorders in Spanish adolescents. The sample consisted of 3571 adolescents (1864 females), aged 13 to 18.5 years, from Spain who participated in the AVENA and AFINOS studies. The risk of eating disorders was evaluated using the SCOFF questionnaire. Body mass index was calculated and the adolescents were classified into two groups: overweight (including obesity) and non-overweight according to Cole's cut-off points. Cardiorespiratory fitness in the AVENA Study was assessed by the 20-m shuttle-run test and the overall physical fitness level was self-reported in the AFINOS Study. Overweight adolescents had a higher risk of developing eating disorders than non-overweight adolescents (odds ratio [OR] = 4.91, 95% confidence interval [CI]: 3.63-6.61 in the AVENA Study and OR = 2.45, 95% CI: 1.83-3.22 in the AFINOS Study). Also, adolescents with medium and low levels of physical fitness had a higher risk of developing eating disorders (OR = 1.51, 95% CI: 1.05-2.16, and OR = 2.25, 95% CI: 1.60-3.19, respectively, in the AVENA Study, and OR = 1.73, 95% CI: 1.37-2.17, and OR = 4.11 95% CI: 2.98-5.65, respectively, in the AFINOS Study) than adolescents with high levels of physical fitness. In both studies, the combined influence of overweight and physical fitness showed that adolescents with lower levels of physical fitness had an increased risk of developing eating disorders in both non-overweight and overweight groups. Physical fitness might attenuate the influence of overweight on the development of eating disorders in adolescents.

Six-Year Trend in Active Commuting to School in Spanish Adolescents

Promoting daily routine activities, such as active commuting to school, may have important health implications for young people. The aim of the study was to examine the secular trend of active commuting to school in Spanish adolescents over a 6-year period (2001-2002 to 2006-2007). We also examined several factors that might explain this trend. Data comes from two separate cross-sectional studies, both representatives from the city of Madrid (Spain): AVENA and AFINOS studies. These took place in 2001-2002 and 2006-2007 and included 415 (198 girls) and 891 (448 girls) adolescents aged 13-17, respectively. Commuting to school was assessed using a standardized question about their habitual mode of transportation to school: walking, cycling, bus/subway, car, or motorcycle. Chi-square and binary logistic regression were used. Percentage of active commuting girls decreased significantly from 61% to 48% (p = 0.002) from 2001-2002 to 2006-2007. Walking declined from 61% to 46% and the use of bus/subway increased from 25% to 37% in girls. Girls belonging to average/small families had lower odds of being active commuters than girls of large families (OR, 95% CI: 0.69, 0.48 to 0.98). There were no significant differences in mode of commuting to school for boys (p = 0.269). Spanish adolescent girls in 2007-2008 had lower levels of active commuting to school, mainly walking, than their counterparts 6years before. Belonging to a large family was related with higher active commuting in girls.

Physical activity among Spanish adolescents: Relationship with their relatives' physical activity – The AVENA Study

Identifying factors related to physical activity levels in young people is important for a more efficient health promotion. The aims of this study were to assess physical activity levels in a national sample of urban Spanish adolescents, and to examine the association between significant others' physical activity (father, mother, brother, sister, and close friends) and that of the adolescents. The present study comprised 2260 adolescents (1157 boys, 1103 girls) aged 13.0–18.5 years participating in the AVENA Study. Both the adolescents' physical activity and that of their relatives and close friends was assessed by questionnaire. The odds of being active were higher in boys than girls (odds ratio = 2.79, 95% confidence interval = 2.34–3.33) and tended to decrease across age groups in both boys and girls. Father's and older brother's physical activity was associated with boys' physical activity, while that of any significant other was associated with girls' physical activity. When both parents reported being active, boys had nearly two times higher odds of being active and girls had nearly three times higher odds of being active. The physical activity levels of Spanish adolescents are in line with those previously reported. Physical activity levels in girls are strongly related to the physical activity of any significant other, whereas physical activity levels in boys are only related to their male relatives' physical activity.

Combined Influence of Lifestyle Risk Factors on Body Fat in Spanish Adolescents – the AVENA Study

Objective: To examine the combined influence of four lifestyle risk factors related to physical activity, television viewing, sleep duration, and meal frequency on body fat (BF) in adolescents. Method: This cross-sectional study comprised 1,310 Spanish adolescents (age 13–18.5 years). Lifestyle variables were self-reported and BF indicators (weight, height, six skinfold thicknesses, waist circumference) measured during the years 2000–2002. Lifestyle risk factors were: physically inactive, ≧3 h/day watching television, <8 h/day sleep duration, and <5 meals a day. The number of lifestyle risk factors was calculated for each participant, ranging from 0 to 4. Results: The number of lifestyle risk factors was positively associated with sum of six skinfolds, %BF, waist circumference, and waist-height ratio (all p < 0.001). The odds ratios (95% confidence interval) of overweight (including obesity) for groups with 1, 2, and 3–4 lifestyle risk factors compared with those with 0 were 2.86 (1.77–4.62), 3.61 (2.16–6.04), and 5.81 (3.07–10.99), respectively (p for trend <0.001). All the observations were independent of age, gender, race, socioeconomic status, and fat free mass. Conclusion: The combined influence of four lifestyle risk factors is positively associated with BF and an approximately sixfold risk of overweight in adolescents.

Influence of socioeconomic factors on fitness and fatness in Spanish adolescents: The AVENA study

This study was to examine the influence of socioeconomic status on fitness and fatness in Spanish adolescents. A total of 1 795 adolescents (833 boys) aged 12.5-18.5 years from the AVENA study participated in this study. The following physical fitness components were assessed: muscular strength (standing long jump), speed-agility (4 × 10 m shuttle run) and cardiorespiratory fitness (20 m shuttle run). Total and central body fat was assessed using skinfold thickness and waist circumference, respectively. Both parents reported their educational and professional level. Girls with higher paternal educational level and boys with higher either maternal or paternal professional level had higher muscular strength levels (all P<0.05). Speed-agility and cardiorespiratory fitness were not associated with parental educational or professional levels in boys. In contrast, girls with higher paternal educational level or higher parental professional level had higher levels in both fitness components (all P<0.05). A higher maternal educational level was associated with lower total and central body fat in boys (all P<0.05), but not in girls. We observed a small effect size (Cohen's d∼0.2) in most of these associations. Our results suggest modest associations of high socioeconomic status with better fitness and fatness levels in Spanish adolescents. These associations greatly depend on the socioeconomic status and fitness parameters studied.

Extra-curricular participation in sports and socio-demographic factors in Spanish adolescents: The AVENA Study

The aims of this study were to identify differences between the sexes in extra-curricular participation in sports and to determine its association with body fat and socio-demographic factors in Spanish adolescents. A total of 2165 adolescents (1124 males and 1041 females) aged 13.0–18.5 years from the AVENA Study participated. Participants filled in an ad hoc questionnaire for extra-curricular participation in sports, which was the dependent variable. Independent variables were: age, percent body fat, and father's and mother's educational level and occupation. Chi-square tests and logistic regression were applied. Bivariate analysis showed for male adolescents that age and father's occupation were related to extra-curricular participation in sports. In addition, body fat and mother's education and occupation (all P < 0.05) were related to extra-curricular participation of in sports for female adolescents. Logistic regression analysis showed that the likelihood of involvement in extra-curricular participation in sports was 5.3-fold (3.86–7.38) higher for males than females. Age and father's education in both males and females were independently associated with extra-curricular participation in sports. In summary, Spanish male adolescents were shown to engage in more extra-curricular sports than females. In addition, age and father's education (in both sexes) were associated with the participation of their offspring in extra-curricular sports during adolescence.

Sleep patterns in Spanish adolescents: associations with TV watching and leisure-time physical activity

We aimed to describe the sleep patterns in Spanish adolescents and to examine the relationships of sleep duration and morning tiredness with participation in leisure-time physical-sporting activities (LT-PA) and television (TV) watching. Sleep duration, morning tiredness, participation in LT-PA and time spent on watching TV were reported by 2,179 (1,139 females) Spanish adolescents (AVENA study). Data were analyzed by binary logistic regression. One-fifth of the adolescents reported insufficient night sleep (<8 h) on school days. The review of the literature (30 studies) showed that the Spanish adolescents sleep as long as adolescents from central Europe, and longer than those from other Mediterranean countries, South Africa, Asia and North America. Insufficient sleep duration doubled the odds of excessive TV watching (≥3 h/day) in males, regardless of morning tiredness (OR 2.15, 95% CI 1.42-3.27). Morning tiredness reduced the odds of participating in any LT-PA in both males and females (0.49, 0.34-0.70 and 0.49, 0.35-0.69, respectively), and increased the odds of excessive TV watching in females, regardless of sleep duration (2.49, 1.64-3.79). We conclude that non-participation in LT-PA is associated with morning tiredness in male and female adolescents, while excessive TV watching is more associated with short sleep or morning tiredness depending on gender.

Health‐related fitness in adolescents: underweight, and not only overweight, as an influencing factor. The AVENA study

This study investigated differences in health-related fitness (20-m shuttle run, handgrip, bent arm hang, standing long jump, shuttle run 4 x 10 m and sit and reach tests) in 2474 Spanish adolescents (1196 boys and 1278 girls; age 13-18.5 years) classed as underweight, normal weight, overweight or obese according to body mass index. Body fat and fat-free mass were derived from skinfold thickness. The prevalence of underweight was higher than obesity in girls (4.8% vs 3.0%, respectively; P<0.05) and the opposite in boys (3.9% vs 5.8%, respectively; P<0.05). Underweight was associated with a higher performance in the bent arm hang test in girls (P<0.05) and a lower performance in handgrip in both genders (P<0.01) compared with normal weight. Overweight and obese adolescents presented a lower performance in 20-m shuttle run, bent arm hang, standing long jump and shuttle run 4 x 10 m tests (P<0.001), but a higher performance in handgrip strength (P<0.001) compared with normal weight. In weight-bearing tests, the association became non-significant after adjusting for fat mass. In conclusion, not only overweight and obesity but also underweight seem to be determinants of health-related fitness in adolescents. The associations could be related to differences in body composition.

Secular trends in health-related physical fitness in Spanish adolescents: The AVENA and HELENA Studies

We analysed the secular trends in health-related physical fitness in Spanish adolescents between 2001–2002 and 2006–2007. Two representative population studies were conducted 5 years apart in adolescents (12.5–17.5 years) from Zaragoza (Spain) that participated in the AVENA study in 2001–2002 and in the HELENA-CSS study in 2006–2007. Both studies used the same tests to assess physical fitness: the handgrip strength, bent arm hang, standing broad jump, 4 × 10 m shuttle run and 20 m shuttle run tests. Performance in 4 × 10 m shuttle run and 20 m shuttle run tests was higher in 2006–2007 (Cohen's d ranging from 0.2 to 0.4, p < 0.05), whereas performance in handgrip strength and standing broad jump tests was lower in 2006–2007 (Cohen's d ranging from 0.3 to 1.1, p < 0.001). Adjustment for age, pubertal status, fat mass, fat free mass and parental education did not alter the results. The odds ratio (OR) of meeting the FITNESSGRAM Standards for healthy cardiorespiratory fitness was higher in 2006–2007 in both boys (OR, 95% CI: 2.123, 1.157–3.908) and girls (OR, 95% CI: 2.420, 1.377–4.255). The results indicate that levels of both speed/agility and cardiorespiratory fitness were higher in 2006–2007 than in 2001–2002, whereas muscular strength components were lower in 2006–2007.

Individual and Combined Effects of ApoE and MTHFR 677C/T Polymorphisms on Cognitive Performance in Spanish Adolescents: The AVENA Study

To examine the individual and combined associations of ApoE and MTHFR 677C/T polymorphisms with cognitive performance in adolescents. The study comprised 412 Spanish adolescents (13 to 18.5 years of age). Cognitive performance (verbal, numeric and reasoning abilities, and an overall score) was measured by the Spanish-version of the SRA-Test of Educational-Ability. We observed no differences in the cognitive performance study variables in adolescents carrying or not carrying the ApoE epsilon4 variant. Adolescents without the MTHFR 677TT genotype had significantly better cognitive performance than their TT peers. The analysis of the combined effect of these polymorphisms revealed that those individuals carrying both the ApoE epsilon4 variant and the MTHFR 677TT genotype had significantly worse cognitive performance than their peers with other genotype combinations. These findings were independent of sex, age pubertal status, socioeconomic status, physical activity, and skipping breakfast. The results of the present study suggest that the ApoE epsilon4 alone is not associated with cognitive performance in adolescents. Individuals with the MTHFR 677TT genotype had slightly impaired cognitive performance, whereas we observed a combined effect of both the ApoE epsilon4 variant and the MTHFR 677TT genotype on cognitive performance. More research is needed in larger population samples to corroborate our findings.

Sleep duration and cognitive performance in adolescence. The AVENA study

1.Department of Medical Physiology, School of Medicine, University of Granada, Granada, Spain 2.Unit for Preventive Nutrition, Department of Biosciences and Nutrition at NOVUM, Karolinska Institutet, Huddinge, Sweden 3.Department of Basic Psychology, School of Psychology, University of Malaga, Malaga, Spain 4.Department of Physical Education and Sport, School of Physical Activity and Sport Sciences, University of Granada, Granada, Spain 5.Department of Nutrition and Food Science, University of the Basque Country, Vitoria, Spain 6.Immunonutrition Research Group, Department of Metabolism and Nutrition, Instituto del Frio, Institute of Food Science, Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain 7.Department of Pediatrics, University of Cantabria, Santander, Spain 8.E.U. Health sciences, University of Zaragoza, Zaragoza, Spain

Il6 gene promoter polymorphism (-174G/C) influences the association between fat mass and cardiovascular risk factors

During the last decades, the prevalence of obesity has increased rapidly among young people. A polymorphism in the promoter region of the IL6 gene (-174G/C), has been previously reported to be involved in obesity and metabolic syndrome development. Therefore, the aim of the study was to examine whether the IL6-174G/C polymorphism influence the association of body fat with low-grade inflammatory markers and blood lipids and lipoproteins in Spanish adolescents. 504 Spanish adolescents participating in the AVENA study were genotyped for the-174G/C polymorphism of the IL6 gene. Anthropometric and body composition measurements were taken and blood samples were collected for plasma molecules determinations. No differences between genotypes were observed in anthropometric values, body composition measurements and plasma markers concentration. Physical activity level differ between genotypes with subjects carrying the C allele of the polymorphism being significantly (p<0.05) more active than GG subjects. The association between body fat mass and plasma glucose was influenced by the -174G/C polymorphism of the IL6 gene. Subjects carrying the C allele of the mutation seem to have higher values of lipoprotein (a) and C-reactive protein as their percentage of body fat mass increase. Our results suggest that this promoter polymorphism influences the association between adiposity and some plasma markers.

The Effect of Early Menarche on Later Body Composition and Fat Distribution in Female Adolescents: Role of Birth Weight

Background: To examine the effect of early menarche (EM) on adolescent body composition and fat distribution, and to explore the possible contribution of birth weight (BW) to this relationship. Methods: From the cross-sectional AVENA study, 788 girls (aged 13–18.5 years) were selected. Post-menarcheal body composition was estimated by anthropometric methods. Results: BW Z-score was associated with age at menarche (β = 0.496, p < 0.001). EM (age of menarche <12 years) adolescents were shorter, had a higher body mass index (BMI), fat free mass index (FFMI), fat mass index (FMI) and waist circumference (all p < 0.01). BW was associated with height (p < 0.001), BMI Z-score (p < 0.01), FFMI (p < 0.01) and FMI (p < 0.05). These relationships did not change when the analysis was controlled for age of menarche. Height and FFM were lower in EM (p < 0.01), but these effects seem to be due to the BW (p < 0.01). Conclusion: EM was strongly associated with unhealthy body composition in female adolescents, but these relationships seem to be due to the programming effect of BW.

Extracurricular physical activity participation modifies the association between high TV watching and low bone mass

Objectives To examine whether different sedentary behaviours are associated with the risk of low bone mineral content in adolescents, and if so, whether extracurricular physical-sporting activity influences this association. Materials and methods A total of 277 adolescents from Zaragoza (168 females and 109 males) aged 13.0–18.5 yr within frame work of the multicentre AVENA study participated in this study. Bone mineral content (BMC), lean mass, and fat mass were measured with DXA. Physical activity and sedentary independent variables: participation in extracurricular physical-sporting activity (PA), h/d of television watching, playing video/computer games during school days and on weekend days and doing homework/studying. They all were assessed by questionnaire. The main outcome was low BMC, as defined by BMC Z-score for age and sex < percentile 10. Logistic regression was used to test the interaction and association of PA and sedentary variables with low BMC, after controlling for confounders like height, maturational status or lean mass. Results Among the sedentary variables studied, only television watching ≥ 3 h/d was associated with an increased risk for low BMC in males (OR, 95% CI: 7.01, 1.73 to 28.40), after controlling for sexual maturation. When PA was in the models, television watching was not any longer associated with low BMC, while PA was so (OR, 95% CI: 0.23, 0.09 to 0.55). Involvement in such activity reduced the risk of low bone mass by 76% ( P < 0.01) independently of body mass, height and fat mass, but not of the lean mass. Conclusion Watching television for 3 or more h/d seems to be associated with an increased risk for low BMC in male adolescents. However, this association is mediated by participation in PA, suggesting that negative consequences of excessive television watching on adolescent bone health could be counteracted by sport participation. Longitudinal data and randomized controlled trials will confirm or contrast our findings.