Evolución de la práctica de la actividad física en los adolescentes españoles

Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 335 Ramos, P.; Jiménez-Iglesias, A.; Rivera, F. y Moreno, C. (2016) Evolución de la práctica de la actividad física en los adolescentes españoles / Physical Activity Trends in Spanish Adolescents. Revista Internacional de Medicina y Ciencias de la Actividad Física y el Deporte vol. 16 (62) pp.335-353 Http://cdeporte.rediris.es/revista/revista62/artevolucion692.htm DOI: http://dx.doi.org/10.15366/rimcafd2016.62.010 ORIGINAL PHYSICAL ACTIVITY TRENDS IN SPANISH ADOLESCENTS EVOLUCIÓN DE LA PRÁCTICA DE LA ACTIVIDAD FÍSICA EN LOS ADOLESCENTES ESPAÑOLES Ramos, P.1; Jiménez-Iglesias, A.2; Rivera, F.3; Moreno, C.4 1 Associate Professor. Department of Developmental and Educational Psychology, University of Seville. Spain. [email protected] 2 Teaching and Research Staff. Department of Developmental and Educational Psychology, University of Seville. Spain. [email protected] 3 Associate Professor. Department of Psychology, University of Huelva. Spain. [email protected] 4 Full Professor. Department of Developmental and Educational Psychology, University of Seville. Spain. mcmoren[email protected] Spanish-English translator: E. Martínez Gorroño, e-mail: [email protected] ACKNOWLEDGEMENT: This research work has been carried out thanks to successive cooperation agreements signed jointly by Ministry of Health and Consumption and University of Seville to apply the Health Behaviour in School-aged Children (HBSC) study in Spain. Código UNESCO / UNESCO code: 6102 Psicología del niño y del adolescente / Adolescent and child psychology Clasificación Consejo de Europa / Council of Europe classification 15 Psicología del deporte / Sport Psychology Recibido 20 de febrero de 2013 Received Frebruary 20, 2013 Aceptado 14 de junio de 2013 Accepted June 14, 2013 Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 336 ABSTRACT This study tries to find out the tendency of moderate-to-vigorous physical activity and to assess whether the trends are maintained with regard to sociodemographic factors such as sex and age, and also socio-economic factors and how they vary depending on the region. The sample comprises Spanish adolescents aged between 11 and 18 years, from the 2002 and 2006 surveys of the Health Behaviour in School-aged Children (HBSC) study. The main results reveal that, despite a certain increase in physical activity level in the four years span between both surveys (particularly in younger adolescents), these levels are still a long way from the recommendations. Likewise, data mark, as immediate needs, the promotion of an active lifestyle among adolescents from 13 years onwards (particularly among the girls) and also among adolescents of lower socio-economic status in some regions. KEY WORDS: moderate-to-vigorous physical activity, adolescence, sex, age, Family Affluence Scale, region. RESUMEN Este estudio se propone conocer la evolución de la práctica de actividad física moderada-vigorosa y examinar si la tendencia se mantiene en función de factores sociodemográficos, como el sexo y la edad, así como de factores socioeconómicos y su influencia según la comunidad autónoma. La muestra está compuesta de adolescentes españoles de 11 a 18 años de las ediciones 2002 y 2006 del estudio Health Behaviour in School-aged Children (HBSC). Los principales resultados muestran que, a pesar de un cierto aumento en el nivel de actividad física en los cuatro años que distan entre ambas ediciones (especialmente en los adolescentes más pequeños), estos niveles se encuentran todavía lejos de las recomendaciones. Asimismo, los datos señalan como necesidades más urgentes promover un estilo de vida activo en los adolescentes de 13 años en adelante (especialmente en las chicas) y en los adolescentes de niveles socioeconómicos más bajos de determinadas comunidades autónomas. PALABRAS CLAVE: actividad física moderada-vigorosa, adolescencia, sexo, edad, capacidad adquisitiva familiar, comunidad autónoma Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 337 INTRODUCTION It is generally acknowledged nowadays that physical activity plays a central role in preventing many diseases, and brings physical, psychological and social benefits, and therefore it is a key factor in a healthy lifestyle. Adolescence is an important developmental stage to generate a healthy lifestyle, particularly, the habit of physical exercise, since it is at this stage when people acquire behaviours of important consequences for their health, for the short as well as for the long term, and which will be hardly changed in adult life (Crockett and Petersen, 1993; Elliot, 1993; Heaven, 1996). It is well known that childhood is a stage of great physical activity, since due to a drive of biological nature games at this stage involve more movement and activity, whereas in adolescence leisure options gradually become more sedentary. In addition to the lack of physical activity in adolescence comes the dramatic increase in leisure new technologies (computers, television, videoconsoles...), which might reduce the time given by young people to other kind of activities (e. g. physical exercise). In this regard, many studies have revealed the connection between these life habits and the increase in people's overweight and obesity, particularly at child-juvenile ages (Hickman, Roberts and Gaspar de Matos, 2000; Roberts, Tynjälä and Komkov, 2004; Vicente- Rodríguez et al., 2008). As a matter of fact, although chronic diseases related to lack of physical activity rarely come up before middle adulthood, some connections have been found now between that lack of activity and overweight and obesity at adolescence, as well as musculoskeletal health and mental health (e.g. Strong et al., 2005). Besides, it has been ascertained that low levels of activity during the first few decades of life are related to more physiological risk factors during adult life (U.S. Department of Health and Human Services, 1996). Also, the importance of preventing the lack of physical activity at adolescence makes more sense even when it is revealed that such lack of activity lingers on in adult life, because a low level of physical activity at young age leads to develop sedentary lifestyles throughout life (Tammelin, Näyhä, Laitinen, Rintamäki and Järvelin, 2003; Larouche, Laurencelle, Shephard and Trudeau, 2012). Some studies have pointed out that the analysis of findings over a long period of time has brought to light a gradual and alarming deterioration of adolescents aerobic capacity as compared to what it was in previous decades (Suris, Michaud, Chossis and Jeannin, 2006; Tomkinson, Olds and Gulbin, 2003; Westerstahl, Barnekow-Bergkvist, Hedberg and Jansson, 2003). There are several hypotheses that explain these results, the most often quoted being the increase in sedentariness in industrialised societies (Garland et al., 2011; Tomkinson et al., 2003), as well as the lack of time for sport, be it due to pressure to be successful at school or in a future career, or be it for the large amount of personal and social activities which nowadays compete for the time and energy that young people can give to sport (Suris et al., 2006). However, Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 338 not all the research agrees about this evolution, in fact a study carried out with adolescents between 11 and 15 years, in seven European countries, reveals that, by and large, vigorous physical activity has remained stable or made just a slight increase from the mid 80s of the 20th century till the beginning of the 21st century (Samdal et al., 2006). On the other hand, a great many of studies confirm a higher rate of physical activity among boys as compared to girls (e.g. Borraccino et al., 2009). As concerns Spanish adolescents, Ortega et al. (2005) show with a sample of adolescents between 13 and 18 years that, except for the test of flexibility, boys are fitter than girls. If other objective measures, as for instance the Computer Science and Applications Inc. (CSA) 7164 activity monitor, are used to assess the differences between boys and girls with regard to physical activity, the differences are corroborated, so that it is still the boys who show a higher rate of physical activity (Trost et al., 2002). Also, with regard to the level of physical activity as they grow up, there is likewise a high coincidence in the findings of different studies, which implies an obvious decrease of activity as adolescents grow up (Olds et al., 2009), particularly in the case of girls (Ramos, Rivera, Moreno and Jiménez-Iglesias, 2012). However, as opposed to those socio-demographic variables, adolescent physical activity variation levels depending on socio-economic status have not been researched in such depth. On this point, some studies show a positive correlation of both variables at this developmental stage (Borraccino et al., 2009; Sallis, Zakarian, Hovell and Hofstetter, 1996; Walters, Barr-Anderson, Wall and Neumark-Sztainer, 2009). Nevertheless, it is important to corroborate such relationship with representative samples of Spanish teenage population. Moreover, taking into account that in Spain each region holds its own healthcare management, it would be relevant to find out if that relationship between physical activity and socio-economic status is the same in all regions. Therefore, the social alarm anticipated by the decreasing tendency in physical activity levels in the last decade needs to be cross-checked with validated data on the target population. In this respect, the purpose of this study is to show, with representative data of the Spanish adolescent population, the differences in physical activity trends between the 2002 and 2006 surveys of the study. In addition, a second aim of this study is to find out in what way sociodemographic and socio-economic differences have developed with regard to physical activity, and also to check if there are any inequalities among regions as concerns this important health habit in adolescence. Furthermore, taking into account the importance that autonomous policies have in reducing socioeconomic inequalities with regard to health, this paper tries to ascertain how region management affects the relationship between family affluence and physical activity. In short, with this information it will be possible to see in further detail the extension of the problem and, if need be, to work out the resources for planning accordingly any necessary intervention. Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 339 METHOD Sample The adolescents under study in this research work were included in the Spanish sample of the Health Behavior in School-aged Children (HBSC) study, in both the 2002 and the 2006 surveys. They were boys and girls between 11 and 18 years attending school (further details on the method of this piece of research can be found in Moreno, Muñoz-Tinoco, Pérez Moreno and Sánchez-Queija, 2005, and in Moreno et al., 2008). The Spanish sample in the HBSC 2002 survey comprised 13,552 adolescents, whereas the HBSC 2006 survey included a higher number of participants, exactly 21,811, as a result of adding an independent sample for each region. That is to say, the 2006 survey includes representative samples of adolescents for each region in Spain. Measures The HBSC questionnaire collects information about several topics related to adolescent lifestyle, positive health and their developmental contexts. After almost 30 years of existence, this study has proved the high standards of its bank of measures, complying with reliability and validity requirements. Since it gives extremely detailed information, the paragraphs below quote only those articles which validate the measures applied for this paper.  Demographic variables. - Sex: boys and girls. - Age group, with four values: 11-12, 13-14, 15-16 and 17-18 years. - Family affluence, estimated by means of the Family Affluence Scale (FAS), with three levels: low, medium and high. This scale has been validated by several experts at London University College by means of a research work comprising over 1,800 adolescents (Wardle, Robb and Johnson, 2002). - Region, with 18 values: Andalucía, Aragón, Principado de Asturias, Islas Baleares, Canarias, Cantabria, Castilla y León, Castilla la Mancha, Cataluña, Comunidad Valenciana, Extremadura, Galicia, Comunidad de Madrid, Región de Murcia, Comunidad Foral de Navarra, País Vasco, La Rioja, Ceuta and Melilla.  Moderate-to-vigorous physical activity. In line with the guidelines established at the Young and Active? international symposium, held in 1997 (Biddle, Cavill and Sallis, 1998), the question used by the HBSC study to assess this physical activity was (Roberts et al., 2007): Over Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 340 the past 7 days, on how many days were you physically active for a total of at least 60 minutes per day? With values between 0 and 7 days. Just before the question, participants were given an explanation which literally read: “Physical activity is any activity that increases your heart rate and makes you get out of breath some of the time. Physical activity can be done in sports, school activities, playing with friends, or walking to school. Some examples of physical activity are running, brisk walking, rollerblading, biking, dancing, skateboarding, swimming, soccer, basketball, football and surfing. For this next question, add up all the time you spent in physical activity each day.” So, it was pointed out that their answers must take into account the total amount of time, that is, it was not necessary to have done 60 minutes in one go, but they could add up different bouts in which they had had some kind of physical activity throughout the day. Procedure For the survey procedure, the HBSC International Coordinator underlines that three basic conditions are abiding: in the first place, the questionnaires must be filled out by the school children themselves; in the second place, the questionnaires must be administered within the school premises and by surveyors specifically trained for this questionnaire and, finally, the anonymity of the answers must be guaranteed and protected, as well as the proper understanding of the questionnaire (with that purpose, in bilingual areas, the questionnaires were wholly printed in both languages). The data analyses used in this paper focused firstly on those significance tests most adequate to the particularities of the studied variables, in this case Student's t-test and ANOVA. Afterwards, statistically significant data were corroborated with effect size measures, specifically with eta squared (η2) and Cohen's d. RESULTS Level of moderate-to-vigorous physical activity in the 2002 and 2006 surveys depending on sex, age and family affluence. Firstly, differences between the HBSC 2002 and 2006 surveys with regard to level of moderate-to-vigorous physical activity were analysed, that is, number of days per week when adolescents reported to have felt physically active for at least 60 minutes. Accordingly, table 1 shows the sample distribution for the seven days of the week and it reveals a slightly higher frequency in 2006 as compared to 2002. Table 1. Number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys. Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 341 2002 2006 N % n % 0 DAYS 684 5.10% 1256 6.00% 1 DAY 1226 9.20% 1846 8.80% 2 DAYS 2492 18.80% 3412 16.30% 3 DAYS 2493 18.80% 3698 17.60% 4 DAYS 1866 14.00% 2993 14.30% 5 DAYS 1566 11.80% 2481 11.80% 6 DAYS 864 6.50% 1281 6.10% 7 DAYS 2098 15.80% 4005 19.10% The analysis of the mean number of days per week in each survey (see Table 2) revealed a statistically significant mean difference t(29057) = 5.66, p < 0.001, 3.68 in 2002 and 3.81 in 2006, however the effect size was negligible (d = 0.06). Table 2. Mean number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys. n M SD Minimum Maximum 2002 13289 3.68 2.07 0 7 2006 20973 3.81 2.15 0 7 After that the differences between the two surveys with regard to sex of the adolescents, age and family affluence were examined with the aim to find out which specific groups gave truly visible differences in the increase of moderate- to-vigorous physical activity. The differences between boys and girls (see Table 3) were virtually the same in both surveys: 2002, t(13146) = 18.32, p < 0.001, d = 0.32, and 2006, t(20418) = 25.71, p < 0.001, d = 0.35. That is, in 2002 as well as in 2006, boys gave more time to physical activity than girls, these were significant differences and with small effect sizes. From the 2002 to the 2006 survey, there was an increase in the mean number of days adolescents felt physically active, although the effect size was negligible for both boys (d = 0.10) and girls (d = 0.05). Otherwise, it must be highlighted that the increase was higher in boys, with a mean 0.21 days, as compared with girls, with a rise of only 0.11 days. Table 3. Mean number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys, depending on sex. BOYS GIRLS n M SD n M SD 2002 6721 4.00 2.13 6831 3.35 1.96 2006 10234 4.21 2.15 11577 3.46 2.09 With regard to age, table 4 shows that developmental differences in 2006 were Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 342 higher than in 2002. Particularly, in 2002 the mean number of days per week adolescents reported to feel physically active decreased with age, from 3.76 days a week in 11-12-year-olds, to 3.51 days in 17-18-year-olds, F(1, 13286) = 336.04, p < 0.001; whereas in the 2006 survey the means decreased from 4.22 days in 11-12-year-olds down to 3.41 days in 17-18-year-olds, F(1, 20969) = 663.10, p < 0.001. This reduction with age happened at an earlier stage in the 2006 survey, since decline started at age 11-12 years, whereas in the 2002 survey decline started at age 13-14 years. Table 4. Mean number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys, depending on age group. 11-12 YEARS 13-14 YEARS 15-16 YEARS 17-18 YEARS n M SD n M SD n M SD n M SD 2002 3273 3.76 2.19 3176 3.85 2.06 3732 3.61 1.96 3371 3.51 2.06 2006 5869 4.22 2.23 5499 3.84 2.14 5733 3.7 1.99 4710 3.41 2.16 Also, effect size tests (Cohen's d) presented on table 5 show that differences as regards age group in the 2002 survey were negligible (d < 0.20). And yet, in 2006 there were small effects for 11-12-year-olds against 15-16 and 17-18-year-olds, and also between 13-14-year-olds and 17-18-year-olds, revealing that the younger adolescents gave a higher mean number of days than the older ones. Table 5. Effect size values (Cohen's d) after cross-checking all values by age group, in HBSC both surveys, 2002 and 2006. 2002 2006 11-12 years 13-14 years 15-16 years 17-18 years 11-12 years 13-14 years 15-16 years 17-18 years 11-12 years 0.04 0.07 0.12 0.17 0.25 0.37 13-14 years 0.12 0.17 0.07 0.2 15-16 years 0.05 0.14 17-18 years When comparing the 2002 with the 2006 survey by age group, only the younger adolescents showed any differences. That is, increase in days per week when they felt physically active over those four years was only detected in 11-12 yearolds, with a small effect size (d = 0.21). Then, differences by age group for boys and girls separately were examined. Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 343 Graph 1 shows that an increase in physical activity in 11-12-year-olds took place in the boys group, who went up from 4.04 days a week in 2002 to 4.46 days in 2006 (d = 0.19), as well as in the girls group, who went up from 3.46 days in 2002 to 4 days in 2006 (d = 0.25). Also, the differences between sexes in all age groups remained the same in both surveys, since it was the boys who felt physically active more often than the girls. Graph 1. Mean number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys, depending on age and sex groups. 4.13 3.97 3.87 4.04 3.46 3.55 3.27 3.18 4.46 4.19 4.16 3.98 4 3.49 3.28 3.01 2,5 3 3,5 4 4,5 5 11-12 years 13-14 years 15-16 years 17-18 years Boys 2002 Girls 2002 Boys 2006 Gilrs 2006 With regard to the differences depending on family affluence, table 6 reveals that those adolescents with the highest family affluence reported a higher level of physical activity. Differences between low affluence adolescents and high affluence ones were significant and with small effect size, as much in the 2002 survey, F(2, 13167) = 43.83, p < 0.001, d = 0.23, as in the 2006 one, F(2, 20772) = 58.75, p < 0.001, d = 0.21. For instance, in the 2006 survey low affluence adolescents claimed to be physically active 3.54 days a week, whereas high affluence adolescents reported 3.99 days a week. On the other hand, the increase in physical activity in Spanish adolescents in 2006 as compared to 2002 was similar in the three levels of the Family Affluence Scale. However, the differences in effect size between 2002 and 2006 were negligible (d = 0.05 low level, d = 0.03 medium level and d = 0.04 high level). Table 6. Mean number of days when adolescents feel physically active for at least 60 minutes a day, in HBSC 2002 and 2006 surveys, depending on family affluence. LOW MEDIUM HIGH n M SD n M SD n M SD Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 350 REFERENCES Biddle, S., Cavill, N., & Sallis, J. (1998). Policy framework for young people and health-enhancing physical activity. In S. Biddle, J. Sallis & N. Cavill (Eds.), Young and Active? Young people and health-enhancing physical activityevidence and implications (pp. 3-16). London: Health Education Authority. Borraccino, A., Lemma, P., Iannotti, R., Zambon, A., Dalmasso, P., Lazzeri, G.,... Cavallo, F. (2009). Socioeconomic effects on meeting physical activity guidelines: Comparisons among 32 countries. Medicine & Science in Sports & Exercise, 41, 749-756. doi: 10.1249/MSS.0b013e3181917722 Boyce, W. & Dallago, L. (2004). Socioeconomic inequality. In C. Currie, C. Roberts, A. Morgan, R. Smith, W. Settertobulte, O. Samdal & V. Barnekow (Eds.), Young people's health in context. Health Behaviour in School-aged Children (HBSC) study: International report from the 2001/2002 survey. Health policy for children and adolescents (Report No. 4). (pp. 13-25). Copenhagen: WHO Regional Office for Europe. Consejo Superior de Deportes (2011). Hábitos deportivos de la población escolar en España. Retrieved from www.csd.gob.es/csd/estaticos/depescolar/encuesta-de-habitos-deportivos-poblacion-escolar-en-espana.pdf Crockett, L. J. & Petersen, A. C. (1993). Adolescent development: Health risks and opportunities for health promotion. In S. G. Millstein, A. C. Petersen & E. O. Nightingale (Eds.), Promoting the health of adolescents. New directions for the twenty-first century (pp. 3-37). Oxford: Oxford University Press. Elliot, D. S. (1993). Health-enhancing and health-compromising lifestyles. In S. G. Millstein, A. C. Petersen & E. O. Nightingale (Eds.), Promoting the health of adolescents. New directions for the twenty-first century (pp. 119- 150). Oxford: Oxford University Press. García-Moya, I., Moreno, C., Rivera, F., Ramos, P., & Jiménez-Iglesias, A. (2012). Iguales, familia y participación en actividades deportivas organizadas durante la adolescencia. Revista de Psicología del Deporte, 21, 153-158. Garland, T., Schutz, H., Chappell, M. A., Keeney, B. K., Meek, T. H., Copes, L. E.,… Eisenmann, J. C. (2011). The biological control of voluntary exercise, spontaneous physical activity and daily energy expenditure in relation to obesity: human and rodent perspectives. Journal of Experimental Biology, 214(2), 206-229. doi:10.1242/jeb.048397 Heaven, P. C. L. (1996). Adolescent health: The role of individual differences. London: Routledge. Hickman, M., Roberts, C., & Gaspar de Matos, M. (2000). Exercise and leisure time activities. In C. Currie, K. Hurrelmann, W. Settertobulte, R. Smith & J. Todd (Eds.), Health and health behaviour among young people. WHO Policy Series: Health policy for children and adolescents Issue 1. International report (pp. 73-82). Copenhagen: WHO Regional Office for Europe. Larouche, R., Laurencelle, L., Shephard, R. J., & Trudeau, F. (2012). Life Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 351 transitions in the waning of physical activity from childhood to adult life in the Trois-Rivières Study. Journal of Physical Activity & Health, 9, 516-524. Lasheras, L., Aznar, S., Merino, B., & López, E. G. (2001). Factors associated with physical activity among Spanish youth through the National Health Survey. Preventive Medicine, 32, 455-464. doi: 10.1006/pmed.2001.0843 Moreno, C., Muñoz-Tinoco, V., Pérez Moreno, P. J., & Sánchez-Queija, I. (2005). Los adolescentes españoles y su salud. Un análisis en chicos y chicas de 11 a 17 años. Madrid: Ministerio de Sanidad y Consumo. Moreno, C., Muñoz-Tinoco, V., Pérez Moreno, P. J., Sánchez-Queija, I., Granado M. C., Ramos, P., & Rivera, F. (2008). Desarrollo adolescente y salud. Resultados del Estudio HBSC-2006 con chicos y chicas españoles de 11 a 17 años. Madrid: Ministerio de Sanidad y Consumo. Motl, R. W., Dishman, R. K., Ward, D. S., Saunders, R. P., Dowda, M., Felton, G., & Pate, R. R. (2005). Perceived physical environment and physical activity across one year among adolescent girls: Self-efficacy as a possible mediator? Journal of Adolescent Health, 37, 403-408. doi: 10.1016/j.jadohealth.2004.10.004 Olds, T., Wake, M., Patton, G., Ridley, K., Waters, E., Williams, J., & Hesketh, K. (2009). How do school-day activity patterns differ with age and gender across adolescence? Journal of Adolescent Health, 44, 64-72. doi: 10.1016/j.jadohealth.2008.05.003 Ortega, F. B., Ruiz, J. R., Castillo, M. J., Moreno, L. A., González-Gross, M., Wärnberg, J., & Gutiérrez, A. (2005). Bajo nivel de forma física en los adolescentes españoles. Importancia para la salud cardiovascular futura (Estudio AVENA). Revista Española de Cardiología, 58, 898-909. doi: 10.1157/13078126 Perula de Torres, L. A., Lluch, C., Ruiz Moral, R., Espejo Espejo, J., Tapia, G., & Mengual Luque, P. (1998). Prevalencia de actividad física y su relación con variables sociodemográficas y ciertos estilos de vida en escolares cordobeses. Revista Española de Salud Pública, 72, 233-244. Ramos, P., Rivera, F., Moreno, C., & Jiménez-Iglesias, A. (2012). Análisis de clúster de la actividad física y las conductas sedentarias de los adolescentes españoles, correlación con la salud biopsicosocial. Revista de Psicología del Deporte, 21, 99-106. Roberts, C., Currie, C., Samdal, O., Currie, D., Smith, R., & Maes, L. (2007) Measuring the health and health behaviours of adolescents through crossnational survey research: Recent developments in the Health Behaviour in School-aged Children (HBSC) study. Journal of Public Health, 15, 179- 186. doi: 10.1007/s10389-007-0100-x Roberts, C., Tynjälä, J., & Komkov, A. (2004). Physical activity. In C. Currie, C. Roberts, A. Morgan, R. Smith, W. Settertobulte, O. Samdal & V. Barnekow (Eds.), Young people's health in context. Health Behaviour in School-aged Children (HBSC) study: International report from the 2001/2002 survey. Health policy for children and adolescents (Report No. 4). (pp. 90-97). Copenhagen: WHO Regional Office for Europe. Sallis, J. (2000). Age-related decline in physical activity: A synthesis of human and animal studies. Medicine & Science in Sports & Exercise, 32, 1598- Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 352 1600. Sallis, J., Zakarian, J., Hovell, M., & Hofstetter, R. (1996). Ethnic, socieconomic, and sex differences in physical activity among adolescents. Journal of Clinical Epidemiology, 49, 125-134. doi: 10.1016/0895-4356(95)00514-5 Samdal, O., Tynjälä, J., Roberts, C., Sallis, J., Villberg, J., & Wold, B. (2006). Trends in vigorous physical activity and TV watching of adolescents from 1986 to 2002 in seven European Countries. European Journal of Public Health, 17, 242-248. doi: 10.1093/eurpub/ckl245 Strong, W. B., Malina, R. M., Blimkie, C. J. R., Daniels, S. R., Dishman, R. K., Gutin, B.,… Trudeau, F. (2005). Evidence based physical activity for school-aged youth. The Journal of Pediatrics, 146, 732-737. doi: 10.1016/j.jpeds.2005.01.055 Suris, J.-C., Michaud, P.-A., Chossis, I., & Jeannin, A. (2006). Towards a sedentary society: Trends in adolescent sport practice in Switzerland (1993-2002). Journal of Adolescent Health, 39, 132-134. doi: 10.1016/j.jadohealth.2005.09.001 Tammelin, T., Näyhä, S., Laitinen, J., Rintamäki, H., & Järvelin, M.-R. (2003). Physical activity and social status in adolescence as predictors of physical inactivity in adulthood. Preventive Medicine, 37, 375-381. doi: 10.1016/S0091-7435(03)00162-2 Tomkinson, G. R., Olds, T. S., & Gulbin, J. (2003). Secular trends in physical performance of Australian children. Evidence from the Talent Search program. The Journal of Sports Medicine and Physical Fitness, 43, 90-98. Trost, S., Pate, R. R., Sallis, J., Freedson, P., Taylor, W., Dowda, M., & Sirard, J. (2002). Age and gender differences in objectively measured physical activity in youth. Medicine & Science in Sports & Exercise, 34, 350-355. U.S. Department of Health and Human Services (1996). Physical activity and health: A report of the Surgeon General. Atlanta: Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Vicente-Rodríguez, G., Rey-López, J. P., Martín-Matillas, M., Moreno, L. A., Wärnberg, J., Redondo, C.,... AVENA Study Group (2008). Television watching, videogames, and excess of body fat in Spanish adolescents: The AVENA study. Nutrition, 24, 654-662. doi: 10.1016/j.nut.2008.03.011 Walters, S., Barr-Anderson, D. J., Wall, M., & Neumark-Sztainer, D. (2009). Does participation in organized sports predict future physical activity for adolescents from diverse economic backgrounds? Journal of Adolescent Health, 44, 268-274. doi: 10.1016/j.jadohealth.2008.08.011 Wardle, J., Robb, K., & Johnson, F. (2002). Assessing socioeconomic status in adolescents: The validity of a home affluence scale. Journal of Epidemiology & Community Health, 56, 595-599. doi: 10.1136/jech.56.8.595 Westerstahl, M., Barnekow-Bergkvist, M., Hedberg, G., & Jansson, E. (2003). Secular trends in body dimensions and physical fitness among adolescents in Sweden from 1974 to 1995. Scandinavian Journal of Medicine and Science in Sports, 13, 128-137. doi: 10.1034/j.1600- Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354 353 0838.2003.10274.x WHO/HBSC Forum (2006). Addressing the socioeconomic determinants of healthy eating habits and physical activity levels among adolescents. Copenhagen: WHO Regional Office for Europe. Número de citas totales / Total references: 25 (100%) Número de citas propias de la revista / Journal's own references: 0 (0%) Rev.int.med.cienc.act.fís.deporte - vol. 16 - número 62 - ISSN: 1577-0354