The aim of this study was to investigate the independent associations among cardiorespiratory fitness, metabolic syndrome (MetS), and C-reactive protein (CRP) in children. The sample consisted of 112 children (11.4？？±？？0.4 years). Data was obtained for children’s anthropometry, cardiorespiratory fitness, MetS components, and CRP levels. MetS was defined using criteria analogous to the Adult Treatment Panel III definition. A MetS risk score was also computed. Prevalence of the MetS was 5.4%, without gender differences. Subjects with low fitness showed significantly higher MetS risk ( ) and CRP ( ), compared to the high-fitness pupils. However, differences in MetS risk, and CRP between fitness groups decreased when adjusted for waist circumference. These data indicate that the mechanisms linking cardiorespiratory fitness, MetS risk and inflammation in children are extensively affected by obesity. Intervention strategies aiming at reducing obesity and improving cardiorespiratory fitness in childhood might contribute to the prevention of the MetS in adulthood. 1. Introduction The prevalence and severity of obesity is increasing dramatically among children and adolescents in many parts of the world, whereas prevalence rates are estimated to increase in the next decades [1]. In children, excess body fat appears to be strongly associated with the clustering of risk factors, such as hyperglycemia, dyslipidemia, and hypertension, which play a key role in the pathogenesis of the metabolic syndrome (MetS) [2]. Obesity and the MetS risk in children have been recently associated with systemic inflammatory markers, in particular C-reactive protein (CRP) [3, 4], implying that low-grade inflammation can already exist in childhood and may be a potential link between the obesity and the MetS. Among behavioral variables, cardiorespiratory fitness has a protective role in MetS and inflammatory factors; however, it is not entirely clear if the interrelations among cardiorespiratory fitness, MetS risk, and inflammation in children are independent or partly due to the mediating effect of obesity, since the existing data are limited and equivocal [5, 6]. Recent evidence indicates that the prevalence rates of childhood obesity in Greece remain high [1, 7] and often coexist with low cardiorespiratory fitness [8] and an unfavorable cardiometabolic risk profile [9]. For the Greek pediatric population these data suggest an increased cardiovascular morbidity in adulthood, given that high-risk children and adolescents are likely to become high-risk adults [10]. Although the
Y. Wang and T. Lobstein, “Worldwide trends in childhood overweight and obesity,” International Journal of Pediatric Obesity, vol. 1, no. 1, pp. 11–25, 2006.
S. R. Srinivasan, L. Myers, and G. S. Berenson, “Predictability of childhood adiposity and insulin for developing insulin resistance syndrome (syndrome X) in young adulthood: the Bogalusa heart study,” Diabetes, vol. 51, no. 1, pp. 204–209, 2002.
M. Hiura, T. Kikuchi, K. Nagasaki, and M. Uchiyama, “Elevation of serum C-reactive protein levels is associated with obesity in boys,” Hypertension Research, vol. 26, no. 7, pp. 541–546, 2003.
M. Lambert, E. E. Delvin, G. Paradis, J. O'Loughlin, J. A. Hanley, and E. Levy, “C-reactive protein and features of the metabolic syndrome in a population-based sample of children and adolescents,” Clinical Chemistry, vol. 50, no. 10, pp. 1762–1768, 2004.
C. R. Isasi, R. J. Deckelbaum, R. P. Tracy, T. J. Starc, L. Berglund, and S. Shea, “Physical fitness and C-reactive protein level in children and young adults: the Columbia University BioMarkers study,” Pediatrics, vol. 111, no. 2, pp. 332–338, 2003.
G. D. C. Ball, G. Q. Shaibi, M. L. Cruz, M. P. Watkins, M. J. Weigensberg, and M. I. Goran, “Insulin sensitivity, cardiorespiratory fitness, and physical activity in overweight hispanic youth,” Obesity Research, vol. 12, no. 1, pp. 77–85, 2004.
K. D. Tambalis, D. B. Panagiotakos, S. A. Kavouras et al., “Eleven-year prevalence trends of obesity in greek children: first evidence that prevalence of obesity is leveling off,” Obesity, vol. 18, no. 1, pp. 161–166, 2010.
S. P. Tokmakidis, A. Kasambalis, and A. D. Christodoulos, “Fitness levels of Greek primary schoolchildren in relationship to overweight and obesity,” European Journal of Pediatrics, vol. 165, no. 12, pp. 867–874, 2006.
F. Magkos, Y. Manios, G. Christakis, and A. G. Kafatos, “Secular trends in cardiovascular risk factors among school-aged boys from Crete, Greece, 1982–2002,” European Journal of Clinical Nutrition, vol. 59, no. 1, pp. 1–7, 2005.
N. F. Chu, E. B. Rimm, D. J. Wang, H. S. Liou, and S. M. Shieh, “Clustering of cardiovascular disease risk factors among obese schoolchildren: the Taipei children heart study,” American Journal of Clinical Nutrition, vol. 67, no. 6, pp. 1141–1146, 1998.
Y. Manios, F. Magkos, G. Christakis, and A. G. Kafatos, “Changing relationships of obesity and dyslipidemia in Greek children: 1982–2002,” Preventive Medicine, vol. 41, no. 5-6, pp. 846–851, 2005.
T. J. Cole, M. C. Bellizzi, K. M. Flegal, and W. H. Dietz, “Establishing a standard definition for child overweight and obesity worldwide: international survey,” British Medical Journal, vol. 320, no. 7244, pp. 1240–1243, 2000.
L. A. Leger, D. Mercier, C. Gadoury, and J. Lambert, “The multistage 20-m shuttle run test for aerobic fitness,” Journal of Sports Sciences, vol. 6, no. 2, pp. 93–101, 1988.
R. D. Bell, M. Má？ek, J. Rutenfranz, and W. H. M. Saris, “Health indicators and risk factors of cardiovascular diseases during childhood and adolescence,” in Children and Exercise 7, J. Rutenfranz, R. Mocellin, and F. Klimt, Eds., pp. 19–27, Human Kinetics, Champaign, Ill, USA, 1986.
National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents, “Update on the 1987 task force report on high blood pressure in children and adolescents: a working group report from the national high blood pressure education program,” Pediatrics, vol. 98, no. 4, pp. 649–658, 1996.
Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults, “Third report of the national cholesterol education program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel III). Final report,” Circulation, vol. 106, pp. 3143–421, 2002.
S. D. de Ferranti, K. Gauvreau, D. S. Ludwig, E. J. Neufeld, J. W. Newburger, and N. Rifai, “Prevalence of the metabolic syndrome in American adolescents: findings from the third national health and nutrition examination survey,” Circulation, vol. 110, no. 16, pp. 2494–2497, 2004.
S. Brage, N. Wedderkopp, U. Ekelund et al., “Features of the metabolic syndrome are associated with objectively measured physical activity and fitness in Danish children: the European youth heart study (EYHS),” Diabetes Care, vol. 27, no. 9, pp. 2141–2148, 2004.
D. R. Ragland, “Dichotomizing continuous outcome variables: dependence of the magnitude of association and statistical power on the cutpoint,” Epidemiology, vol. 3, no. 5, pp. 434–440, 1992.
S. Cook, M. Weitzman, P. Auinger, M. Nguyen, and W. H. Dietz, “Prevalence of a metabolic syndrome phenotype in adolescents: findings from the third national health and nutrition examination survey, 1988–1994,” Archives of Pediatrics and Adolescent Medicine, vol. 157, no. 8, pp. 821–827, 2003.
E. S. Ford, U. A. Ajani, and A. H. Mokdad, “The metabolic syndrome and concentrations of C-reactive protein among U.S. youth,” Diabetes Care, vol. 28, no. 4, pp. 878–881, 2005.
C. Platat, A. Wagner, T. Klumpp, B. Schweitzer, and C. Simon, “Relationships of physical activity with metabolic syndrome features and low-grade inflammation in adolescents,” Diabetologia, vol. 49, no. 9, pp. 2078–2085, 2006.
R. Kelishadi, E. M. Razaghi, M. M. Gouya et al., “Association of physical activity and the metabolic syndrome in children and adolescents: CASPIAN study,” Hormone Research, vol. 67, no. 1, pp. 46–52, 2007.
J. R. Ruiz, N. S. Rizzo, F. B. Ortega, H. M. Loit, T. Veidebaum, and M. Sj？strom, “Markers of insulin resistance are associated with fatness and fitness in school-aged children: the European Youth Heart Study,” Diabetologia, vol. 50, no. 7, pp. 1401–1408, 2007.
U. Ekelund, S. Anderssen, L. B. Andersen et al., “Prevalence and correlates of the metabolic syndrome in a population-based sample of European youth,” American Journal of Clinical Nutrition, vol. 89, no. 1, pp. 90–96, 2009.
D. M. Cummings, K. D. Dubose, S. Imai, and D. N. Collier, “Fitness versus fatness and insulin resistance in U.S. adolescents,” Journal of Obesity, vol. 2010, Article ID 195729, 7 pages, 2010.
L. B. Andersen, M. Harro, L. B. Sardinha et al., “Physical activity and clustered cardiovascular risk in children: a cross-sectional study (The European youth heart study),” The Lancet, vol. 368, no. 9532, pp. 299–304, 2006.
L. B. Andersen, N. Wedderkopp, H. S. Hansen, A. R. Cooper, and K. Froberg, “Biological cardiovascular risk factors cluster in Danish children and adolescents: the European youth heart study,” Preventive Medicine, vol. 37, no. 4, pp. 363–367, 2003.
A. D. Flouris, C. H. Canham, B. E. Faught, and P. Klentrou, “Prevalence of cardiovascular disease risk in Ontario adolescents,” Archives of Disease in Childhood, vol. 92, no. 6, pp. 521–523, 2007.
T. Olds, G. Tomkinson, L. Léger, and G. Cazorla, “Worldwide variation in the performance of children and adolescents: an analysis of 109 studies of the 20-m shuttle run test in 37 countries,” Journal of Sports Sciences, vol. 24, no. 10, pp. 1025–1038, 2006.
G. P. Nassis, K. Papantakou, K. Skenderi et al., “Aerobic exercise training improves insulin sensitivity without changes in body weight, body fat, adiponectin, and inflammatory markers in overweight and obese girls,” Metabolism, vol. 54, no. 11, pp. 1472–1479, 2005.
N. E. Thomas, J. S. Baker, M. R. Graham, S. M. Cooper, and B. Davies, “C-reactive protein in schoolchildren and its relation to adiposity, physical activity, aerobic fitness and habitual diet,” British Journal of Sports Medicine, vol. 42, no. 5, pp. 357–360, 2008.
D. G. Cook, M. A. Mendall, P. H. Whincup et al., “C-reactive protein concentration in children: relationship to adiposity and other cardiovascular risk factors,” Atherosclerosis, vol. 149, no. 1, pp. 139–150, 2000.
B. Harmse and H. S. Kruger, “Significant differences between serum CRP levels in children in different categories of physical activity: the PLAY study,” Cardiovascular Journal of Africa, vol. 21, no. 6, pp. 316–322, 2010.
A. A. Meyer, G. Kundt, U. Lenschow, P. Schuff-Werner, and W. Kienast, “Improvement of early vascular changes and cardiovascular risk factors in obese children after a six-month exercise program,” Journal of the American College of Cardiology, vol. 48, no. 9, pp. 1865–1870, 2006.
T. Dwyer, C. G. Magnussen, M. D. Schmidt et al., “Decline in physical fitness from childhood to adulthood associated with increased obesity and insulin resistance in adults,” Diabetes Care, vol. 32, no. 4, pp. 683–687, 2009.
I. Ferreira, J. W. R. Twisk, W. van Mechelen, H. C. G. Kemper, and C. D. A. Stehouwer, “Development of fatness, fitness, and lifestyle from adolescence to the age of 36 years: determinants of the metabolic syndrome in young adults: the Amsterdam Growth and Health Longitudinal Study,” Archives of Internal Medicine, vol. 165, no. 1, pp. 42–48, 2005.
A. D. Flouris, C. Bouziotas, A. D. Christodoulos, and Y. Koutedakis, “Longitudinal preventive-screening cutoffs for metabolic syndrome in adolescents,” International Journal of Obesity, vol. 32, no. 10, pp. 1506–1512, 2008.
