Associations of physical activity and fitness with adipocytokines in adolescents: The AFINOS study
Introduction
Several novel cardiovascular disease (CVD) markers have emerged in the last years [1]. Since obesity is considered an independent CVD risk factor, research studies have addressed the pathophysiological link between adipose tissue and CVD and metabolic abnormalities [2]. The trigger for this research was the identification of the adipose tissue as an endocrine organ [3]. It is now known that adipocytes secrete a diverse group of proteins called adipocytokines, which have shown to take part in different biological functions including immunity, insulin sensitivity, appetite, angiogenesis, lipid metabolism, vascular function, and inflammation [3].
One relevant adipocytokine, known as adiponectin, has shown to predict the development of atherosclerosis and metabolic risk in adults [4], [5]. In youth, hypoadiponectinemia has been associated with CVD risk factors and insulin resistance [6], [7]. Another key adipocytokine is leptin, which in contrast to adiponectin, is positively associated with damage to the arterial walls, type 2 diabetes, obesity, and metabolic syndrome risk factors in both youth and adults [5], [8], [9], [10]. Thus, adiponectin and leptin seem to play a key role in CVD and type 2 diabetes.
Physical activity (PA), cardiorespiratory fitness (CRF) and muscular fitness (MF) are key constructs in exercise science and have been shown to be negatively associated with death from all causes, including CVD mortality [11], [12]. In addition, PA, CRF and MF have been also associated with traditional CVD risk factors in childhood and adolescence [13], [14]. However, the literature is scarce regarding the potential role of PA and fitness on new CVD biomarkers such as adiponectin and leptin in youth. This research is important since CVD risk factors often track from childhood to adulthood [15], thus making adolescence a crucial age group for a better knowledge of the associations between lifestyle behaviors, health-related fitness, and CVD risk factors. Therefore, the aim of the present study was to examine the independent and joint associations of objectively measured PA, CRF and MF with adiponectin and leptin in adolescents.
Section snippets
Participants
Participants for the current study were enrolled in the AFINOS (La Actividad Física como Agente Preventivo del Desarrollo de Sobrepeso, Obesidad, Alergias, Infecciones y Factores de Riesgo Cardiovascular en Adolescentes: Physical Activity as a Preventive Agent of the Development of Overweight, Obesity, Infections, Allergies and Factors of Cardiovascular Risk in Adolescents) study [16]. The AFINOS study is a cross-sectional study where health status and lifestyle indicators were assessed by
Results
Characteristics of the sample are shown in Table 1. Relationships between body fat, insulin resistance and adipocytokines after adjustments for age, sex and pubertal status are shown in Table 2. Waist circumference showed the highest correlations between body fat measurements and adipocytokines (r = −0.256 and 0.615, P < 0.001, for adiponectin and leptin, respectively). Insulin resistance markers were only significantly related to leptin, and not to adiponectin. On the other hand, vigorous PA (r
Discussion
The results of this study indicate that high levels of PA (vigorous), CRF and MF were independently and jointly associated with lower concentrations of leptin in adolescents. Paradoxically, CRF and MF were independently and inversely associated with adiponectin, whereas PA, CRF and MF were also jointly and inversely associated with adiponectin levels.
Despite that CRF and MF levels were associated with adiponectin in our adolescent sample, the inverse association found may seem contradictory and
Acknowledgements
The authors would like to thank all the adolescent participants and their families. This study was supported by the Spanish Ministry of Education and Science (DEP2006-56184-C03-02/PREV) and E.U. funding (FEDER). DMG had a scholarship from the Spanish Ministry of Education and Science (AP2006-02464). None of the authors had any conflicts of interest.
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Cited by (0)
- 1
Study coordinator: Marcos A.
Sub-study coordinators: Calle ME, Villagra A, Marcos A.
Sub-study 1: Calle ME, Regidor E, Martínez-Hernández D, Esteban-Gonzalo L. Department of Preventive Medicine and Public Health, Universidad Complutense de Madrid, E-28040 Madrid Spain.
Sub-study 2: Villagra A, Veiga OL, del-Campo J, Moya JM, Martínez-Gómez D, Zapatera B. Department of Physical Education, Sport and Human Movement, Facultad de Formación del Profesorado y Educación, Universidad Autonoma de Madrid, E-28049 Madrid, Spain.
Sub-study 3: Marcos A, Gómez-Martínez S, Nova E, Wärnberg J, Romeo J, Diaz LE, Pozo T, Puertollano MA, Martínez-Gómez D, Zapatera B, Veses A. Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN), Instituto del Frio, Spanish National Research Council (CSIC), E-28040 Madrid, Spain.