title: Physical fitness as a mediator between objectively measured physical activity and clustered metabolic syndrome in children and adolescents: The UP&DOWN study.
abstract: The extent to which physical fitness (PF) attenuates or modifies the association between physical activity (PA) and clustered metabolic syndrome risk factors (CMetSRF) is controversial. We aimed: i) To examine the independent and combined association of objectively measured PA and PF with CMetSRF in children and adolescents; ii) To test the mediating effect of PF in the association of PA with CMetSRF.
  
  
  
  A total of 226 children and 256 adolescents participated. Levels of PA (light, moderate, vigorous and moderate-to-vigorous [MVPA]) and PF were measured by accelerometry and ALPHA battery, respectively. Cardiorespiratory and muscular fitness values were combined in a global PF variable. A CMetSRF was computed by assessing the following variables: waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides and glucose. In children, the highest vigorous PA (β = -0.193; P = 0.003) and MVPA (β = -0.149; P = 0.025) were individually associated with lower CMetSRF, but these associations were not independent of global PF. In adolescents, the association of moderate (β = -0.123; P = 0.046) and MVPA (β = -0.147; P = 0.024) with CMetSRF was independent of PF. Among unfit adolescents, the higher time they spent in MVPA the lower CMetSRF levels were found (P = 0.032).
  
  
  
  The results are suggestive of a full mediation of global PF in the association of MVPA and vigorous PA with CMetSRF in children. In adolescents, the association of higher moderate and MVPA with lower CMetSRF was independent of levels of PF, and mediation analyses suggest only a partial mediation of global PF in the association of MVPA with CMetSRF.
authors: Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain; Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain. Electronic address: victor.segura@uca.es.
authors: V
authors: V
authors: Segura-Jiménez
authors: Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain.
authors: F
authors: F
authors: Parrilla-Moreno
authors: Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain.
authors: J R
authors: JR
authors: Fernández-Santos
authors: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain; Department of Physical Education, Sports and Human Movement, Autonomous University of Madrid, Madrid, Spain.
authors: I
authors: I
authors: Esteban-Cornejo
authors: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science and Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain.
authors: S
authors: S
authors: Gómez-Martínez
authors: Department of Physical Education, Sports and Human Movement, Autonomous University of Madrid, Madrid, Spain.
authors: D
authors: D
authors: Martinez-Gomez
authors: Immunonutrition Research Group, Department of Metabolism and Nutrition, Institute of Food Science and Technology and Nutrition (ICTAN), Spanish National Research Council (CSIC), Madrid, Spain.
authors: A
authors: A
authors: Marcos
authors: Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain.
authors: J
authors: J
authors: Castro-Piñero
mesh_terms: D056044:Actigraphy / Q000295:instrumentation; D000293:Adolescent; D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D000072599:Cardiorespiratory Fitness; D002648:Child; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D012307:Risk Factors; D057185:Sedentary Behavior; D013030:Spain; D055105:Waist Circumference
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D008055:Lipids
keywords: Cardiorespiratory fitness; Metabolic syndrome; Moderate-to-vigorous physical activity; Muscular strength; Vigorous physical activity