Physical Activity is Related to Fatty Liver Marker in Obese Youth, Independently of Central Obesity or Cardiorespiratory Fitness.
Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity and has been identified as the leading cause of liver disease in pediatric populations worldwide. Because cardiorespiratory fitness (CRF) is related to physical activity (PA) levels, and increased PA plays a protective role against NAFLD risk factors, the aim of this study was to analyze the association between PA and a fatty liver marker (alanine aminotransferase - ALT) in obese children and adolescents, independently of central adiposity or CRF. 131 obese children (83 girls, 7-15 year-olds) involved in a PA promotion program comprised the sample. Measurements included anthropometric and body composition evaluations (DEXA), biological measurements (venipuncture), CRF (progressive treadmill test), PA (accelerometry), and maturational stage (Tanner criteria). The associations between ALT with PA intensities, central obesity, and CRF were calculated by three different models of linear regression, adjusted for potential confounders. Level of significance was set at 95%.


RESULTS
ALT was negatively associated with MVPA (β = -0.305), and CRF (β = -0.426), and positively associated with central obesity (β=.468). After adjustment for central obesity the negative and statistically significant association between ALT with MVPA (β = -0.364) and CRF (β = -0.550) still persists while a positive and significantly correlation was shown between ALT and SB (β = 0.382). Additional adjustment for CRF (Model 3) showed significant associations for all the PA intensities analyzed including light activity. PA at different intensities is associated to a fatty liver marker in obese children and adolescents, independently of central adiposity or CRF. Key pointsIn a previous study our group observed that there might be a potential protective effect of cardiorespiratory fitness (CRF) against abnormal ALT values;Considering that CRF is related to physical activity (PA), and increased PA plays a protective role against fatty liver, we hypothesized that it might be an association between PA and fatty liver in obese youth, independently of central adiposity or CRF;No other study has investigated these associations in obese youth;Our findings stresses the fact that moderate-to-vigorous and light physical activities, as well as lower sedentary behavior, is associated with lower fatty liver marker, independent of the effect of potential mediators, such as central obesity or CRF.
Research Centre in Physical Activity, Health and Leisure, Porto University , Portugal; Federal Rural University of Pernambuco , Brazil.
Clarice
C
Martins
Research Centre in Physical Activity, Health and Leisure, Porto University , Portugal ; University Institute of Maia.
Luisa
L
Aires
Research Centre of Assessment and Exercise Prescription, Univ Estadual Paulista , Sao Paulo, Brazil.
Ismael Freitas
IF
Júnior
Research Centre in Physical Activity, Health and Leisure, Porto University , Portugal.
Gustavo
G
Silva
Federal University of Paraiba , Brazil.
Alexandre
A
Silva
Federal University of Paraiba , Brazil.
Luís
L
Lemos
Research Centre in Physical Activity, Health and Leisure, Porto University , Portugal.
Jorge
J
Mota
Physical activity; cardiorespiratory fitness; central obesity; fatty liver; obese youth