title: A 12-week aerobic exercise program reduces hepatic fat accumulation and insulin resistance in obese, Hispanic adolescents.
abstract: The rise in obesity-related morbidity in children and adolescents requires urgent prevention and treatment strategies. Currently, only limited data are available on the effects of exercise programs on insulin resistance, and visceral, hepatic, and intramyocellular fat accumulation. We hypothesized that a 12-week controlled aerobic exercise program without weight loss reduces visceral, hepatic, and intramyocellular fat content and decreases insulin resistance in sedentary Hispanic adolescents. Twenty-nine postpubertal (Tanner stage IV and V), Hispanic adolescents, 15 obese (7 boys, 8 girls; 15.6 +/- 0.4 years; 33.7 +/- 1.1 kg/m(2); 38.3 +/- 1.5% body fat) and 14 lean (10 boys, 4 girls; 15.1 +/- 0.3 years; 20.6 +/- 0.8 kg/m(2); 18.9 +/- 1.5% body fat), completed a 12-week aerobic exercise program (4 x 30 min/week at > or =70% of peak oxygen consumption (VO(2)peak)). Measurements of cardiovascular fitness, visceral, hepatic, and intramyocellular fat content (magnetic resonance imaging (MRI)/magnetic resonance spectroscopy (MRS)), and insulin resistance were obtained at baseline and postexercise. In both groups, fitness increased (obese: 13 +/- 2%, lean: 16 +/- 4%; both P < 0.01). In obese participants, intramyocellular fat remained unchanged, whereas hepatic fat content decreased from 8.9 +/- 3.2 to 5.6 +/- 1.8%; P < 0.05 and visceral fat content from 54.7 +/- 6.0 to 49.6 +/- 5.5 cm(2); P < 0.05. Insulin resistance decreased indicated by decreased fasting insulin (21.8 +/- 2.7 to 18.2 +/- 2.4 microU/ml; P < 0.01) and homeostasis model assessment of insulin resistance (HOMA(IR)) (4.9 +/- 0.7 to 4.1 +/- 0.6; P < 0.01). The decrease in visceral fat correlated with the decrease in fasting insulin (R(2) = 0.40; P < 0.05). No significant changes were observed in any parameter in lean participants except a small increase in lean body mass (LBM). Thus, a controlled aerobic exercise program, without weight loss, reduced hepatic and visceral fat accumulation, and decreased insulin resistance in obese adolescents.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: van der Heijden
authors.forename: Zhiyue J
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Zili D
authors.initials: ZD
authors.lastname: Chu
authors.forename: Pieter J J
authors.initials: PJ
authors.lastname: Sauer
authors.forename: Morey W
authors.initials: MW
authors.lastname: Haymond
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Rodriguez
authors.forename: Agneta L
authors.initials: AL
authors.lastname: Sunehag
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000208:ethnology*; D000293:Adolescent; D041923:Adolescent Development; D015992:Body Mass Index; D002149:Energy Intake; D005081:Exercise Therapy; D017079:Exercise Tolerance; D005234:Fatty Liver / Q000208:ethnology / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D005260:Female; D006339:Heart Rate; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology*; D050152:Intra-Abdominal Fat / Q000503:physiopathology; D008099:Liver / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009765:Obesity / Q000150:complications / Q000208:ethnology / Q000503:physiopathology / Q000628:therapy*; D010101:Oxygen Consumption; D010349:Patient Compliance; D057185:Sedentary Behavior / Q000208:ethnology; D013997:Time Factors; D016896:Treatment Outcome