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Effects of exercise and lifestyle modification on fitness, insulin resistance, skeletal muscle oxidative phosphorylation and intramyocellular lipid content in obese children and adolescents
Author(s) -
McCormack S. E.,
McCarthy M. A.,
Harrington S. G.,
Farilla L.,
Hrovat M. I.,
Systrom D. M.,
Thomas B. J.,
Torriani M.,
McInnis K.,
Grinspoon S. K.,
Fleischman A.
Publication year - 2014
Publication title -
pediatric obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.226
H-Index - 69
eISSN - 2047-6310
pISSN - 2047-6302
DOI - 10.1111/j.2047-6310.2013.00180.x
Subject(s) - medicine , insulin resistance , aerobic exercise , endocrinology , body mass index , obesity , physical fitness , type 2 diabetes , cardiorespiratory fitness , population , insulin , physical therapy , diabetes mellitus , environmental health
Summary What is already known about this subject Obesity‐related insulin resistance is highly prevalent in children and adolescents, and contributes to an increased lifetime risk of type 2 diabetes mellitus and cardiovascular disease. Intensive exercise training may improve insulin sensitivity.What this study adds Three monitored exercise training sessions per week for 8 weeks can improve fitness‐related insulin sensitivity in obese, insulin resistant children. Insulin sensitivity and skeletal muscle oxidative phosphorylation may be dissociable in this population. Improvements in fitness may be accompanied by a rise in intramyocellular lipid content and an associated increase in resting energy expenditure.Background Obesity is associated with poor fitness and adverse metabolic consequences in children. Objective To investigate how exercise and lifestyle modification may improve fitness and insulin sensitivity in this population. Design and subjects Randomized controlled trial, 21 obese (body mass index ≥ 95% percentile) subjects, ages 10 to 17 years. Methods Subjects were given standardized healthful lifestyle advice for 8 weeks. In addition, they were randomized to an in‐home supervised exercise intervention ( n = 10) or control group ( n = 11). Measurements Fasting laboratory studies (insulin, glucose, lipid profile) and assessments of fitness, body composition, skeletal muscle oxidative phosphorylation and intramyocellular lipid content ( IMCL ), were performed at baseline and study completion.Results Subjects were 13.0 ± 1.9 (standard deviation) years old, 72% female and 44% non‐white. Exercise improved fitness ( P = 0.03) and power ( P = 0.01), and increased IMCL ( P = 0.02). HOMA‐IR decreased among all subjects in response to lifestyle modification advice ( P = 0.01), regardless of exercise training assignment. In univariate analysis in all subjects, change in cardiovascular fitness was associated with change in HOMA‐IR . In exploratory analyses, increased IMCL was associated with greater resting energy expenditure (r = 0.78, P = 0.005) and a decrease in fasting respiratory quotient (r = −0.70, P = 0.02) ( n = 11). Conclusions Change in fitness was found to be related to change in insulin resistance in response to lifestyle modification and exercise in obese children. IMCL increased with exercise in these obese children, which may reflect greater muscle lipid oxidative capacity.