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 RCT, 21 obese (BMI ≥ 95%ile) 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 (SD) 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 over 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 RQ (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.

Given the increasing use of MRI in the pediatric population, the need for sedation in MRI performed in young children is a topic of growing importance. Although sedation is generally tolerated well by children, the financial and operational impacts of anesthesia on MRI workflow, as well as potential adverse effects of anesthetic medications, highlight the need to perform MRI in children without sedation whenever possible. This review focuses on current techniques to facilitate non-sedation MRI in children, including exam preparation with MRI simulation; asleep but not sedated techniques; awake and relaxed techniques using certified child life specialists, animal-assisted therapy, a child-friendly environment and in-scan entertainment; and non-sedated MRI protocol modifications such as shorter scan time, prioritizing sequences, reducing motion artifact, noise reduction, limiting use of gadolinium, employing an open MRI and modifying protocols.

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