Objective This experiment tested the hypothesis that exercise would improve executive function. Design Sedentary, overweight 7- to 11-year-old children (N = 171, 56% female, 61% Black, M ± SD age 9.3 ± 1.0 yrs, body mass index (BMI) 26 ± 4.6 kg/m2, BMI z-score 2.1 ± 0.4) were randomized to 13 ± 1.6 weeks of an exercise program (20 or 40 minutes/day), or a control condition. Main outcome measures Blinded, standardized psychological evaluations (Cognitive Assessment System and Woodcock-Johnson Tests of Achievement III) assessed cognition and academic achievement. Functional magnetic resonance imaging measured brain activity during executive function tasks. Results Intent to treat analysis revealed dose response benefits of exercise on executive function and mathematics achievement. Preliminary evidence of increased bilateral prefrontal cortex activity and reduced bilateral posterior parietal cortex activity due to exercise was also observed. Conclusion Consistent with results obtained in older adults, a specific improvement on executive function and brain activation changes due to exercise were observed. The cognitive and achievement results add evidence of dose response, and extend experimental evidence into childhood. This study provides information on an educational outcome. Besides its importance for maintaining weight and reducing health risks during a childhood obesity epidemic, physical activity may prove to be a simple, important method of enhancing aspects of children’s mental functioning that are central to cognitive development. This information may persuade educators to implement vigorous physical activity.

Studies that examine the effects of exercise on children's intelligence, cognition, or academic achievement were reviewed and results were discussed in light of (a) contemporary cognitive theory development directed toward exercise, (b) recent research demonstrating the salutary effects of exercise on adults' cognitive functioning, and (c) studies conducted with animals that have linked physical activity to changes in neurological development and behavior. Similar to adults, exercise facilitates children's executive function (i.e., processes required to select, organize, and properly initiate goal-directed actions). Exercise may prove to be a simple, yet important, method of enhancing those aspects of children's mental functioning central to cognitive development.

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Adipose tissue is a known source of proinflammatory cytokines in obese humans and animal models, including the db/db mouse, in which obesity arises as a result of leptin receptor insensitivity. Inflammatory cytokines induce cognitive deficits across numerous conditions, but no studies have determined whether obesity-induced inflammation mediates synaptic dysfunction. To address this question, we used a treadmill training paradigm in which mice were exposed to daily training sessions or an immobile belt, with motivation achieved by delivery of compressed air on noncompliance. Treadmill training prevented hippocampal microgliosis, abolished expression of microglial activation markers, and also blocked the functional sensitization observed in isolated cells after ex vivo exposure to lipopolysaccharide. Reduced microglial reactivity with exercise was associated with reinstatement of hippocampus-dependent memory, reversal of deficits in long-term potentiation, and normalization of hippocampal dendritic spine density. Because treadmill training evokes broad responses not limited to the immune system, we next assessed whether directly manipulating adiposity through lipectomy and fat transplantation influences inflammation, cognition, and synaptic plasticity. Lipectomy prevents and fat transplantation promotes systemic and central inflammation, with associated alterations in cognitive and synaptic function. Levels of interleukin 1␤ (IL1␤) emerged as a correlate of adiposity and cognitive impairment across both the treadmill and lipectomy studies, so we manipulated hippocampal IL1 signaling using intrahippocampal delivery of IL1 receptor antagonist (IL1ra). Intrahippocampal IL1ra prevented synaptic dysfunction, proinflammatory priming, and cognitive impairment. This pattern supports a central role for IL1-mediated neuroinflammation as a mechanism for cognitive deficits in obesity and diabetes.

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Objective: The goal of this study was to evaluate the impact of a 10-month after-school physical activity (PA) program on body composition and cardiovascular (CV) fitness in young black girls. Research Methods and Procedures: Subjects were 8-to 12-year-olds recruited from elementary schools. Body composition was measured using anthropometrics {waist circumference and BMI, DXA [percentage body fat (%BF)] and bone mineral density (BMD)}, and magnetic resonance imaging [visceral adipose tissue (VAT)]. CV fitness was measured using a graded treadmill test. The intervention consisted of 30 minutes homework/healthy snack time and 80 minutes PA (i.e., 25 minutes skills instruction, 35 minutes aerobic PA, and 20 minutes strengthening/stretching). Analyses were adjusted for age, baseline value of the dependent variable, and sexual maturation (pediatrician observation). Results: Mean attendance was 54%. Compared with the control group, the intervention group had a relative decrease in %BF (p Ͻ 0.0001), BMI (p Ͻ 0.01), and VAT (p Ͻ 0.01) and a relative increase in BMD (p Ͻ 0.0001) and CV fitness (p Ͻ 0.05). Higher attendance was associated with greater increases in BMD (p Ͻ 0.05) and greater decreases in %BF (p Ͻ 0.01) and BMI (p Ͻ 0.05). Higher heart rate during PA was associated with greater increases in BMD (p Ͻ 0.05) and greater decreases in %BF (p Ͻ 0.005). Discussion: An after-school PA program can lead to beneficial changes in body composition and CV fitness in young black girls. It is noteworthy that the control and intervention groups differed in change in VAT but not waist circumference. This suggests that changes in central adiposity can occur in response to PA, even in young children, but that waist circumference may not be a good indicator of central adiposity.

Background This study examined associations of fitness and fatness with cognitive processes, academic achievement, and behavior, independent of demographic factors, at the baseline of an exercise trial. Methods Overweight, sedentary but otherwise healthy 7–11 year olds (N=170) participated in a study of health, cognition and achievement in the Augusta, GA area from 2003–2006. Children underwent evaluations of fatness and fitness, psychological assessments of cognition and academic achievement, and behavior ratings by parents and teachers. Partial correlations examined associations of fitness and fatness with cognitive and achievement scores and behavior ratings, controlling for demographic factors. Results Fitness was associated with better cognition, achievement and behavior, and fatness with worse scores. Specifically, executive function, mathematics and reading achievement, and parent ratings of child behavior were related to fitness and fatness. Teacher ratings were related to fitness. Conclusion These results extend prior studies by providing reliable, standardized measures of cognitive processes, achievement, and behavior in relation to detailed measures of fitness and fatness. However, cross-sectional associations do not necessarily indicate that improving one factor, such as fatness or fitness, will result in improvements in factors that were associated with it. Thus, randomized clinical trials are necessary to determine the effects of interventions.

Objectives-To examine the relations of race, sex, adiposity, adipokines and physical activity to telomere length in adolescents.Study design-Leukocyte telomere length (T/S ratio) was assessed cross-sectionally in 667 adolescents (aged 14-18 years, 48% blacks, 51% girls) using a quantitative PCR method. Generalized Estimating Equations analyses were performed.Results-Black adolescents had longer telomeres than white adolescents (age and sex adjusted T/S ratio ± SE: 1.32 ± 0.01 vs. 1.27 ± 0.01, p=0.014) and girls had longer telomeres than boys (age and race adjusted T/S ratio ± SE: 1.31 ± 0.01 vs. 1.27 ± 0.01, p=0.007). None of the adiposity or adipokine measures explained a significant proportion of the variance in telomere length. Vigorous physical activity was positively associated with telomere length (adjusted R 2 =0.019, p=0.009) and accounted for 1.9% of the total variance only in girls.Conclusion-This study, conducted in a biracial adolescent cohort, demonstrated that: (1) race and sex differences in telomere length have already emerged during adolescence; (2) adiposity and adipokines are not associated with telomere length at this age; and (3) the anti-aging effect of vigorous physical activity may begin in youth especially in girls. KeywordsTelomere length; race; sex; adiposity; adipokines; physical activity; adolescents © 2010 Mosby, Inc. All rights reserved. * Address for correspondence: Haidong Zhu MD PhD, Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, GA, USA, 1120 15 th Street, HS-1640, Augusta, GA 30912-3715, Phone: (706) 721 5470, hzhu@mail.mcg.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.The authors declare no conflicts of interest. In contrast to the considerable information available in adult literature, the knowledge about LTL in adolescent populations is limited. Therefore, the present study aimed to examine the relations of race, sex, adiposity, adipokines and physical activity to telomere length in a relatively large sample of healthy white and black adolescents. NIH Public Access MethodsHealthy adolescents aged 14-18 years including 348 whites and 319 blacks (324 boys) were previously recruited from local public high schools. Written informed consent was obtained from these 18 year olds. For 14-17 year olds, parental consent and subject assent were obtained. Race was determined by self-report of each subject, and by a parent if subject was under 18 years of age. The adolescents were apparently healthy, had no contraindications to any of the study procedures and were taking no medication t...