Interrelationships Among Changes in Leptin, Insulin, Cortisol and Growth Hormone and Weight Status in Youth

Objective: While acute alterations in leptin, insulin, cortisol and growth hormone (GH) levels have been reported in children following weight change interventions, little is known about natural hormonal changes as children grow and how these changes are affected b

The Relationship between Changes in Weight Status and Insulin Resistance in Youth

This study examined changes in insulin resistance (IR) in 120 youth over two years. IR was quantified via homeostatic model (HOMA-IR), and weight status changes were quantified via body mass index (BMI). When all participants were considered, the mean HOMA-IR and BMI increased 13.4% and 1.65 units, respectively. Change in BMI z-score and percent change in HOMA-IR were moderately associated (r = 0.39). Follow-up analyses were performed for the following weight groups: NN (normal at baseline and two years later), NO (normal to overweight), ON (overweight to normal), and OO (overweight at both points). The NO group had a greater change in HOMA-IR (+50%) compared to other groups: ON (−8%), NN (+2%), and OO (−0.1%) (P < .05). The association between changes in BMI z-score and HOMA-IR was r = 0.49 when only the NO and ON groups were included. These results reinforce the importance of preventing youth from becoming overweight to control IR

Relationship between Cardiovascular Risk Factors and Adipokines in Adolescents

This study evaluated the associations of adipokines with cardiovascular risk factors

The association between insulin resistance and cytokines in adolescents: the role of weight status and exercise

Increased adiposity is associated with insulin resistance (IR) and an inflammatory response in adults. We tested the hypotheses that cytokines associated with adiposity are also correlated with IR in early adolescents and that these relationships are moderated by weight status, levels of vigorous physical activity (VPA), or maximal aerobic power (pVO2max). Body mass, stature, and a fasting blood sample were obtained from 120 mid-pubertal adolescents (60 girls & 60 boys). Habitual VPA was obtained by a survey. Predicted VO2max was determined using a cycle-ergometer test. Weight status was based on body mass index percentiles (normal weight = BMI 95th %tile). Glucose, insulin, adiponectin, resistin, tumor necrosis factor-α, and interleukin-6 were measured, and IR index was based on the Homeostatic Model Assessment (HOMA). Adiponectin, resistin and TNF-α were associated with IR in all adolescents (R2=0.329, p0.050). Exercise did not moderate the association between these cytokines and IR. However, higher levels of VPA and/or pVO2max were associated with higher adiponectin, lower resistin and lower TNF- α in at least one of the genders. Our results indicate that the pathophysiology of obesity is already established in early adolescents. Increased adiposity, resulting in reduced adiponectin and increased resistin and TNF-α may link these cytokines with insulin resistance in adolescents

Adolescents with metabolic syndrome have a history of low aerobic fitness and physical activity levels

Abstract: Purpose: Metabolic syndrome (MS) is a clustering of cardiovascular disease risk factors that identifies individuals with the highest risk for heart disease. Two factors that may influence the MS are physical activity and aerobic fitness. This study determined if adolescent with the MS had low levels of aerobic fitness and physical activity as children. Methods: This longitudinal, exploratory study had 389 participants: 51% girls, 84% Caucasian, 12% African American, 1% Hispanic, and 3% other races, from the State of North Carolina. Habitual physical activity (PA survey), aerobic fitness (VO2max), body mass index (BMI), blood pressure, and lipids obtained at 7–10 y of age were compared to their results obtained 7 y later at ages 14–17 y. Results: Eighteen adolescents (4.6%) developed 3 or more characteristics of the MS. Logistic regression, adjusting for BMI percentile, blood pressure, and cholesterol levels, found that adolescents with the MS were 6.08 (95%CI = 1.18–60.08) times more likely to have low aerobic fitness as children and 5.16 (95%CI = 1.06–49.66) times more likely to have low PA levels. Conclusion: Low levels of childhood physical activity and aerobic fitness are associated with the presence of the metabolic syndrome in adolescents. Thus, efforts need to begin early in childhood to increase exercise

The Children\u27s Computerized Physical Activity Reporter: Children as Partners in the Design and Usability Evaluation of an Application for Self-reporting Physical Activity.

The objectives of this three-phased study were to design and evaluate the usability of a computerized questionnaire, The Children\u27s Computerized Physical Activity Reporter, designed with and for middle school children\u27s self-report of physical activity. Study design was qualitative, descriptive, and collaborative, framed in a usability engineering model, with 22 participating children (grades 6-8; mean age, 12.5 years; range, 11-15 years) of three ethnic backgrounds. In Phase 1, children\u27s understanding of physical activity and needs for reporting were determined, which were then translated in Phase 2 to the design features and content of the questionnaire; content validity, readability, and algorithm reliability were completed. Phase 3 involved children\u27s evaluation of the questionnaire\u27s usability (ease of use, efficiency, and aesthetics). The children all liked the questionnaire but identified several usability issues within instructions and reports. Working collaboratively with children was highly effective in ascertaining their understanding of physical activity and their self-reporting needs. Thus, the questionnaire\u27s design was created from children\u27s understanding of physical activity and their needs for recalling activities. The development of the questionnaire and its usability evaluation contribute to understanding children\u27s physical activity and to the importance of designing for usability. Additional research is needed to ascertain reliability and validity of data derived from its use and to explore its usefulness in clinical or research venues

Gender and ethnic changes in physical work capacity from childhood through adolescence

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