Exercise for Prevention of Obesity and Diabetes in Children and Adolescents

Ovarian hormones mediate running-induced changes in high fat diet choice patterns in female rats

Physical inactivity and increased consumption of energy dense, high fat (HF) foods often leads to a state of positive energy balance. Regular exercise can facilitate the maintenance of a healthy body weight and mediate changes in dietary selection. Past studies using a two-diet choice (chow vs. HF) and voluntary wheel running paradigm found that when a novel HF diet and wheel running are simultaneously introduced, male rats show complete and persistent HF diet avoidance whereas the majority of females show HF diet avoidance for a few days, but then revert to HF diet preference. Ovariectomy (OVX) appears to decrease preference for the HF diet bringing it closer to that of males. Given that estradiol but not progesterone mediates changes in food intake and energy balance, we hypothesized that estradiol signaling is required for the reversal of HF diet avoidance in female rats. Accordingly, Experiment 1 compared the persistency of running-induced HF diet avoidance in males, sham-operated females, and OVX rats with replacement of oil vehicle, estradiol benzoate (E), progesterone (P), or both (E + P). The number of wheel running rats that either avoided or preferred the HF diet varied with hormone treatment. The reversal of HF diet avoidance in running females and OVX E + P rats occurred more rapidly and frequently than male running rats. E + P but not E or P replaced OVX wheel running rats significantly reversed HF diet avoidance. OVX oil rats avoided HF diet to the same extent as male rats for the first 11 days of diet choice and then rapidly increased HF diet intake and began preferring it. This incomplete elimination of sex differences suggests that developmental factors or androgens might play a role in sustaining running-induced HF diet avoidance. Subsequently, Experiment 2 aimed to determine the role of androgens in the persistency of running-associated HF diet avoidance with sham-operated and orchiectomized (GDX) male rats. Both intact and GDX male running rats persistently avoided the HF diet to the same extent. Taken together, these results suggest that activational effects of ovarian hormones play a role in female specific running-induced changes in diet choice patterns. Furthermore, the activational effects of androgens are not required for the expression of HF diet avoidance in males.

A School-Based Program for Overweight and Obese Adolescents: A Randomized Controlled Trial

BACKGROUND

Given the dramatic increase in adolescent overweight and obesity, models are needed for implementing weight management treatment through readily accessible venues. We evaluated the acceptability and efficacy of a school-based intervention consisting of school nurse-delivered counseling and an afterschool exercise program in improving diet, activity, and body mass index (BMI) among overweight and obese adolescents.

METHODS

A pair-matched cluster-randomized controlled school-based trial was conducted in which 8 public high schools were randomized to either a 12-session school nurse-delivered cognitive-behavioral counseling intervention plus school-based after school exercise program, or 12-session nurse contact with weight management information (control). Overweight or obese adolescents (N = 126) completed anthropometric and behavioral assessments at baseline and 8-month follow-up. Main outcome measures included diet, activity, and BMI. Mixed effects regression models were conducted to examine differences at follow-up.

RESULTS

At follow-up, students in intervention compared with control schools were not different in BMI, percent body fat, and waist circumference. Students reported eating breakfast (adjusted mean difference 0.81 days; 95% confidence interval [CI] 0.11-1.52) on more days/week; there were no differences in other behaviors targeted by the intervention.

CONCLUSIONS

While a school-based intervention including counseling and access to an after-school exercise program is theoretically promising with public health potential, it was not effective in reducing BMI or key obesogenic behaviors. Our findings are important in highlighting that interventions targeted at the individual level are not likely to be sufficient in addressing the adolescent obesity epidemic without changes in social norms and the environment.

Exercise increases the binding of MEF2A to the Cpt1b promoter in mouse skeletal muscle

AIM

Muscle-type carnitine palmitoyltransferase 1 (CPT1b) plays an important role in skeletal muscle mitochondrial fatty acid β-oxidation. A myocyte-specific enhancer factor (MEF2) site that binds MEF2A in the promoter of Cpt1b has been identified. The aim of this study is to determine whether Cpt1b expression is regulated by MEF2 in response to exercise training.

METHODS

Twelve male, 14-week-old C57BL/6 mice underwent 6 weeks of treadmill exercise at 12 m min(-1), for 60 min day(-1), 5 days week(-1). Quadriceps muscles were analysed by real-time PCR, Western blot, chromatin immunoprecipitation.

RESULTS

The binding of MEF2A to the Cpt1b promoter was elevated in the quadriceps muscle of mice after 6-week aerobic exercise intervention. The repressor partner of MEF2, histone deacetylase 5 (HDAC5), binding to the Cpt1b promoter was decreased by exercise training. In C2C12 myoblast, MEF2A overexpression increased the Cpt1b mRNA expression and the Cpt1b promoter transcriptional activity, which were suppressed by HDAC5. Moreover, exercise training induced MEF2A hyperacetylation, which is strongly associated with its enhanced DNA-binding ability. The binding of both HDAC5 and histone deacetylase 3 (HDAC3) to MEF2A was decreased by exercise training. Overexpression of HDAC5 decreased exogenous MEF2A acetylation level with an increased binding of endogenous HDAC3 to MEF2A. Finally, the phosphorylation levels of HDAC5 Ser259 and Ser498 were increased by exercise training. Exercise training decreased the abundance of HDAC5 in the nucleus while increasing its abundance in the cytoplasm.

CONCLUSION

Our results indicated that exercise-induced CPT1b expression was at least in part mediated by HDAC5/MEF2A interaction.

Exercise-deficit disorder in children: are we ready to make this diagnosis?

Primary care physicians, particularly pediatricians, are expected to promote physical activity and prescribe exercise to patients. Unfortunately, many health care professionals do not have adequate skills or experience in this area, making exercise intervention logistically and psychologically challenging. Exercise-deficit disorder (EDD), which is a new term to the literature, is defined as reduced levels of moderate-to-vigorous physical activity, inconsistent with public health recommendations. Physicians are in a unique position to identify children who are deficient in exercise and initiate prevention strategies. To aid physicians in the diagnosis and treatment of children with EDD, we propose integrating exercise assessment into primary care practice, and, when appropriate, referral to a pediatric exercise specialist. This approach should ensure adequate development of muscle strength and motor skills that are required for successful physical activity participation. The timely identification of children with EDD is essential in preventing resistance to intervention. Connecting pediatric health care professionals with pediatric exercise specialists, culminating in an established professional collaborative system, is critical for promoting healthy behaviors throughout childhood and adolescence.

Forced and voluntary exercise counteract insulin resistance in rats: the role of coping style

There are large individual differences in the success rates of exercise intervention programs aimed at the prevention and treatment of obesity-related disorders. In the present study, we tested the hypothesis that differences in coping style may impact the success rates of these intervention programs. We tested insulin responses before and after voluntary wheel running in both passive (insulin resistant) Roman Low Avoidance (RLA) and proactive (insulin sensitive) Roman High Avoidance (RHA) rats using intravenous glucose tolerance tests (IVGTTs). To control for a potential difference between voluntary and forced exercise, we also included RLA and RHA rats that were subjected to forced running. We found the following: 1) when given the opportunity to run voluntarily in a running wheel, passive RLA rats run more than proactively than RHA rats; 2) voluntary exercise leads to a normalization of insulin responses during an IVGTTs in RLA rats; and 3) there were no behavioral and physiological differences in efficacy between voluntary and forced running. We conclude that exercise, both forced and voluntary, is a successful lifestyle intervention for the treatment of hyperinsulinemia, especially in individuals with a passive coping style.

Non-alcoholic fatty liver disease and metabolic syndrome in adolescents: pathogenetic role of genetic background and intrauterine environment

In the last three decades the incidence of metabolic syndrome (MetS) has been growing worldwide along with an increase of obesity, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). In children and adolescents such epidemics are particularly worrisome, since the metabolic consequences in adulthood will significantly burden the health care system. Although the definition of MetS in childhood is still controversial, there is agreement with respect to NAFLD being the hepatic manifestation of MetS. However, the molecular pathogenesis of MetS and its contribution to NAFLD is complex and closely related to the pre- and postnatal environment as well as to genetic predisposing factors. The analysis of the possible relationships between NAFLD and MetS is particularly interesting, not only from an epidemiological point of view, but also to better understand the genetic and environmental factors contributing to the development of both diseases. We here summarize the most recent epidemiological data on the incidence of both diseases in adolescents, and several aspects linking MetS with NAFLD, discussing the possible role played by genetics and intrauterine environment.

Exercise research on children and adolescents

This paper is a review of studies published during the last several years on exercise effects on overweight, growth, chronic illnesses, depression and anxiety in children and adolescents. Although the lion's share of the research involves aerobic exercise, studies on yoga and tai chi are also reviewed. Following exercise, body mass index and lipid profiles have improved in overweight children, and those with asthma, diabetes and depression have also benefited from exercise. The yoga studies reviewed here focused on ADHD and anxiety, and the tai chi studies involved children with ADHD and asthma. A potential underlying mechanism for the positive effects of exercise, yoga and tai chi may be the stimulation of pressure receptors leading to increased vagal activity, decreased stress hormones and increased production of anti-pain and antidepressant neurotransmitters such as serotonin. Further studies are needed using convergent behavioral, physiological and biochemical measures. Nonetheless, the current literature highlights the importance of adding exercise programs to clinics, schools and families for the physical and psychological well-being of children and adolescents.

Healthy outcomes for teens project: diabetes prevention through distributed interactive learning

AIM AND METHODS

This study assessed whether distributed interactive learning via web-based modules and grounded in schema and social cognitive theory (treatment group, n = 101) would increase knowledge about diabetes prevention in adolescents from three middle schools to a greater extent than the control group (n = 80) and examined whether the school environment used to convey the education had an effect.

RESULTS

The treatment group showed substantially greater increases in overall and individual modular content knowledge, with 72 voluntarily choosing to retake evaluations that significantly improved their scores. The treatment (t[3.8], β ≥ 0.30, P < 0.001) and format of delivery (after school, pull out from physical education, or health education curriculum) (t[3.41], β ≥ 0.24, P < 0.001) influenced knowledge.

CONCLUSIONS

Thus, distributed interactive learning was more effective than its passive counterpart, and a more structured delivery enhanced knowledge, as did opportunities to self-regulate learning. Attention to these process components will facilitate effective interventions by educators in schools.

The Effect of Exercise on Leptin, Insulin, Cortisol and Lipid Profiles in Obese Children

This prospective, randomized study investigated the effect of exercise on leptin, insulin, cortisol and lipid profiles in obese children. A total of 40 obese boys aged 10-12 years with a body mass index (BMI) ≥ 30 kg/m2 were randomly separated into an exercise group ( n = 20) that underwent a 12-week aerobic exercise programme and a non-exercise (control) group ( n = 20). The BMI, low-density lipoprotein, cortisol, leptin and insulin levels were significantly lower in the exercise group after 12 weeks compared with baseline values, whereas high-density lipoprotein levels were significantly higher. In contrast, in the control group, low-density lipoprotein, cortisol and leptin levels were significantly higher after 12 weeks compared with baseline values while high-density lipoprotein levels were significantly lower. These findings indicate the importance of regular exercise in the regulation of body weight and protection against cardiovascular risk factors in obese children.