Pediatric Exercise Science, 2015, 27, 42-47 http://dx.doi.org/10.1123/pes.2015-0035 © 2015 Human Kinetics, Inc.
Childhood Obesity, Physical Activity, and Exercise Dan Nemet Tel Aviv University
Aerobic, Resistance, or Both for the Treatment of Pediatric Obesity Citation Sigal RJ, Alberga AS, Goldfield GS, Prud’homme D, et al. Effects of aerobic training, resistance training, or both on percentage body fat and cardiometabolic risk markers in obese adolescents: The healthy eating aerobic and resistance training in youth randomized clinical trial. JAMA Pediatr. 2014; 168(11):1006–1014.
Importance: Little evidence exists on which exercise modality is optimal for obese adolescents. Objective: To determine the effects of aerobic training, resistance training, and combined training on percentage body fat in overweight and obese adolescents. Design, Setting, and Participants: Randomized, parallel-group clinical trial at community-based exercise facilities in Ottawa (Ontario) and Gatineau (Quebec), Canada, among previously inactive postpubertal adolescents aged 14–18 years (Tanner stage IV or V) with body mass index at or above the 95th percentile for age and sex or at or above the 85th percentile plus an additional diabetes mellitus or cardiovascular risk factor. Interventions: After a 4-week run-in period, 304 participants were randomized to the following 4 groups for 22 weeks: aerobic training (n = 75), resistance training (n = 78), combined aerobic and resistance training (n = 75), or nonexercising control (n = 76). All participants received dietary counseling, with a daily energy deficit of 250 kcal. Main Outcomes and Measures: The primary outcome was percentage body fat measured by magnetic resonance imaging at baseline and 6 months. We hypothesized that aerobic training and resistance training would each yield greater decreases than the control and that combined training would cause greater decreases than aerobic or resistance training alone. Results: Decreases in percentage body fat were –0.3 (95% CI, –0.9 to 0.3) in the control group, –1.1 (95% CI, –1.7 to –0.5) in the aerobic training group (p = .06 vs. controls), and –1.6 (95% CI, –2.2 to –1.0) in the resistance training group (p = .002 vs controls). The –1.4 (95% CI, –2.0 to –0.8) decrease in the combined training group did not differ significantly from that in the aerobic or resistance training group. Waist circumference changes were –0.2 (95% CI, –1.7 to 1.2) cm in the control group, -3.0 (95% CI, –4.4 to –1.6) cm in the aerobic group (p = .006 vs controls), –2.2 (95% CI –3.7 to –0.8) cm in the resistance training group (p = .048 vs controls), and -4.1 (95% CI, –5.5 to –2.7) cm in the combined training group. In per-protocol analyses (≥ 70% adherence), the combined training group had greater changes in percentage body fat (–2.4, 95% CI, –3.2 to –1.6) vs the aerobic group (–1.2; 95% CI, –2.0 to –0.5; p = .04 vs the combined group) but not the resistance group (-1.6; 95% CI, –2.5 to –0.8). Conclusions and Relevance: Aerobic, resistance, and combined training reduced total body fat and waist circumference in obese adolescents. In more adherent participants, combined training may cause greater decreases than aerobic or resistance training alone.
Commentary Despite major efforts to promote weight reduction, the prevalence of childhood obesity is increasing worldwide in epidemic proportions, and it affects now approximately The author is with the Child Helath and Sports Center, Meir Medical Center, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel. Address author correspondence to Dan Nemet at [email protected].
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one third of all children (3). The mechanisms responsible for the continuing increase in childhood obesity are not yet completely understood. However, weight gain clearly results from an imbalance between energy intake and energy expenditure. Therefore, overeating, increased caloric intake, increased inactivity, and sedentary lifestyle (e.g., television viewing, computer games) probably play a major role (8). Long-term follow-up indicates that obese children and adolescents tend to become obese adults (1). Obesity and inactivity independently
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increase risks of chronic disease in adolescence and allcause mortality in adulthood. Moreover, adults who were obese children have increased morbidity and mortality independent of their adult weight. Several studies have demonstrated that changes in exercise and diet can reduce adiposity and risk of diabetes and other chronic diseases in obese adults and youth. Today, in many school systems, physical education is mandatory in elementary school but not high school, and physical activity often declines during adolescence, a period of rapid growth and development. Because physical activity habits track from adolescence to adulthood, adolescence may represent a critical period for establishing a physically active lifestyle to prevent diseases associated with inactivity in adulthood (4). Obesity can further make adherence to aerobic activity challenging, but would present less of an obstacle to resistance training, since obese children have higher muscle mass. Resistance exercise has shown favorable effects on lean body mass, metabolic rate, insulin resistance, and quality of life in adults, but almost no research has examined thus far the effects of resistance training in obese adolescents. In the highlighted study, Sigal et al. aimed to evaluate, for the first time, in a randomized controlled trial, the effects of resistance training, aerobic training, and combined aerobic and resistance training on percent body fat measured using magnetic resonance imaging (MRI) in a large cohort of sedentary late-pubertal overweight or obese youth aged 14–18 years. Secondary outcomes included anthropometrics, and risk markers for cardiometabolic diseases. Following a 4 week Run-in period, 304 participants were randomly assigned to 4 groups; control, aerobic, resistance and combined training. The primary finding was that modest, yet significant reductions in body fat percentage can be achieved through aerobic, resistant, or combined training in obese adolescents. In a per-protocol analyses they found that combined aerobic and resistance training may produce a greater decrease in percentage body fat, waist circumference, and BMI than aerobic training alone. Although all exercising groups had an improvement in fitness, aerobic training was associated with a greater improvement in peak VO2. Thus, significant different effects can be achieved through either aerobic, resistance, or combined moderate-vigorous training interventions. This is further supported by a recent study by Carson et al. (2). The clinical implications of these modest changes need further assessment. Attenuation of the increase in abdominal fat, especially in the critical period of adolescence, could confer important cardiometabolic effects since each additional year of abdominal obesity is known
to be associated with a 4% greater risk of developing Diabetes-Mellitus (6), and subclinical coronary heart disease (7). An interesting, yet troubling finding of the current study was a mean adherence rate of 62%, with no significant difference between the groups. One can speculate that without the study component, attrition rate from all training would probably be higher. In contrast to the author’s hypothesis, resistance training was not associated with higher adherence. This highlights the fact that when applying an exercise intervention to obese children, and especially if lifetime adherence is sought, additional components (psychosocial, family involvement and others) are necessary to overcome barriers to physical activity (5).
References 1. Barlow SE, and the Expert Committee. Expert committee recommendations regarding the prevention, assessment, and treatment of child and adolescent overweight and obesity: Summary report. Pediatrics. 2007; 120(Supplement 4):S164–S192. PubMed doi:10.1542/peds.2007-2329C 2. Carson V, Rinaldi RL, Torrance B, et al. Vigorous physical activity and longitudinal associations with cardiometabolic risk factors in youth. Int J Obes (Lond). 2014; 38(1):16–21. PubMed doi:10.1038/ijo.2013.135 3. Dietz WH. Reversing the tide of obesity. Lancet. 2011; 378(9793):744–746. PubMed doi:10.1016/ S0140-6736(11)61218-X 4. Dohle S, Wansink B. Fit in 50 years: participation in high school sports best predicts one’s physical activity after age 70. BMC Public Health. 2013; 13:1100. PubMed doi:10.1186/1471-2458-13-1100 5. Nemet D, Barkan S, Epstein Y, Friedland O, Kowen G, Eliakim A. Short- and long-term beneficial effects of a combined dietary-behavioral-physical activity intervention for the treatment of childhood obesity. Pediatrics. 2005; 115(4):e443–e449. PubMed doi:10.1542/peds.2004-2172 6. Reis JP, Hankinson AL, Loria CM, et al. Duration of abdominal obesity beginning in young adulthood and incident diabetes through middle age: The CARDIA study. Diabetes Care. 2013; 36(5):1241–1247. PubMed doi:10.2337/dc12-1714 7. Reis JP, Loria CM, Lewis CE, et al. Association between duration of overall and abdominal obesity beginning in young adulthood and coronary artery calcification in middle age. JAMA. 2013; 310(3):280–288. PubMed doi:10.1001/jama.2013.7833 8. Schonfeld-Warden N, Warden CH. Pediatric obesity. An overview of etiology and treatment. Pediatr Clin North Am. 1997; 44(2):339–361. PubMed doi:10.1016/S00313955(05)70480-6
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B. Exercise Deficit Disorder in Youth—Research Challenges Citation
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Faigenbaum AD, Best TM, MacDonald J, Myer GD, Stracciolini A. Top 10 research questions related to exercise deficit disorder (EDD) in youth. Res Q Exerc Sport. 2014; 85(3):297–307.
Exercise deficit disorder (EDD) is a pediatric medical condition characterized by reduced levels of moderateto-vigorous physical activity (MVPA) that are below current recommendations and inconsistent with positive health outcomes. At present, a majority of children and adolescents meet the diagnostic criteria for EDD because they are not accumulating minimum thresholds of daily MVPA. The purpose of this article is to highlight 10 important research questions related to EDD in youth. The critical research needs to better define the clinical spectrum of EDD to include an assessment of physical activity behaviors to determine the age or stage of maturation at which EDD first emerges; an examination of the kinesiogenesis of movement skills and physical abilities; and an evaluation of lifestyle factors that can influence the MVPA trajectory in youth. Research questions about interventions and policies to treat EDD include evaluating the education and training of health care providers on the importance of exercise medicine; determining the effectiveness of strategies to identify and treat youth with EDD in clinical practice; developing sensitive, specific, and cost-effective methods to diagnose youth with EDD; and assessing methods to promote health care reimbursement for the treatment of this condition. Without future research to optimize identification, treatment, and management strategies for youth with EDD, new health care concerns with significant biomedical, psychosocial, economic, and political ramifications will continue to emerge.
Commentary There is strong evidence for beneficial effects of physical activity and disadvantageous effects of a sedentary lifestyle on the overall health of children and adolescents across a broad array of domains. Many studies in children and adolescents strongly link increased time spent in sedentary activities with reduced overall activity levels and with disadvantageous lipid profiles, higher systolic blood pressure, higher levels of obesity, and other cardiometabolic risk factors including hypertension, insulin resistance and type 2 diabetes. Recently, the term Exercise Deficient Disorder (EDD) was introduced to the medical literature. EDD is a condition of reduced levels of MVPA that are inconsistent with the current public health recommendations (2). The Physical Activity Guidelines for Americans, issued by the U.S. Department of Health and Human Services, recommend that children and adolescents aged 6–17 years should have 60 min (1 hr) or more of moderate to vigorous physical activity (MVPA) each day. At present, although most children meet the diagnostic criteria of EDD, we tend to focus mainly on obese EDD youth. While the idea that “exercise is good for children” seems axiomatic, translating this vague notion into specific, scientifically based guidelines that actually influence health has proved to be difficult, and is in need for further critical research (1). Never before has the need for such guidelines been so great. Unfortunately, current health care systems are designed to treat diseases, and not to provide opportunities for pediatric exercise specialists to collaborate with health care providers to enhance motor skills and promote physical activity as an ongoing lifestyle preventive measure (3). In their paper, Faigenbaum et al. highlight several out of many unanswered research questions related to EDD in children and adolescents. When does EDD start,
who is most affected? Is there a link between sedentary behavior and EDD? Does EDD lead to obesity, or does obesity lead to EDD? What is the role of schools in EDD? Do organized sport teams play a role in EDD? As for the treatment of EDD, we should ask ourselves do we really know if the current recommendations for MVPA are the way to overcome EDD? Can we use one exercise prescription for all children? Probably not, and if so, what should be the recommended physical activity for children with diseases and disabilities? Clearly, nowadays there are more questions than answers about EDD, and this is before the introduction of genetics, psychosocial, economic, and environmental and other factors to the EDD equation. Still, there is enough evidence to support the importance of primary prevention as part of a comprehensive approach to treat physical inactivity in children and promote long-term health. It is imperative that the pediatric exercise research community will enhance its efforts to seek answers to the questions raised, in oredr to assist the medical community, before further inactivity related health care concerns emerge.
References 1. Cooper DM, Nemet D, Galassetti P. Exercise, stress, and inflammation in the growing child: from the bench to the playground. Curr Opin Pediatr. 2004; 16(3):286–292. PubMed doi:10.1097/01.mop.0000126601.29787.39 2. Faigenbaum AD, Stracciolini A, Myer GD. Exercise deficit disorder in youth: a hidden truth. Acta Paediatr. 2011; 100(11):1423–1425. PubMed doi:10.1111/j.16512227.2011.02461.x 3. Myer GD, Faigenbaum AD, Stracciolini A, Hewett TE, Micheli LJ, Best TM. Comprehensive Management Strategies for Physical Inactivity in Youth. Curr Sports Med Rep. 2013; 12(4):248–255. PubMed doi:10.1249/ JSR.0b013e31829a74cd
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C. Childhood Obesity, Exercise, and Brain Function Citation
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Kinder M, Lotze M, Davids S, Domin M, et al. Functional imaging in obese children responding to long-term sports therapy. Behav Brain Res. 2014; 272:25–31.
Functional imaging studies on responders and nonresponders to therapeutic interventions in obese children are rare. We applied fMRI before and after a one-year sports therapy in 14 obese or overweight children aged 7–16 years. During scanning, participants observed a set of standardized pictures from food categories, sports, and pleasant and neutral images. We were interested in alterations of the cerebral activation to food images in association with changes in the BMI-standard deviation score (BMI-SDS) after therapy and therefore separated the observation group into two outcome subgroups. One with reduction of BMI-SDS >0.2 (responder group) and one without (nonresponder group). Before therapy fMRI-activation between groups did not differ. After therapy we found the following results: in response to food images, obese children of the responder group showed increased activation in the left putamen when compared with the nonresponder group. Pleasant images evoked increased insula activation in the responder group. Only the responder group showed enhanced activity within areas known to store trained motor patterns in response to sports images. Both the putamen and the insula are involved in the processing of emotional valence and were only active for the therapy responders during the observation of food or pleasant stimuli. Elevated activity in these regions might possibly be seen in the context of an increase of dopaminergic response to emotional positive stimuli during intervention. In addition, sport images activated motor representations only in those subjects who profited from the sports therapy. Overall, an altered response to rewarding and pleasant images and an increased recruitment of motor engrams during observations of sports pictures indicates a more normal cerebral processing in response to these stimuli after successful sports therapy in obese children.
Commentary It is increasingly recognized that obesity in youth is associated with poorer cognitive function, specifically executive functioning skills such as inhibitory control and working memory, which are critical for academic achievement. Moreover, it has been proposed that obesity increases the risk for developing dementia and Alzheimer’s disease later in life (2). The mechanisms for these deficits are not yet understood; some suggest that it may be associated with marked differences in specific brain structure volumes, while others highlight obesityassociated biomarkers such as adipokines, obesity-associated inflammatory cytokines, and obesity-associated gut hormones that are associated with learning, memory, and general cognitive function. During 2014, several research groups examined exercise, obesity and brain interactions and studied the effect of exercise training on brain function in an effort to try and mitigate obesity-related brain alterations. At the beginning of 2014, Alosco et al. (1) examined the associations between body mass index (BMI) and regional gray matter volume and white matter integrity in 120 healthy children and adolescents (6–18 years of age) who underwent magnetic resonance (MRI) and diffusion tensor imaging. Their findings suggested that obesity in children and adolescents is associated with structural brain changes of decreased volume of frontal and limbic cerebral gray matter regions. Behavioral and cognitive information are processed in several cortical and subcortical circuits, with the pre frontal cortex (PFC) being responsible for processing
motor, sensory and limbic information. Davids et al. (3) previously demonstrated highly discriminative brain (PFC and putamen) activation patterns in response to food pictures in obese compared with non obese children. In the selected publication, Kinder et al. used the same functional imaging to study brain function alterations in obese children participating in an exercise treatment. Obese children underwent fMRI before and after participating in a 45 week exercise training program. The authors were interested to compare alterations in cerebral activation in treatment responders (those who lost weight) and non responders. They demonstrated, only in the responders group, that successful treatment lead to brain activation and enhanced activity of the putamen, that is similar to that previously seen in lean healthy subjects. Krafft et al., in a series of publications of randomized control trials using functional MRI (fMRI) examined the effects of an 8 month intervention on resting state synchrony (4), brain activation during cognitive tasks (5), and white matter integrity (6) in obese children. They demonstrated that exercise per se causes decreased resting state synchrony associated with default mode, cognitive control, and motor networks. Exercise intervention lead to changes in brain activation within the context of two separate cognitive control tasks. This suggests that exercise leads to alterations in neural circuitry supporting cognitive control in obese children. All together, these studies highlight the need for better understanding of the effects of exercise on brain function and activity. This is important in both healthy children and children with disease and disabilities, such as obesity. Obviously, exercise-brain interactions are
46 Rowland
important for both developing interventions to improve children’s neurocognitive function, as well as to support our efforts to “tailor” specific exercise regimens to children in need.
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References 1. Alosco ML, Stanek KM, Galioto R, et al. Body mass index and brain structure in healthy childrenand adolescents. Int J Neurosci. 2014; 124(1):49–55. PubMed doi:10.3109/00 207454.2013.817408 2. Bauer CC, Moreno B, González-Santos L, Concha L, Barquera S, Barrios FA. Child overweight and obesity are associated with reduced executive cognitive performance and brain alterations: a magnetic resonance imaging study in Mexican children. Pediatr Obes. 2014 Jul 3. 3. Davids S, Lauffer H, Thoms K, et al. Increased dorsolateral prefrontal cortex activation in obese children during
observation of food stimuli. Int J Obes (Lond). 2010; 34(1):94–104. PubMed doi:10.1038/ijo.2009.193 4. Krafft CE, Pierce JE, Schwarz NF, et al. An eightmonth randomized controlled exercise intervention alters resting state synchrony in overweight children. Neuroscience. 2014; 256:445–455. PubMed doi:10.1016/j.neuroscience.2013.09.052 5. Krafft CE, Schwarz NF, Chi L, et al. An 8-month randomized controlled exercise trial alters brain activation during cognitive tasks in overweight children. Obesity (Silver Spring). 2014; 22(1):232–242. PubMed doi:10.1002/ oby.20518 6. Schaeffer DJ, Krafft CE, Schwarz NF, et al. An 8-month exercise intervention alters frontotemporal white matter integrity in overweight children. Psychophysiology. 2014; 51(8):728–733. PubMed doi:10.1111/psyp.12227
D. Obesity Treatment and Telomere Length Citation García-Calzón S, Moleres A, Marcos A, et al. Telomere length as a biomarker for adiposity changes after a multidisciplinaryintervention in overweight/obese adolescents: THE EVASYON study. PLoS One. 2014; 9:e89828.
Context: Telomeres are biomarkers of biological aging. Shorter telomeres have been associated with increased adiposity in adults. However, this relationship remains unclear in children and adolescents. Objective: To evaluate the association between telomere length (TL) and adiposity markers in overweight/obese adolescents after an intensive program. We hypothesize that greater TL at baseline would predict a better response to a weight loss treatment. Design Setting Patients and Intervention: The EVASYON is a multidisciplinary treatment program for adolescents with overweight and obesity that is aimed at applying the intervention to all possibly involved areas of the individual, such as dietary habits, physical activity, and cognitive and psychological profiles. Seventy-four participants (36 males, 38 females, 12–16 yr) were enrolled in the intervention program: 2 months of an energy-restricted diet and a follow-up period (6 months). Main Outcome: TL was measured by quantitative real-time polymerase chain reaction at baseline and after 2 months; meanwhile, anthropometric variables were also assessed after 6 months of follow-up. Results: TL lengthened in participants during the intensive period (+1.9 ± 1.0, p < .001) being greater in overweight/obese adolescents with the shortest telomeres at baseline (r = –0.962, p < .001). Multivariable linear regression analysis showed that higher baseline TL significantly predicted a higher decrease in body weight (B = –1.53, p = .005; B = -2.25, p = 0.047) and in standard deviation score for body mass index (BMI-SDS) (B = –0.22, p = 0.010; B = –0.47, p = .005) after the intensive and extensive period treatment respectively, in boys. Conclusion: Our study shows that a weight loss intervention is accompanied by a significant increase in TL in overweight/obese adolescents. Moreover, we suggest that initial longer TL could be a potential predictor for a better weight loss response.
Commentary Obesity is a state of chronic inflammation, with heightened oxidative stress. Telomeres, are tandem TTAGGG repeats of DNA that together with associated protein factors, cap the ends of chromosomes and promotes their stability. Telomere attrition throughout life depends on cell replication rate and exposure to stressors that may produce DNA damage, such as oxidative, inflammatory, and other stressors. Existing data on the relations between telomere and obesity in children are lacking and demonstrate equivocal results, most suggesting shorter telomere length in obese children (2).
In the highlighted study, Garcia-Calzon et al. studied for the first time the relationship between telomere length (TL) and adiposity indices after a lifestyle multidisciplinary education intervention (EVASYON) in obese children. The multidisciplinary intervention resulted in a significant weight loss and lead to an increase in TL length in both boys and girls, with TL increasing in 88% of participants. TL increased more in children with baseline shorter telomeres. Yet, a significant positive association was found between baseline TL length and the decrease in body weight in boys, the longer the telomere, the higher likelihood to succeed.
Cardiovascular Physiology and Disease 47
If indeed, inflammation and oxidative stress are a cause of shorter telomere in obesity, one can speculate that those with longer baseline telomers, have lower inflammatory and oxidative stress (not measured in the current study) and are therefore more likely to respond to exercise treatment. Although shorter telomeres in adulthood are related to hypertension and diabetes (1,4), while longer telomers are associated with higher HDL cholesterol (3), the clinical importance of telomere lengthening following multidisciplinary weight loss intervention is unknown.
References
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1. Adaikalakoteswari A, Balasubramanyam M, Ravikumar R, Deepa R, Mohan V. Association of telomere shortening
with impaired glucose tolerance and diabetic macroangiopathy. Atherosclerosis. 2007; 195:83–89. PubMed doi:10.1016/j.atherosclerosis.2006.12.003 2. Buxton JL, Walters RG, Visvikis-Siest S, Meyre D, Froguel P, Blakemore AI. Childhood obesity is associated with shorter leukocyte telomere length. J Clin Endocrinol Metab. 2011; 96(5):1500–1505. PubMed doi:10.1210/ jc.2010-2924 3. Chen W, Gardner JP, Kimura M, et al. Leukocyte telomere length is associated with HDL cholesterol levels: the Bogalusa heart study. Atherosclerosis. 2009; 205:620–625. PubMed doi:10.1016/j.atherosclerosis.2009.01.021 4. Yang Z, Huang X, Jiang H, et al. Short telomeres and prognosis of hypertension in a Chinese population. Hypertension. 2009; 53:639–645. PubMed doi:10.1161/ HYPERTENSIONAHA.108.123752
Childhood Obesity, Physical Activity, and Exercise Dan Nemet Tel Aviv University
Aerobic, Resistance, or Both for the Treatment of Pediatric Obesity Citation Sigal RJ, Alberga AS, Goldfield GS, Prud’homme D, et al. Effects of aerobic training, resistance training, or both on percentage body fat and cardiometabolic risk markers in obese adolescents: The healthy eating aerobic and resistance training in youth randomized clinical trial. JAMA Pediatr. 2014; 168(11):1006–1014.
Importance: Little evidence exists on which exercise modality is optimal for obese adolescents. Objective: To determine the effects of aerobic training, resistance training, and combined training on percentage body fat in overweight and obese adolescents. Design, Setting, and Participants: Randomized, parallel-group clinical trial at community-based exercise facilities in Ottawa (Ontario) and Gatineau (Quebec), Canada, among previously inactive postpubertal adolescents aged 14–18 years (Tanner stage IV or V) with body mass index at or above the 95th percentile for age and sex or at or above the 85th percentile plus an additional diabetes mellitus or cardiovascular risk factor. Interventions: After a 4-week run-in period, 304 participants were randomized to the following 4 groups for 22 weeks: aerobic training (n = 75), resistance training (n = 78), combined aerobic and resistance training (n = 75), or nonexercising control (n = 76). All participants received dietary counseling, with a daily energy deficit of 250 kcal. Main Outcomes and Measures: The primary outcome was percentage body fat measured by magnetic resonance imaging at baseline and 6 months. We hypothesized that aerobic training and resistance training would each yield greater decreases than the control and that combined training would cause greater decreases than aerobic or resistance training alone. Results: Decreases in percentage body fat were –0.3 (95% CI, –0.9 to 0.3) in the control group, –1.1 (95% CI, –1.7 to –0.5) in the aerobic training group (p = .06 vs. controls), and –1.6 (95% CI, –2.2 to –1.0) in the resistance training group (p = .002 vs controls). The –1.4 (95% CI, –2.0 to –0.8) decrease in the combined training group did not differ significantly from that in the aerobic or resistance training group. Waist circumference changes were –0.2 (95% CI, –1.7 to 1.2) cm in the control group, -3.0 (95% CI, –4.4 to –1.6) cm in the aerobic group (p = .006 vs controls), –2.2 (95% CI –3.7 to –0.8) cm in the resistance training group (p = .048 vs controls), and -4.1 (95% CI, –5.5 to –2.7) cm in the combined training group. In per-protocol analyses (≥ 70% adherence), the combined training group had greater changes in percentage body fat (–2.4, 95% CI, –3.2 to –1.6) vs the aerobic group (–1.2; 95% CI, –2.0 to –0.5; p = .04 vs the combined group) but not the resistance group (-1.6; 95% CI, –2.5 to –0.8). Conclusions and Relevance: Aerobic, resistance, and combined training reduced total body fat and waist circumference in obese adolescents. In more adherent participants, combined training may cause greater decreases than aerobic or resistance training alone.
Commentary Despite major efforts to promote weight reduction, the prevalence of childhood obesity is increasing worldwide in epidemic proportions, and it affects now approximately The author is with the Child Helath and Sports Center, Meir Medical Center, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel. Address author correspondence to Dan Nemet at [email protected].
42
one third of all children (3). The mechanisms responsible for the continuing increase in childhood obesity are not yet completely understood. However, weight gain clearly results from an imbalance between energy intake and energy expenditure. Therefore, overeating, increased caloric intake, increased inactivity, and sedentary lifestyle (e.g., television viewing, computer games) probably play a major role (8). Long-term follow-up indicates that obese children and adolescents tend to become obese adults (1). Obesity and inactivity independently
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Cardiovascular Physiology and Disease 43
increase risks of chronic disease in adolescence and allcause mortality in adulthood. Moreover, adults who were obese children have increased morbidity and mortality independent of their adult weight. Several studies have demonstrated that changes in exercise and diet can reduce adiposity and risk of diabetes and other chronic diseases in obese adults and youth. Today, in many school systems, physical education is mandatory in elementary school but not high school, and physical activity often declines during adolescence, a period of rapid growth and development. Because physical activity habits track from adolescence to adulthood, adolescence may represent a critical period for establishing a physically active lifestyle to prevent diseases associated with inactivity in adulthood (4). Obesity can further make adherence to aerobic activity challenging, but would present less of an obstacle to resistance training, since obese children have higher muscle mass. Resistance exercise has shown favorable effects on lean body mass, metabolic rate, insulin resistance, and quality of life in adults, but almost no research has examined thus far the effects of resistance training in obese adolescents. In the highlighted study, Sigal et al. aimed to evaluate, for the first time, in a randomized controlled trial, the effects of resistance training, aerobic training, and combined aerobic and resistance training on percent body fat measured using magnetic resonance imaging (MRI) in a large cohort of sedentary late-pubertal overweight or obese youth aged 14–18 years. Secondary outcomes included anthropometrics, and risk markers for cardiometabolic diseases. Following a 4 week Run-in period, 304 participants were randomly assigned to 4 groups; control, aerobic, resistance and combined training. The primary finding was that modest, yet significant reductions in body fat percentage can be achieved through aerobic, resistant, or combined training in obese adolescents. In a per-protocol analyses they found that combined aerobic and resistance training may produce a greater decrease in percentage body fat, waist circumference, and BMI than aerobic training alone. Although all exercising groups had an improvement in fitness, aerobic training was associated with a greater improvement in peak VO2. Thus, significant different effects can be achieved through either aerobic, resistance, or combined moderate-vigorous training interventions. This is further supported by a recent study by Carson et al. (2). The clinical implications of these modest changes need further assessment. Attenuation of the increase in abdominal fat, especially in the critical period of adolescence, could confer important cardiometabolic effects since each additional year of abdominal obesity is known
to be associated with a 4% greater risk of developing Diabetes-Mellitus (6), and subclinical coronary heart disease (7). An interesting, yet troubling finding of the current study was a mean adherence rate of 62%, with no significant difference between the groups. One can speculate that without the study component, attrition rate from all training would probably be higher. In contrast to the author’s hypothesis, resistance training was not associated with higher adherence. This highlights the fact that when applying an exercise intervention to obese children, and especially if lifetime adherence is sought, additional components (psychosocial, family involvement and others) are necessary to overcome barriers to physical activity (5).
References 1. Barlow SE, and the Expert Committee. Expert committee recommendations regarding the prevention, assessment, and treatment of child and adolescent overweight and obesity: Summary report. Pediatrics. 2007; 120(Supplement 4):S164–S192. PubMed doi:10.1542/peds.2007-2329C 2. Carson V, Rinaldi RL, Torrance B, et al. Vigorous physical activity and longitudinal associations with cardiometabolic risk factors in youth. Int J Obes (Lond). 2014; 38(1):16–21. PubMed doi:10.1038/ijo.2013.135 3. Dietz WH. Reversing the tide of obesity. Lancet. 2011; 378(9793):744–746. PubMed doi:10.1016/ S0140-6736(11)61218-X 4. Dohle S, Wansink B. Fit in 50 years: participation in high school sports best predicts one’s physical activity after age 70. BMC Public Health. 2013; 13:1100. PubMed doi:10.1186/1471-2458-13-1100 5. Nemet D, Barkan S, Epstein Y, Friedland O, Kowen G, Eliakim A. Short- and long-term beneficial effects of a combined dietary-behavioral-physical activity intervention for the treatment of childhood obesity. Pediatrics. 2005; 115(4):e443–e449. PubMed doi:10.1542/peds.2004-2172 6. Reis JP, Hankinson AL, Loria CM, et al. Duration of abdominal obesity beginning in young adulthood and incident diabetes through middle age: The CARDIA study. Diabetes Care. 2013; 36(5):1241–1247. PubMed doi:10.2337/dc12-1714 7. Reis JP, Loria CM, Lewis CE, et al. Association between duration of overall and abdominal obesity beginning in young adulthood and coronary artery calcification in middle age. JAMA. 2013; 310(3):280–288. PubMed doi:10.1001/jama.2013.7833 8. Schonfeld-Warden N, Warden CH. Pediatric obesity. An overview of etiology and treatment. Pediatr Clin North Am. 1997; 44(2):339–361. PubMed doi:10.1016/S00313955(05)70480-6
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B. Exercise Deficit Disorder in Youth—Research Challenges Citation
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Faigenbaum AD, Best TM, MacDonald J, Myer GD, Stracciolini A. Top 10 research questions related to exercise deficit disorder (EDD) in youth. Res Q Exerc Sport. 2014; 85(3):297–307.
Exercise deficit disorder (EDD) is a pediatric medical condition characterized by reduced levels of moderateto-vigorous physical activity (MVPA) that are below current recommendations and inconsistent with positive health outcomes. At present, a majority of children and adolescents meet the diagnostic criteria for EDD because they are not accumulating minimum thresholds of daily MVPA. The purpose of this article is to highlight 10 important research questions related to EDD in youth. The critical research needs to better define the clinical spectrum of EDD to include an assessment of physical activity behaviors to determine the age or stage of maturation at which EDD first emerges; an examination of the kinesiogenesis of movement skills and physical abilities; and an evaluation of lifestyle factors that can influence the MVPA trajectory in youth. Research questions about interventions and policies to treat EDD include evaluating the education and training of health care providers on the importance of exercise medicine; determining the effectiveness of strategies to identify and treat youth with EDD in clinical practice; developing sensitive, specific, and cost-effective methods to diagnose youth with EDD; and assessing methods to promote health care reimbursement for the treatment of this condition. Without future research to optimize identification, treatment, and management strategies for youth with EDD, new health care concerns with significant biomedical, psychosocial, economic, and political ramifications will continue to emerge.
Commentary There is strong evidence for beneficial effects of physical activity and disadvantageous effects of a sedentary lifestyle on the overall health of children and adolescents across a broad array of domains. Many studies in children and adolescents strongly link increased time spent in sedentary activities with reduced overall activity levels and with disadvantageous lipid profiles, higher systolic blood pressure, higher levels of obesity, and other cardiometabolic risk factors including hypertension, insulin resistance and type 2 diabetes. Recently, the term Exercise Deficient Disorder (EDD) was introduced to the medical literature. EDD is a condition of reduced levels of MVPA that are inconsistent with the current public health recommendations (2). The Physical Activity Guidelines for Americans, issued by the U.S. Department of Health and Human Services, recommend that children and adolescents aged 6–17 years should have 60 min (1 hr) or more of moderate to vigorous physical activity (MVPA) each day. At present, although most children meet the diagnostic criteria of EDD, we tend to focus mainly on obese EDD youth. While the idea that “exercise is good for children” seems axiomatic, translating this vague notion into specific, scientifically based guidelines that actually influence health has proved to be difficult, and is in need for further critical research (1). Never before has the need for such guidelines been so great. Unfortunately, current health care systems are designed to treat diseases, and not to provide opportunities for pediatric exercise specialists to collaborate with health care providers to enhance motor skills and promote physical activity as an ongoing lifestyle preventive measure (3). In their paper, Faigenbaum et al. highlight several out of many unanswered research questions related to EDD in children and adolescents. When does EDD start,
who is most affected? Is there a link between sedentary behavior and EDD? Does EDD lead to obesity, or does obesity lead to EDD? What is the role of schools in EDD? Do organized sport teams play a role in EDD? As for the treatment of EDD, we should ask ourselves do we really know if the current recommendations for MVPA are the way to overcome EDD? Can we use one exercise prescription for all children? Probably not, and if so, what should be the recommended physical activity for children with diseases and disabilities? Clearly, nowadays there are more questions than answers about EDD, and this is before the introduction of genetics, psychosocial, economic, and environmental and other factors to the EDD equation. Still, there is enough evidence to support the importance of primary prevention as part of a comprehensive approach to treat physical inactivity in children and promote long-term health. It is imperative that the pediatric exercise research community will enhance its efforts to seek answers to the questions raised, in oredr to assist the medical community, before further inactivity related health care concerns emerge.
References 1. Cooper DM, Nemet D, Galassetti P. Exercise, stress, and inflammation in the growing child: from the bench to the playground. Curr Opin Pediatr. 2004; 16(3):286–292. PubMed doi:10.1097/01.mop.0000126601.29787.39 2. Faigenbaum AD, Stracciolini A, Myer GD. Exercise deficit disorder in youth: a hidden truth. Acta Paediatr. 2011; 100(11):1423–1425. PubMed doi:10.1111/j.16512227.2011.02461.x 3. Myer GD, Faigenbaum AD, Stracciolini A, Hewett TE, Micheli LJ, Best TM. Comprehensive Management Strategies for Physical Inactivity in Youth. Curr Sports Med Rep. 2013; 12(4):248–255. PubMed doi:10.1249/ JSR.0b013e31829a74cd
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C. Childhood Obesity, Exercise, and Brain Function Citation
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Kinder M, Lotze M, Davids S, Domin M, et al. Functional imaging in obese children responding to long-term sports therapy. Behav Brain Res. 2014; 272:25–31.
Functional imaging studies on responders and nonresponders to therapeutic interventions in obese children are rare. We applied fMRI before and after a one-year sports therapy in 14 obese or overweight children aged 7–16 years. During scanning, participants observed a set of standardized pictures from food categories, sports, and pleasant and neutral images. We were interested in alterations of the cerebral activation to food images in association with changes in the BMI-standard deviation score (BMI-SDS) after therapy and therefore separated the observation group into two outcome subgroups. One with reduction of BMI-SDS >0.2 (responder group) and one without (nonresponder group). Before therapy fMRI-activation between groups did not differ. After therapy we found the following results: in response to food images, obese children of the responder group showed increased activation in the left putamen when compared with the nonresponder group. Pleasant images evoked increased insula activation in the responder group. Only the responder group showed enhanced activity within areas known to store trained motor patterns in response to sports images. Both the putamen and the insula are involved in the processing of emotional valence and were only active for the therapy responders during the observation of food or pleasant stimuli. Elevated activity in these regions might possibly be seen in the context of an increase of dopaminergic response to emotional positive stimuli during intervention. In addition, sport images activated motor representations only in those subjects who profited from the sports therapy. Overall, an altered response to rewarding and pleasant images and an increased recruitment of motor engrams during observations of sports pictures indicates a more normal cerebral processing in response to these stimuli after successful sports therapy in obese children.
Commentary It is increasingly recognized that obesity in youth is associated with poorer cognitive function, specifically executive functioning skills such as inhibitory control and working memory, which are critical for academic achievement. Moreover, it has been proposed that obesity increases the risk for developing dementia and Alzheimer’s disease later in life (2). The mechanisms for these deficits are not yet understood; some suggest that it may be associated with marked differences in specific brain structure volumes, while others highlight obesityassociated biomarkers such as adipokines, obesity-associated inflammatory cytokines, and obesity-associated gut hormones that are associated with learning, memory, and general cognitive function. During 2014, several research groups examined exercise, obesity and brain interactions and studied the effect of exercise training on brain function in an effort to try and mitigate obesity-related brain alterations. At the beginning of 2014, Alosco et al. (1) examined the associations between body mass index (BMI) and regional gray matter volume and white matter integrity in 120 healthy children and adolescents (6–18 years of age) who underwent magnetic resonance (MRI) and diffusion tensor imaging. Their findings suggested that obesity in children and adolescents is associated with structural brain changes of decreased volume of frontal and limbic cerebral gray matter regions. Behavioral and cognitive information are processed in several cortical and subcortical circuits, with the pre frontal cortex (PFC) being responsible for processing
motor, sensory and limbic information. Davids et al. (3) previously demonstrated highly discriminative brain (PFC and putamen) activation patterns in response to food pictures in obese compared with non obese children. In the selected publication, Kinder et al. used the same functional imaging to study brain function alterations in obese children participating in an exercise treatment. Obese children underwent fMRI before and after participating in a 45 week exercise training program. The authors were interested to compare alterations in cerebral activation in treatment responders (those who lost weight) and non responders. They demonstrated, only in the responders group, that successful treatment lead to brain activation and enhanced activity of the putamen, that is similar to that previously seen in lean healthy subjects. Krafft et al., in a series of publications of randomized control trials using functional MRI (fMRI) examined the effects of an 8 month intervention on resting state synchrony (4), brain activation during cognitive tasks (5), and white matter integrity (6) in obese children. They demonstrated that exercise per se causes decreased resting state synchrony associated with default mode, cognitive control, and motor networks. Exercise intervention lead to changes in brain activation within the context of two separate cognitive control tasks. This suggests that exercise leads to alterations in neural circuitry supporting cognitive control in obese children. All together, these studies highlight the need for better understanding of the effects of exercise on brain function and activity. This is important in both healthy children and children with disease and disabilities, such as obesity. Obviously, exercise-brain interactions are
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important for both developing interventions to improve children’s neurocognitive function, as well as to support our efforts to “tailor” specific exercise regimens to children in need.
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References 1. Alosco ML, Stanek KM, Galioto R, et al. Body mass index and brain structure in healthy childrenand adolescents. Int J Neurosci. 2014; 124(1):49–55. PubMed doi:10.3109/00 207454.2013.817408 2. Bauer CC, Moreno B, González-Santos L, Concha L, Barquera S, Barrios FA. Child overweight and obesity are associated with reduced executive cognitive performance and brain alterations: a magnetic resonance imaging study in Mexican children. Pediatr Obes. 2014 Jul 3. 3. Davids S, Lauffer H, Thoms K, et al. Increased dorsolateral prefrontal cortex activation in obese children during
observation of food stimuli. Int J Obes (Lond). 2010; 34(1):94–104. PubMed doi:10.1038/ijo.2009.193 4. Krafft CE, Pierce JE, Schwarz NF, et al. An eightmonth randomized controlled exercise intervention alters resting state synchrony in overweight children. Neuroscience. 2014; 256:445–455. PubMed doi:10.1016/j.neuroscience.2013.09.052 5. Krafft CE, Schwarz NF, Chi L, et al. An 8-month randomized controlled exercise trial alters brain activation during cognitive tasks in overweight children. Obesity (Silver Spring). 2014; 22(1):232–242. PubMed doi:10.1002/ oby.20518 6. Schaeffer DJ, Krafft CE, Schwarz NF, et al. An 8-month exercise intervention alters frontotemporal white matter integrity in overweight children. Psychophysiology. 2014; 51(8):728–733. PubMed doi:10.1111/psyp.12227
D. Obesity Treatment and Telomere Length Citation García-Calzón S, Moleres A, Marcos A, et al. Telomere length as a biomarker for adiposity changes after a multidisciplinaryintervention in overweight/obese adolescents: THE EVASYON study. PLoS One. 2014; 9:e89828.
Context: Telomeres are biomarkers of biological aging. Shorter telomeres have been associated with increased adiposity in adults. However, this relationship remains unclear in children and adolescents. Objective: To evaluate the association between telomere length (TL) and adiposity markers in overweight/obese adolescents after an intensive program. We hypothesize that greater TL at baseline would predict a better response to a weight loss treatment. Design Setting Patients and Intervention: The EVASYON is a multidisciplinary treatment program for adolescents with overweight and obesity that is aimed at applying the intervention to all possibly involved areas of the individual, such as dietary habits, physical activity, and cognitive and psychological profiles. Seventy-four participants (36 males, 38 females, 12–16 yr) were enrolled in the intervention program: 2 months of an energy-restricted diet and a follow-up period (6 months). Main Outcome: TL was measured by quantitative real-time polymerase chain reaction at baseline and after 2 months; meanwhile, anthropometric variables were also assessed after 6 months of follow-up. Results: TL lengthened in participants during the intensive period (+1.9 ± 1.0, p < .001) being greater in overweight/obese adolescents with the shortest telomeres at baseline (r = –0.962, p < .001). Multivariable linear regression analysis showed that higher baseline TL significantly predicted a higher decrease in body weight (B = –1.53, p = .005; B = -2.25, p = 0.047) and in standard deviation score for body mass index (BMI-SDS) (B = –0.22, p = 0.010; B = –0.47, p = .005) after the intensive and extensive period treatment respectively, in boys. Conclusion: Our study shows that a weight loss intervention is accompanied by a significant increase in TL in overweight/obese adolescents. Moreover, we suggest that initial longer TL could be a potential predictor for a better weight loss response.
Commentary Obesity is a state of chronic inflammation, with heightened oxidative stress. Telomeres, are tandem TTAGGG repeats of DNA that together with associated protein factors, cap the ends of chromosomes and promotes their stability. Telomere attrition throughout life depends on cell replication rate and exposure to stressors that may produce DNA damage, such as oxidative, inflammatory, and other stressors. Existing data on the relations between telomere and obesity in children are lacking and demonstrate equivocal results, most suggesting shorter telomere length in obese children (2).
In the highlighted study, Garcia-Calzon et al. studied for the first time the relationship between telomere length (TL) and adiposity indices after a lifestyle multidisciplinary education intervention (EVASYON) in obese children. The multidisciplinary intervention resulted in a significant weight loss and lead to an increase in TL length in both boys and girls, with TL increasing in 88% of participants. TL increased more in children with baseline shorter telomeres. Yet, a significant positive association was found between baseline TL length and the decrease in body weight in boys, the longer the telomere, the higher likelihood to succeed.
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If indeed, inflammation and oxidative stress are a cause of shorter telomere in obesity, one can speculate that those with longer baseline telomers, have lower inflammatory and oxidative stress (not measured in the current study) and are therefore more likely to respond to exercise treatment. Although shorter telomeres in adulthood are related to hypertension and diabetes (1,4), while longer telomers are associated with higher HDL cholesterol (3), the clinical importance of telomere lengthening following multidisciplinary weight loss intervention is unknown.
References
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1. Adaikalakoteswari A, Balasubramanyam M, Ravikumar R, Deepa R, Mohan V. Association of telomere shortening
with impaired glucose tolerance and diabetic macroangiopathy. Atherosclerosis. 2007; 195:83–89. PubMed doi:10.1016/j.atherosclerosis.2006.12.003 2. Buxton JL, Walters RG, Visvikis-Siest S, Meyre D, Froguel P, Blakemore AI. Childhood obesity is associated with shorter leukocyte telomere length. J Clin Endocrinol Metab. 2011; 96(5):1500–1505. PubMed doi:10.1210/ jc.2010-2924 3. Chen W, Gardner JP, Kimura M, et al. Leukocyte telomere length is associated with HDL cholesterol levels: the Bogalusa heart study. Atherosclerosis. 2009; 205:620–625. PubMed doi:10.1016/j.atherosclerosis.2009.01.021 4. Yang Z, Huang X, Jiang H, et al. Short telomeres and prognosis of hypertension in a Chinese population. Hypertension. 2009; 53:639–645. PubMed doi:10.1161/ HYPERTENSIONAHA.108.123752
