Safety, feasibility, and efficacy of a resistance training program in preadolescent obese children

The Dutch 'Focus on Strength' intervention study protocol: programme design and production, implementation and evaluation plan

BACKGROUND

Overweight youngsters are better in absolute strength exercises than their normal-weight counterparts; a physiological phenomenon with promising psychological impact. In this paper we describe the study protocol of the Dutch, school-based program 'Focus on Strength' that aims to improve body composition of 11-13 year old students, and with that to ultimately improve their quality of life.

METHODS

The development of this intervention is based on the Intervention Mapping (IM) protocol, which starts from a needs assessment, uses theory and empirical research to develop a detailed intervention plan, and anticipates program implementation and evaluation. This novel intervention targets first year students in preparatory secondary vocational education (11-13 years of age). Teachers are the program implementers. One part of the intervention involves a 30 % increase of strength exercises in the physical education lessons. The other part is based on Motivational Interviewing, promoting autonomous motivation of students to become more physically active outside school. Performance and change objectives are described for both teachers and students. The effectiveness of the intervention will be tested in a Randomized Controlled Trial in 9 Dutch high schools.

DISCUSSION

Intervention Mapping is a useful framework for program planning a school-based program to improve body composition and motivation to exercise in 11-13 year old adolescents by a "Focus on Strength".

TRIAL REGISTRATION

NTR5676 , registered 8 February 2016 (retrospectively registered).

Windows of opportunity for physical activity in the prevention of obesity

Tackling increasing rates of obesity is likely to be a defining feature of health care over the next several decades. Adult obesity is a persistent and treatment-resistant problem. Consequently, an emerging theme in the literature is to commence prevention efforts earlier in the developmental time course. This view is based primarily on epidemiological data demonstrating a link between traits manifesting early during development and increased obesity risk in adulthood. Physical activity is a perennial factor in discussions of obesity prevention. However, the optimal timing and type of physical activity interventions to commence remains unclear. Critical developmental windows of plasticity may afford time-limited opportunities to shape body composition across the life course; however, physical activity has not been explicitly considered in these discussions. Although animal models suggest that physical activity commenced earlier in development has differential effects on obesity onset compared to physical activity commenced in adulthood, human research is lacking. In this conceptual review, we consider physical activity during critical developmental periods as a way to mitigate obesity risk later in life.

Aerobic and strength exercises for youngsters aged 12 to 15: what do parents think?

BACKGROUND

Although strength exercises evidently have both physiological and psychological health benefits across all ages, they are erroneously considered to adversely affect health status in youngsters. The aim of this study was to examine parental attitudes towards their child's physical activity in general, as well as aerobic and strength exercises in particular.

METHODS

In total, 314 parents from an online panel representative of the Dutch population completed an online survey about their own physical activity and that of their child (12-15 years old). The study also explored reasons for non-participation, and attitudes about the parents' own and their child's physical activity level.

RESULTS

Parents consistently reported a positive attitude towards aerobic exercises, but a less positive attitude regarding strength exercises. Parents were more likely to indicate that their child was not allowed to participate in strength exercises (29.6 %) than aerobic exercises (4.0 %). They thought that strength exercises could interfere with optimal physical development.

CONCLUSIONS

This study consistently shows that parents have a positive attitude towards aerobic exercises, but a less positive attitude regarding strength exercises. We suggest testing interventions to increase parental understanding of the advantages of and possibilities for (e.g., facilities) strength training on their child's health.

Physiological adaptations to resistance training in prepubertal boys

PURPOSE

The purpose of this study was to investigate the physiological adaptations of resistance training (RT) in prepubertal boys.

METHODS

Eighteen healthy boys were divided into RT (n = 9, Mage = 10.4 ± 0.5 years) and control (CTR; n = 9, Mage = 10.9 ± 0.7 years) groups. The RT group underwent a resistance training during 12 weeks, 3 times per week, performing 3 sets of 6 to 15 repetitions at intensities ranging from 60% to 80% of maximal dynamic strength (1-repetition maximum [1-RM] values). Before and after the training, the groups were assessed in their body mass and composition (dual-energy X-ray absorptiometry), isokinetic dynamometry, 1-RM, and ergoespirometry. Moreover, force per unit of muscle volume was calculated by the quotient between 1-RM and lean mass.

RESULTS

Both groups presented statistically significant (p < .05) increases in the 1-RM and force per unit of muscle volume in the knee extension and elbow flexion, but these strength increases were statistically significantly greater in the RT group (effect size [ES] = 2.83-9.00) than in the CTR group (ES = 0.72-1.00). Moreover, both groups statistically significantly increased in lean body mass variables (ES = 0.12-0.38). However, increases in the fat mass variables occurred only in the CTR group (ES = - 0.01-0.50), whereas no changes were observed in the RT group. Furthermore, there were statistically significant increases in all bone mineral content variables (ES = 0.13-0.43), without differences between groups. No cardiorespiratory changes were observed.

CONCLUSION

Twelve weeks of RT was effective in improving strength and force per unit of muscle volume and prevented fat mass increases in boys.

Lift weights to fight overweight

Although resistance training (RT) has long been accepted as a means for developing and maintaining muscular strength, endurance, power and muscle mass, its beneficial relationship with health factors and chronic disease has only recently been recognized in the scientific literature. Prior to 1990, resistance training was not a part of the recommended guidelines for exercise training and rehabilitation for either the American Heart Association or the American College of Sports Medicine (ACSM). In 1990, the ACSM recognized resistance training as a significant component of a comprehensive fitness programme for healthy adults of all ages, a position subsequently confirmed few years after. At present, even though interest in clinical applications of RT is increasing, there are still some concerns, among physicians, about the use of this exercise methodology in weight control programmes. This review aims to explore the metabolic effects of RT and its efficacy and feasibility in overweight subjects.

A 12-week after-school physical activity programme improves endothelial cell function in overweight and obese children: a randomised controlled study

Background

Endothelial dysfunction is associated with childhood obesity and is closely linked to the amount and function of endothelial progenitor cells. However, it remains unclear whether endothelial progenitor cells increase with after-school exercise in overweight and obese children. The purpose of this study was to investigate the effects of an after-school exercise programme on endothelial cell function in overweight and obese children.

Methods

A total of 29 overweight/obese children (12.2 ± 0.1 years) were randomly divided into control (i.e. no after-school exercise, n = 14) and after-school exercise (n = 15) groups. The 12-week after-school exercise intervention consisted of 3 days of combined aerobic and resistance exercise per week. Each 80-minute exercise programme included 10 minutes of warm-up and 10 minutes of cool-down after school. CD34⁺ (a cell surface marker on hematopoietic stem cells), CD133⁺ (a cell surface marker on hematopoietic progenitor cells) and CD34⁺/CD133⁺ (considered as endothelial progenitor cells) were measured at baseline and after 12 weeks using flow cytometry.

Results

Increased percentages of CD34⁺, CD133⁺ and CD34⁺/CD133⁺ cells were observed in the after-school exercise group (p = 0.018; p = 0.001; p = 0.002, respectively) compared with the control group. Carotid intima-media thickness decreased after 12 weeks in the after-school exercise group (p = 0.020) compared with the control group.

Conclusions

This study provides preliminary evidence that a combined after-school exercise programme may represent an effective intervention strategy for improving vascular repair and endothelial cell function, leading to improved cardiovascular health in overweight and obese children.

Trial registration

Current Controlled Trials ISRCTN19037201

Healthy Eating, Aerobic and Resistance Training in Youth (HEARTY): study rationale, design and methods

PURPOSE

The objective of the Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) trial (ClinicalTrials.Gov # NCT00195858) was to examine the effects of resistance training, with and without aerobic training, on percent body fat in sedentary, post-pubertal overweight or obese adolescents aged 14-18 years. This paper describes the HEARTY study rationale, design and methods.

METHODS

After a 4-week supervised low-intensity exercise run-in period, 304 overweight or obese adolescents with a body mass index≥85th percentile for age and sex were randomized to 4 groups for 22 weeks (5 months): diet+aerobic exercise, diet+resistance exercise, diet+combined aerobic and resistance exercise, or a diet only waiting-list control. All participants received dietary counseling designed to promote healthy eating with a maximum daily energy deficit of -250 kcal.

OUTCOMES

The primary outcome is percent body fat measured by Magnetic Resonance Imaging. Secondary outcomes include changes in anthropometry, regional body composition, resting energy expenditure, cardiorespiratory fitness, musculoskeletal fitness, cardiometabolic risk markers, and psychological health.

SUMMARY

To our knowledge, HEARTY is the largest clinical trial examining effects of aerobic training, resistance training, and combined aerobic and resistance training on changes in adiposity and cardiometabolic risk markers in overweight and obese adolescents. The findings will have important clinical implications regarding the role that resistance training should play in the management of adolescent obesity and its co-morbidities.

Effects of a randomized maintenance intervention on adiposity and metabolic risk factors in overweight minority adolescents

OBJECTIVE

The objective of this study was to assess the effects of a maintenance programme (monthly newsletters vs. monthly group classes and telephone behavioural sessions) on obesity and metabolic disease risk at 1 year in overweight minority adolescents.

METHODS

After a 4-month nutrition and strength training intervention, 53 overweight Latino and African-American adolescents (15.4 ± 1.1 years) were randomized into one of two maintenance groups for 8 months: monthly newsletters (n = 23) or group classes (n = 30; monthly classes + individualized behavioural telephone sessions). The following outcomes were measured at months 4 (immediately following the intense intervention) and 12: height, weight, blood pressure, body composition via BodPod™ (Life Measurement Instruments, Concord, CA, USA), lipids and glucose/insulin indices via frequently sampled intravenous glucose tolerance test.

RESULTS

There were no significant group by time interactions for any of the health outcomes. There were significant time effects in several outcomes for both groups from months 4 to 12: bench press and leg press decreased by 5% and 14%, respectively (P = 0.004 & P = 0.01), fasting insulin and acute insulin response decreased by 26% and 16%, respectively (P < 0.001 & P = 0.046); while high-density lipoprotein cholesterol and insulin sensitivity improved by 5% and 14% (P = 0.042 & P = 0.039).

CONCLUSIONS

Newsletters as opposed to group classes may suffice as follow-up maintenance programmes to decrease type 2 diabetes and cardiovascular risk in overweight minority adolescents.

External validity reporting in behavioral treatment of childhood obesity: a systematic review

CONTEXT

To aid translation of childhood obesity interventions evidence into practice, research studies must report results in a way that better supports pragmatic decision making. The current review evaluated the extent to which information on key external validity dimensions, participants, settings, interventions, outcomes, and maintenance of effects, was included in research studies on behavioral treatments for childhood obesity.

EVIDENCE ACQUISITION

Peer-reviewed studies of behavioral childhood obesity treatments published between 1980 and 2008 were identified from (1) electronic searches of social science and medical databases; (2) research reviews of childhood obesity interventions; and (3) reference lists cited in these reviews. Included studies reported on a controlled obesity intervention trial, targeted overweight or obese children aged 2-18 years, included a primary or secondary anthropometric outcome, and targeted change in dietary intake or physical activity behaviors.

EVIDENCE SYNTHESIS

1071 publications were identified and 77 met selection criteria. Studies were coded on established review criteria for external validity elements. All studies lacked full reporting of generalizability elements. Across criteria, the average reporting was 23.9% (range=0%-100%). Infrequently reported were setting-level selection criteria and representativeness, characteristics regarding intervention staff, implementation of the intervention content, costs, and program sustainability.

CONCLUSIONS

Enhanced reporting of relevant and pragmatic information in behavioral investigations of childhood obesity interventions is needed to improve the ability to evaluate the applicability of results to practice implementation. Such evidence would improve translation of research to practice, provide additional explanation for variability in intervention outcomes, and provide insights into successful adaptations of interventions to local conditions.

How to make overweight children exercise and follow the recommendations

As regular physical activity of high enough intensity is essential in the management of overweight, efforts should be made to increase physical activity adherence in overweight children. To make overweight children exercise and follow the recommendations, it is essential to have insight into determinants of exercise initiation and adherence. According to the Self-determination Theory, creating opportunities to satisfy the need for autonomy (i.e., having choices), competence (i.e., feeling effective) and relatedness (i.e., being socially connected) might increase autonomous motivation for physical activity in overweight children and promote a long-lasting active lifestyle. To increase feelings of autonomy in overweight children, exercise programs could be delivered in an autonomy-supportive manner by providing choices, supporting the child's initiatives, avoiding use of external rewards, offering relevant information and rationale for changing behaviour, making a decisional balance and using autonomy supportive language, while minimizing pressure and control. Perceived competence in physical activities could be increased by offering activities tailored to the capabilities of the overweight child, helping the children set realistic goals, learning the children self-management skills, providing the children with appropriate feedback and organizing separate exercise sessions for overweight children. Feelings of relatedness in overweight children might increase by adopting an empathic approach, showing interest in the child's well-being and problems, showing enjoyment and enthusiasm, knowing the names of the children, talking to the children as equals, offering group sessions and talks, encouraging club participation and having a sports partner and encouraging parental support.

Influence of exclusive resistance training on body composition and cardiovascular risk factors in overweight or obese children: a systematic review

OBJECTIVE

Since the last decade, a significant increase in the prevalence of overweight and obesity among children has been reported. Low aerobic fitness and a low compliance with endurance sports in such children are theoretical reasons to favor the use of resistance training in intervention studies, even though positive effects of resistance training on morbidity without accompanying dietary modifications are a matter of debate. In this review we summarize the studies that have shown the isolated effect of resistance training on body composition and cardiovascular risk factors in overweight and obese children.

METHOD

We systematically reviewed interventional studies that exclusively applied resistance training to overweight and obese 3- to 18-year-old children. Outcome measurements were body composition or cardiovascular risk factors.

RESULTS

Only six studies passed the inclusion criteria. All studies preferred an individually planned and supervised whole-body resistance training of moderate to submaximal intensity during treatment. The mean compliance was 84%. Four studies reported significant changes in body composition, with an increase in fat free mass and BMI, along with a decrease in fat mass. Three studies analyzed the effect of resistance training on cardiovascular risk factors, and only one study reported a significant decrease in systolic blood pressure.

CONCLUSION

An individually planned and supervised whole-body resistance training of moderate to submaximal intensity in children seems to be safe and tends to show positive effects on body composition. Similar to interventions based on endurance exercise alone or in combination with dietary modifications, the effects on cardiovascular risk factors cannot be substantiated. In consequence, we suggest to substantiate the effect of resistance training on cardiovascular risk factors in overweight and obese children in upcoming randomized controlled trials with high case numbers, applying both resistance training only and resistance training in combination with dietary intervention to get knowledge about whether resistance training alone is effectual in the treatment of overweight and obesity in youth or if a combination of resistance training and dietary interventions is actually needed.

From fatness to leaness: where did we go wrong?

INTRODUCTION

In humans, using adipose tissue to store fat represents the most effective means to 'store' energy. On the whole and over an extended period of time, intake of energy has exceeded energy expenditure and where previously the excess of energy was regularly turned over through physical activity, this crucial circle has now been broken. In this way obesity ascribed to either 'overeating' or 'under-activity'. Central adiposity poses a major risk for chronic diseases such as hypertension, cardiovascular diseases and diabetes, and possibly mortality. Predictors and potential factors underlying the development of excess adiposity were well studied and established with emphasis on fat mass.

OBJECTIVE

When studying the development of body composition, bone mass, fat mass and lean mass should be considered together. The purposes of the present paper are to briefly analyze the methodologies used to estimate the lean mass (LM), understanding the interrelationship between fat mass (FM) and LM and underline the importance of LM during growth.

RESULTS

As muscle and adipose tissue are closely linked anatomically, biologically and pathologically, the interrelationship between these two tissues is of great importance in understanding the pathogenesis and development of diseases related to obesity and physical activity/inactivity. LM estimation, and LM programming could show several implications for the early origin of obesity.

CONCLUSION

Measurements of lean mass may improve the capacity to tailor nutrition, treatment and management to metabolic criteria. This approach could offer a unique opportunity of putting lean mass in the first line keeping in mind that this metabolic active tissue need to be preserved when obesity prevention and treatment are considered.

Factors influencing overweight children's commencement of and continuation in a resistance training program

BACKGROUND

In light of the child overweight and obesity problem in Australia, resistance training programs have been trialled as an innovative way of assisting children increase lean body mass and reduce body fat. The purpose of this study was to investigate the factors influencing overweight children's participation in a resistance training trial program.

METHOD

Parent-child pairs who participated in the trial program were invited to take part in a follow-up individual interview to discuss their program experiences. In total, 22 semi-structured interviews were conducted with 11 parent-child pairs.

RESULTS

The factors found to be most relevant to program commencement among parents were a desire for their child to lose weight and gain confidence, the proximity of the venue, and no cost for participation. For children, the most relevant factors were the opportunity to build strength and improve fitness and having supportive parents who facilitated program initiation. The factors most relevant to continuation for parents were the quality of the program management, being able to stay for the sessions, the child's improved weight status, coordination, and confidence, and no cost for participation. Weight loss and improved confidence were also motivators for continuation among the children, along with pleasant social interaction with peers and trainers and ongoing parental support.

CONCLUSION

Different factors variably influence program commencement and program continuation in both parents and children. This has important implications for future interventions that aim to successfully recruit and retain intervention participants.

Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents

Many position stands and review papers have refuted the myths associated with resistance training (RT) in children and adolescents. With proper training methods, RT for children and adolescents can be relatively safe and improve overall health. The objective of this position paper and review is to highlight research and provide recommendations in aspects of RT that have not been extensively reported in the pediatric literature. In addition to the well-documented increases in muscular strength and endurance, RT has been used to improve function in pediatric patients with cystic fibrosis and cerebral palsy, as well as pediatric burn victims. Increases in children's muscular strength have been attributed primarily to neurological adaptations due to the disproportionately higher increase in muscle strength than in muscle size. Although most studies using anthropometric measures have not shown significant muscle hypertrophy in children, more sensitive measures such as magnetic resonance imaging and ultrasound have suggested hypertrophy may occur. There is no minimum age for RT for children. However, the training and instruction must be appropriate for children and adolescents, involving a proper warm-up, cool-down, and appropriate choice of exercises. It is recommended that low- to moderate-intensity resistance exercise should be done 2-3 times/week on non-consecutive days, with 1-2 sets initially, progressing to 4 sets of 8-15 repetitions for 8-12 exercises. These exercises can include more advanced movements such as Olympic-style lifting, plyometrics, and balance training, which can enhance strength, power, co-ordination, and balance. However, specific guidelines for these more advanced techniques need to be established for youth. In conclusion, an RT program that is within a child's or adolescent's capacity and involves gradual progression under qualified instruction and supervision with appropriately sized equipment can involve more advanced or intense RT exercises, which can lead to functional (i.e., muscular strength, endurance, power, balance, and co-ordination) and health benefits.

Active healthy living: prevention of childhood obesity through increased physical activity

The current epidemic of inactivity and the associated epidemic of obesity are being driven by multiple factors (societal, technologic, industrial, commercial, financial) and must be addressed likewise on several fronts. Foremost among these are the expansion of school physical education, dissuading children from pursuing sedentary activities, providing suitable role models for physical activity, and making activity-promoting changes in the environment. This statement outlines ways that pediatric health care providers and public health officials can encourage, monitor, and advocate for increased physical activity for children and teenagers.

Follow up exercise studies in paediatric obesity: implications for long term effectiveness

OBJECTIVES

To examine the effects of exercise training on paediatric obesity immediately after training and at a one year follow up and to provide recommendations for future research.

METHODS

Studies that met the following criteria were included in a meta-analysis: (a) at least six subjects per group; (b) subject groups consisting of children in the 4-17 year age range; (c) pre-test and post-test values for body composition; (d) used exercise such as walking, jogging, cycle ergometry, high repetition resistance exercise, and combinations; (e) training programmes lasting eight weeks or more; (f) full length publications; (g) apparently healthy children.

RESULTS

A total of 135 studies of exercise as a method of treatment of paediatric obesity were located. Eight, containing 236 subjects, met our criteria for inclusion. Across all designs and categories, fixed effects modelling yielded significant decreases in the dependent variable percentage body fat immediately (0=1.04 (0.35); 95% confidence interval (CI) 0.41 to 1.6) and one year after the exercise intervention (0=0.84 (0.51); 95% CI 0.22 to 0.94). Forward stepwise linear regression suggested that the percentage body fat measured at the end of exercise training, exercise duration, and programme length accounted for 53-86% of the variance for percentage body fat at one year.

CONCLUSIONS

These data indicate that exercise is efficacious for reducing percentage body fat in obese children and adolescents, and that exercise intervention may encourage long term maintenance of the observed gains.

The association between adiposity and the response to resistance training among pre- and early-pubertal boys

Resistance training has been shown to be effective in enhancing muscle strength among prepubertal and adolescent boys. Lately, it has been recommended for obese children. We hypothesized that resistance training will be similarly effective among boys of different adiposity. Thirty boys, aged 9.2 +/- 0.3 years, participated in progressive resistance training twice weekly during the first and second school years and thrice weekly during the third year. Training sessions included 1-4 sets of 3-6 exercises, with 5-30 repetitions/set. The mean load was 50-60% of 1 repetition maximum. Subjects were divided into responders (R--upper tertile) and non-responders (NR--lower tertile), according to the three-year improvement in muscle strength, as assessed by means of changes in concentric strength of knee flexors and extensors. Differences between groups were observed at baseline (p <0.05) in all variables reflecting adiposity (mean +/- SD): % body fat (14.1 +/- 2.6 vs 23.5 +/- 7.5% for R and NR, respectively), sum of four skinfolds (25.4 +/- 4.7 vs 47.8 +/- 21.6 mm for R and NR, respectively), BMI (15.5 +/- 1.1 vs 18.6 +/- 2.6 kg x m(-2) for R and NR, respectively). Additionally, the changes in adiposity were inversely related to the training effect (r = -0.60 to -0.34). No differences were observed in initial height and maturation between R and NR groups and there was no difference in linear growth and physical maturation with time between groups. These data suggest that resistance-training loads which may be appropriate to increase strength of knee flexors and extensors in normal-weight children may be insufficient to do so in overweight children. More research is required to elucidate the efficacy of resistance training among overweight children.

Factors that alter body fat, body mass, and fat-free mass in pediatric obesity

PURPOSE

The purpose of this study was to quantify the effects of exercise treatment programs on changes in body mass, fat-free mass, and body fat in obese children and adolescents.

METHODS

By using the meta-analytic approach, studies that met the following criteria were included in our analyses: 1) at least six subjects per group; 2) subject groups consisting of children in the 5- to 17-yr age range; 3) pretest and posttest values for either body mass, percent body fat, or fat-free mass (FFM); 4) used exercise as a mode of treatment (e.g., walking, jogging, cycle ergometry, high-repetition resistance exercise, and combinations); 6) training programs >or= 3 wk; 7) full-length publications (not conference proceedings); 8) apparently "healthy" children (i.e., free from endocrine diseases and disorders); and 9) published studies in English language journals only.

RESULTS

A total of 120 investigations were located that addressed the issue of exercise as a method of treatment in pediatric obesity. Of those, 30 met our criteria for inclusion. Across all designs and categories, fixed-effects modeling yielded significant decreases in the following dependent variables: 1) percent body fat (mean = 0.70 +/- 0.35; 95% CI = 0.21 to 1.1); 2) FFM (mean = 0.50 +/- 0.38; 95% CI = 0.03 to 0.57); 3) body mass (mean = 0.34 +/- 0.18; 95% CI = 0.01 to 0.46); 4) BMI (mean = 0.76 +/- 0.55; 95% CI = 4.24 to 1.7), and 5) VO2max (mean = 0.52 +/- 0.16; 95% CI = 0.18 to 0.89), respectively. Significant differences were found as a function of the type intervention groups (exercise vs exercise + behavioral modification; P < 0.04); body composition assessment methods (skinfold vs hydrostatic weighing, DEXA, and total body water; P < 0.006); exercise intensity (60-65%, vs >or= 71% VO2max; P < 0.01); duration (<or= 30 min vs > 30 min; P < 0.03); and mode (aerobic vs aerobic + resistance training; P < 0.02). Stepwise linear regression suggested that initial body fat levels (or body mass), type of treatment intervention, exercise intensity, and exercise mode accounted for most of the variance associated with changes in body composition after training.

CONCLUSIONS

Exercise is efficacious for reducing selected body composition variables in children and adolescents. The most favorable alterations in body composition occurred with 1) low-intensity, long-duration exercise; 2) aerobic exercise combined with high-repetition resistance training; and 3) exercise programs combined with a behavioral-modification component.

Committed to kids: an integrated, 4-level team approach to weight management in adolescents

The integrated, 4-level approach of Committed to Kids is successful because of several factors: The sessions are designed to entertain the adolescents and promote initial success; The program features parent-training methods in short, interactive, educational sessions; In severely obese adolescents, the diet intervention results in noticeable weight loss that motivates the patient to continue; also, the improved exercise tolerance resulting from the weight loss promotes increased physical activity; and The program team provides consistent feedback-patients and their families receive results and updates every 3 months. Most importantly, the program is conducted in groups of families. The adolescent group dynamics and peer modeling are primary components of the successful management of obesity in youth.

Exercise in weight management of obesity

Obesity is a chronic metabolic disorder associated with CVD and increased morbidity and mortality. When the BMI is > or = 30 kg/m2, mortality rates from all causes, and especially CVD, are increased by 50% to 100%. There is strong evidence that weight loss in overweight and obese individuals improves risk factors for diabetes and CVD. Additional evidence indicates that weight loss and the associated diuresis reduce blood pressure in both overweight hypertensive and nonhypertensive individuals, reduce serum TG levels, increase high-density lipoprotein cholesterol levels, and may produce some reduction in low-density lipoprotein cholesterol concentrations. Of interest, even if weight loss is minimal, obese individuals showing a good level of cardiorespiratory fitness are at reduced risk for cardiovascular mortality than lean but poorly fit subjects. Insulin and catecholamines have pronounced metabolic effects on human adipose tissue metabolism. Insulin stimulates LPL and inhibits HSL; the opposite is true for catecholamines. There is regional variation in adipocyte TG turnover favoring lipid mobilization in the visceral fat depots and lipid storage in the peripheral subcutaneous sites. The hormonal regulation of adipocyte TG turnover is altered in obesity and is most marked in central obesity. There is resistance to insulin stimulation of LPL; however, LPL activity in fasted obese subjects is increased and remains so following weight reduction. Catecholamine-induced lipolysis is enhanced in visceral fat but decreased in subcutaneous fat. Numerous adaptive responses take place with physical training. These adaptations result in a more efficient system for oxygen transfer to muscle, which is now able to better utilize the unlimited lipid stores instead of the limited carbohydrate reserves available. In addition, the reduced adipose tissue mass represents an important mechanical advantage, allowing better long-term work. Gender differences have been reported in the adaptation of adipose tissue metabolism to aerobic exercise training. Physical training helps counteract the permissive and affluent environment that predisposes reduced-obese subjects to regain weight. An exercise program using weight resistance modalities may also be included safely, and it improved program retention in a multidisciplinary weight management program that was designed for obese children. Thirty to 45 minutes of physical activity of moderate intensity, performed 3 to 5 days a week, should be encouraged. All adults should set a long-term goal to accumulate at least 30 minutes or more of moderate-intensity physical activity on most, and preferably all days. Public health interventions promoting walking are likely to be the most successful. Indeed, walking is unique because of its safety, accessibility, and popularity. It is noteworthy that there is a clear dissociation between the adaptation of cardiorespiratory fitness and the improvements in the metabolic risk profile that can be induced by endurance training programs. It appears that as long as the increase in energy expenditure is sufficient, low-intensity endurance exercise is likely to generate beneficial metabolic effects that would be essentially similar to those produced by high-intensity exercise. The clinician should therefore focus on the improvement of the metabolic profile rather than on weight loss alone. Realistic goals should be set between the clinician and the patient, with a weight loss of approximately of 0.5 to 1 pound per week. It should be kept in mind that since it generally takes years to become overweight or obese, a weight loss pattern of 0.5 or 1 pound per week will require time and perseverance to reach the proposed target. However, the use of physical activity as a method to lose weight seems inversely related to patients' age and BMI and directly related to the level of education. Thus, public health interventions helping these groups to become physically active remain a challenge and further emphasize the importance of the one-on-one interaction between the clinician/health care professional with the obese individual "at risk" of CVD. This notion is critical, as it has been shown that less than half of obese adults have reported being advised to lose weight under the guidance of health care professionals.

Exercise as a modality in the treatment of childhood obesity

In a review of the literature, Glenny et al determined that family therapy and lifestyle modification seem to be effective in the prevention and treatment of childhood but not necessarily adult obesity. Furthermore, research indicates that obese children are better able to maintain weight loss over a long-term period than are adults. Based on the limited research in the treatment of obesity in children, approaches should include family interventions with nutrition and physical activity education, structured exercise, and behavior modification. These interventions should be delivered by a team of health care experts in a nurturing, nonintimidating environment; however, obese children respond differently physiologically and emotionally to exercise than do normal-weight children. Therefore, obese children may experience negative consequences to participation in activities considered appropriate for normal-weight children. In clinical settings, specialized exercise programs based on appropriate theories that include specific recommendations for children with varied obese conditions have been shown to enhance safety, efficacy, and compliance during pediatric obesity treatment. Optimal results may be achieved by combining programs to reduce sedentary behaviors based on similar theories with specialized, structured exercise prescriptions. When used in conjunction with appropriate dietary prescriptions and consistent behavior modification, exercise serves as a promising modality that may reverse obese conditions during childhood and, perhaps, prevent the onset of adult obesity.