Twelve weeks of moderate aerobic exercise without dietary intervention or weight loss does not affect 24-h energy expenditure in lean and obese adolescents

Improved walking energy efficiency might persist in presence of simulated full weight regain after multidisciplinary weight loss in adolescents with obesity: the POWELL study

AIM

Weight loss leads to a reduction of the energy cost of walking but the respective implications of the metabolic and mechanic changes remain unknown. The present study compares the post-weight loss energy cost of walking (Cw) with and without a total reload of the induced weight reduction in adolescents with obesity.

METHODS

Energy cost of walking and substrate use were evaluated during a graded walking exercise (4×6-min at 0.75, 1, 1.25, 1.5 m.s-1) before (V1) and after a 12-week intervention in 21 adolescents with obesity (11 girls; 13.8 ± 1.4 y). After weight loss, the walking exercise was randomly repeated once without weight reload (V2) and once with a loading corresponding to the total induced weight loss during the program (V2L). Body composition was assessed before and after the intervention.

RESULTS

Body weight and fat mass decreased in response to the 12-week intervention (p < 0.001), while FFM did not change. The absolute gross Cw (ml.m-1) was higher on V1 compared with V2 at every speed. The absolute net Cw (ml.m-1) was higher on V1 compared to V2L at 0.75 m.s-1 (p = 0.04) and 1 m.s-1 (p = 0.02) and higher on V2L compared with V2 at 1.5 m.s-1 (p = 0.03). Net Cw (ml.m-1.kg-1) on V1 being higher than V2 (p < 0.001), and V2L higher than V2 (p = 0.006). The absolute CHO oxidation (mg.min-1) did not show any condition effect (p = 0.12) while fat utilization was higher on V1 compared to V2 and V2L (p < 0.001). Relative to body weight CHO oxidation was lower on V1 compared to V2 (p = 0.04) and V2L (p = 0.004) while relative to body weight fat oxidation was higher on V1 than V2 (p = 0.002).

CONCLUSION

Adolescents with obesity might not show an entire rise back to pre-weight loss values of their metabolic cost of walking when weight gain is simulated. These new findings suggest metabolic and physiological adaptations to weight loss of the energy metabolism that remain to be clarified.

Targeted dietary approaches for the management of obesity and severe obesity in children and adolescents: A systematic review and meta-analysis

There is a need for a detailed understanding of effective dietary interventions for children with obesity. This systematic review examined the effectiveness of diets of varying energy content as a component of weight treatment in children and adolescents with obesity, severe obesity and obesity-related comorbidity. A systematic search of six databases, from 2000 to 2021, for intervention studies of targeted dietary treatment for obesity in children aged 2-18 years identified 125 studies. Dietary interventions were grouped according to diet type and energy target. Risk of bias was assessed using the Effective Public Healthcare Panacea Project assessment tool. Meta-analysis examined change in body mass index (BMI) at intervention end. A broad array of diet types were effective at reducing BMI in children with obesity. When dietary types were considered by energy target, a gradient effect was observed. Very-low energy diets were most effective with a - 4.40 kg/m² (n = 3; 95% CI -7.01 to -1.79). While dietary interventions with no specified energy target were ineffective, resulting in a BMI gain of +0.17 kg/m² (n = 22; 95% CI 0.05 to 0.40). Practical definitions of dietary energy target in the management of obesity and severe obesity are urgently required to ensure treatment seeking children have timely access to efficacious interventions.

Understanding the role of aerobic fitness, spatial learning, and hippocampal subfields in adolescent males

Physical exercise during adolescence, a critical developmental window, can facilitate neurogenesis in the dentate gyrus and astrogliogenesis in Cornu Ammonis (CA) hippocampal subfields of rats, and which have been associated with improved hippocampal dependent memory performance. Recent translational studies in humans also suggest that aerobic fitness is associated with hippocampal volume and better spatial memory during adolescence. However, associations between fitness, hippocampal subfield morphology, and learning capabilities in human adolescents remain largely unknown. Employing a translational study design in 34 adolescent males, we explored the relationship between aerobic fitness, hippocampal subfield volumes, and both spatial and verbal memory. Aerobic fitness, assessed by peak oxygen utilization on a high-intensity exercise test (VO2 peak), was positively associated with the volumetric enlargement of the hippocampal head, and the CA1 head region specifically. Larger CA1 volumes were also associated with spatial learning on a Virtual Morris Water Maze task and verbal learning on the Rey Auditory Verbal Learning Test, but not recall memory. In line with previous animal work, the current findings lend support for the long-axis specialization of the hippocampus in the areas of exercise and learning during adolescence.

Effects of a 12-Week Exercise Intervention on Subsequent Compensatory Behaviors in Adolescent Girls: An Exploratory Study

PURPOSE

Chronic exercise programs can induce adaptive compensatory behavioral responses through increased energy intake (EI) and/or decreased free-living physical activity in adults. These responses can negate the benefits of an exercise-induced energy deficit; however, it is unclear whether young people experience similar responses. This study examined whether exercise-induced compensation occurs in adolescent girls.

METHODS

Twenty-three adolescent girls, heterogeneous for weight status, completed the study. Eleven adolescent girls aged 13 years completed a 12-week supervised exercise intervention (EX). Twelve body size-matched girls comprised the nonexercise control group (CON). Body composition, EI, free-living energy expenditure (EE), and peak oxygen uptake (V˙O2) were measured repeatedly over the intervention.

RESULTS

Laboratory EI (EX: 9027, 9610, and 9243 kJ·d-1 and CON: 9953, 9770, and 10,052 kJ·d-1 at 0, 12, and 18 wk, respectively; effect size [ES] = 0.26, P = .46) and free-living EI (EX: 7288, 6412, and 5273, 4916 kJ·d-1 and CON: 7227, 7128, and 6470, 6337 kJ·d-1 at 0, 6, 12, and 18 wk, respectively; ES ≤ 0.26, P = .90) did not change significantly over time and were similar between groups across the duration of the study. Free-living EE was higher in EX than CON (13,295 vs 12,115 kJ·d-1, ES ≥ 0.88, P ≥ .16), but no significant condition by time interactions were observed (P ≥ .17).

CONCLUSION

The current findings indicate that compensatory changes in EI and EE behaviors did not occur at a group level within a small cohort of adolescent girls. However, analysis at the individual level highlights large interindividual variability in behaviors, which suggests a larger study may be prudent to extend this initial exploratory research.

Can metabolic function and physical fitness improve without weight loss for inactive, obese, Hispanic adolescents? A feasibility study

INTRODUCTION

A case series that examines the effects of a 12-week combined resistance and aerobic training program for four sedentary obese, Hispanic adolescents without weight loss.

SUBJECTS/METHODS

Baseline and post-intervention anthropometric, metabolic and physical fitness measures were obtained. Body composition, hepatic, visceral, and intramuscular fat contents were analyzed via imaging. Fasting levels of alanine transaminase (ALT), insulin, glucose, free fatty acids, triglycerides, high- and low-density lipoproteins (LDL), and C-reactive protein were obtained via blood samples.

RESULTS

Two subjects decreased their glucose levels by 1.86% and 4.06%. Subjects 1, 3, and 4 increased their lean body mass by 4.12%, 9.70%, and 5.48%. ALT was reduced 13.0%, 16.0%, and 35.7% for subjects 2, 3, and 4, respectively. LDLs were reduced by 37.7%, 4.5%, and 7.5% for subjects 1, 2, and 3. Triglycerides were reduced by 25.4%, 37.8%, and 4.6% for subjects 1, 2, and 3. Visceral fat reductions by 16.5%, 14.2%, and 13.0% occurred for subjects 1, 2, and 3. C-reactive protein was reduced for subjects 1, 2, and 3 by 19.4%, 16.3%, and 32.0%.

CONCLUSION

Expected directions of change were made for most indicators of metabolic function and body composition, but measures of physical fitness improved for all four subjects.

The role of metabonomics as a tool for augmenting nutritional information in epidemiological studies

Most chronic diseases have been demonstrated to have a link to nutrition. Within food and nutritional research there is a major driver to understand the relationship between diet and disease in order to improve health of individuals. However, the lack of accurate dietary intake assessment in free-living populations, makes accurate estimation of how diet is associated with disease risk difficulty. Thus, there is a pressing need to find solutions to the inaccuracy of dietary reporting. Metabolic profiling of urine or plasma can provide an unbiased approach to characterizing dietary intake and various high-throughput analytical platforms have been used in order to implement targeted and nontargeted assays in nutritional clinical trials and nutritional epidemiology studies. This review describes first the challenges presented in interpreting the relationship between diet and health within individual and epidemiological frameworks. Second, we aim to explore how metabonomics can benefit different types of nutritional studies and discuss the critical importance of selecting appropriate analytical techniques in these studies. Third, we propose a strategy capable of providing accurate assessment of food intake within an epidemiological framework in order establish accurate associations between diet and health.

Physical activity and exercise in the regulation of human adipose tissue physiology

Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.

Secular trends of sports participation, sedentary activity and physical self-perceptions in Hong Kong adolescents, 1995-2000

AIM

To assess the 5-year secular changes in sports participation, sedentary activity, and physical self-perceptions among Hong Kong adolescents.

METHODS

A total of 2932 and 5692 secondary students, aged 13-18 participated in the Health Related Behavior General (HRBG) Survey in 1995-1996 and 2000-2001, respectively. Extracurricular sports participation at least weekly or as a team member (none, 1-2 events, 3 or more events), sedentary activities (0-1 h/day, 2 h/day or more) including television/video watching and homework were assessed. Additionally, physical self-perceptions, physical fitness (fit/very fit, moderately fit, unfit/very unfit) and body weight (intention to lose weight, satisfied, intention to gain weight) were reported. Secular trends of sports participation, and sedentary activities and physical self-perceptions were assessed.

RESULTS

During the 5 years, the prevalence of sports participation (at least weekly or membership) decreased significantly in boys. The prevalence of both TV/video watching and homework for at least 2 h/day increased significantly in both sexes. The prevalence of being unfit/very unfit increased significantly in girls. No significant secular difference in weight perception was observed for both sexes.

CONCLUSIONS

Sports participation decreased and sedentary activities increased during the 5-year period. Physical self-perceptions did not change significantly, except an increase in being physically unfit was observed in girls.