Aerobic endurance, energy expenditure, and serum leptin response in obese, sedentary, prepubertal children and adolescents participating in a short-term treadmill protocol

The ALINFA Intervention Improves Diet Quality and Nutritional Status in Children 6 to 12 Years Old

The study aimed to evaluate the efficacy of a new nutritional intervention, focused on improving the quality of the diet in children aged 6 to 12 years. A 2-month parallel, controlled randomized trial was conducted in the Spanish child population. The children were randomized to ALINFA nutritional intervention, which consisted of a normocaloric diet that incorporates products, ready-to-eat meals and healthy recipes specifically designed for the study, or a control group, which received the usual advice on healthy eating. The change in diet quality was assessed through the Kidmed index. The secondary outcomes were anthropometry, glucose and lipid profiles, inflammation markers, dietary intake and lifestyle. The participants in the intervention group showed an increase in the mean score of the Kidmed index (p < 0.001). Alongside that, these children decreased their intake of calories (p = 0.046), and total and saturated fat (p = 0.016//p = 0.011), and increased fiber intake (p < 0.001). Likewise, the children in the ALINFA group increased the intake of white fish (p = 0.001), pulses (p = 0.004), whole grains (p < 0.001) and nuts (p < 0.001), and decreased fatty meat (p = 0.014), refined grain (p = 0.008), pastry (p < 0.001), fast food (p < 0.001) and sugar (p = 0.001) intake. Moreover, these children had a significantly decreased BMI (p < 0.001), BMI z-score (p < 0.001), waist circumference (p = 0.016) and fat mass (p = 0.011), as well as leptin (p = 0.004). Participants in the control group did not report significant changes in diet quality. In conclusion, ALINFA nutritional intervention is possibly a useful strategy to increase the diet quality in children, which is associated to improvements in the nutritional status. These results highlight the importance of developing well-designed nutritional interventions.

Resting Energy Expenditure Is Not Altered in Children and Adolescents with Obesity. Effect of Age and Gender and Association with Serum Leptin Levels

In children and adolescents, obesity does not seem to depend on a reduction of resting energy expenditure (REE). Moreover, in this young population, the interactions between either age and obesity or between age and gender, or the role of leptin on REE are not clearly understood. To compare the levels of REE in children and adolescents we studied 181 Caucasian individuals (62% girls) classified on the basis of age- and sex-specific body mass index (BMI) percentile as healthy weight (n = 50), with overweight (n = 34), or with obesity (n = 97) and in different age groups: 8–10 (n = 38), 11–13 (n = 50), and 14–17 years (n = 93). REE was measured by indirect calorimetry and body composition by air displacement plethysmography. Statistically significant differences in REE/fat-free mass (FFM) regarding obesity or gender were not observed. Absolute REE increases with age (p < 0.001), but REE/FFM decreases (p < 0.001) and there is an interaction between gender and age (p < 0.001) on absolute REE showing that the age-related increase is more marked in boys than in girls, in line with a higher FFM. Interestingly, the effect of obesity on absolute REE is not observed in the 8–10 year-old group, in which serum leptin concentrations correlate with the REE/FFM (r = 0.48; p = 0.011). In conclusion, REE/FFM is not affected by obesity or gender, while the effect of age on absolute REE is gender-dependent and leptin may influence the REE/FFM in 8–10 year-olds.

Effects of physical training on anthropometrics, physical and physiological capacities in individuals with obesity: A systematic review

Increasing the amount of physical activity is an important strategy for weight loss. This systematic review summarizes recent findings on the effects of physical training on anthropometric characteristics, physical performances and physiological capacities in individuals with overweight and obesity. A systematic literature search strategy was conducted from inception until June 2019 using four electronic databases that identified 2,708 records. After screening for titles, abstracts and full texts, 116 studies were included in our final analysis. Both aerobic (e.g., endurance training) and anaerobic training (e.g., high-intensity training, resistance training) improved body composition and physical fitness indicators in adults, adolescents and children with obesity (effect size: 0.08 < d < 2.67, trivial to very large). This systematic review suggests that both low- and high-intensity training significantly reduced body weight and fat mass while increasing fat-free mass in individuals with obesity (effect size: 0.04 <d <3.2, trivial to very large). A significant increase in VO_2max also occurs in individuals with obesity in response to aerobic training or high-intensity interval training (effect size: 0.13 < d < 6.24, trivial to very large). Further studies are needed to define the optimal combination of training intensity and duration needed to produce the most efficacious results in individuals with obesity.

The Effect of Body Mass Index on Acute Cardiometabolic Responses to Graded Exercise Testing in Children: A Narrative Review

Although the beneficial role of exercise for health is widely recognized, it is not clear to what extent the acute physiological responses (e.g., heart rate (HR) and oxygen uptake (VO₂)) to a graded exercise test are influenced by nutritional status (i.e., overweight vs. normal-weight). Therefore, the main objectives of the present narrative review were to examine the effect of nutritional status on acute HR, and VO₂ responses of children to exercise testing. For this purpose, we examined existing literature using PubMed, ISI, Scopus, and Google Scholar search engines. Compared with their normal-body mass index (BMI) peers, a trend of higher HRrest, higher HR during submaximal exercise testing, and lower HRmax was observed among overweight and obese children (according to BMI). Independent from exercise mode (walking, running, cycling, or stepping), exercise testing was metabolically more demanding (i.e., higher VO₂) for obese and overweight children than for their normal-weight peers. Considering these cardiometabolic differences according to BMI in children might help exercise specialists to evaluate the outcome of a graded exercise test (GXT) (e.g., VO2max, HRmax) and to prescribe optimal exercise intensity in the context of development of exercise programs for the management of body mass.

Efeito do treinamento concorrente e destreinamento sobre o biomarcador anti-inflamatório e níveis de condicionamento físico em crianças obesas

OBJETIVO: Examinar o efeito de 12 semanas de (3 dias/sem) de treinamento concorrente e 4 semanas de destreinamento nas concentrações séricas de adiponectina e níveis de condicionamento físico em meninos obesos sem intervenção dietética. MÉTODOS: vinte e quatro meninos saudáveis, 11-13 anos de idade com índice de massa corporal > 28 participaram voluntariamente do estudo. Estes foram divididos em dois grupos, experimental (n= 12) e controle (n=12). RESULTADOS: Concentrações de adiponectina após 12 semanas tiveram declínio significativo em ambos os grupos em comparação com o nível basal (p < 0,05). VO2 pico, flexibilidade, força, endurance de abdominais e agilidade aumentaram significativamente no grupo experimental comparado com o grupo controle (p < 0.05). Foi evidenciado que após destreinamento de 4 semanas, a adiponectina sérica não se alterou significativamente no grupo experimental e que condicionamento físico benéfico foi gradualmente diminuído. CONCLUSÃO: Nossos resultados sugerem que os efeitos benéficos do exercício físico no condicionamento são temporários. Uma vez que o processo de adaptação é reversível, parece que as concentrações de adiponectina foram inevitavelmente afetadas pelas alterações morfológicas e hormonais que ocorreram durante a puberdade em meninos.

Leptin, adiponectin, and short-term and long-term weight loss after a lifestyle intervention in obese children

OBJECTIVE

In overweight children, high leptin levels are independently associated with higher risk for cardiovascular disease, whereas adiponectin seems to be protective against type 2 diabetes and atherosclerosis. The study examines the predictive value of leptin for weight loss after a 4- to 6-wk inpatient therapy and again after 1 y; as well as the association among weight loss, leptin, and adiponectin levels and changes in cardiometabolic risk factors after therapy.

METHODS

Body mass index (BMI), blood pressure, Tanner stage, and cardiometabolic risk factors were studied in 402 children (59.2% females, 13.9 ± 2.3 y, BMI 33.8 ± 5.7 kg/m(2)) before and after a 4-to 6-wk inpatient intervention (exercise, diet, and behavioral therapy) and BMI 1 y later (n = 206).

RESULTS

BMI was reduced from 33.8 ± 5.7 to 30.5 ± 5.1 kg/m(2) (P < 0.001) during the lifestyle intervention and remained unchanged after 1 y. Baseline BMI was positively associated with leptin (r = 0.60; P < 0.001) and cardiometabolic risk factors (blood pressure, high-density lipoprotein [HDL] cholesterol, triglycerides). Baseline leptin was associated with BMI and triglycerides (r = 0.39; P < 0.001), baseline adiponectin with HDL-cholesterol (r = 0.40; P < 0.001). Baseline BMI explained 40.7% of the variance in weight loss during therapy. The combination of BMI, sex, and leptin explained 50.4% of the variance. Neither BMI nor leptin predicted weight changes over the long term.

CONCLUSIONS

Overweight children maintained a substantial amount of weight loss after participation in a short-term inpatient lifestyle intervention. Baseline BMI was positively associated with weight reduction during the intervention, whereas baseline leptin had only a minor predictive value.

Plasma leptin and adiponectin concentrations in healthy, non-obese children

BACKGROUND

Alterations in plasma leptin and adiponectin concentrations are associated with an adverse metabolic profile in obese children.

OBJECTIVE

To simultaneously assess multiple factors with possible effects on plasma leptin and adiponectin concentrations in healthy, non-obese children.

SUBJECTS

We studied 170 healthy non-obese children (86 males, age 10+1.5 years), with available medical records from birth.

METHODS

Plasma leptin and adiponectin concentrations were assessed by immunoassay. The ratio of current weight/birth weight (WBWR) was used as an index of children growth from birth. Children's intensity of physical activity and parental characteristics were also assessed.

RESULTS

Leptin was positively associated with WBWR (p<0.0001); parental smoking (analysis of variance, ANOVA; p-=0.03) and parental obesity (ANOVA; p<0.001) were negatively associated with breastfeeding (p<0.01) and children's access to exercise (p<0.0001). Adiponectin was negatively associated with WBWR (p<0.0001) and parental smoking (p=0.04), with an additive negative effect of parental smoking status and parental obesity on children's adiponectin levels (ANOVA; p=0.02).

CONCLUSIONS

Children's and parental factors are related and could possibly influence leptin and adiponectin concentrations in healthy non-obese children. Early preventive strategies that target both children and parents could improve the profile of adipocytokine in these children.

Acquired obesity and poor physical fitness impair expression of genes of mitochondrial oxidative phosphorylation in monozygotic twins discordant for obesity

Defects in expression of genes of oxidative phosphorylation in mitochondria have been suggested to be a key pathophysiological feature in familial insulin resistance. We examined whether such defects can arise from lifestyle-related factors alone. Fourteen obesity-discordant (BMI difference 5.2 +/- 1.8 kg/m(2)) and 10 concordant (1.0 +/- 0.7 kg/m(2)) monozygotic (MZ) twin pairs aged 24-27 yr were identified among 658 MZ pairs in the population-based FinnTwin16 study. Whole body insulin sensitivity was measured using the euglycemic hyperinsulinemic clamp technique. Transcript profiles of mitochondrial genes were compared using microarray data of fat biopsies from discordant twins. Body composition of twins was determined using DEXA and maximal oxygen uptake (Vo(2max)) and working capacity (W(max)) using a bicycle ergometer exercise test with gas exchange analysis. The obese cotwins had lower insulin sensitivity than their nonobese counterparts (M value 6.1 +/- 2.0 vs. 9.2 +/- 3.2 mg x kg LBM(-1) x min(-1), P < 0.01). Transcript levels of genes involved in the oxidative phosphorylation pathway (GO:0006119) in adipose tissue were lower (P < 0.05) in the obese compared with the nonobese cotwins. The obese cotwins were also less fit, as measured by Vo(2max) (50.6 +/- 6.5 vs. 54.2 +/- 6.4 ml x kg LBM(-1) x min(-1), for obese vs. nonobese, P < 0.05), W(max) (3.9 +/- 0.5 vs. 4.4 +/- 0.7 W/kg LBM, P < 0.01) and also less active, by the Baecke leisure time physical activity index (2.8 +/- 0.5 vs. 3.3 +/- 0.6, P < 0.01). This implies that acquired poor physical fitness is associated with defective expression of the oxidative pathway components in adipose tissue mitochondria.

[Leptin, ghrelin, and physical exercise]

Obesity is a major public health problem in the Western world resulting in serious social, physical and psychological damages. The genesis of obesity is complex involving a variety of factors such as genetic, psychological, metabolic and environmental factors. Progress in endocrinology and metabolism show that adipocyte is considered now as an endocrine tissue producing several substance including adiponectin, tumor necrosis factor-alpha, interleukin-6 and leptin. Specifically, leptin is the main peptide produced by the adipocyte and its serum concentration represents an important peripheral signal in the regulation of food intake and energy expenditure in mammals. In addition to leptin, a new peptide was discovered recently named ghrelin. Ghrelin, a peptide hormone identified in the stomach, is directly involved with the regulation of energy balance and obesity. Physical exercise has been used as a non-pharmacological tool in management of body weight and the effect of physical activity on weight control is an important issue for clinical studies in endocrinology field. Thus, this review will attempt to update the knowledge of leptin and ghrelin on the body weight regulation and the effect of exercise training on these peptide concentrations. It can be concluded that the relationship between physical exercise and the plasma concentration of these peptides is not clear. The reasons for that could be related to the differences in duration, intensity and frequency of the training program employed in each study. Indeed, most of the studies have not analyzed the intensity of training program by either plasma lactate concentration or maximum oxygen consumption. On the other hand, genetic basis could also explain the discrepancies found in some studies, since it has been shown that polymorphism for a variety of genes might be an important factor to determine the differences of cellular response to physical training.

Leptin: a potential biomarker for childhood obesity?

Leptin, a hormone made by adipocytes, is an important circulating signal for the regulation of body weight. A review of the scientific literature (PubMed Search 1994 to 2005) for studies examining the relationship among leptin, pediatric obesity and the impact of exercise intervention programmes on leptin concentrations are summarized. The potential utility of leptin as a biomarker for identifying children at risk of obesity is discussed. This literature review demonstrated that (1) leptin directly interacts with the hypothalamus for energy balance regulation; (2) the measurement of free, bound and total leptin as well as soluble leptin receptor concentration are critical for our understanding of obesity in children; and (3) leptin concentration may be an important factor for determining intervention programme responsiveness in pediatric obesity.