Impact of exercise training without caloric restriction on inflammation, insulin resistance and visceral fat mass in obese adolescents

Effect of physical activity on free fatty acids, insulin resistance, and blood pressure in obese older women

PURPOSE

Obesity is characterized by a progressive increase in body fat accompanied by insulin resistance (IR) and elevated blood pressure (BP), and presents significant health risks, particularly in aged individuals. This study aimed to evaluate the effects of physical activity (PA) on free fatty acid (FFA) levels, IR, and BP in obese older women.

METHODS

Twenty-three participants were randomly assigned to either the control group (CON, n = 11) or the physical activity group (PA, n = 12). The PA group was provided with a target of achieving >7,000 steps/day for 5 days each week. Body composition, FFA levels, IR, and BP were measured at pre- and post- of the 12-week intervention.

RESULTS

The analysis revealed a statistically significant interaction between FFA (p < 0.01), IR (p < 0.01), and SBP (p < 0.001). FFA (p < 0.5), IR (p < 0.5), and systolic blood pressure (SBP) (p < 0.01) were significantly decreased in the PA group compared to those in the CON group, which showed no significant changes in FFA, IR, and SBP.

CONCLUSION

PA significantly decreased FFA, IR, and SBP in older women with obesity. Therefore, PA is an effective intervention for the prevention and management of obesity and cardiovascular diseases in obese older women.

The effects of exercise training on inflammatory markers in children and adolescents: A systematic review and meta-analysis

INTRODUCTION AND AIM

Exercise training is effective for improving cardiometabolic health in children and adolescents, but less is known about its impact on inflammatory markers. We therefore, undertook a systematic review and meta-analysis to investigate the role of exercise training on pro-inflammatory cytokines including interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) in children and adolescents.

METHOD

A comprehensive search was conducted in three electronic databases including PubMed, Web of Science, and Scopus, from inception to December 2023 to identify exercise trials with and without control groups, involving participants with mean ages ranging from ≥ 6 to < 18 years, of age with measurements of at least one of the following pro-inflammatory cytokines IL-6, TNF-α, or CRP. Standardized mean differences (SMD) and 95 % confidence interval (ICs) were calculated using random effects models.

RESULTS

Thirty-eight studies involving 2043 children and adolescents were included. The results show that exercise training resulted in significant reductions in IL-6 [SMD: -0.44; 95 % CI: -0.68, -0.21; P = 0.001] and CRP [SMD: -0.28; 95 % CI: -0.41, -0.16; P = 0.001], but not TNF-α [SMD: -0.15; 95 % CI: -0.38, -0.07; P = 0.19]. Subgroup analyses showed that IL-6 and CRP were reduced with aerobic training in adolescents, as was CRP with high-intensity interval training.

CONCLUSION

These results provide evidence that exercise training is effective for reducing IL-6 and CRP in adolescents, but not in children, and any benefits may be modulated by the type of exercise performed.

Toward Exercise Guidelines for Optimizing Fat Oxidation During Exercise in Obesity: A Systematic Review and Meta-Regression

BACKGROUND

Exercise training performed at maximal fat oxidation (FATmax) is an efficient non-pharmacological approach for the management of obesity and its related cardio-metabolic disorders.

OBJECTIVES

Therefore, this work aimed to provide exercise intensity guidelines and training volume recommendations for maximizing fat oxidation in patients with obesity.

METHODS

A systematic review of original articles published in English, Spanish or French languages was carried out in EBSCOhost, PubMed and Scopus by strictly following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Those studies that analyzed maximal fat oxidation (MFO) and FATmax in patients with obesity (body fat > 25% for men; > 35% for women) by calculating substrate oxidation rates through indirect calorimetry during a graded exercise test with short-duration stages (< 10 min) were selected for quantitative analysis. The accuracy of relative oxygen uptake (% peak oxygen uptake [%[Formula: see text]O2peak]) and relative heart rate (% peak heart rate [%HRpeak]) for establishing FATmax reference values was investigated by analyzing their intra-individual and inter-study variation. Moreover, cluster analysis and meta-regression were used for determining the influence of biological factors and methodological procedures on MFO and FATmax.

RESULTS

Sixty-four manuscripts were selected from 146 records; 23 studies only recruited men (n = 465), 14 studies only evaluated women (n = 575), and 27 studies included individuals from both sexes (n = 6434). The majority of the evaluated subjects were middle-aged adults (aged 40-60 y; 84%) with a poor cardiorespiratory fitness (≤ 43 mL·kg-1·min-1; 81%), and the reported MFO ranged from 0.27 to 0.33 g·min-1. The relative heart rate at FATmax (coefficient of variation [CV]: 8.8%) showed a lower intra-individual variation compared with relative oxygen uptake (CV: 17.2%). Furthermore, blood lactate levels at FATmax ranged from 1.3 to 2.7 mmol·L-1 while the speed and power output at FATmax fluctuated from 4 to 5.1 km·h-1 and 42.8-60.2 watts, respectively. Age, body mass index, cardiorespiratory fitness, FATmax, the type of ergometer and the stoichiometric equation used to calculate the MFO independently explained MFO values (R2 = 0.85; p < 0.01). The MFO in adolescents was superior in comparison with MFO observed in young and middle-aged adults. On the other hand, the MFO was higher during treadmill walking in comparison with stationary cycling. Body fat and MFO alone determined 29% of the variation in FATmax (p < 0.01), noting that individuals with body fat > 35% showed a heart rate of 61-66% HRpeak while individuals with < 35% body fat showed a heart rate between 57 and 64% HRpeak. Neither biological sex nor the analytical procedure for computing the fat oxidation kinetics were associated with MFO and FATmax.

CONCLUSION

Relative heart rate rather than relative oxygen uptake should be used for establishing FATmax reference values in patients with obesity. A heart rate of 61-66% HRpeak should be recommended to patients with > 35% body fat while a heart rate of 57-64% HRpeak should be recommended to patients with body fat < 35%. Moreover, training volume must be higher in adults to achieve a similar fat oxidation compared with adolescents whereas exercising on a treadmill requires a lower training volume to achieve significant fat oxidation in comparison with stationary cycling.

A low‐intensity 10‐min resistance exercise program that ameliorated hepatic fibrosis indices and altered G‐CSF / IP ‐10/ PDGF‐BB in a patient with nonalcoholic fatty liver disease: A case report

We developed a low-intensity 10-min resistance exercise program for nonalcoholic fatty liver disease (NAFLD). We report a case of NAFLD with elevated hepatic fibrosis indices, which were improved by a 60-week daily exercise program. A 71-year-old female patient with NAFLD whose hepatic fibrosis stage corresponded to F2 was referred to our hospital. She performed the exercise once a day with no changes in other lifestyle habits and medications. The homeostasis model assessment-insulin resistance value and NAFLD-liver fat score, the Hepamet fibrosis score, and the enhanced liver fibrosis score decreased. The FIB-4 index and serum levels of Mac-2 binding protein glycosylation isomer decreased to the reference values. We investigated the changes in chemokines/cytokines. The serum granulocyte-colony stimulating factor level was increased, and serum interferon-gamma-induced protein-10 and platelet-derived growth factor-BB levels were decreased. Our program may be beneficial for improving hepatic fibrosis in patients with NAFLD.

The Effects of Resistance Training on some Inflammatory Markers, Appetite-Regulating Peptides and Insulin Resistance Index in Obese Women

Purpose

Obesity is associated with a chronic inflammatory condition, which plays an important role in the development of insulin resistance and disorder in appetite regulation. Resistance training (RT) can improve low-grade systemic inflammation caused by obesity by improving body composition. Hence, this study aimed to investigate whether RT with improvement in inflammatory status leads to improvement of metabolic markers and appetite-regulating peptides in obese women.

Methods

Sixteen obese and healthy women were randomly divided into RT and control groups. The RT group participated in 8 weeks of RT. Blood samples and anthropometric characteristics were taken before the start of the exercise protocol and 3 days after the last training session. Serum levels of leptin, ghrelin, adiponectin, tumour necrosis factor (TNF-α), fasting glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) were also measured.

Results

After 8 weeks of training, body weight (BW) and body mass index (BMI) in the control group increased significantly (P < 0.01), but in the training group, anthropometric characteristics remained unchanged. Serum levels of ghrelin and leptin, adiponectin and tumour necrosis factor remained unchanged after 8 weeks of RT. A significant increase in insulin and homeostatic model assessment of insulin resistance levels was observed in the control group (P < 0.05).

Conclusion

It seems that 8 weeks of RT is not enough to induce an anti-inflammatory response and improve body composition and subsequently improve appetite and metabolic markers.

Adipose tissue dysfunction and visceral fat are associated with hepatic insulin resistance and severity of NASH even in lean individuals

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is a heterogeneous disorder, but the factors that determine this heterogeneity remain poorly understood. Adipose tissue dysfunction is causally linked to NAFLD since it causes intrahepatic triglyceride (IHTG) accumulation through increased hepatic lipid flow, due to insulin resistance and pro-inflammatory adipokines release. While many studies in NAFLD have looked at total adiposity (i.e. mainly subcutaneous fat, SC-AT), it is still unclear the possible impact of visceral fat (VF). Thus, we investigated how VF versus SC-AT was related to NAFLD severity in lean, overweight and obese individuals versus lean controls.

METHODS

Thirty-two non-diabetic NAFLD with liver biopsy (BMI 21.4-34.7 kg/m² ) and eight lean individuals (BMI 19.6-22.8 kg/m² ) were characterized for fat distribution (VF, SC-AT and IHTG by magnetic resonance imaging), lipolysis and insulin resistance by tracer infusion, free fatty acids (FFAs) and triglyceride (TAG) concentration and composition (by mass spectrometry).

RESULTS

Intrahepatic triglyceride was positively associated with lipolysis, adipose tissue insulin resistance (Adipo-IR), TAG concentrations, and increased saturated/unsaturated FFA ratio. Compared to controls VF was higher in NAFLD (including lean individuals), increased with fibrosis stage and associated with insulin resistance in liver, muscle and adipose tissue, increased lipolysis and decreased adiponectin levels. Collectively, our results suggest that VF accumulation, given its location close to the liver, is one of the major risk factors for NAFLD.

CONCLUSIONS

These findings propose VF as an early indicator of NAFLD progression independently of BMI, which may allow for evidence-based prevention and intervention strategies.

High-intensity interval training to promote cerebral oxygenation and affective valence during exercise in individuals with obesity

Left/right prefrontal cortex (PFC) activation is linked to positive/negative affects, respectively. Besides, larger left PFC oxygenation during exercise relates to higher cardiorespiratory fitness (CRF). High-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. The influence of training on PFC oxygenation and affects during exercise in individuals with obesity is, however, currently unknown. Twenty participants with obesity (14 males, 48 ± 8 years, body-mass index = 35 ± 6 kg·m^-2) were randomised to MICT [50% peak work rate (WR_peak)] or HIIT (1-min bouts 100% WR_peak; 3 sessions/week, 8 weeks). Before/after training, participants completed an incremental ergocycle test. Near-infrared spectroscopy and the Feeling Scale assessed PFC oxygenation and affects during exercise, respectively. Improvements in CRF (e.g., WR_peak: 32 ± 14 vs 20 ± 13 W) were greater after HIIT vs MICT (p < 0.05). Only HIIT induced larger left PFC oxygenation (haemoglobin difference from 7 ± 6 to 10 ± 7 μmol) and enhanced affective valence (from 0.7 ± 2.9 to 2.2 ± 2.0; p < 0.05) at intensities ≥ second ventilatory threshold. Exercise-training induced changes in left PFC oxygenation correlated with changes in CRF [e.g., WR_peak (% predicted), r = 0.46] and post-training affective valence (r = 0.45; p < 0.05). HIIT specifically improved left PFC oxygenation and affects during exercise in individuals with obesity. Implementing HIIT in exercise programmes may therefore have relevant implications for the management of obesity, since greater affective response to exercise is thought to be associated with future commitment to physical activity.

Exercise Outcomes in Childhood Obesity-Related Inflammation and Oxidative Status

Childhood obesity is identified as one of the major public health issues to increase the risk for cardiometabolic diseases and related complications in adulthood. The literature has supported inflammation and oxidative stress as the primary underlying mechanisms involved in the pathogenesis of obesity-related diseases. Epidemiological evidence consistently shows the benefits of physical activity in the improvement of obesity-mediated inflammation and oxidative stress status. In this narrative mini-review, the available scientific evidence on the potential effects of exercise in alleviating these susceptibilities in childhood obesity will be assessed.

Effects of high intensity interval training on sustained reduction in cardiometabolic risk associated with overweight/obesity. A randomized trial

Background

Considering the potential greater cardiocirculatory effects of high intensity interval training (HIIT), we hypothesized that a 2-month supervised high volume short interval HIIT would induce greater improvements in CRF and cardiometabolic risk and increase long-term maintenance to physical activity compared to isocaloric moderate intensity continuous training (MICT) in overweight/obesity.

Methods

Sixty (19 females) subjects with overweight/obesity were randomized to three training programs (3 times/week for 2 months): MICT (45 min, 50% peak power output-PPO), HIIT (22 × 1-min cycling at 100% PPO/1-min passive recovery) and HIIT-RM (RM: recovery modulation, i.e. subjects adjusted passive recovery duration between 30s and 2 min). After the intervention, participants no longer benefited from supervised physical activity and were instructed to maintain the same exercise modalities on their own. We assessed anthropometrics, body composition, CRF, fat oxidation, lipid profile, glycemic balance, low-grade inflammation, vascular function, spontaneous physical activity and motivation for eating at three time points: baseline (T0), 4 days after the end of the 2-month supervised training program (T2) and 4 months after the end of the training program (T6).

Results

HIIT/HIIT-RM induced greater improvement in VO_2peak (between +14% and +17%), power output at ventilatory thresholds and at maximal fat oxidation rate (+25%) and waist circumference (−1.53 cm) compared to MICT and tended to decrease insulin resistance. During the four-month follow-up period during which exercise in autonomy was prescribed, HIIT induced a greater preservation of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL.

Conclusion

We have shown greater short-term benefits induced by a high volume short interval (1 min) HIIT on cardiorespiratory fitness and cardiometabolic risk over an isocaloric moderate intensity continuous exercise in persons with overweight/obesity. We also showed greater long-term effects (i.e. after 4 months) of this exercise modality on the maintenance of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL.

An update of the consensus statement on insulin resistance in children 2010

In our modern society, where highly palatable and calorie-rich foods are readily available, and sedentary lifestyle is common among children and adolescents, we face the pandemic of obesity, nonalcoholic fatty liver disease, hypertension, atherosclerosis, and T2D. Insulin resistance (IR) is known to be the main underlying mechanism of all these associated health consequences; therefore, the early detection of IR is fundamental for preventing them.A Consensus Statement, internationally supported by all the major scientific societies in pediatric endocrinology, was published in 2010, providing all the most recent reliable evidence to identify the definition of IR in children, its measurement, its risk factors, and the effective strategies to prevent and treat it. However, the 2010 Consensus concluded that further research was necessary to assess some of the discussed points, in particular the best way to measure insulin sensitivity, standardization of insulin measurements, identification of strong surrogate biomarkers of IR, and the effective role of lifestyle intervention and medications in the prevention and treatment of IR.The aim of this review is to update each point of the consensus with the most recent available studies, with the goal of giving a picture of the current state of the scientific literature regarding IR in children, with a particular regard for issues that are not yet fully clarified.

Effects of Extreme Weight Loss on Cardiometabolic Health in Children With Metabolic Syndrome: A Metabolomic Study

Objectives: To evaluate the effect of extreme weight loss programs on circulating metabolites and their relationship with cardiometabolic health in children with metabolic syndrome.

Methods: This study was a quasi-experimental design with a pretest and post-test. Thirty children with metabolic syndrome and aged 10–17years were recruited to an extreme weight loss program (i.e., exercise combined with diet control). The primary outcomes included plasma metabolites, body composition, and cardiometabolic risk factors. A total of 324 metabolites were quantitatively detected by an ultra-performance liquid chromatography coupled to tandem mass spectrometry system, and the variable importance in the projection (VIP) value of each metabolite was calculated by the orthogonal projection to latent structures discriminant analysis. The fold change (FC) and p value of each metabolite were used to screen differential metabolites with the following values: VIP>1, p value<0.05, and |log2FC|>0.25. Pathway enrichment and correlation analyses between metabolites and cardiometabolic risk factors were also performed.

Result: A large effect size was observed, presenting a weight loss of −8.9kg (Cohen’s d=1.00, p<0.001), body mass index reduction of −3.3kg/m² (Cohen’s d=1.47, p<0.001), and body fat percent reduction of −4.1 (%) (Cohen’s d=1.22, p<0.001) after the intervention. Similar improvements were found in total cholesterol (Cohen’s d=2.65, p<0.001), triglycerides (Cohen’s d=2.59, p<0.001), low-density lipoprotein cholesterol (Cohen’s d=2.81, p<0.001), glucose metabolism, and blood pressure. A total of 59 metabolites were changed after the intervention (e.g., aminoacyl-tRNA biosynthesis, glycine, serine, and threonine metabolism; nitrogen metabolism, tricarboxylic acid cycle, and phenylalanine, tyrosine, and tryptophan biosynthesis). The changes in metabolites (e.g., amino acids, fatty acids, organic acids, and carnitine) were related to lipid metabolism improvement (p<0.05). Organic acids and carnitines were associated with changes in the body composition (p<0.05).

Conclusion: Exercise combined with dietary control improved the body composition and cardiometabolic health in children with metabolic syndrome, and these changes may be related to plasma metabolites.

Effect of the Rehabilitation Program, ReStOre, on Serum Biomarkers in a Randomized Control Trial of Esophagogastric Cancer Survivors

Background

The Rehabilitation Strategies Following Esophagogastric cancer (ReStOre) randomized control trial demonstrated a significant improvement in cardiorespiratory fitness of esophagogastric cancer survivors. This follow-up, exploratory study analyzed the biological effect of exercise intervention on levels of 55 serum proteins, encompassing mediators of angiogenesis, inflammation, and vascular injury, from participants on the ReStOre trial.

Methods

Patients >6 months disease free from esophagogastric cancer were randomized to usual care or the 12-week ReStOre program (exercise training, dietary counselling, and multidisciplinary education). Serum was collected at baseline (T0), post-intervention (T1), and at 3-month follow up (T2). Serum biomarkers were quantified by enzyme-linked immunosorbent assay (ELISA).

Results

Thirty-seven patients participated in this study; 17 in the control arm and 20 in the intervention arm. Exercise intervention resulted in significant alterations in the level of expression of serum IP-10 (mean difference (MD): 38.02 (95% CI: 0.69 to 75.35)), IL-27 (MD: 249.48 (95% CI: 22.43 to 476.53)), and the vascular injury biomarkers, ICAM-1 (MD: 1.05 (95% CI: 1.07 to 1.66)), and VCAM-1 (MD: 1.51 (95% CI: 1.04 to 2.14)) at T1. A significant increase in eotaxin-3 (MD: 2.59 (95% CI: 0.23 to 4.96)), IL-15 (MD: 0.27 (95% CI: 0 to 0.54)) and decrease in bFGF (MD: 1.62 (95% CI: -2.99 to 0.26)) expression was observed between control and intervention cohorts at T2 (p<0.05).

Conclusions

Exercise intervention significantly altered the expression of a number of serum biomarkers in disease-free patients who had prior treatment for esophagogastric cancer.

Impact

Exercise rehabilitation causes a significant biological effect on serum biomarkers in esophagogastric cancer survivors.

Clinical Trial Registration

ClinicalTrials.gov (NCT03314311).

Anemarrhena saponins attenuate insulin resistance in rats with high-fat diet-induced obesity via the IRS-1/PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Anemarrhena asphodeloides is the dry rhizome of Anemarrhena asphodeloides Bge. Anemarrhena Saponins isolated from Anemarrhena asphodeloides are one of the pharmacologically active components of this plant and have blood lipid reduction and blood glucose reduction properties. These facts suggest that these saponins might be helpful in the treatment of insulin resistance.

AIM OF THE STUDY

To determine the therapeutic effect of anemarrhena saponins on insulin resistance and the probable underlying mechanism.

MATERIALS AND METHODS

Insulin-resistant rats were used as the experimental subject, to observe the therapeutic effect of anemarrhena saponins. The blood glucose and blood lipid parameters were determined using the relevant kits. We used hematoxylin and eosin (H&E) staining to observe the protective effect of anemarrhena saponins on the livers of insulin-resistant rats and reverser transcripition polymerase chain reaction (RT-PCR) to analyze the mRNA expressions patterns of genes related to glucose metabolism and inflammatory factors. The toxicity of anemarrhena saponins to HepG2 cells was calculated using the MTT assay. Further, we conducted in vivo and in vitro experiments, and Western-blot analysis to study the effects of anemarrhena saponins on the IRS-1/PI3K/AKT pathway.

RESULTS

Anemarrhena saponins were found to improve dyslipidemia, reduce obesity and inflammation, and alleviate liver injury in insulin-resistant rats. Anemarrhena saponins also reduced the mRNA expression of gluconeogenesis-related genes sunch as G6pase, PEPCK, and GSK3β in the liver. Moreover, anemarrhena saponins up-regulated the phosphorylation levels of IRS-1, PI3K and AKT, promoted insulin signal transduction, and reduced liver injury induced by insulin resistance.

CONCLUSIONS

These findings suggest that anemarrhena saponins could promote insulin signal transduction through the IRS-1/PI3K/AKT pathway, thereby reducing the damage caused by insulin resistance.

Electric pulse stimulation inhibited lipid accumulation on C2C12 myotubes incubated with oleic acid and palmitic acid

OBJECTIVE

To investigate the effect of electrical pulse stimulation (EPS) on lipid accumulation and alteration of fatty acid-related enzymes in C2C12 myotubes incubated with fatty acids.

METHODS

Mouse C2C12 myotubes were incubated with oleic acid and palmitic acid, and differentiated C2C12 myotubes were treated with EPS, oil-red O (ORO), BODIPY staining and triglyceride (TG) content were examined. Total RNA was isolated, and real-time polymerase chain reaction analysis was performed.

RESULTS

(1) EPS decreased TG content (p < .01). (2) EPS significantly induced the mRNA expression of FAD/CD36 (p < .05), FATP4 (p < .001), FABP1 (p < .01) and FABP5 (p < .01). (3) EPS significantly inhibited the mRNA expression of fatty acid synthase (p < .01). (4) Adipose triglyceride lipase and hormone-sensitive lipase expression were significantly elevated (p < .001), and induced the mRNA expression of CPT1 (p < .01), ACOX1 (p < .05), UCP3 (p < .05) and PPARα (p < .001) after EPS.

CONCLUSION

EPS reduced lipid droplet accumulation; enhanced CD36, FATP4, FABP1 and FABP5 expression; inhibited C2C12 myotube fatty acid re-esterification; and promoted fatty acid oxidation in C2C12 myotubes.

Hypoxic Exercise Training to Improve Exercise Capacity in Obese Individuals

INTRODUCTION

Combining exercise training with hypoxic exposure has been recently proposed as a new therapeutic strategy to improve health status of obese individuals. Whether hypoxic exercise training (HET) provides greater benefits regarding body composition and cardiometabolic parameters than normoxic exercise training (NET) remains, however, unclear. We hypothesized that HET would induce greater improvement in exercise capacity and health status than NET in overweight and obese individuals.

METHODS

Twenty-three subjects were randomized into 8-wk HET (11 men and 1 woman; age, 52 ± 12 yr; body mass index, 31.2 ± 2.4 kg·m) or NET (eight men and three women; age, 56 ± 11 yr; body mass index, 31.8 ± 3.2 kg·m) programs (three sessions per week; constant-load cycling at 75% of maximal heart rate; target arterial oxygen saturation for HET 80%, FiO2 ~0.13, i.e., ~3700 m a.s.l.). Before and after the training programs, the following evaluations were performed: incremental maximal and submaximal cycling tests, measurements of pulse-wave velocity, endothelial function, fasting glucose, insulin and lipid profile, blood NO metabolites and oxidative stress, and determination of body composition by magnetic resonance imaging.

RESULTS

Peak oxygen consumption and maximal power output increased significantly after HET only (peak oxygen consumption HET + 10% ± 11% vs NET + 1% ± 10% and maximal power output HET + 11% ± 7% vs NET + 3% ± 10%, P < 0.05). Submaximal exercise responses improved similarly after HET and NET. Except diastolic blood pressure which decreased significantly after both HET and NET, no change in vascular function, metabolic status and body composition was observed after training. Hypoxic exercise training only increased nitrite and reduced superoxide dismutase concentrations.

CONCLUSIONS

Combining exercise training and hypoxic exposure may provide some additional benefits to standard NET for obese individual health status.

Assessing the utility of cardiorespiratory fitness, visceral fat, and liver fat in predicting changes in insulin sensitivity beyond simple changes in body weight after exercise training in adolescents

To examine the utility of changes in cardiorespiratory fitness (CRF) and body composition in response to exercise training in adolescents with obesity beyond simple measures of body weight change. This is a secondary analysis of our previously published randomized trials of aerobic, resistance, and combined training. We included 104 adolescents (body mass index (BMI) ≥85th percentile) who had complete baseline and post-intervention data for CRF, regional body fat, insulin sensitivity, and oral glucose tolerance. Associations between changes in body composition and CRF with cardiometabolic variables were examined adjusted for age, sex, Tanner stage, race, exercise group, and weight loss. At baseline, CRF, visceral fat and liver fat were correlated with insulin sensitivity with and without adjustment for BMI percentile. Training-associated changes in CRF, visceral fat, and liver fat were also correlated with insulin sensitivity changes, but not independent of body weight change. After accounting for body weight change, none of the body composition or CRF were associated with changes in insulin sensitivity, glucose tolerance, systolic blood pressure, or high-density lipoprotein cholesterol. Although CRF and body composition were strong independent correlates of insulin sensitivity at baseline, changes in CRF and visceral fat were not associated with changes in insulin sensitivity after accounting for body weight change. Clinicaltrials.gov registration nos.: NCT00739180, NCT01323088, NCT01938950. Novelty With exercise training, changes in body weight, CRF, visceral fat, and liver fat were correlated with changes in insulin sensitivity. Changes in body composition or CRF generally did not remain significant correlates of changes in insulin sensitivity after adjusting for body weight changes.

HIIT, RESISTANCE TRAINING, AND RISK FACTORS IN ADOLESCENTS: A SYSTEMATIC REVIEW

ABSTRACT It has been shown that combined physical exercise is an efficient non-pharmacological approach in the context of public health, since it has demonstrated satisfactory results in the prevention, treatment and control of various morbidities. Therefore, it is essential to systematize current knowledge to enable professionals involved in the prescription of physical exercise to do so based on evidence. Thus, the objective of this study was to perform a systematic review of randomized clinical trials to verify changes in cardiometabolic risk factors induced by high-intensity interval training (HIIT) and resistance training (RT) in adolescents. The systematic search was performed in the following databases: Pubmed, ScienceDirect, Cochrane, LILACS and Scielo. Initially 933 studies were identified, then two researchers eliminated duplications and manuscripts that did not meet the eligibility criteria. Thus, two articles were included that met these criteria: a randomized clinical trial conducted with adolescents (10 to 19 years) of both sexes, an intervention lasting for at least four weeks, which prescribed HIIT and RT in the same session or not, and evaluation of at least one cardiometabolic risk factor. The results demonstrated that eight to 12 weeks of HIIT and RT without nutritional intervention were effective in significantly reducing waist circumference and body fat percentage. However, data pertinent to the efficacy of this combination on risk of developing type 2 diabetes mellitus and arterial hypertension are controversial. In view of the above, it is ascertained from the included studies that the combination of HIIT and RT has the potential to reduce cardiometabolic risk factors in adolescents; therefore, further studies should be conducted to determine the effectiveness of this prescription of physical exercise. Level of Evidence II; Systematic review of Level II or Level I Studies with discrepant results.

A 2 year physical activity and dietary intervention attenuates the increase in insulin resistance in a general population of children: the PANIC study

AIMS/HYPOTHESIS

We studied for the first time the long-term effects of a combined physical activity and dietary intervention on insulin resistance and fasting plasma glucose in a general population of predominantly normal-weight children.

METHODS

We carried out a 2 year non-randomised controlled trial in a population sample of 504 children aged 6-9 years at baseline. The children were allocated to a combined physical activity and dietary intervention group (306 children at baseline, 261 children at 2-year follow-up) or a control group (198 children, 177 children) without blinding. We measured fasting insulin and fasting glucose, calculated HOMA-IR, assessed physical activity and sedentary time by combined heart rate and body movement monitoring, assessed dietary factors by a 4 day food record, used the Finnish Children Healthy Eating Index (FCHEI) as a measure of overall diet quality, and measured body fat percentage (BF%) and lean body mass by dual-energy x-ray absorptiometry. The intervention effects on insulin, glucose and HOMA-IR were analysed using the intention-to-treat principle and linear mixed-effects models after adjustment for sex, age at baseline, and pubertal status at baseline and 2 year follow-up. The measures of physical activity, sedentary time, diet and body composition at baseline and 2 year follow-up were entered one-by-one as covariates into the models to study whether changes in these variables might partly explain the observed intervention effects.

RESULTS

Compared with the control group, fasting insulin increased 4.65 pmol/l less (absolute change +8.96 vs +13.61 pmol/l) and HOMA-IR increased 0.18 units less (+0.31 vs +0.49 units) over 2 years in the combined physical activity and dietary intervention group. The intervention effects on fasting insulin (regression coefficient β for intervention effect -0.33 [95% CI -0.62, -0.04], p = 0.026) and HOMA-IR (β for intervention effect -0.084 [95% CI -0.156, -0.012], p = 0.023) were statistically significant after adjustment for sex, age at baseline, and pubertal status at baseline and 2 year follow-up. The intervention had no effect on fasting glucose, BF% or lean body mass. Changes in total physical activity energy expenditure, light physical activity, moderate-to-vigorous physical activity, total sedentary time, the reported consumption of high-fat (≥60%) vegetable oil-based spreads, and FCHEI, but not a change in BF% or lean body mass, partly explained the intervention effects on fasting insulin and HOMA-IR.

CONCLUSIONS/INTERPRETATION

The combined physical activity and dietary intervention attenuated the increase in insulin resistance over 2 years in a general population of predominantly normal-weight children. This beneficial effect was partly mediated by changes in physical activity, sedentary time and diet but not changes in body composition.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01803776 Graphical abstract.

Effects of Time-Restricted Feeding during Ramadan on Dietary Intake, Body Composition and Metabolic Outcomes

Ramadan fasting is a form of time-restricted feeding which combines a fast and feast period daily for a duration of one month every year. During Ramadan, Muslims abstain from food and drink consumption from dawn till sunset and this change in the meal schedule and frequency results in significant changes to the composition of the diet, such as energy and nutrient intake. These changes in dietary habits and their corresponding effects on cardiometabolic disease risk are compiled in this review. Ramadan fasting shows limited benefits to body composition via reductions in body mass in both healthy and obese individuals, although the results are often found to be transient and heterogeneous. There is, however, a more consistent improvement in blood lipid profile during Ramadan fasting, which often lasts beyond the Ramadan period. The results for glucose homeostasis, on the contrary, are more conflicting and inconclusive. The heterogeneity in the findings from the various studies can be generally attributed to cultural variations in dietary habits, differences in the duration of fasting due to seasonal/climatic differences at various geographical locations, age, gender and socioeconomic status, as well as other health and lifestyle factors of the various study populations.

The Role of Aberrant Metabolism in Cancer: Insights Into the Interplay Between Cell Metabolic Reprogramming, Metabolic Syndrome, and Cancer

Metabolic syndrome (MetS) is characterized by hyperglycemia, hypertension, dyslipidemia and abdominal obesity. Patients with MetS or other metabolic disorders are more susceptible to cancer development and recurrence and have a worse long-term prognosis. Moreover, the metabolic reprogramming observed in cancer cells has also been described as one of the new hallmarks of cancer. Thus, aberrant metabolism has been proposed as an important risk factor for cancer. Chronic inflammation, reactive oxygen species (ROS), and oncogenic signaling pathways are considered as main potential triggers. Considering the strong association between metabolism and cancer, metabolism-modulating drugs, including metformin and statins, as well as adopting a healthy lifestyle, have been extensively investigated as strategies to combat cancer. Furthermore, strategies that interfere with the metabolic rewiring of cells may also have potent anti-cancer effects. In this article, we provide a comprehensive review of current knowledge on the relationship between aberrant metabolism and cancer and discuss the potential use of metabolism-targeting strategy for the treatment of cancer.

The effects of exercise on vascular markers and C-reactive protein among obese children and adolescents: An evidence-based review

Numerous studies have evaluated the effects of exercise training on obese children and adolescents. However, the impact of aerobic and/or resistance exercise alone, without any other interventions, on vascular markers and C-reactive protein (CRP) in obese children and adolescents is still not clear. We performed a literature search in Ovid Medline, PubMed, and SCOPUS databases to identify articles on the effects of exercise on vascular markers and CRP among obese children and adolescents, published between January 2009 and May 2019. Only full-text articles in English that reported on the effect of aerobic and/or resistance exercise on the vascular markers pulse wave velocity (PWV), carotid intima-media thickness (CIMT), flow-mediated dilatation (FMD), augmentation index (AIx), or CRP in obese children and adolescents (5-19 years old) were included. The literature search identified 36 relevant articles; 9 articles that fulfilled all the inclusion criteria were selected by two independent reviewers. Aerobic exercise or a combination of aerobic and resistance exercise training significantly improved CIMT and PWV in obese children and adolescents in all studies in which they were measured (2 studies for PWV and 4 studies for CIMT). However, the effects of exercise on FMD and CRP levels were inconclusive, as only half of the studies demonstrated significant improvements (1/2 studies for FMD and 4/8 studies for CRP). The results of our review support the ability of exercise to improve vascular markers such as PWV and CIMT in obese children and adolescents. This finding is important as obesity is a modifiable risk factor of cardiovascular disease (CVD), and exercise may help in reducing the future occurrence of CVD in this population.

Metabolic syndrome in children

Despite plenty of currently available information on metabolic syndrome (MetS) in children and adolescents, there are still uncertainties regarding definition, prevention, management and treatment of MetS in children. The first approach to MetS in children consists of lifestyle interventions (nutritional education, physical activity). These recommendations are often difficult to achieve, especially for adolescents, therefore, there is usually a lack of successful outcomes. A pharmacological intervention in obese children may be needed in some cases, with the aim to improve the effects of these primary prevention interventions. Metformin seems to be safe and presents evident positive effects on insulin sensitivity, but long-term and consistent data are still missing to establish its role in the pediatric population and the possible effectiveness of other emergent treatments such as glucagon-like peptide-1 analogues, dipeptidylpeptidase-4 inhibitors, dual inhibitors of SGLT1 and SGLT2 and weight loss drugs. Bariatric surgery might be helpful in selected cases. The aim of this review is to present the most recent available treatments for the main components of metabolic syndrome, with a focus on insulin resistance. A short mention of management of congenital forms of insulin resistance will be included too.

Exercise and Insulin Resistance

In insulin resistance, alterations occur in the signalling pathways that modulate glucose uptake into cells, especially skeletal muscle cells, resulting in impaired glucose homeostasis. Glucose uptake into cells is controlled by a number of pathways, some of which are insulin-dependent. During exercise glucose uptake can occur independently of insulin regulation, and hence research into the effects of exercise on insulin resistance must be clearly defined to reflect whether glucose uptake has been enhanced as a result of the utilisation of these insulin-independent pathways, or whether exercise directly affects insulin resistance in cells. Research into the benefits of exercise for insulin resistance is also problematic in the need to clarify whether it is the exercise itself, or the visceral fat/weight loss that has resulted from the exercise, that has led to improved insulin sensitivity. The research presents a promising picture for the benefits of exercise in insulin resistance.

Exercise improves metabolic function and alters the microbiome in rats with gestational diabetes

Gestational diabetes mellitus (GDM) is a common pregnancy complication, particularly prevalent in obese women. Importantly, exercise has beneficial impacts on maternal glucose control and may prevent GDM in "at-risk" women. We aimed to determine whether a high-fat diet (HFD) exacerbates metabolic dysfunction and alters gut microbiome in GDM and whether endurance exercise prevents these changes. Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (Restricted) or sham (Control) surgery on E18 in Wistar-Kyoto rats. Female offspring were fed a Chow or HFD (23% fat) from weaning (5 weeks) and at 16 weeks randomly allocated to remain Sedentary or to an exercise protocol of either Exercise prior to and during pregnancy (Exercise); or Exercise during pregnancy only (PregEx). Females were mated (20 weeks) and underwent indirect calorimetry (embryonic day 16; E16), glucose tolerance testing (E18), followed by 24-hr feces collection at E19 (n = 8-10/group). HFD consumption in female rats with GDM exacerbated the adverse metabolic adaptations to pregnancy and altered gut microbial populations. Specifically, the Firmicutes-to-Bacteroidetes ratio was increased, due to an underlying change in abundance of the orders Clostridiales and Bacteroidales. Maternal Exercise, but not PregEx, prevented the development of metabolic dysfunction, increased pancreatic β-cell mass, and prevented the alteration of the gut microbiome in GDM females. Our findings suggest that maternal exercise and diet influence metabolic and microbiome dysfunction in females with GDM, which may impact long-term maternal and offspring health.

Differential Reduction of IP-10 and C-Reactive Protein via Aerobic Exercise or Mindfulness-Based Stress-Reduction Training in a Large Randomized Controlled Trial

Exercise and meditation improve health and well-being, potentially through decreasing systemic inflammation. In this study, healthy adults (N = 413) were randomized to 8 weeks of training in aerobic exercise, matched mindfulness-based stress reduction, or wait-list control. Three inflammation-related biomarkers (C-reactive protein, interleukin-6, and interferon-gamma-inducible protein-10) were assessed preintervention, directly postintervention, and 17 weeks later. Within-group analyses found that exercise participants had decreased serum interferon-gamma-inducible protein-10 postintervention and 17 weeks later, whereas C-reactive protein was lower in mindfulness-based stress-reduction participants 17 weeks postintervention only. Self-reported physical activity or amount of meditation practice did not predict biomarker changes. This study suggests that (a) training in aerobic exercise can lower interferon-gamma-inducible protein-10, a chemokine associated with interferon activity and illness, and (b) training in mindfulness meditation may have a delayed effect on C-reactive protein, an important inflammatory biomarker. The findings highlight the likelihood of multiple, distinct pathways underlying the health-promoting effects of these lifestyle interventions.

Physical activity in adolescents and children and relationship to metabolic health

PURPOSE OF REVIEW

To summarize the recent developments relating to the role of physical activity in improving insulin resistance and metabolic syndrome in children and adolescents.

RECENT FINDINGS

The current literature strengthens previous findings on the relationship between physical activity and metabolic health in children; suggests a protective role for physical activity in the setting of obesity; examines population-specific findings; addresses specific effects of different modalities of physical activity in improving health; reveals potential mediators in the relationship between physical activity and metabolic health; and suggests new markers of metabolic health that could potentially be used as outcomes in future physical activity studies.

SUMMARY

Recent research generally confirms the role of physical activity in decreasing insulin resistance and metabolic syndrome in children and adolescents. However, the current literature is limited by unstandardized research methods and definitions, and also aggregation of different age groups, genders, and weight status. Future research should address these issues to offer targeted physical activity interventions.

Effects of exercise intervention on visceral fat in obese children and adolescents

INTRODUCTION

This meta-analysis study was aimed to assess the effects of exercise intervention on visceral fat in obese children and adolescents.

EVIDENCE ACQUISITION

Electronic database searches were performed in Academic Search Complete, CINAHL, Healthsource, MEDLINE, and SportDiscus, and from the earliest record to November 2017. Keywords included "exercise or training," "visceral fat," and "child or adolescent or youth." The inclusion criteria for eligible studies were as follows: 1) subjects were obese at baseline; 2) aged 6-19 years; 3) visceral fat was reported at baseline and after an intervention; and 4) studies were published in peer-reviewed journals written in English.

EVIDENCE SYNTHESIS

A total of 207 studies were observed at the initial search and 73 effect sizes (ESs) were derived from the 34 selected studies. The overall exercise intervention effect was large (Cohen's d [ES]=-1.003, 95% CI=-1.114, -0.892). Moderator analyses results showed that gender (Qb=8.23, df=2, P=0.016), exercise type (Qb=10.68, df=2, P=0.005), and intervention length (Qb=24.71, df=2, P<0.001) influenced the overall ES.

CONCLUSIONS

The group of both boys and girls (ES=-0.95) who participated combined exercise program (Aerobic + Resistance training; ES=-1.17) for 12 months (ES=-1.24) appeared to be the most effective exercise strategy for reducing visceral fat in obese youth.

Effect of Low- Versus High-Intensity Exercise Training on Biomarkers of Inflammation and Endothelial Dysfunction in Adolescents With Obesity: A 6-Month Randomized Exercise Intervention Study

PURPOSE

To investigate the effects of a low- versus high-intensity aerobic training on biomarkers of inflammation and endothelial dysfunction in adolescents with obesity.

METHODS

Sixty-two adolescents with obesity [age = 15 (14) y, body mass index = 34.87 (4.22) kg·m^-2] were randomized to receive either a high-intensity training (HIT, n = 31) or a low-intensity training (LIT, n = 31) for 24 weeks. All participants also received nutritional, psychological, and clinical counseling. Leptin, total and subtype leukocyte counts, tumor necrosis factor-alpha, interleukin-6, myeloperoxidase, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were obtained at baseline and after 24 weeks.

RESULTS

HIT reduced neutrophils [from 4.4 (1.9) to 3.6 (1.3) µL^-1 × 10³; P = .01] and monocytes [from 7.2 (2.5) to 5.2 (1.8) µL^-1 × 10²; P < .01], but LIT increased neutrophils [from 4.5 (1.7) to 5.2 (3.3) µL^-1 × 10³; P = .01]. Although tumor necrosis factor-alpha increased in LIT [from 13.3 (7.5) to 17.7 (10.8) pg·mL^-1; P = .01], it decreased in HIT [from 12.4 (7.5) to 11.3 (6.2) pg·mL^-1; P = .01]. No changes in leukocyte counts, soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule-1, and homeostasis assessment model for insulin resistance were observed.

CONCLUSIONS

Both HIT and LIT improved the inflammatory profile. The study, however, indicated that the number of biomarkers and the magnitude of changes were higher in the HIT compared with LIT.

Aerobic exercise improves endothelial function and serum adropin levels in obese adolescents independent of body weight loss

Adropin is a secreted protein that regulates endothelial function. However, adropin levels in obese adolescent patients are currently uncertain. Therefore, we evaluated the association between plasma adropin levels and vascular endothelial function and investigated the effect of aerobic exercise in obese adolescents. A total of 45 obese adolescents and 20 controls (age 16-19 years) were included in our study. The obese adolescents received 12 weeks of aerobic exercise training. Serum adropin was detected using enzyme-linked immunosorbent assay. Vascular reactive hyperemia indexes (RHIs) were obtained using Endo-PAT2000. Adropin levels and RHI were significantly lower in obese adolescents than in normal-weight adolescents. Adropin levels and RHI increased significantly independently of changes in body weight after an exercise intervention (P < 0.01). Pearson correlation analysis revealed that adropin levels positively correlated with HDL-C levels (r = 0.389, P < 0.01) and RHI (r = 0.32, P < 0.01). Multiple linear stepwise regression analysis showed that the insulin resistance index (t = -3.301, P < 0.01) and HDL-C level (t = 2.620, P = 0.011) were independent risk factors of adropin levels. In addition, Δadropin (t = 3.261, P < 0.01) was an independent influencing factor of ΔRHI. Our findings suggest that adropin plays an important role in vascular endothelial function in obese adolescents.

The Effect of Ramadan Fasting on Biochemical Parameters in Healthy Thai Subjects

Introduction

Although, the effect of Ramadan fasting on the risks for Cardiovascular Disease (CVD) has been reported in several studies, the results were inconsistent. In addition, the effect of Ramadan fasting on biochemical parameters in Thai subjects has not been evaluated.

Aim

The aim of this study was to investigate the effect of Ramadan fasting on anthropometry, blood pressure, Fasting Blood Glucose (FBG), lipid profiles, and body composition in healthy Thai subjects.

Materials and Methods

A total of 65 healthy subjects (21 men and 44 women) aged between 19-24 years were randomly recruited. Anthropometry, blood pressure, FBG, Total Cholesterol (TC), Triglyceride (TG), High Density Lipoprotein-Cholesterol (HDL-C), Low Density Lipoprotein-Cholesterol (LDL-C), and body composition were measured before Ramadan, end of Ramadan and after one month of Ramadan.

Results

There were no changes in anthropometry, blood pressure, lipid profiles and body composition in both genders before Ramadan, end of Ramadan and after one month of Ramadan. Nevertheless, FBG levels were significantly increased after one month of Ramadan compared with baseline (5.09±0.50 versus 4.83±0.38 mmol/L, p=0.016, respectively) in women.

Conclusion

The Ramadan fasting did not affect the lipid, anthropometric and body composition in healthy Thai subjects. However, the increased FBG levels after one month of Ramadan were observed in women. To improve the favourable biochemical parameters after Ramadan fasting, the lifestyle modifications such as, increased intake of healthy diets and increased physical activity should be recommended.

Adolescent's Health Behaviors and Risk for Insulin Resistance: A Review of the Literature

PURPOSE OF REVIEW

One-third of US adolescents are obese, and related comorbidities exist in this population. Preventing early indicators of these diseases, such as insulin resistance (IR), may impact future morbidity and mortality. Interventions to date have only focused on diet or exercise. Additional targets to prevent disease are needed. This paper reviews the evidence in adolescents examining multiple health behaviors that have been associated with IR.

RECENT FINDINGS

Health behaviors (i.e., diet, activity, sleep) have been individually examined as possible contributors to disease, but an understanding of the complex interplay between these behaviors is lacking. A better understanding of how multiple health behaviors contribute to IR in adolescents is needed. Future studies using both advanced statistical methodology and robust measures of each health behavior may facilitate better understanding of the impact of lifestyle factors on IR and guide intervention strategies to reduce the risk of disease.

A systematic review and meta-analysis of energy and macronutrient intake responses to physical activity interventions in children and adolescents with obesity

BACKGROUND

The effects of regular physical activity on energy intake in obese adolescents are unknown.

OBJECTIVE

The objective is to determine how physical activity interventions affect energy and macronutrient intake in overweight/obese youth.

DATA SOURCES

Databases were searched from December 2014 to December 2015 for studies that measured energy and/or macronutrient consumption in response to physical activity intervention in overweight/obese youth.

DATA SELECTION

The review comprises primary source articles published in English in peer-reviewed journals. Articles that presented data on energy and/or macronutrient intake before and after a physical activity intervention (without dietary restriction) in overweight or obese children and teenagers (up to 18 years old) were included. Of the initial 307 references found, nine were included.

RESULTS

The nine included studies analysed the effect of 15 different physical activity interventions. Nine showed a decrease and six unchanged energy intakes. The effect size for total energy intake ranged from -2.108 to -0.207 (n = 14). Results of the meta-analysis revealed a mean effect of physical intervention to reduce intake of -1.003 (95% confidence interval = -1.261 to -0.745, p < 0.001). Results for heterogeneity among these studies were I²  = 67.421; Q = 39.903; d_f  = 13, p < 0.001. The mean energy intake reduction was -323 ± 286 kcal. Macronutrient intake was assessed in 11 interventions. Protein intake was found decreased in five (reduction of -26.8 ± 19.2 g), seven reported fat decrease (reduction of -26.4 ± 17.8 g) and five a decrease in CHO (reduction of -72.5 ± 22.8 g). The meta-analysis revealed significant decreases of each macronutrient (p < 0.001).

CONCLUSION

Structured physical activity interventions favour decreased daily energy intake in obese adolescents.

The association among skeletal muscle phosphocreatine recovery, adiposity, and insulin resistance in children

BACKGROUND

Obesity is associated with cardiometabolic disturbances, which may have significant implications for musculoskeletal health and exercise tolerance.

OBJECTIVE

We sought to determine the association between muscle structure, function, and metabolism in adolescents across the weight spectrum.

METHODS

This cross-sectional case-control study included overweight and obese participants (n = 24) 8-18 years of age with a body mass index (BMI) ≥ 85th percentile for age and gender, and non-obese participants (n = 24) with a BMI < 85^th percentile. Body composition, physical activity, peak aerobic capacity, cardiometabolic blood markers and insulin resistance (measured by the homeostatic model assessment of insulin resistance, HOMA-IR), skeletal muscle mitochondrial oxidative capacity (via ³¹ Phosphorous-Magnetic Resonance Spectroscopy, ³¹ P-MRS, to assess phosphocreatine (PCr) recovery after exercise), and extramyocellular and intramyocellular lipid (IMCL) levels (via ¹ Hydrogen-MRS) were assessed. Stepwise regression was performed to examine the factors associated with oxidative capacity.

RESULTS

bese and overweight patients had similar age, height, and physical activity to non-obese controls, but obese and overweight participants exhibited higher insulin resistance. Obese and overweight participants had longer PCr recovery than non-obese controls following 5x30s of moderate-intensity exercise (51.2 ± 20.1 s vs. 23.9 ± 7.5 s, p = 0.004). In univariate correlation analysis, impaired PCr recovery was associated with a higher BMI z-score (r_s  = 0.51, p < 0.001), circulating triglycerides (r_s  = 0.41, p = 0.005), and HOMA-IR (r_s  = 0.46, p = 0.001). In stepwise multivariate regression analysis, impaired PCr recovery was associated with a higher BMI z-score (β = 0.47, p = 0.002), but not insulin resistance (β = 0.07, p = 0.07) or circulating triglycerides (β = 0.16 p = 0.33).

CONCLUSION

A slower phosphocreatine recovery following aerobic exercise is strongly associated with increasing adiposity. A slower metabolic recovery following aerobic exercise stress suggests that endurance exercise training in obese adolescents may be an optimal strategy to target exercise intolerance in this cohort.

Swimming exercise reduces preference for a high-fat diet by increasing insulin sensitivity in C57BL/6 mice

The present study examined the effect of 4-week swimming training on the preference for a high-fat diet and insulin sensitivity in mice. C57BL/6 J mice were placed on either a low-fat diet or a choice diet (with both low-fat and high-fat diets available) for 6 weeks. During this period, a group of mice on the free-choice diet were randomly selected to receive a 4-week swimming exercise intervention. Mice that received the swimming exercise intervention showed a reduced preference for the high-fat diet as well as a slower rate of weight gain. Moreover, changes in insulin sensitivity, tyrosine hydroxylase expression in the ventral tegmental area-nucleus accumbens system, and the expression of IRS2, IRS2, and high-fat diet-induced Akt phosphorylation in the nucleus accumbens were delayed in the swimming exercise intervention group. Taken together, these results suggest that swimming exercise regulates the dopaminergic reward system to decrease high-fat diet intake, thereby controlling body weight to prevent obesity, in a manner likely mediated by increased insulin signal transduction in the nucleus accumbens.

Glucocorticoid antagonism limits adiposity rebound and glucose intolerance in young male rats following the cessation of daily exercise and caloric restriction

Severe caloric restriction (CR), in a setting of regular physical exercise, may be a stress that sets the stage for adiposity rebound and insulin resistance when the food restriction and exercise stop. In this study, we examined the effect of mifepristone, a glucocorticoid (GC) receptor antagonist, on limiting adipose tissue mass gain and preserving whole body insulin sensitivity following the cessation of daily running and CR. We calorically restricted male Sprague-Dawley rats and provided access to voluntary running wheels for 3 wk followed by locking of the wheels and reintroduction to ad libitum feeding with or without mifepristone (80 mg·kg(-1)·day(-1)) for 1 wk. Cessation of daily running and CR increased HOMA-IR and visceral adipose mass as well as glucose and insulin area under the curve during an oral glucose tolerance test vs. pre-wheel lock exercised rats and sedentary rats (all P < 0.05). Insulin sensitivity and glucose tolerance were preserved and adipose tissue mass gain was attenuated by daily mifepristone treatment during the post-wheel lock period. These findings suggest that following regular exercise and CR there are GC-induced mechanisms that promote adipose tissue mass gain and impaired metabolic control in healthy organisms and that this phenomenon can be inhibited by the GC receptor antagonist mifepristone.

Associations of sedentary time patterns and TV viewing time with inflammatory and endothelial function biomarkers in children

OBJECTIVE

Investigate associations of TV viewing time and accelerometry-derived sedentary time with inflammatory and endothelial function biomarkers in children.

METHODS

Cross-sectional analysis of 164 7-10-year-old children. TV viewing time was assessed by parental proxy report and total and patterns of sedentary time accumulation (e.g. prolonged bouts) were assessed by accelerometry. C-reactive protein (CRP), homeostasis model assessment of insulin resistance, interleukin-2, -6, -8, -10, tumour necrosis factor alpha, adiponectin, resistin, brain-derived neurotrophic factor, soluble intercellular and vascular adhesion molecule 1, plasminogen activator inhibitor 1 and soluble E-selectin were assessed. Generalised linear models assessed the associations of TV viewing and sedentary time with biomarkers, adjusting for sex, waist circumference, moderate- to vigorous-intensity physical activity and diet density.

RESULTS

Each additional h week(-1) of TV viewing was associated with 4.4% (95% CI: 2.1, 6.7) greater CRP and 0.6% (0.2, 1.0) greater sVCAM-1 in the fully adjusted model. The association between frequency and duration of 5-10 min bouts of sedentary time and CRP was positive after adjustment for sex and waist circumference but attenuated after adjustment for diet density.

CONCLUSIONS

This study suggests that TV viewing was unfavourably associated with several markers of inflammation and endothelial dysfunction. The detrimental association between 5 and 10 min bouts of sedentary time and CRP approached significance, suggesting that further research with a stronger study design (longitudinal and/or experimental) is needed to better understand how the accumulation of sedentary time early in life may influence short and longer term health.

Sleep quality, sleep duration and physical activity in obese adolescents: effects of exercise training

BACKGROUND

Decreased sleep duration and altered sleep quality are risk factors for obesity in youth. Structured exercise training has been shown to increase sleep duration and improve sleep quality.

OBJECTIVES

This study aimed at evaluating the impact of exercise training for improving sleep duration, sleep quality and physical activity in obese adolescents (OB).

METHODS

Twenty OB (age: 14.5 ± 1.5 years; body mass index: 34.0 ± 4.7 kg m(-2) ) and 20 healthy-weight adolescents (HW) completed an overnight polysomnography and wore an accelerometer (SenseWear Bodymedia) for 7 days. OB participated in a 12-week supervised exercise-training programme consisting of 180 min of exercise weekly. Exercise training was a combination of aerobic exercise and resistance training.

RESULTS

Sleep duration was greater in HW compared with OB (P < 0.05). OB presented higher apnoea-hypopnoea index than HW (P < 0.05). Physical activity (average daily metabolic equivalent of tasks [METs]) by accelerometer was lower in OB (P < 0.05). After exercise training, obese adolescents increased their sleep duration (+64.4 min; effect size: 0.88; P = 0.025) and sleep efficiency (+7.6%; effect size: 0.76; P = 0.028). Physical activity levels were increased in OB as evidenced by increased steps per day and average daily METs (P < 0.05). Improved sleep duration was associated with improved average daily METs (r = 0.48, P = 0.04).

CONCLUSION

The present study confirms altered sleep duration and quality in OB. Exercise training improves sleep duration, sleep quality and physical activity.

Effects of Ramadan fasting on glucose homeostasis and adiponectin levels in healthy adult males

BACKGROUND

Adiponectin is a hormone secreted by adipocytes during the fasting phase of the fast-fed cycle. Ramadan fasting involves prolonged fasting for up to twelve hours and thus could lead to increased secretion of adiponectin by adipocytes. However, studies on the role of adiponectin on glucose and body weight homeostasis during Ramadan fasting is still a matter of controversy. Thus the specific aim of this study was to assess the effect of fasting during Ramadan on the adiponectin levels, body weight and glucose homeostasis in healthy male Malaysian subjects.

METHODS

Twenty healthy male (19-23 years) Muslim subjects were followed up during the fasting month of Ramadan. Anthropometry and blood samples were taken one week before and during the fourth week of fasting. Plasma glucose, insulin and adiponectin were estimated and insulin sensitivity indices were estimated using the Homeostasis Model Assessment.

RESULTS

Subjects experienced a significant decrease in body weight (2.4 %, p < 0.001) and body mass index (5.5 %, p < 0.01). There was also a significant decrease of 12.3 %, 52.8 % and 45.6 % of plasma glucose, insulin and adiponectin respectively (p < 0.01). The drop in adiponectin was positively correlated with the decrease in body weight (r = 0.45, p < 0.05). There was also a significant increase in insulin sensitivity and a decrease in insulin resistance (p < 0.01).

CONCLUSIONS

These results indicate that Ramadan fasting in young healthy individuals has a positive impact on the maintenance of glucose homeostasis. It also shows that adiponectin levels dropped along with significant loss in weight. We feel caloric restriction during the Ramadan fasting is in itself sufficient to improve insulin sensitivity in healthy individuals.

Attenuating type 2 diabetes with postpartum interventions following gestational diabetes mellitus

Women with a history of gestational diabetes should be screened during and after the postpartum period because of a high risk for developing type 2 diabetes mellitus. Although differences exist between guidelines practiced throughout various parts of the world, all recommend the use of cutoffs for fasting and/or post-load plasma glucose to diagnose diabetes or pre-diabetes. The use of these glycemic parameters could be optimized when a trend is observed, rather than considering them as isolated values at various time points. As the presence of insulin resistance and beta-cell dysfunction start before glycemic changes are evident, the estimation of insulin sensitivity and beta-cell function by Homeostatic Model Assessment is suggested for women who have additional risk factors for diabetes, such as obesity. Disease-modifying lifestyle intervention should be the first-line strategy to prevent or delay the onset of diabetes in women with a history of gestational diabetes mellitus. Intensive lifestyle interventions are designed to decrease caloric intake and increase physical activity in order to reduce body weight and fat, which will in turn reduce insulin resistance. This article also reviews unique problems of postpartum women, which should be considered when designing and implementing an intervention. Innovative “out of the box” thinking is appreciated, as continued adherence to a program is a challenge to both the women and the health care personnel who deal with them.

One-week high-fat diet leads to reduced toll-like receptor 2 expression and function in young healthy men

Toll-like receptor 2 (TLR2) is implicated in inflammatory responses to high-fat diet (HFD)-induced obesity in rodents, but human HFD studies examining TLR2-mediated immune responses are lacking. Our aim was to determine whether HFD affected TLR2 function in humans. We hypothesized that a short-term HFD in humans would impair TLR2-mediated immune function. Fasting blood samples were obtained from healthy young men (N = 9) before and after a 7-day HFD. Toll-like receptor 2 function was assessed in ex vivo whole blood cultures stimulated with the TLR2 agonist N-palmitoyl-S-[2,3-bis[palmitoyloxy]-[2RS]-propyl]-[R]-cysteinyl-[S]-seryl-[S]-lysyl-[S]-lysyl-[S]-lysyl-[S]-lysine (Pam3-Cys-SK4). Peripheral blood mononuclear cells (PBMCs) were isolated to examine TLR2, TLR4, and p47 subunit of nicotinamide adenine dinucleotide phosphate oxidase (p47(phox)) protein expression via Western blotting. Pam3-Cys-SK4-stimulated secretion of interleukin-1β (-35%, P = .005), interleukin-6 (-32%, P = .01), and tumor necrosis factor-α (-33%, P = .06) was reduced following the HFD. High-fat diet resulted in decreased TLR2 (P = .049) and p47(phox) (P = .037) protein expression from PBMCs. To mimic lipid overload ex vivo, follow-up experiments were performed in whole blood cultures exposed to a mixture of free fatty acids for 24 hours; and surface protein expression of TLR2 and TLR4 on CD14+ monocytes was measured by flow cytometry. Free fatty acid exposure for 24 hours ex vivo reduced monocyte TLR2 levels by about 20% (P = .028). A 7-day HFD in young healthy men resulted in impaired TLR2 function. Decreased TLR2 and p47(phox) protein expression in PBMCs, possibly due to excess free fatty acids, may mediate this response. Our current findings indicate that impaired TLR2 response after HFD might be partially responsible for increased risk of infection in diet-induced obesity.