Relationships of cardiorespiratory fitness with metabolic risk factors, inflammation, and liver transaminases in overweight youths

The effectiveness of multidisciplinary weight loss interventions is associated with initial cardiorespiratory fitness in adolescents with obesity

BACKGROUND

The identification of predictive parameters of the success of multidisciplinary weight loss interventions (MWLI) appears essential to optimize obesity management. The association between baseline cardiorespiratory fitness (CRF) and changes in anthropometric parameters and body composition during MWLI remains underexplored in adolescents with obesity.

OBJECTIVES

To assess whether baseline CRF was associated with the effectiveness of a 16-week MWLI measured through improved body mass, body mass index (BMI) and body composition (percentage of total fat mass (FM) as the main criterion).

METHODS

Cardiorespiratory fitness and body composition were respectively measured by peak oxygen consumption (VO2peak) during maximal exercise tests and dual-photon x-ray absorptiometry (DXA), before (T0) and after (T1) a 16-week MWLI in 165 adolescents (aged 13.3 ± 1.38 years, 61.2% female, BMI 35.11 ± 5.16 kg/m2).

RESULTS

Reductions in BMI and total FM percentage between T0 and T1 were greater in subjects with a baseline VO2peak ≥ 3rd quartile compared to the first quartile (p < 0.001) and the interquartile range (p < 0.05 and p < 0.001, respectively). Baseline VO2peak and VO2 at the first ventilator threshold were positively correlated with the reductions in body mass, BMI and total and visceral FM percentages and with the increase in lean mass (LM) percentage between T0 and T1 after adjustment for age and gender (p < 0.001).

CONCLUSION

Initial CRF is associated with the success of MWLI in adolescents with obesity. Improving their aerobic fitness before starting a MWLI might be a promising strategy to optimize its benefits.

Left atrial remodeling in adolescents with obesity evaluated by speckle-tracking echocardiography

BACKGROUND AND AIMS

In adolescents with obesity, a left atrial (LA) enlargement has been reported. However, data regarding its function and its stiffness are missing. The aim of this study was to describe LA morphology and function, using speckle-tracking echocardiography (STE) and to explore their potential determinants in adolescents with obesity.

METHODS

Twenty-eight adolescent women with obesity (13.2 ± 1.4 yr) with an illness duration of 130 ± 27 months and 33 controls (14.1 ± 2.0 yr) underwent a resting echocardiography including an analysis of left ventricular (LV) and LA morphologies and strains. A fasting venous blood sample was performed to biochemical determinations including inflammation markers.

RESULTS

LA volume and stiffness index were increased in adolescents with obesity compared to controls. LA reservoir, conduit and booster pump functions were not different between groups. By stepwise forward multivariate regression analyses, systolic blood pressures, cardiac output and sedimentation rate were the independent determinants of LA volume (p < 0.0001, β-coefficient = 0.460) whereas only the body mass index was an independent determinant of LA stiffness (p = 0.003, β-coefficient = 0.413).

CONCLUSION

In adolescents with obesity, we observed a specific LA remodeling, including higher volume and lower stiffness, which could constitute early signs of an altered LV diastolic function.

Cardiorespiratory fitness, waist circumference, and alanine aminotransferase in youth

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is considered the liver component of the metabolic syndrome and is strongly associated with cardiometabolic diseases. In adults, cardiorespiratory fitness (CRF) is inversely associated with alanine aminotransferase (ALT), a blood biomarker for NAFLD. However, information regarding these associations is scarce for youth. The objective of this study is to examine associations between CRF, waist circumference, and ALT in youth.

METHODS

Data were obtained from youth (n = 2844, 12-19 yr) in the National Health and Nutrition Examination Survey 2001-2004. CRF was dichotomized into youth FITNESSGRAM categories of "low" and "adequate" CRF. Logistic and quantile regression were used for a comprehensive analysis of associations, and variables with previously reported associations with ALT were a priori included in the models.

RESULTS

Results from logistic regression suggested that youth with low CRF had 1.5 times the odds of having an ALT >30 than youth with adequate CRF, although the association was not statistically significant (P = 0.09). However, quantile regression demonstrated that youth with low CRF had statistically significantly higher ALT (+1.04, +1.05, and +2.57 U·L) at the upper end of the ALT distribution (80th, 85th, and 90th percentiles, respectively) than youth with adequate CRF. For every 1-cm increase in waist circumference, the odds of having an ALT >30 increased by 1.06 (P < 0.001), and the strength of this association increased across the ALT distribution.

CONCLUSIONS

Future studies should examine whether interventions to improve CRF can decrease hepatic fat and liver enzyme concentrations in youth with ALT ≥80th percentile or in youth diagnosed with NAFLD.

Serum levels of choline-containing compounds are associated with aerobic fitness level: the HUNT-study

Background

Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of people at risk is continuously growing. New methods for early risk prediction are therefore needed to actuate prevention strategies before the individuals are diagnosed with CVD. Several studies report that aerobic fitness level, measured as maximal oxygen uptake (VO_2max), is the single best predictor of future CVD mortality in healthy people. Based on this, we wanted to study differences between healthy individuals with a large difference in VO_2max-level to identify new biomarkers of low aerobic fitness that may also have potential as early biomarkers of CVD risk.

Methodology/Principal Findings

Serum samples from 218 healthy individuals with a low VO_2max (n = 108, 63 women) or high VO_2max (n = 110, 64 women) were analysed with MR metabolomics. In addition, standard clinical-chemical analyses for glucose, lipids, liver enzymes, micro-CRP, and colorimetric analysis on circulating choline were performed. Individuals in the low VO_2max-group had increased serum levels of free choline, decreased phosphatidylcholine, increased glucosę and decreased unsaturated fatty acids compared to the individuals in the high VO_2max–group.

Conclusions/Significance

Aerobic fitness dependent differences in serum levels of free choline and phosphatidylcholine are observed. They should be further studied as potential early markers of CVD risk.

Physical activity is related to insulin sensitivity in children and adolescents, independent of adiposity: a review of the literature

In adults, there is evidence that physical activity effectively improves insulin sensitivity regardless of adiposity. Whether this is also the case in children and adolescents is less clear. Clarifying this matter may help to identify the best outcomes to target in exercise programs for these age groups, where changes in adiposity may not always be desirable or realistic. A review of the literature was conducted on studies that examined the relationships of physical activity, cardiorespiratory fitness and strength with insulin sensitivity independent of adiposity in children and adolescents. Experimental (intervention) and correlational (longitudinal and cross-sectional) studies on participants ages 18 years and younger were identified. A total of 42 studies were included in this review. Sample sizes in the studies ranged from 14 to 4955 participants, with individual ages ranging from 5 to 19 years. A significant relationship with insulin sensitivity existed in 78% of studies on physical activity, 69% of studies on cardiorespiratory fitness and 66% of studies on strength. In studies that examined both physical activity and cardiorespiratory fitness concurrently, evidence suggests that they are both correlated with insulin sensitivity independent of adiposity, especially when physical activity is at higher intensities. However, the strength of this relationship might be influenced by study design, measurement techniques and participant characteristics. This is the first review of its type to take research design into account and to examine study outcomes according to participant ethnicity, gender, age, pubertal status and weight status.

Trace glucose and lipid metabolism in high androgen and high-fat diet induced polycystic ovary syndrome rats

BACKGROUND

There is a high prevalence of diabetes mellitus (DM) and dyslipidemia in women with polycystic ovary syndrome (PCOS). The purpose of this study was to investigate the role of different metabolic pathways in the development of diabetes mellitus in high-androgen female mice fed with a high-fat diet.

METHODS

Female Sprague-Dawley rats were divided into 3 groups: the control group(C), n = 10; the andronate-treated group (Andronate), n = 10 (treated with andronate, 1 mg/100 g body weight/day for 8 weeks); and the andronate-treated and high-fat diet group (Andronate+HFD), n = 10. The rate of glucose appearance (Ra of glucose), gluconeogenesis (GNG), and the rate of glycerol appearance (Ra of glycerol) were assessed with a stable isotope tracer. The serum sex hormone levels, insulin levels, glucose concentration, and the lipid profile were also measured.

RESULTS

Compared with control group, both andronate-treated groups exhibited obesity with higher insulin concentrations (P < 0.05) but similar blood glucose concentrations. Of the two andronate-treated groups, the andronate+HFD group had the most serious insulin resistance (IR). Estrus cycles were completely acyclic, with polycystic ovaries and elevated serum lipid profiles in the andronate+HFD group (P < 0.05). Ra of glucose and GNG increased significantly in the andronate+HFD rats. However, the Ra of glycerol was similar in the three groups.

CONCLUSIONS

Andronate with HFD rat model showed ovarian and metabolic features of PCOS, significant increase in glucose Ra, GNG, and lipid profiles, as well as normal blood glucose levels. Therefore, aberrant IR, increased glucose Ra, GNG, and lipid metabolism may represent the early-stage of glucose and lipid kinetics disorder, thereby might be used as potential early-stage treatment targets for PCOS.

Non-traditional markers of metabolic risk in prepubertal children with different levels of cardiorespiratory fitness

OBJECTIVE

To assess classical and non-classical metabolic risk biomarkers in prepubertal children with different levels of cardiorespiratory fitness (CRF).

DESIGN

CRF was assessed by the 20 m shuttle run test. To estimate physical activity, participants were observed while engaged in an after-school programme. Additionally, a short test based on a validated questionnaire was used to obtain information about physical activity practice and sedentary habits. Anthropometric parameters, blood pressure, and classical and non-traditional metabolic risk biomarkers--plasma lipid profile, glucose and insulin, homeostasis model assessment-insulin resistance index (HOMA-IR), plasma uric acid, transaminases and C-reactive protein (CRP)--were measured.

SETTING

The study was conducted in local elementary schools in Córdoba, Spain.

SUBJECTS

One hundred and forty-one healthy children (eighty-eight boys, fifty-three girls) aged 7-12 years, in Tanner stage I, were recruited. They were divided into two groups after they performed the 20 m shuttle run test: equal or higher cardiovascular fitness (EHCF) group and low cardiovascular fitness (LCF) group.

RESULTS

The LCF group displayed significantly higher TAG (P = 0.004) and lower HDL cholesterol levels (P = 0.001), as well as significantly lower values for the non-traditional lipid marker apo-A1 (P = 0.001) compared with the EHCF group. The LCF children displayed higher plasma glucose (P = 0.003) and insulin levels, higher HOMA-IR scores (P < 0.001) and higher plasma uric acid and CRP levels (P < 0.05). After adjustment for BMI, age and sex, no statistically significant differences were found between groups for the biomarkers analysed.

CONCLUSIONS

The study provides new information to understand the role not only of weight status but also of the level of CRF on the metabolic health profile of prepubertal children.

Assessing and treating insulin resistance in women with polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a highly prevalent hormonal and metabolic disorder among reproductive aged women worldwide. Women with PCOS have widely varying phenotypes and seek medical care for differing reasons. In addition to concern for menstrual cycle function, ovulation, hirsutism and acne, many PCOS women have abnormal glucose metabolism. While diabetes mellitus and impaired glucose tolerance are easily diagnosed, the diagnosis of and concern for insulin resistance as a precursor disorder is underappreciated. Insulin resistance may be the first important marker of metabolic disease in PCOS women at risk for metabolic syndrome and coronary artery disease.