Fecal microbiota composition is related to brown adipose tissue 18F-fluorodeoxyglucose uptake in young adults.

OBJECTIVE: Human brown adipose tissue (BAT) has gained considerable attention as a potential therapeutic target for obesity and its related cardiometabolic diseases; however, whether the gut microbiota might be an efficient stimulus to activate BAT metabolism remains to be ascertained. We aimed to investigate the association of fecal microbiota composition with BAT volume and activity and mean radiodensity in young adults. METHODS: 82 young adults (58 women, 21.8 ± 2.2 years old) participated in this cross-sectional study. DNA was extracted from fecal samples and 16S rRNA sequencing was performed to analyse the fecal microbiota composition. BAT was determined via a static 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography scan (PET/CT) after a 2 h personalized cooling protocol. 18F-FDG uptake was also quantified in white adipose tissue (WAT) and skeletal muscles. RESULTS: The relative abundance of Akkermansia, Lachnospiraceae sp. and Ruminococcus genera was negatively correlated with BAT volume, BAT SUVmean and BAT SUVpeak (all rho ≤ - 0.232, P ≤ 0.027), whereas the relative abundance of Bifidobacterium genus was positively correlated with BAT SUVmean and BAT SUVpeak (all rho ≥ 0.262, P ≤ 0.012). On the other hand, the relative abundance of Sutterellaceae and Bifidobacteriaceae families was positively correlated with 18F-FDG uptake by WAT and skeletal muscles (all rho ≥ 0.213, P ≤ 0.042). All the analyses were adjusted for the PET/CT scan date as a proxy of seasonality. CONCLUSION: Our results suggest that fecal microbiota composition is involved in the regulation of BAT and glucose uptake by other tissues in young adults. Further studies are needed to confirm these findings. CLINICAL TRIAL INFORMATION: ClinicalTrials.gov no. NCT02365129 (registered 18 February 2015).

Congruent validity and inter-day reliability of two breath by breath metabolic carts to measure resting metabolic rate in young adults.

BACKGROUND & AIMS: Achieving high inter-day reliability is a key factor to analyze the magnitude of change in RMR, for instance after an intervention. The aims of this study were: i) to determine the congruent validity of RMR and respiratory quotient (RQ) with two breath by breath commercially available metabolic carts [CCM Express (CCM) and Ultima CardiO2 (MGU)]; and ii) to analyze the inter-day reliability of RMR and RQ measurements. METHODS & RESULTS: Seventeen young adults participated in the study. RMR measurements were performed during two consecutive 30-min periods, on two consecutive days with both metabolic carts. The 5-min period that met the steady state criteria [Coefficient of variance (CV) < 10% for VO2, VCO2, and VE, and CV<5% for RQ] and with the lowest CV average was included in further analysis. RMR values were higher with the MGU than with the CCM on both days (two-way ANOVA, P = 0.021), however, no differences were found on RQ values obtained by both metabolic carts (P = 0.642). Absolute inter-day RMR differences obtained with the MGU were higher than those obtained with the CCM (219 ± 185 vs. 158 ± 154 kcal/day, respectively, P = 0.002; 18.3 ± 17.2% vs. 13.5 ± 15.3%, respectively, P = 0.046). We observed a significant positive association of absolute inter-day differences in RMR obtained with both metabolic carts (ß = 0.717; R2 = 0.743; P < 0.001). CONCLUSIONS: The CCM metabolic cart provides lower RMR values and seems more reliable than the MGU in our sample of young adults. Our findings also suggest that a great part of inter-day variability is explained by the individuals.

Health-related physical fitness is associated with total and central body fat in preschool children aged 3 to 5 years.

OBJECTIVES: To investigate whether health-related physical fitness is associated with total and central body fat in preschool children. METHODS: A total of 403 Spanish children aged 3-5 years (57.8% boys) participated in the study. Health-related physical fitness was measured by the PREFIT battery: the handgrip strength and the standing long-jump tests (muscular strength), the 4 × 10 m shuttle run (speed-agility), the one-leg stance tests (balance) and the PREFIT-20 m shuttle run test (cardiorespiratory fitness). Body mass index and waist circumference were used as markers of total and central body fat, respectively. RESULTS: There were significant associations between all health-related physical fitness tests and body mass index (ß = 0.280 ± 0.054, ß = -0.020 ± 0.006, ß = 0.154 ± 0.065 and ß = -0.034 ± 0.011 for the handgrip strength, standing long jump, 4 × 10 m shuttle run and PREFIT-20 m shuttle run tests, respectively, all P ≤ 0.019) after adjusting for sex and age. Similarly, there was significant associations of standing long jump (ß = -0.072 ± 0.014), 4 × 10 m shuttle run (ß = 0.652 ± 0.150) and PREFIT-20 m shuttle run tests (ß = -0.102 ± 0.025) with waist circumference (all P ≤ 0.001), except for handgrip strength (ß = 0.254 ± 0.145, P = 0.081) and one-leg stance (ß = -0.012 ± 0.009, P = 0.156). CONCLUSIONS: The present study extends previous findings in older youth. Fitness assessment should be introduced in future epidemiological and intervention studies in preschool children because it seems to be an important factor determining health.

Prevalence of overweight/obesity and fitness level in preschool children from the north compared with the south of Europe: an exploration with two countries.

BACKGROUND: North-south differences in the prevalence of obesity and fitness levels have been found in European adolescents, yet it is unknown if such differences already exist in very young children. OBJECTIVES: This study aims to compare the prevalence of overweight/obesity and fitness levels in preschool children aged 4 years from Sweden (north of Europe) and Spain (south of Europe). METHODS: The sample consisted of 315 Swedish and 128 Spanish preschoolers. Anthropometry (weight, height, waist circumference) and fitness (strength, speed-agility, balance and cardiorespiratory fitness) were assessed. Analysis of covariance adjusted for age, sex and height/body mass index (BMI) was used. RESULTS: Preschool children from Sweden had lower prevalence of overweight/obesity than their peers from Spain (World Obesity Federation, mean difference, MD = -9%, P = 0.010; World Health Organization, MD = -11%, P = 0.011). Concerning fitness, preschoolers from Spain were more fit in terms of upper-muscular strength (MD = +0.4 kg, P = 0.010), speed-agility (MD = -1.9 s, P = 0.001), balance (MD = +4.0 s, P = 0.001) and cardiorespiratory fitness (MD = boys = +6.6 laps, girls = +2.3 laps; P < 0.001 for all), yet they had worse lower-muscular strength (MD = -7.1, P ≤ 0.001) than those from Sweden. Differences in upper-muscular strength were largely explained by differences in BMI, and differences in cardiorespiratory fitness should be interpreted cautiously due to some methodological deviations. CONCLUSIONS: These findings suggest that a higher prevalence of overweight/obesity in Spain compared with Sweden is present already at early childhood, while differences in physical fitness components showed mixed findings.

Assessment of handgrip strength in preschool children aged 3 to 5 years.

We investigated whether there is an optimal grip span for determining the maximum handgrip strength in preschool children and if it is influenced by gender, age, or hand size. A total of 292 preschool children (3-5 years; 59.2% boys) carried out the handgrip strength test with different grip spans (4.0, 4.5, 5.0, 5.5, and 6.0 cm). The hand size was also measured. We also determined the reliability of the optimal grip span in another group of children (n = 56, 57% boys) who did the test twice, with a 3-hour difference between tests. The results showed that 4.0 cm is the optimal grip span to determine the maximum handgrip strength in preschool children. This result applied to both genders, all age groups, and hand sizes. Paired t-tests showed no significant differences between test and retest. These findings may guide clinicians and researchers in selecting the optimal grip span when measuring handgrip strength in preschool children.Level IV.