BUSCADOR RECOLECTA

In humans, the variation in resting metabolic rate (RMR) might be associated with health-related factors, as suggested by previous studies. This study explored whether the intra-assessment RMR variability (expressed as a coefficient of variation (CV; %)) is similar in men and women and if it is similarly associated with diverse health-related factors. The RMR of 107 young, and relatively healthy adults, was assessed using indirect calorimetry. Then, the CV for volumes of oxygen consumption (VO2) and carbon dioxide production (VCO2), respiratory exchange ratio (RER), and resting energy expenditure (REE) were computed as indicators of intra-assessment RMR variability. Body composition, cardiorespiratory fitness (peak VO2 uptake), circulating cardiometabolic risk factors, and heart rate and its variability (HR and HRV) were assessed. Men presented higher CVs for VO2, VCO2, and REE (all p <= 0.001) compared to women. Furthermore, in men, the intra-assessment RER variability was associated with vagal-related HRV parameters and with mean HR (standardized beta = -0.36, -0.38, and 0.41, respectively; all p < 0.04). In contrast, no associations were observed in women. In conclusion, men exhibited higher variability (CVs for VO2, VCO2, and REE) compared to women. The CV for RER could be a potential marker of cardiometabolic risk in young men., This research was funded by the Spanish Ministry of Economy and Competitiveness
(DEP2016-79512-R and PTA 12264-I). J.M.A.A., F.J.O.P., and A.P.F. are supported by the Spanish Ministry of Education, Culture and Sport (FPU15/04059, FPU16/02828, and FPU 16/02760, respectively). J.M.A.A. is supported by the University of Granada, Plan Propio de Investigación 2020 Programa de Contratos Puente, and by the Grant FJC2020-044453-I funded by MCIN/AEI/10.13039/501100011033
and by “European Union NextGenerationEU/PRTR”. F.J.O.P. is supported by the University of
Granada, Plan Propio de Investigación 2022 Programa de Contratos Puente. A.P.F. is supported in part by NIH grant #: U01 TR002004 (REACH project). Additional support was obtained from the
Unit of Excellence on Exercise and Health (UCEES) and the EXERNET Research Network on Exercise
and Health in Special Populations (DEP2005-00046/ACTI). This study was additionally supported by the Unit of Excellence in Sport and Health (UCEES), granted by the University of Granada and Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Funds (ref. SOMM17/6107/UGR).

Background: There is a subset of individuals with overweight/obesity characterized by a lower risk of cardiometabolic complications, the so-called metabolically healthy overweight/obesity (MHOO) phenotype. Despite the relatively higher levels of subcutaneous adipose tissue and lower visceral adipose tissue observed in individuals with MHOO than individuals with metabolically unhealthy overweight/obesity (MUOO), little is known about the differences in brown adipose tissue (BAT). Methods: This study included 53 young adults (28 women) with a body mass index (BMI) ¿25 kg/m2 which were classified as MHOO (n = 34) or MUOO (n = 19). BAT was assessed through a static 18F-FDG positron emission tomography/computed tomography scan after a 2-h personalized cooling protocol. Energy expenditure, skin temperature, and thermal perception were assessed during a standardized mixed meal test (3.5 h) and a 1-h personalized cold exposure. Body composition was assessed by dual-energy x-ray absorptiometry, energy intake was determined during an ad libitum meal test and dietary recalls, and physical activity levels were determined by a wrist-worn accelerometer. Findings: Participants with MHOO presented higher BAT volume (+124%, P = 0.008), SUVmean (+63%, P = 0.001), and SUVpeak (+133%, P = 0.003) than MUOO, despite having similar BAT mean radiodensity (P = 0.354). In addition, individuals with MHOO exhibited marginally higher meal-induced thermogenesis (P = 0.096) and cold-induced thermogenesis (+158%, P = 0.050). Moreover, MHOO participants showed higher supraclavicular skin temperature than MUOO during the first hour of the postprandial period and during the cold exposure, while no statistically significant differences were observed in other skin temperature parameters. We observed no statistically significant differences between MHOO and MUOO in thermal perception, body composition, outdoor ambient temperature exposure, resting metabolic rate, energy intake, or physical activity levels. Interpretation: Adults with MHOO present higher BAT volume and activity than MUOO. The higher meal- and cold-induced thermogenesis and cold-induced supraclavicular skin temperature are compatible with a higher BAT activity. Overall, these results suggest that BAT presence and activity might be linked to a healthier phenotype in young adults with overweight or obesity., The study was supported by the Junta de Andalucía, Consejería de Transformación Económica, Industria, Conocimiento y Universidades Dirección General de Investigación y Transferencia del Conocimiento (ref. P18-RT-4455, ref. SOMM17/6107/UGR, and DOC 01151) and European Regional Development Funds (ERDF), the Spanish Ministry of Economy and Competitiveness via the Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01393), and PTA-12264, Retos de la Sociedad (DEP2016-79512-R), the Spanish Ministry of Education (FPU13/04365, FPU15/04059 and FPU19/01609), the Fundación Iberoamericana de Nutrición (FINUT), the Redes Temáticas de Investigación Cooperativa RETIC (Red SAMID RD16/0022), the AstraZeneca HealthCare Foundation, the University of Granada Plan Propio de Investigación 2016 -Excellence actions: Unit of Excellence on Exercise and Health (UCEES). G.SD is supported by a Marie Sklodowska-Curie Actions-Individual Fellowship (101028941; Horizon 2020, European Commission). B.MT is supported by a grant for the requalification of the Spanish university system from the Ministry of Universities of the Government of Spain, funded by the European Union, NextGeneration EU (María Zambrano program, reference RR _C_2021_04). J.M.A.A. is supported by the Juan de la Cierva-Formación Grant FJC2020-044453-I funded by MCIN/AEI/10.13039/501100011033 and 'European Union NextGeneration EU/PRTR'

Objective: To determine differences in resting heart rate variability (HRV) and heart rate (HR) between young adults with normal-weight obesity (NWO) and normal-weight lean (NWL). Methods: A total of 65 normal-weight individuals (18-25 years old, 50 women, body mass index 18.5 to 24.9 kg/m2) were included in this cross-sectional study. Body fat percentage was determined using a whole-body dual energy x-ray absorptiometry scanner. Resting HRV and HR were assessed with the Polar RS800CX. Forty-one participants were classified as NWO and 24 NWL using cutoff points for body fat percentage (33.3% for women and 23.1% for men). Results: There were no differences in HRV between NWO and NWL groups (all p >.05). HR was higher in NWO (mean 70 beats per minute [bpm], standard deviation [SD] 8) than in NWL adults (mean 65 bpm, SD 10), the adjusted mean difference 5 bpm (95% CI, 0 to 10 bpm). Conclusion: HR is a noninvasive biomarker and relatively cheap, fast, and easy to measure that could detect 'apparently healthy' young individuals with an adverse cardiovascular disease risk profile despite presenting a normal body weight., Spanish Ministry of Economy andCompetitiveness, Grant/Award Numbers:PTA 12264-I, DEP2016-79512-R; SpanishMinistry of Education, Culture and Sport,Grant/Award Number: FPU15/04059;MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR,Grant/Award Number: FJC2020-044453-I;PERC Systems Biology Fund; Unit ofExcellence on Exercise and Health (UCEES);EXERNET Research Network on ExerciseandHealthinSpecialPopulations,Grant/Award Number: DEP2005-00046/ACTI; University of Granada and Junta deAndalucía, Consejería de Conocimiento,Investigacion y Universidades and EuropeanRegional Development Funds, Grant/AwardNumber: SOMM17/6107/UGR

Purpose Metabolic fexibility (MetF), which is a surrogate of metabolic health, can be assessed by the change in the respiratory exchange ratio (RER) in response to an oral glucose tolerance test (OGTT). We aimed to determine the day-to-day
reproducibility of the energy expenditure (EE) and RER response to an OGTT, and whether a simulation-based postcalorimetric correction of metabolic cart readouts improves day-to-day reproducibility.
Methods The EE was assessed (12 young adults, 6 women, 27±2 years old) using an Omnical metabolic cart (Maastricht
Instruments, Maastricht, The Netherlands) after an overnight fast (12 h) and after a 75-g oral glucose dose on 2 separate
days (48 h). On both days, we assessed EE in 7 periods (one 30-min baseline and six 15-min postprandial). The ICcE was
performed immediately after each recording period, and capillary glucose concentration (using a digital glucometer) was
determined.
Results We observed a high day-to-day reproducibility for the assessed RER (coefcients of variation [CV]<4%) and EE
(CVs<9%) in the 7 diferent periods. In contrast, the RER and EE areas under the curve showed a low day-to-day reproducibility (CV=22% and 56%, respectively). Contrary to our expectations, the postcalorimetric correction procedure did
not infuence the day-to-day reproducibility of the energy metabolism response, possibly because the Omnical’s accuracy
was~100%.
Conclusion Our study demonstrates that the energy metabolism response to an OGTT is poorly reproducible (CVs>20%)
even using a very accurate metabolic cart. Furthermore, the postcalorimetric correction procedure did not infuence the
day-to-day reproducibility.
Trial registration NCT04320433; March 25, 2020., Funding for open access charge: Universidad de Granada / CBUA. Supported by the Spanish Ministry of Economy and Competitiveness via Retos de la Sociedad grant DEP2016-79512-R (to JRR), and European Regional Development Funds (ERDF); Spanish Ministry of Education grant (FPU15/04059 to JMAA; and FPU19/01609 to LJ-F); the University of Granada Plan Propio de Investigación 2016-Excellence actions: Unit of Excellence on Exercise and Health (to JRR)—Plan Propio de Investigación 2018 and 2020 Programa Contratos-Puente and Programa Perfeccionamiento de Doctores (to GS-D, and to JMAA respectively); Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades grant SOMM17/6107/UGR (to JRR) via the ERDF; and the Fundación Alfonso Martín Escudero (to GS-D).

Aim:
Previous evidence suggest that a sexual dimorphism in exercise fat oxidation and adipokines levels may explain a lower risk of cardio-metabolic disorders in women. Therefore, we investigated the role of sex in the relationship between adipokines levels, maximal fat oxidation (MFO) during exercise and insulin resistance.

Methods:
Fifty young adults with excess adiposity (31 women; body fat: 38.7 ± 5.3%) were included in this study. The fasting levels of leptin, adiponectin, glucose and insulin were determined from blood samples and the homeostatic model assessment of insulin resistance index (HOMA-IR) subsequently calculated. Body fat percentage and visceral adipose tissue (VAT) were assessed through dual-energy X-ray absorptiometry whereas MFO was estimated during an incremental-load exercise test after an overnight fasting through indirect calorimetry.

Results:
Men had lower levels of body fat (d = 1.80), adiponectin (d = 1.35), leptin (d = 0.43) and MFO (d = 1.25) than women. Conversely, men showed higher VAT (d = 0.85) and fasting glucose levels (d = 0.89). No sex differences were observed in HOMA-IR (d = 0.34). Adipokines levels were not associated with MFO in both sexes (r < 0.30), whereas adiponectin levels were inversely related with HOMA-IR in both men (r = −0.58) and women (r = −0.50). Leptin concentration was associated to HOMA-IR only in men (r = 0.41), while no statistically significant relationships were observed between MFO and HOMA-IR in both sexes (r < 0.44).

Conclusion:
Insulin resistance was similar between sexes regardless of superior levels of adipokines and MFO during exercise in women. Therefore, adiponectin and leptin may regulate glucose homeostasis without altering whole body fat oxidation rate during exercise., This study was funded by the Spanish Ministry of Economy and Competitiveness via the Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01393; J.R.R.) and PTA-12264I, Retos de la Sociedad (DEP2016-79512-R; J.R.R.) and European Regional Development Funds (ERDF; J.R.R.), the Spanish Ministry of Education (FPU13/04365 (G.S.D), FPU14/04172 (F.A.G.) and FPU15/04059 (J.M.A.)), FJOP is supported by the Margarita Salas postdoctoral research contract programm (Ministry of Universities of Spain, European Union - NextGenerationEU) the Fundación Iberoamericana de Nutrición (FINUT; JRR), the Redes Temáticas de Investigación Cooperativa RETIC (Red SAMID RD16/0022; J.R.R.), the AstraZeneca HealthCare Foundation (J.R.R.), the University of Granada Plan Propio de Investigación 2016 -Excellence actions: Unit of Excellence on Exercise, Nutrition and Health (UCEENS) (J.R.R.), the Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades (ERDF; ref. SOMM17/6107/UGR; JRR), the Junta de Andalucía, Consejería de Economía, Conocimiento, Empresas y Universidad (ref. P18-RT-4455; J.R.R.) and by the CIBEROBN, Centro de Investigación Biomédica en Red (CB22/03/00058), Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea – European Regional Development Fund (J.R.R.).

Objective This study aimed to describe the energy expenditure (EE) and macronutrient oxidation response to an individualized nonshivering cold exposure in young healthy adults. Methods Two different groups of 44 (study 1: 22.1 [SD 2.1] years old, 25.6 [SD 5.2] kg/m(2), 34% men) and 13 young healthy adults (study 2: 25.6 [SD 3.0] years old, 23.6 [SD 2.4] kg/m(2), 54% men) participated in this study. Resting metabolic rate (RMR) and macronutrient oxidation rates were measured by indirect calorimetry under fasting conditions in a warm environment (for 30 minutes) and in mild cold conditions (for 65 minutes, with the individual wearing a water-perfused cooling vest set at an individualized temperature adjusted to the individual's shivering threshold). Results In study 1, EE increased in the initial stage of cold exposure and remained stable for the whole cold exposure (P < 0.001). Mean cold-induced thermogenesis (9.56 +/- 7.9 kcal/h) was 13.9% +/- 11.6% of the RMR (range: -14.8% to 39.9% of the RMR). Carbohydrate oxidation decreased during the first 30 minutes of the cold exposure and later recovered up to the baseline values (P < 0.01) in parallel to opposite changes in fat oxidation (P < 0.01). Results were replicated in study 2. Conclusions A 1-hour mild cold exposure individually adjusted to elicit maximum nonshivering thermogenesis induces a very modest increase in EE and a shift of macronutrient oxidation that may underlie a shift in thermogenic tissue activity., This study was supported by the Spanish Ministry of Economy and Competitiveness via the Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III (PI13/01393 and PTA 12264-I); the Retos de la Sociedad (DEP2016-79512-R) and European Regional Development Funds (ERDF); the Spanish Ministry of Education (FPU13/04365, FPU14/04172, and FPU15/04059); the Fundacion Iberoamericana de Nutricion; the Redes Tematicas de Investigacion Cooperativa (RETIC, red de Salud Materno Infantil y del Desarrollo 16/0022); the AstraZeneca HealthCare Foundation; the University of Granada Plan Propio de Investigación 2016 excellence actions (Unit of Excellence on Exercise and Health and Plan Propio de Investigacion 2018: Programa Contratos-Puente and Programa Perfeccionamiento de Doctores); the Junta de Andalucía, Consejeria de Conocimiento, Investigación y Universidades (ERDF; SOMM17/6107/UGR); and the Fundación Alfonso Maríin Escudero.

Background and aims: Accomplishing a high day-to-day reproducibility is important to detect changes in resting metabolic rate (RMR) and respiratory exchange ratio (RER) that may be produced after an intervention or for monitoring patients’ metabolism over time. We aimed to analyze: (i) the influence of different methods for selecting indirect calorimetry data on RMR and RER assessments; and, (ii) whether these methods influence RMR and RER day-to-day reproducibility. Methods and results: Twenty-eight young adults accomplished 4 consecutive RMR assessments (30-min each), using the Q-NRG (Cosmed, Rome, Italy), the Vyntus CPX (Jaeger-CareFusion, Höchberg, Germany), the Omnical (Maastricht Instruments, Maastricht, The Netherlands), and the Ultima CardiO2 (Medgraphics Corporation, St. Paul, Minnesota, USA) carts, on 2 consecutive mornings. Three types of methods were used: (i) short (periods of 5 consecutive minutes; 6e10, 11e15, 16e20, 21e25, and 26e30 min) and long time intervals (TI) methods (6e25 and 6 e30 min); (ii) steady state (SSt methods); and, (iii) methods filtering the data by thresholding from the mean RMR (filtering methods). RMR and RER were similar when using different methods (except RMR for the Vyntus and RER for the Q-NRG). Conversely, using different methods impacted RMR (all P 0.037) and/or RER (P 0.009) day-to-day reproducibility in all carts. The 6e25 min and the 6e30 min long TI methods yielded more reproducible measurements for all metabolic carts.
Conclusion: The 6e25 min and 6e30 min should be the preferred methods for selecting data, as they result in the highest day-to-day reproducibility of RMR and RER assessments., This work was supported by the Spanish Ministry of Economy and Competitiveness via Retos de la Sociedad grant DEP2016-79512-R (to JRR), and European Regional Development Funds (ERDF); Spanish Ministry of Education grant (FPU15/04059 to JMAA; FPU19/01609 to LJ-F; and FPU18/03357 to MD-M); the University of Granada Plan Propio de Investigación 2016-Excellence actions: Unit of Excellence on Exercise and Health (to JRR); the University of Granada Plan Propio 2020 and 2018 Programa Contratos-Puente (to JMA and GS-D, respectively), and Programa Perfeccionamiento de Doctores (to GS-D); Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades grant SOMM17/6107/UGR (to JRR) via the ERDF; Grant FJC2020-044453-I funded by MCIN/AEI/10.13039/501100011033 and by “European Union NextGenerationEU/PRTR” (to JMA); the Fundación Alfonso Martín Escudero (to GS-D); and a Marie Skłodowska-Curie Actions-Individual Fellowship grant (Horizon2020, 101028941, to GS-D).

Where people live and work together it is not always possible to modify the ambient temperature; ways must therefore be found that allow individuals to feel thermally comfortable in such settings. The Embr Wave (R) is a wrist-worn device marketed as a 'personal thermostat' that can apply a local cooling stimulus to the skin. The aim of the present study was to determine the effect of an intermittent mild cold stimulus of 25 degrees C for 15-20 s every 5 min over 3.5 days under free-living conditions on 1) skin temperature, 2) perception of skin temperature, 3) sleep quality and 4) resting energy expenditure (REE) in young, healthy adults. Ten subjects wore the device for 3.5 consecutive days. This intervention reduced distal skin temperature after correcting for personal ambient temperature (P < 0.05), but did not affect the subjects' the perception of skin temperature, sleep quality or REE (all P >= 0.051). Thus, this intermittent mild cold regime can reduce distal skin temperature, and wearing it under free-living conditions for 3.5 days does not seem to impair the perception of skin temperature and sleep quality or modify REE., The study was funded by the Spanish Ministry of Economy and Competitiveness via the Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III (PI13/01393 and CB16/10/00239) and PTA 12264-I, Retos de la Sociedad (DEP2016-79512-R), and European Regional Development Funds (ERDF). Other funders included the Spanish Ministry of Education (FPU 16/05159, 15/04059 and 19/02326), the Fundacion Iberoamericana de Nutricion (FINUT), the Redes Tematicas De Investigacion Cooperativa RETIC (Red SAMID RD16/0022), the AstraZeneca Health Care Foundation, the University of Granada Plan Propio de Investigacion 2016 (Excellence actions: Unit of Excellence on Exercise, Nutrition and Health [UCEENS]), and by the Junta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades (ERDF, SOMM17/6107/UGR). AMT was supported by Seneca Foundation through grant 19899/GERM/15 and the Ministry of Science Innovation and Universities RTI2018-093528-B-I0, as well as DJP (MINECO; RYC-2014-16938). BMT was supported by an individual postdoctoral grant from the Fundacion Alfonso Martin Escudero. We thank Dr. Matt Smith of Embr Labs Inc. for configuring the Embr Wave (R) devices used in this experiment.