Higher Resting Metabolic Rate Research Articles

Resting Metabolic Rate in Indian Adolescents and Youth with Type 1 Diabetes Mellitus: A Case Controlled Study

Abstract Introduction: Energy metabolism in type 1 diabetes (T1D) is known to be different. Resting metabolic rate (RMR) accounts for the largest portion of total energy needs. The objective of our study was to assess resting metabolic rate and its determinants in adolescents and young adults with T1D in comparison with age- and gender-matched healthy controls. Methods: This cross-sectional study included 97 children and young adults (10–19 years) with type 1 diabetes having a disease duration of at least 1 year. For the control population, 95 age- and gender-matched healthy adolescents were enrolled. Clinical examination and biochemical evaluation of parameters pertaining to diabetes and body composition were estimated, and RMR was measured using indirect calorimetry for both cases and controls. Results: Adolescents with T1D were significantly shorter, and had significantly lower calorie intake, higher RMR and volume of oxygen consumed (VO2) as compared to the healthy controls (P < 0.05). RMR adjusted for weight showed a significant positive correlation with lean body mass (LBM) percentage, and energy intake and a negative correlation with disease duration. Those with a T1D duration of less than 5 years demonstrated a significantly higher RMR, lower body fat percentage, higher LBM percentage, carbohydrate and energy intake/kg body weight and higher calculated insulin sensitivity (IS) as compared to those with greater disease duration. Muscle mass percentage and higher energy intake were found to be significant positive predictors and advancing age/diabetes duration was a negative predictor of weight-adjusted RMR (P < 0.05), whereas IS and male gender tended towards significant negative association (P = 0.06). Conclusion: Indian children with type 1 diabetes had a higher resting metabolic rate as compared to healthy children. Muscle mass, energy intake and diabetes duration were observed to be important predictors of RMR in T1D. Reduction in RMR with advancing age/disease duration may predispose to weight gain and subsequent double diabetes in T1D.

The combined association of dietary inflammatory index and resting metabolic rate on cardiorespiratory fitness in adults

BackgroundNo study has examined the combined association of dietary inflammatory index (DII) of the diet and resting metabolic rate (RMR) on cardiorespiratory fitness (CRF). Therefore, we investigated the combined association between DII and RMR on CRF.MethodsThis cross-sectional study was conducted on 270 adult subjects. The DII was calculated using a validated semi-quantified food frequency questionnaire. RMR was measured using an indirect calorimetric method. Socioeconomic status, anthropometric measures, body composition and blood pressure were documented by a trained interviewer. CRF was assessed by using Bruce protocol. Binary logistic regression was performed to find the association of CRF with DII/RMR categories in various models.ResultsThe participants categorized into four groups including: (1) low DII/high RMR, (2) low DII/low RMR, (3) high DII/low RMR, (4) high DII/high RMR. The mean of VO2Max (mL/kg/min), VO2max (L/min) and VO2max relative to lean body mass (LBM) was lower in participants that were classified as high DII/low RMR compared to those in low DII/high RMR. After controlling for age, sex, education status, smoking status, and physical activity those who were in the high DII/low RMR group, compared to the low DII/high RMR group were 28% less likely to have higher VO2max (ml/kg/min) (OR 0.72; 95% CI 0.18, 0.82, p = 0.04). Moreover, had 25% lower odds of VO2max (L/min) which was significant (OR 0.75, 95% CI 0.11, 0.89, p = 0.03). In addition, were 21% less likely to have higher VO2max (LBM) (OR 0.79; 95% CI 0.30, 0.92, p = 0.02).ConclusionsOverall, consumption of a pro-inflammatory diet in combination with low RMR status is associated with lower odds of CRF compared to those who had anti-inflammatory diet in combination with high RMR status among Iranian healthy adults. This study suggests that researchers should focus on combined relationships rather than single pair-wise associations for having a better judgment.

Resting Metabolic Rate for Diagnosing Tae-Eum Sasang Type and Unraveling the Mechanism of Type-Specific Obesity

Increased resting metabolic rate (RMR), representing augmented energy expenditure, is a preferred physical characteristic; however, the Tae-Eum Sasang type, with a high incidence of obesity and metabolic diseases, has a higher RMR. This study scrutinized the physical characteristics of Sasang typology, a traditional Korean personalized medicine, to resolve this discrepancy, which can unravel the mechanism of Tae-Eum-type-specific obesity and improve the Tae-Eum Sasang-type diagnosis. A total of 395 healthy participants provided Sasang-type diagnosis using Sasang Constitutional Analysis Tool and physical features, including skeletal muscle mass, body fat mass, and RMR, along with those standardized using body weight. The Tae-Eum-type group showed significantly higher body weight, body mass index, body fat mass, and unstandardized RMR (kcal/day) than others, while their standardized measures of RMR per weigh (RMRw, kcal/day/kg) and percent skeletal muscle (PSM, %) were significantly lower. The logistic regression model revealed that the RMRw is pivotal for discriminating Tae-Eum type from others and explaining the developmental mechanism of Tae-Eum-type obesity. The aforementioned might provide a theoretical framework for Sasang-type diagnosis and Sasang-type-specific health promotion using bodily exercise and medical herbs.

Resting metabolic rate in relation to incident disability and mobility decline among older adults: the modifying role of frailty.

Alterations in resting metabolic rate (RMR), the largest component of daily total energy expenditure, with aging have been shown in various studies. However, little is known about the associations between RMR and health outcomes in later life. To analyze whether RMR is associated with incident disability and mobility decline in a 10-year longitudinal study, as well as the moderating role of frailty in these associations. Data from 298 older adults aged 70 and over from the Frailty and Dependence in Albacete (FRADEA) study in Spain were used, including a baseline measurement in 2007-2009 and a follow-up measurement 10years later. RMR was measured by indirect calorimetry. Outcomes were incident disability in basic activities of daily living (BADL, Barthel Index), incident disability in instrumental ADL (IADL, Lawton index), and mobility decline (Functional Ambulation Categories scores). Fried's frailty phenotype was used as an indicator of frailty. Logistic regression analyses were conducted. Fully adjusted and stratified analyses revealed that only in the pre-frail/frail group, a higher RMR was associated with a lower risk of incident BADL disability (OR = 0.47, 95% CI = 0.23-0.96, p = 0.037), incident IADL disability (OR = 0.39, 95% CI = 0.18-0.84, p = 0.017), and mobility decline (OR = 0.30, 95% CI = 0.14-0.64, p = 0.002). To our knowledge, this is the first study looking at the associations between RMR and functional health using a longitudinal research design. The results suggest that RMR could be used as an early identifier of a specific resilient group within the pre-frail and frail older population, with a lower risk of further health decline.

Juvenile semi-wild fish have a higher metabolic rate than farmed fish

Fish from commercially farmed stocks are often released into the natural environment to supplement wild populations. This practice is often applied to salmonid fish as they are an essential fishery resource and also used for recreational angling. However, farmed fish tend to show lower survival rates after release than wild fish. For this reason, the release of semi-wild fish is increasingly used in Japan; these fish are generated using female fish from domesticated stocks and male fish of wild origin. The survival rate of released semi-wild fish is higher than that of farmed fish, but the reason for this is unknown. This study compared the metabolism and swimming performance of semi-wild and farmed masu salmon (Oncorynchus masou). The analyses showed that resting metabolic rate (RMR), maximum metabolic rate (MMR) and swimming speeds that minimize energy costs of travel (optimal swimming speed) were higher in semi-wild fish than in farmed fish. Critical swimming speed did not differ significantly between the two groups of fish. Semi-wild fish with high RMR may have a social status advantage over farmed fish because a previous study reported that SMR, which is the value closest to basal metabolism significantly affects feeding motivation. This means that individuals with higher social status may be more motivated to feed. As RMR is proportional to food requirements, then release programs should be planned taking food resources at the release site into consideration.

Feasibility of Using Bioelectrical Impedance Analysis for Assessing Youth Weight and Health Status: Preliminary Findings.

Background. This study assessed the accuracy of bioimpedance analysis (BIA) for measuring body composition and resting metabolic rate (RMR) in fasted and non-fasted state and the prospect of using phase angle (PA) to indicate cellular health in youth. Methods. BIA body composition, RMR, and hydration measures were compared to dual-energy x-ray absorptiometry (DXA), MedGem metabolic analyzer, and urine specific gravity, respectively, at baseline in a fasted state using one-way ANOVAs. Repeated BIAs at 0, 30, 60, 90, and 120 min post-prandial were compared to baseline using repeated-measures ANOVA. Correlations were used to assess the relationship among PA and health (blood lipids and glucose, resting BP) and fitness (grip strength and a 3 min step test) measures. Results. BIA scans (N = 58; 11.4 ± 2.9 y) measured lower body fat % (BF%) in healthy weight youth (BMI < 85th percentile; 16.4 ± 1.1 vs. 25.1 ± 1.0%) and lower visceral adipose tissue (VAT) in males (44.5 ± 2.9 vs. 34.1 ± 6.0 cm2) than DXA and higher RMR in all youth (1244 ± 41 vs. 1104 ± 39 kcals/day), healthy weight (1231 ± 48 vs. 1049 ± 44 kcals/day), and teens (1541 ± 62 vs. 1234 ± 72 kcals/day) than MedGem. Compared to baseline, immediate post-prandial values were significantly higher for BF% (21.4 ± 1.4 vs. 22.0 ± 1.4%) and VAT (45.4 ± 6.1 vs. 46.2 ± 6.2 cm2). PA was significantly correlated with BF% (r = −0.33; p = 0.01), fat-free mass (r = 0.59; p < 0.001), grip strength (r = 0.56; p < 0.001). Conclusions. While more data are needed to confirm these preliminary findings, the results suggest caution is necessary in using BIA to assess aspects of youth health and weight status, especially in males, healthy weight, and teens. However, these preliminary findings do indicate that phase angle maybe be a valuable, non-invasive tool for identifying youth who are heading towards obesity and/or obesity-related health consequences.

The low-carbohydrate-diet score is associated with resting metabolic rate: an epidemiologic study among Iranian adults

Low-carbohydrate diet (LCD) has been used for weight loss and preventing obesity, but the association of adherence to LCD and resting metabolic rate (RMR) has not been investigated. This study aimed to investigate the association between the low-carbohydrate-diet score (LCDS) and RMR among Iranian adults. This cross-sectional study was conducted on 270 Iranian adults 18-70 y of age. To assess dietary intakes, participants completed a validated food frequency questionnaire. The LCDS was calculated based on carbohydrate, protein and fat intake, expressed as a percentage of energy. The higher score indicates the lower carbohydrate and the higher protein and fat intake. RMR was measured by indirect calorimetry after an overnight fast. Multivariate-adjusted means showed that RMR significantly increased across tertiles (p = 0.041). However, there were no significant differences in the mean of fat mass (FM) and fat-free mass (FFM) across tertiles of LCDS (p = 0.986 and p = 0.621, respectively). Also LCDS and RMR (r = 0.14, p = 0.021) were found to be correlated, but LCDS and FFM (r = 0.06, p = 0.323), FM (r = -0.05, p = 0.412), had no statistically significant correlation. RMR had a significant positive association with LCDs in the crude model (β = 18.81, 95% CI: 2.55, 35.07, P = 0.024). Moreover, after controlling for covariates this association changed to non-significant (β = -0.14, 95% CI: -7.05, 19.25, P = 0.03). Adherence to diets lower in carbohydrates and higher in fat and protein were associated with higher RMR. Further studies with a larger sample size are needed to confirm these findings.

Integrating humans into pace-of-life studies: The Big Five personality traits and metabolic rate in young adults.

The pace-of-life syndrome (POLS) predicts that personality and metabolism should be correlated if they function as an integrated unit along a slow-fast continuum. Over the last decade, this conceptual framework has been tested in several empirical studies over a wide array of non-human animal taxa, across multiple personality traits and using standardized measures of metabolism. However, studies associating metabolic rate and personality in humans have been surprisingly scarce. Here, we tested whether there was covariation among personality scores, measured using the Big Five Inventory test, resting metabolic rate (RMR) and preferred walking speed (PWS) in a cohort of young human adults aged between 18 and 27 years old. We found a significant, negative relationship between RMR and Extraversion; less extraverted individuals had a 30% higher RMR than the most extraverted ones. No other personality traits correlated with RMR and none correlated with PWS. The negative correlation between Extraversion and RMR may suggest an allocation energy trade-off between personality and basal metabolism. Our results yielded equivocal support for the POLS and emphasized the need for more research on human to test the generality of this conceptual framework and further assess its validity.

Greater Skeletal Muscle Oxidative Capacity Is Associated With Higher Resting Metabolic Rate: Results From the BLSA

Resting metabolic rate (RMR) tends to decline with aging. The age-trajectory of decline in RMR is similar to changes that occur in muscle mass, muscle strength and fitness. However, while the decline in these phenotypes have been related to changes of mitochondrial function and oxidative capacity, whether lower RMR is associated with poorer mitochondrial oxidative capacity is unknown. In 619 participants of the Baltimore Longitudinal Study of Aging, we analyzed the cross-sectional association between RMR (kcal/day), assessed by indirect calorimetry, and skeletal muscle maximal oxidative phosphorylation capacity, assessed as post-exercise phosphocreatine recovery time constant (tau-PCr), by phosphorous magnetic resonance spectroscopy. Linear regression models were used to evaluate the relationship between tau-PCr and RMR, adjusting for potential confounders. We found that independent of age, sex, lean body mass, muscle density and fat mass, higher RMR was significantly associated with shorter tau-PCr, indicating greater mitochondrial oxidative capacity. In conclusion, higher RMR appears to be associated with a higher mitochondrial oxidative capacity in skeletal muscle. This association may reflect a relationship between better muscle quality and greater mitochondrial health.

Maximal oxygen consumption is positively associated with resting metabolic rate and better body composition profile

Abstract Aims It was investigated that regular exercise improves cardiorespiratory fitness (CRF) and lean body mass (LBM). Considering the effect of CRF on LBM as factors influencing resting metabolic rate (RMR), there might be a relation between CRF and RMR. The purpose of this study was to investigate the relation between CRF and RMR among Iranian adults. Methods 271 subjects participated in this study. Body composition (multi-frequency bio-impedance), RMR (indirect calorimetry), Maximal oxygen consumption (Bruce protocol) was measured. Student's t-test test and χ2 analysis were performed to compare two groups of RMR and also RER. Polynomial model fit was also obtained to assess departure from linearity. Results Participants with higher RMR had significantly higher VO2max (34.44 ± 8.47 vs. 29.94 ± 7.16, P Conclusion We found a positive association between VO2max and RMR with a better body composition profile. Therefore, enhancing VO2max which shows the better CRF may be recommended as a strategy to prevent obesity prevalence and effective weight loss program.

Factors Associated With Energy Expenditure and Energy Balance in Acute Sport-Related Concussion.

Sport-related concussion (SRC) is characterized by a pathologic neurometabolic cascade that results in an increased intracranial energy demand and a decreased energy supply. Little is known about the whole-body energy-related effects of SRC. To examine factors associated with whole-body resting metabolic rate (RMR), total energy expenditure (TEE), energy consumption (EC), and energy balance (EBal) in student-athletes acutely after SRC and healthy matched control individuals. Case-control study. University research laboratory. Student-athletes diagnosed with SRC (n = 28, 50% female, age = 18.4 ± 1.8 years, body mass index [BMI] = 24.1 ± 4.1 kg/m2) assessed ≤72 hours postinjury and a matched control group (n = 28, 50% female, age = 19.4 ± 2.9 years, BMI = 24.7 ± 4.78 kg/m2). Resting metabolic rate was measured via indirect calorimetry. Participants reported their physical activity and dietary intake for 3 days, which we used to estimate TEE and EC, respectively, and to calculate EBal (EC:TEE ratio). Resting metabolic rate, TEE, and EC were normalized to body mass. Group and group-by-sex comparisons were conducted for RMR·kg-1, TEE·kg-1, EC·kg-1, and EBal using independent t tests with the a priori α = .05. Associations of age, sex, concussion history, BMI, and symptom burden with RMR·kg-1 and EBal were explored with linear regression models. Total energy expenditure·kg-1 was lower (P < .01; mean difference ± SD = -5.31 ± 1.41 kcal·kg-1) and EBal was higher (P < .01; 0.28 ± 0.10) in SRC participants than in control participants. Both sexes with SRC had lower TEE·kg-1 than did the control participants (P values ≤ .04); females with SRC had higher EBal than controls (P = .01), but male groups did not differ. Higher RMR·kg-1 was associated with history of concussion (adjusted R2 = .10, β = 0.65). Younger age (β = -0.35), fewer concussions (β = -0.35), lower BMI (β = -0.32), greater symptom duration (β = 1.50), and lower symptom severity (β = -1.59) were associated with higher EBal (adjusted R2 = .54). Total energy expenditure·kg-1 and EBal appeared to be affected by acute SRC, despite no differences in RMR·kg-1. Sex, concussion history, BMI, and symptom burden were associated with acute energy-related outcomes.

Metabolic and behavioral adaptations of greater white-toothed shrews to urban conditions

Abstract The global trend of urbanization is creating novel challenges for many animal species. Studies investigating behavioral differences between rural and urban populations often report a general increase in risk-taking behaviors in urban populations. According to the most common energy management model (the performance model), behaviors that increase access to resources, such as aggression and boldness, and behaviors that consume net energy, like locomotion and stress responses, are both positively correlated to resting metabolic rate (RMR). Thus, we expect urban populations to not only exhibit a higher level of risk-taking behavior but also a higher RMR. However, these interactions remain poorly investigated. Our main goal was to analyze the relationship between RMR and risk-taking behaviors in the greater white-toothed shrew (Crocidura russula) in rural versus urban populations. Trapped shrews were brought to captivity where we measured RMR, boldness, and exploration rate three times in each individual. Our findings revealed that urban shrews were indeed bolder and more exploratory, but contrary to our expectations, their RMR was lower than that of rural shrews. This is likely explained by differences in the environmental conditions of these two habitats, such as higher ambient temperatures and/or lower prey availability in cities. When looking at each population separately, this relationship remained similar: urban shrews with a higher RMR were less bold, and rural shrews with a higher RMR showed a lower exploration rate. We conclude that the energetic strategy of C. russula is dependent on the environmental and observational context and cannot be explained by the performance model.

Longitudinal Changes in Resting Metabolic Rates with Aging Are Accelerated by Diseases.

Resting metabolic rate (RMR) declines with aging and is related to changes in health status, but how specific health impairments impact basal metabolism over time has been largely unexplored. We analyzed the association of RMR with 15 common age-related chronic diseases for up to 13 years of follow-up in a population of 997 participants to the Baltimore Longitudinal Study of Aging. At each visit, participants underwent measurements of RMR by indirect calorimetry and body composition by DEXA. Linear regression models and linear mixed effect models were used to test cross-sectional and longitudinal associations of RMR and changes in disease status. Cancer and diabetes were associated with higher RMR at baseline. Independent of covariates, prevalent COPD and cancer, as well as incident diabetes, heart failure, and CKD were associated with a steeper decline in RMR over time. Chronic diseases seem to have a two-phase association with RMR. Initially, RMR may increase because of the high cost of resiliency homeostatic mechanisms. However, as the reserve capacity becomes exhausted, a catabolic cascade becomes unavoidable, resulting in loss of total and metabolically active mass and consequent RMR decline.

Association Of Leptin And RMR In Obese Elderly Adults With Different Levels Of Physical Activity

PURPOSE: The aims of this study were1) to examine potential sex-related differences in leptin, resting metabolic rate (RMR) and metabolic markers2) to assess differences in leptin, RMR and metabolic markers between low MVPA group and high MVPA group3) to assess whether being physically active may play a role in the associations between leptin, RMR and physical activity. METHODS: The subjects were 73 women (age=64.1±6.1years,percent body fat=39.1±4.8%) and 37 men (age=66.3±5.6years,percent body fat=29.7±4.7%). RMR was measured by indirect calorimetry (Metamax 3B-R2 Metabolic Measurement system, German) and body composition by the DXA (GE Lunar Prodigy, USA). Serum leptin and lipid and glucose metabolism makers’ levels were determined by radioimmunoassay. Waist-mounted triaxial accelerometer Actigraph GT3X-BT was used to make objective 7-day recordings of physical activity. Based on the mean of the minutes spent in MVPA (180 min/week), subjects were divided into low MVPA group (n=50, percent body fat=37.1±7.0%) and high MVPA group (n=56, percent body fat=34.5±6.1%). RESULTS: Leptin and HDL cholesterol levels were higher in women than men (both p<0.01), while men presented higher fat free mass and RMR (both p<0.01) than women. Leptin, insulin, HOMA-IR, percent body fat were higher in low MVPA than high MVPA group (all p<0.05), RMR and metabolic markers, however, were not found significant differences (all p>0.05). Leptin levels was associated with RMR negatively and PBF positively (r=-0.36, p=0.013;r=0.645,p=0.0001)in low MVPA group, leptin levels was associated with RMR negatively and PBF positively (r=-0.511, p=0.0001;r=0.631,p=0.0001)in high MVPA group. The negative association of RMR with proportion of sedentary (r=-0.304, p=0.027) and the negative association of leptin with proportion of MVPA (r=-0.303, p=0.023)were only found in high MVPA group. CONCLUSIONS: Leptin may play a role in energy metabolism in overweight and obese elderly adults. Obesity is associated with energy metabolism and metabolic markers both in women and men. The relationship of leptin with energy metabolism and insulin resistance might be moderated by levels of physical activity. Acknowledgements: This work was supported by Ministry of Science and Technology of the People's Republic of China (Grants No.2013FY114700).

0139 Associations of Actigraphic Sleep Parameters with Maximal Oxygen Consumption and Resting Metabolism in Well-Functioning Older Adults

Abstract Introduction Both poor sleep and poor cardiorespiratory fitness are common in older age and associated with negative health outcomes. Additionally, among older adults, higher resting metabolic rate (RMR) has been associated with increased morbidity and mortality risk. To evaluate whether, and in what ways, sleep may affect these relationships, we investigated the association of actigraphic sleep indices with cardiorespiratory fitness and RMR in older adults. Methods We studied 393 community-dwelling participants in the Baltimore Longitudinal Study of Aging (mean age 73.5±10.3 years, 52% women) who completed 6.7±0.9 nights of wrist actigraphy, RMR testing, and a maximal graded exercise test. Primary predictors included mean actigraphic total sleep time (TST, minutes), sleep efficiency (SE, %), wake after sleep onset (WASO, minutes), and average wake bout length (WBL, minutes). Cardiorespiratory fitness, as measured by maximal oxygen consumption (V O2MAX; ml/kg/min), and RMR (kcal/day) were the primary outcomes. Results After adjustment for age, sex, race, body mass index, comorbidity index, and depressive symptoms, longer WBL was associated with lower V O2MAX (β=-0.12, 95% confidence interval (CI)=-0.20, -0.04), greater WASO was associated with lower V O2MAX (β=-0.09, 95% CI=-0.17, -0.01), and greater SE was associated with higher V O2MAX (β=0.12, 95% CI=0.03, 0.20). In addition, longer TST was associated with lower RMR (β=-0.10, 95% CI=-0.19, -0.01) and longer WBL was linked to higher RMR (β=0.12, 95% CI=0.04, 0.21). Conclusion In well-functioning older adults, indices of greater wakefulness after sleep onset are linked with poorer cardiorespiratory fitness and higher resting metabolism, while longer and more efficient sleep are associated with better fitness and lower resting metabolic rate. Our findings suggest that sleep disturbance may be linked to disrupted energy homeostasis, evidenced by excessive energy expenditure at rest and inefficient energy utilization in response to maximal demands. Prospective analyses are necessary to determine the nature of these associations. Support This study was supported in part by National Institute on Aging (NIA) grants R01AG050507 and T32-AG027668, the NIA Intramural Research Program (IRP), and Research and Development Contract HHSN-260-2004-00012C.

Males Exceeding Females in Whole-Fish Polychlorinated Biphenyl Concentration Mainly Attributable to Higher Energy Expenditure Rate.

Males Exceeding Females in Whole-Fish Polychlorinated Biphenyl Concentration Mainly Attributable to Higher Energy Expenditure Rate.

Integration of physiology, behaviour and life history traits: personality and pace of life in a marine gastropod

Attempts to unravel the proximate and ultimate causes of individual behavioural and life history variation have often pointed to predicted correlations between behavioural, physiological and life history traits, forming pace-of-life syndromes (POLS). The POLS hypothesis predicts that high levels of production (growth, fecundity) require high levels of foraging effort and risk taking, supported by high metabolism. Despite tremendous interest in this topic, the POLS hypothesis still has limited empirical support, which has led to calls for more stringent empirical tests of the hypothesis and its assumptions. To that end, we examined the associations between risk-taking behaviour (boldness), resting metabolic rate (RMR) and somatic growth rate in a marine gastropod, Littoraria irrorata, under controlled laboratory conditions using a longitudinal repeated measures design. After accounting for the effects of sex, size and time (trial number), a multivariate mixed model revealed that bolder individuals had higher RMR, and grew faster, whereas RMR and growth were not strongly correlated. Further, if individuals were bolder than their average on a given day, then their RMR was also higher. Our study represents rare and compelling support for the POLS hypothesis, simultaneously studying its three key components (behaviour, energetics and life history), the success of which we attribute to careful control, concurrent sampling of each trait, and rigorous analysis of the among- and within-individual patterns of variation and covariance.

Greater Skeletal Muscle Oxidative Capacity Is Associated With Higher Resting Metabolic Rate: Results From the Baltimore Longitudinal Study of Aging.

Resting metabolic rate (RMR) tends to decline with aging. The age-trajectory of decline in RMR is similar to changes that occur in muscle mass, muscle strength, and fitness, but while the decline in these phenotypes has been related to changes of mitochondrial function and oxidative capacity, whether lower RMR is associated with poorer mitochondrial oxidative capacity is unknown. In 619 participants of the Baltimore Longitudinal Study of Aging, we analyzed the cross-sectional association between RMR (kcal/day), assessed by indirect calorimetry, and skeletal muscle maximal oxidative phosphorylation capacity, assessed as postexercise phosphocreatine recovery time constant (τ PCr), by phosphorous magnetic resonance spectroscopy. Linear regression models were used to evaluate the relationship between τ PCr and RMR, adjusting for potential confounders. Independent of age, sex, lean body mass, muscle density, and fat mass, higher RMR was significantly associated with shorter τ PCr, indicating greater mitochondrial oxidative capacity. Higher RMR is associated with a higher mitochondrial oxidative capacity in skeletal muscle. This association may reflect a relationship between better muscle quality and greater mitochondrial health.

Age differences in night-time metabolic rate and body temperature in a small passerine

Spending the winter in northern climes with short days and cold ambient temperatures (Ta) can be energetically challenging for small birds that have high metabolic and heat loss rates. Hence, maintaining body temperature (Tb) in Ta below thermoneutrality can be energetically costly for a small bird. We still know little about how increased heat production below thermoneutrality affects the level at which Tb is maintained, and if these patterns are age specific. To test this, we measured subcutaneous body temperature (Ts) and resting metabolic rate (RMR) simultaneously in blue tits (Cyanistes caeruleus) during winter nights in Ta’s ranging from 25 to − 15 °C. RMR increased below the lower critical temperature (LCT, estimated at 14 °C) and was 6% higher in young (birds in their first winter) compared to old birds (birds in their second winter or older). The higher RMR was also mirrored in higher Ts and thermal conductance (C) in young birds, which we suggest could be caused by age differences in plumage quality, likely driven by time constraints during moult. Reduction in nightly predicted Tb was modest and increased again at the coldest ambient temperatures, suggesting that either heat retention or heat production (or both) improved when Ta reached levels which are cold by the standards of birds in our population. Our results show that levels of heat production and Tb can be age specific. Further studies should address age-specific differences on quality, structure, and thermal conductivity of plumage more explicitly, to investigate the role of variation in insulation in age-linked metabolic phenotypes.

&lt;p&gt;Low FEV1 Is Associated With Increased Risk Of Cachexia In COPD Patients&lt;/p&gt;

BackgroundChronic obstructive pulmonary disease (COPD) has been introduced as a major public health problem. It has been suggested that disruption in function or some adipokines and serum proteins' signaling could play crucial roles in lung diseases. This study's purpose was to investigate the association between serum levels of S100A1, ZAG, and adiponectin with FEV1 in COPD patients.MethodsIn this cross-sectional study, 90 clinically stable outpatient males with age ranging from 40 to 70 years with COPD diagnosis – FEV1/FVC < 70% – were divided into two groups: mild–moderate COPD patients; FEV1 ≥ 50 (n=52) VS severe and very severe COPD patients; FEV1 < 50 (n=38). The serum levels of ZAG, S100A1, and adiponectin were measured by the use of enzyme-linked immunosorbent assay.ResultsIn the present study, lower FEV1 was significantly associated with increased risk of cachexia (OR = 5.76, 95% CI: 2.28–14.54). The serum level of ZAG was significantly higher in the mild–moderate COPD patients in comparison with the severe–very severe COPD patients (p<0.035). However, the resting metabolic rate (RMR) level was significantly higher in FEV1<50 group compared to FEV1≥50 group (p<0.024). Also, strong positive associations between serum S100A1–ZAG, serum adiponectin–ZAG, and serum adiponectin–S100A1 (β>0.800, p<0.001) were shown.ConclusionIn the present study, we found that low FEV1 was associated with increased risk of cachexia in COPD patients. Additionally, lower serum level of ZAG and higher RMR were observed in patients with severe–very severe COPD as compared to mild–moderate COPD. Therefore, it could be claimed that there is a mechanistic chain of causality between FEV1, serum ZAG, RMR, and cachexia.