Variation In Energy Expenditure Research Articles

Energy Expenditure, a New Tool for Monitoring Surgical Stress in Colorectal Oncological Patients: A Prospective, Monocentric Study.

Surgical stress response in colorectal surgery consists of a neurohormonal and an immunological response and influences oncological outcomes. The intensity of surgical trauma influences mortality, morbidity, and metastasis' occurrence in colorectal neoplasia. Energy expenditure (EE) stands for the body's energy consumed to keep its homeostasis and can be either calculated or measured by direct or indirect calorimetry. The present study attempted to evaluate surgical stress response using EE measurement and compare it to the postoperative cortisol dynamic. A prospective, monocentric study was conducted over a period of one year in the Anesthesiology Department including 21 patients from whom serum cortisol values were collected in the preoperative periodand on the first postoperative day, and EE was measured and recorded every 15 minutes throughout surgery using the indirect calorimetry method. The studycompared EE values' dynamic registered 30 minutes after intubation and 30 minutes before extubating (after abdominal closure) to cortisol perioperative dynamic. We enrolled 21 patients and84 measurements were recorded, 42 probes of serum cortisoland 42 measurements of EE. The mean value of the first measurement of serum cortisol was 13.60±3.6 µgand the second was 16.21±6.52 µg. The average value of the first EE recording was 1273.9±278 kcal and 1463.4±398.2 kcal of the second recording. The bivariate analysis performed showed a good correlation between cortisol variation and EE's variation (Spearman coefficient=0.666, p<0.001, CI=0.285, 0.865). In nine cases (42.85%), cortisol value at 24 hours reached the baseline or below the baselines preoperative value. In eight cases (38.09%), patients' EE at the end of the surgery was lower than that recorded at the beginning of the surgery. Intraoperative EE variation correlated well with cortisol perioperative dynamic and stood out in this study as a valuable and accessible predictor of surgical stress in colorectal surgery.

Impact of room thermal conditions on thermal response and energy expenditure of people of different body compositions

We performed a climatic chamber study with the participation of sixteen people in all BMI categories at different thermal conditions (16.4°C, 22.1°C, 28.0°C) and activity levels (light, medium, high). There was no substantial influence of the BMI value on the thermal and humidity sensations and the thermal preferences of the subjects. Underweight people had the lowest thermal sensation in cold conditions, while obese people declared sensations most similar to neutral in hot conditions. The net energy expenditure values were the highest in all weight groups during cold conditions and the lowest during warm conditions. We observed that energy expenditure increases with an increase in BMI. The energy expenditure variability depending on body fat percentage was entirely different for women and men. In the former group, energy expenditure increased with the increase in body fat content (especially for medium and high activity). In the case of men, this dependence was not noticed – the energy expenditure was at a similar level regardless of the fat content.

Assessment of the Physical Invasiveness of Peroral Endoscopic Myotomy during the Perioperative Period Based on Changes in Energy Metabolism.

A novel treatment method for achalasia of the esophagus and related disorders is known as peroral endoscopic myotomy (POEM). This study aimed to calculate the resting energy expenditure (REE) and evaluated the degree of physical invasiveness based on metabolic changes during the perioperative period of POEM. Fifty-eight patients who underwent POEM were prospectively enrolled; REE, body weight (BW), and basal energy expenditure were measured on the day of POEM, postoperative day 1 (POD 1), and three days after POEM (POD 3). The median REE/BW increased from 19.6 kcal/kg on the day of POEM to 24.5 kcal/kg on POD 1. On POD 3, it remained elevated at 20.9 kcal/kg. The stress factor on POD 1 was 1.20. Among the factors, including the Eckardt score, operation time, and the length of myotomy, the length of myotomy was associated with changes in REE/BW. During the perioperative period of POEM, the level of variation in energy expenditure was lower than that of esophageal cancer surgeries performed under general anesthesia. However, because the length of myotomy is a factor affecting changes in energy expenditure, careful perioperative management is desirable for patients with longer myotomy lengths.

Validation of Oura ring energy expenditure and steps in laboratory and free-living

BackgroundCommercial activity trackers are increasingly used in research and compared with research-based accelerometers are often less intrusive, cheaper, with improved storage and battery capacity, although typically less validated. The present study aimed to determine the validity of Oura Ring step-count and energy expenditure (EE) in both laboratory and free-living.MethodsOura Ring EE was compared against indirect calorimetry in the laboratory, followed by a 14-day free-living study with 32 participants wearing an Oura Ring and reference monitors (three accelerometers positioned at hip, thigh, and wrist, and pedometer) to evaluate Oura EE variables and step count.ResultsStrong correlations were shown for Oura versus indirect calorimetry in the laboratory (r = 0.93), and versus reference monitors for all variables in free-living (r ≥ 0.76). Significant (p < 0.05) mean differences for Oura versus reference methods were found for laboratory measured sitting (− 0.12 ± 0.28 MET), standing (− 0.27 ± 0.33 MET), fast walk (− 0.82 ± 1.92 MET) and very fast run (− 3.49 ± 3.94 MET), and for free-living step-count (2124 ± 4256 steps) and EE variables (MET: − 0.34-0.26; TEE: 362–494 kcal; AEE: − 487-259 kcal). In the laboratory, Oura tended to underestimate EE with increasing discrepancy as intensity increased. The combined activities and slow running in the laboratory, and all MET placements, TEE hip and wrist, and step count in free-living had acceptable measurement errors (< 10% MAPE), whereas the remaining free-living variables showed close to (≤13.2%) acceptable limits.ConclusionThis is the first study investigating the validity of Oura Ring EE against gold standard methods. Oura successfully identified major changes between activities and/or intensities but was less responsive to detailed deviations within activities. In free-living, Oura step-count and EE variables tightly correlated with reference monitors, though with systemic over- or underestimations indicating somewhat low intra-individual validity of the ring versus the reference monitors. However, the correlations between the devices were high, suggesting that the Oura can detect differences at group-level for active and total energy expenditure, as well as step count.

Large Estimate Variations in Assessed Energy Expenditure and Physical Activity Levels during Active Virtual Reality Gaming: A Short Report.

The purpose of the study was to compare methods for estimating energy expenditure (EE) and physical activity (PA) intensity during a 30 min session of active virtual reality (VR) gaming. Eight individuals (age = 25.4 ± 2.0 yrs) participated, with a maximal oxygen consumption (VO2max) of 41.3 ± 5.7 mL∙kg-1∙min-1. All tests were conducted over two days. An incremental test to determine the VO2max when running was performed on day 1, while 30 min of active VR gaming was performed on day 2. The instruments used for EE estimations and PA measurements were indirect calorimetry, a heart rate (HR) monitor, and waist- and wrist-worn accelerometer. Compared to indirect calorimetry, waist-worn accelerometers underestimated EE (mean difference: -157.3 ± 55.9 kcal, p &lt; 0.01) and PA levels. HR-based equations overestimated EE (mean difference: 114.8 ± 39.0 kcal, p &lt; 0.01 and mean difference: 141.0 ± 81.6 kcal, p &lt; 0.01). The wrist-worn accelerometer was the most accurate in estimating EE (mean difference: 23.9 ± 45.4 kcal, p = 0.95). The large variations in EE have implications for population-based surveillance of PA levels and for clinical studies using active VR gaming.

Variability in energy expenditure is much greater in males than females

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

Metabolic profile in women differs between high versus low energy spenders during a low intensity exercise on a cycle-desk

Active-desks are emerging strategies aiming at reducing sedentary time while working. A large inter-individual variability in energy expenditure (EE) profile has been identified and has to be explored to better optimize and individualize those strategies. Thus the present study aimed at comparing the metabolic and physical profile of individuals characterized as high spenders (H-Spenders) versus low spenders (L-Spenders) based on EE during a cycle-desk low intensity exercise. 28 healthy women working in administrative positions were enrolled. Anthropometric, body composition and fasting metabolic profile parameters were assessed. EE was determined by indirect calorimetry, at rest and during a 30-min cycle-desk use. Participants were categorized as H-Spenders and L-Spenders using the median of the difference between EE at rest and during the 30-min exercise. H-Spenders had higher mean EE (p < 0.001) and carbohydrate oxidation (p = 0.009) during exercise. H-Spenders displayed higher values for fasting plasma insulin (p = 0.002) and HOMA-IR (p = 0.002) and lower values for HDL-cholesterol (p = 0.014) than L-Spenders. The percentage of body fat mass was significantly higher in H-Spenders (p = 0.034). Individuals expending more energy during a low intensity cycling exercise presented a less healthy metabolic profile compared with L-Spenders. Future studies will have to explore whether the chronic use of cycle-desks during work time can improve energy profile regarding metabolic parameters.

Socioecological Factors Associated With Physical Activity and Sedentary Behavior Among Workers: Using the PRECEDE-PROCEED Model.

Physical inactivity is a major global health problem. Industrial automation has led to an increased number of workers who are sedentary at work. We examined whether three socioecological factors (i.e., predisposing, reinforcing, and enabling factors) derived from the PRECEDE-PROCEED model would be significantly associated with the physical activity and sedentary behavior among workers. A cross-sectional study was conducted among 539 employees at an electronic manufacturing plant in Gumi, South Korea. Physical activity variables of energy expenditure (MET-min/week) and sitting time at work (minutes/day) were measured by the International Physical Activity Questionnaire and the Workforce Sitting Questionnaire, respectively. Of the socioecological factors, a predisposing factor defined as self-determined motivation was measured by the Exercise Self-Regulation Questionnaire; a reinforcing factor defined as autonomy support was measured by the Work Climate Questionnaire; and an enabling factor defined as supportive workplace environment was measured by the Perceived Workplace Environment Scale. Self-determined motivation (i.e., autonomous and controlled forms of motivation), autonomy support, and a supportive workplace environment were all significantly associated with increased physical activity energy expenditure during leisure-time. However, they were not significantly associated with sitting time on working and non-working days. Three socioecological factors of the PRECEDE-PROCEED model were significantly associated with leisure-time physical activity among workers. Our findings may help occupational health nurses use a socioecological approach for designing effective workplace strategies to increase leisure-time physical activity among workers.

Chia Flour (Salvia hispanica L.) Intake Does Not Affect Weight Loss and Lipid Profile but Improve Systolic Blood Pressure Control in Obesity

Background Obesity is an epidemic, multifactorial and difficult-to-control disease, besides being a risk factor for cardiovascular diseases. Among the multiple intervention proposals, the addition of chia in meals has been considered due to its composition and possible effects on weight loss and cardiovascular parameters. Objective We evaluate the influence of chia flour (Salvia hispanica L.) intake on body weight, body composition, energy expenditure (EE) and cardiovascular risk in obese women. Methods This study is a clinical trial performed with 20 adult women with obesity randomized into experimental (chia flour) and control (placebo) groups. We assessed anthropometric and biochemical measurements, as well as clinical, dietary and EE variables before intervention and 90 days later. Results There were no differences in anthropometric indicators, body composition or EE between groups, but a decrease in HDL-c (p = 0.049) and a trend towards the reduction of systolic blood pressure (SBP) (p = 0.062) was observed in the experimental group. Conclusion Chia flour had a possible positive effect on SBP control, but negatively affected the lipid profile and did not seem to influence obesity control.

Oxygen pulse best predicts energy expenditure during stair ascent and descent in individuals with chronic stroke.

To determine whether minute ventilation-to-carbon dioxide production (VE/VCO2), oxygen pulse (VO2/HR), and rate pressure product (RPP: VO2 * HR/1000) can explain energy expenditure during stair ascent/descent and whether energy expenditure during stair ascent/descent can discriminate between walking abilities in individuals with chronic stroke. Regression analysis of cross-sectional data from 50 individuals between 1 and 4 years post-stroke was carried out to investigate the prediction of energy expenditure during stair ascent/descent. In addition, discriminant analysis was carried out to investigate the discrimination between walking abilities for energy expenditure: community (walking speed ≥ 0.8 m/s) and non-community (walking speed < 0.8 m/s) walkers. Oxygen pulse and rate pressure product were retained in the model. Oxygen pulse alone explained 70% of the variance in energy expenditure during stair ascent/descent. By adding rate pressure product, 79% of the variance was explained. Energy expenditure was able to discriminate the community from the non-community walkers, with a cutoff value of 13.8 ml∙kg-1∙min-1 and correctly classified 62% of the non-community and 78% of the community walkers. Oxygen pulse and rate pressure product significantly predicted energy expenditure during stair ascent/descent in individuals with chronic stroke. Energy expenditure during stair ascent/descent discriminated community from non-community walkers.

Nutrition Management in Patients With Traumatic Brain Injury: A Narrative Review.

Traumatic brain injury (TBI) is a major cause of long-term physical and psychological disability and death. In patients with TBI, undernutrition is associated with an increased mortality rate, more infectious complications, and worse neurologic outcomes. Therefore, timely and effective nutritional therapy is particularly crucial in the management of TBI to improve patients' prognoses. This narrative review summarizes the issues encountered in clinical practice for patients with neurotrauma who receive acute and post-acute in-patient rehabilitation services, and it comprehensively incorporates a wide range of studies, including recent clinical practice guidelines (CPGs), with the aim of better understanding the current evidence for optimal nutritional therapy focused on TBI patients. Recent CPGs were reviewed for 6 topics: 1) hypermetabolism and variation in energy expenditure in patients with TBI, 2) delayed gastric emptying and intolerance to enteral nutrition, 3) decision-making on the route and timing of access in patients with TBI who are unable to maintain volitional intake (enteral nutrition versus parenteral nutrition), 4) decision-making on the enteral formula (standard or immune-modulating formulas), 5) glycemic control, and 6) protein support. We also identified areas that need further research in the future.

Indirect Calorimetry as an Instrument of Research to Identify the Effect of Hypermetabolism in Critical Patients’ Prognosis

Background: Energy expenditure (EE) evaluation in Intensive Care Unit (ICU) patients can be very challenging. Critical illness is characterized by great variability in EE, which is influenced by the disease itself and the effects of treatment. Indirect calorimetry (IC) is currently the gold standard to measure EE in Intensive Care Unit (ICU) patients. However, calorimeters are not widely available, and predictive formulas (PF) are still commonly used, leading to under or overfeeding and deleterious consequences.Important metabolic changes occur and catabolism becomes prominent in critically ill patients.Both hyper and hypometabolism can be observed, but hypermetabolic patients appear to have higher mortality rates compared to metabolically normal patients. This study aimed to assess hypermetabolism incidence and compare clinical outcomes between hypermetabolic and normometabolic patients in ICU.Methods: A single-center, retrospective, and observational study was conducted in the ICU of the Hospital do Divino Espírito Santo in Ponta Delgada, between August 2018 and February 2021. Only invasively mechanically ventilated patients were included. Resting energy expenditure (REE) was predicted by 25 kcal/kg/day formula to obtain predicted resting energy expenditure (PREE), and REE was measured by IC to obtain measured resting energy expenditure (MREE). According to their metabolic state (PREE/MREE), patients were divided into hypermetabolic (≥1.3) and normometabolic (<1.3). To determine the limits of agreement between PREE and MREE, we performed a Bland-Altman (BA) analysis. Baseline characteristics, severity criteria, nutritional status, and main diagnosis on admission were compared. The primary outcome considered was 30-day mortality. Other outcomes such as the ICU length of stay (LOS), in-hospital LOS, and length of invasive ventilation were also evaluated.Results: Among the 80 ICU patients included in the final analysis, 67 patients were normometabolic (83.4%). Patients admitted due to pneumonia were more hypermetabolic, 8 (61.5%) vs. 10 (14.9%); p<0.001. Hypermetabolism was found also in patients admitted due to sepsis/septic shock, 7 (53.8%) vs. 16 (23.9%); p=0.029. Hypermetabolic patients had lower body mass index (22.5 [interquartile range (IQR): 21.5-24.9] vs. 27.7 [IQR: 25.0-32.4] kg/m2; p=0.001) and higher MREE (2715.0 [2399.0-3090.0] vs. 1690.0 [1410.0-2190.0] kcal/day; p<0.001). Bland-Altman analysis showed a mean difference of -5.6 ± 744.7 Kcal/day between the PREE and MREE by IC. No statistically significant difference was found between the two groups, neither in 30-day mortality nor in the other outcomes considered.Conclusions: Hypermetabolism was not seen to present a greater risk of death in mechanically ventilated patients in ICU. Lower BMI, sepsis/septic shock, and pneumonia appear to be associated with a hypermetabolic state.

Energy Expenditure of Level Overground Walking in Young Adults: Comparison With Prediction Equations

The purpose of this study was to investigate the accuracy of the published prediction equations for determining level overground walking energy cost in young adults. In total, 148 healthy young adults volunteered to participate in this study. Resting metabolic rate and energy expenditure variables at speeds of 4, 5, and 6km/h were measured by indirect calorimetry, walking energy expenditure was estimated by 3 published equations. The gross and net metabolic rate per mile of level overground walking increased with increased speed (all P < .01). Females were less economical than males. The present findings revealed that the American College of Sports Medicine and Pandolf etal equations significantly underestimated the energy cost of overground walking at all speeds (all P < .01) in young adults. The percentage mean bias for American College of Sports Medicine, Pandolf etal, and Weyand etal was 12.4%, 16.8%, 1.4% (4km/h); 21.6%, 15.8%, 7.1% (5km/h); and 27.6%, 12%, 6.6% (6km/h). Bland-Altman plots and prediction error analysis showed that the Weyand etal was the most accurate in 3 existing equations. The Weyand etal equation appears to be the most suitable for the prediction of overground walking energy expenditure in young adults.

Sex differences and shifts in body composition, physical activity, and total energy expenditure across a 3-month expedition.

An energetically demanding environment like a wilderness expedition can lead to potent stressors on human physiology and homeostatic balance causing shifts in energy expenditure and body composition. These shifts likely have consequences on overall health and performance and may potentially differ by sex. It is therefore critical to understand the potential differential body composition and energy expenditure changes in response to a novel and challenging environment in both males and female bodies. Data were collected from 75 healthy individuals (female=41; ages 18-53) throughout a 3-month long expedition in the American Rockies. Body mass, body fat, and lean muscle mass were measured before, during, and after the course. Physical activity intensity and energy expenditure were also measured in a subset of participants using the wGT3X-BT Actigraph wrist monitor and an accompanying Bluetooth heart rate monitor. Over the 3-month period, individuals initially experienced declines in body mass, body fat percentage, and lean muscle mass. Participants partially rebounded from these deficits to maintain overall body mass with a slight recomposition of body fat and lean muscle mass. Our data also demonstrated that sex moderated total energy expenditure, where females experienced a modest decline whereas males experienced an increase in energy expenditure from the beginning to the end of the course. Understanding changes in energy storage in the body and variation in energy expenditure between sexes during a 3-month expedition has critical implications for maintaining health and performance in an energetically demanding environment where resources may be scarce.

Indirect calorimetry in critical illness: a new standard of care?

Review recent literature on the role of indirect calorimetry in critical care nutrition management. Critical illness demands objective, targeted nutritional therapy to prevent adverse effects of underfeeding/over feeding. Thus, all recent societal guidelines recommend indirect calorimetry use to determine energy needs. Very recently, indirect calorimetry technology has finally evolved to allow for accurate, simple, and routine utilization in a wider range of ICU patients. Recent data continues to confirm poor correlation between measured and equation-predicted energy expenditure emphasizing need for indirect calorimetry to be standard of care. This may be particularly true in COVID-19, where significant progressive hypermetabolism and variability in energy expenditure has been shown. Metabolic physiology can change frequently during ICU stay in response to changes in clinical condition or care. Thus, repeated longitudinal indirect calorimetry measures are needed throughout ICU stay to optimize care, with initial data showing improved clinical outcomes when indirect calorimetry targets are utilized. Personalized ICU care demands objective data to guide therapy. This includes use of indirect calorimetry to determine energy expenditure and guide ICU nutrition therapy. Long-awaited new innovations in indirect calorimetry technology should finally lead to indirect calorimetry to becoming a fundamental component of modern ICU standard of care and clinical research moving forward.

Hypocaloric diet with lower meal frequency did not affect weight loss, body composition and insulin responsiveness, but improved lipid profile: a randomized clinical trial.

Dietary approaches are essential to control obesity, but the effectiveness of changes in meal frequency (MF) as a strategy for body weight loss or maintenance remain unclear. This study aimed to evaluate the influence of MF of a hypocaloric diet on weight loss, body composition, active ghrelin levels and metabolic indicators of obese women. This is a randomized, parallel clinical trial, including 40 women divided into two groups that received a hypocaloric diet with different MFs: MF6: six meals per day, and MF3: three meals per day. Dietary, laboratory, anthropometric and body composition indicators were assessed, as well as energy expenditure (EE), before and after the 90 days of the intervention. Dietary consumption did not differ between groups, before or after intervention. The two groups reduced their energy intake after intervention, but there were no differences between the groups. Waist circumference (WC) was reduced and resting metabolic rate had increased in the MF3 group at the end compared to baseline. Moreover, there was a significant difference in the triglyceride levels between groups after intervention, with an important reduction in the MF3 group, although changes in body composition, blood glucose, plasma ghrelin levels and EE variables did not differ between the groups at the end. It is concluded that, the hypocaloric diet with different MF each day did not change weight loss, body composition or insulin responsiveness, but there was an improvement of triglyceridemia in the MF3 group. The present study suggests that eating snacks between meals is not an important factor for weight loss and improvement of metabolic health in women with obesity.

Day and night changes in energy expenditure of patients on automated peritoneal dialysis

Automated peritoneal dialysis (APD) treatment for end-stage kidney disease affords patients a degree of autonomy in everyday life. Clinical investigations of their energy expenditure (EE) are usually based on resting EE, which could mask day and night variations in EE. The aim of this study, therefore, was to compare the components of EE in APD patients and healthy control (C) subjects. Patients treated with APD for more than 3 months were compared with C volunteers matched for age and lean body mass (LBM). Biochemical analyses were performed and body composition was determined by DEXA to adjust EE to LBM. Total EE, its different components and respiratory quotients (RQ) were measured by a gas exchange method in calorimetric chambers. Spontaneous total and activity-related EE (AEE) were also measured in free-living conditions over 4 days by a calibrated accelerometer and a heart rate monitor. APD (n=7) and C (n=7) patients did not differ in age and body composition. REE did not differ between the two groups. However, prandial increase in EE adjusted for dietary energy intake was higher in APD patients (+57.5±12.71kcal/h) than in C subjects (+33.8±10.5kcal/h, p=0.003) and nocturnal decrease in EE tended to be lower in APD patients undergoing dialysis sessions (- 4.53±8.37kcal/h) than in subjects (- 11.8±7.69kcal/h, p=0.059). Resting RQ (0.91±0.09 vs 0.81±0.04, p=0.032) and nocturnal RQ (0.91±0.09 vs 0.81±0.04, p=0.032) were significantly higher in APD patients, indicating a preferential use of glucose substrate potentially absorbed across the peritoneum. AEE was lower in APD patients (595.9±383.2kcal/d) than in C subjects (1205.2±370.5kcal/d, p=0.011). In contrast, energy intakes were not significantly different (1986±465 vs 2083±377kcal/d, p=0.677). Although the two groups had identical resting EE, APD patients had a higher prandial increase in EE, a lower activity-related EE and higher resting and nocturnal RQ than healthy subjects.

A big-data approach to understanding metabolic rate and response to obesity in laboratory mice.

Maintaining a healthy body weight requires an exquisite balance between energy intake and energy expenditure. To understand the genetic and environmental factors that contribute to the regulation of body weight, an important first step is to establish the normal range of metabolic values and primary sources contributing to variability. Energy metabolism is measured by powerful and sensitive indirect calorimetry devices. Analysis of nearly 10,000 wild-type mice from two large-scale experiments revealed that the largest variation in energy expenditure is due to body composition, ambient temperature, and institutional site of experimentation. We also analyze variation in 2329 knockout strains and establish a reference for the magnitude of metabolic changes. Based on these findings, we provide suggestions for how best to design and conduct energy balance experiments in rodents. These recommendations will move us closer to the goal of a centralized physiological repository to foster transparency, rigor and reproducibility in metabolic physiology experimentation.

An observational study of feeding practice in ventilated patients with spinal cord injury

Cervical spinal cord injuries (CSCI) are frequently complicated by respiratory failure requiring prolonged invasive mechanical ventilation in the intensive care unit (ICU). Providing adequate nutrition may be an important factor in the recovery of respiratory muscle function for ventilator weaning. The aim of this study was to examine the practical implementation of a multi-disciplinary approach to nutrition combining indirect calorimetry and the modified Harris Benedict equation to achieve target rates of nutrition for patients with CSCI. A retrospective observational study was performed by collecting data of normal nutrition practice in a series of adult ventilated patients with CSCI admitted between 2014 and 2017 to the ICU. Administered calories by enteral nutrition and measured total energy expenditure (TEE) by indirect calorimetry were recorded for the first 3-weeks. Calculations were performed to measure the adequacy of calorie administration relative to TEE. Average daily temperatures and minute ventilation were recorded to support evidence for hypermetabolism. TEE estimates using the modified Harris Benedict equation were compared to indirect calorimetry measures for each patient. Sixteen patients were included in the study. Calorie administration rapidly increased to a plateau of 2300-2400kcal per day over the first four days. The median measured TEE by indirect calorimetry was initially high, starting at 3472kcal/day and decreasing to 2784kcal/day at three weeks. However, there was wide variation in energy expenditure amongst patients. Average daily temperatures and minute ventilation were high supporting hypermetabolism. Adequacy of calorie administration to TEE ranged between 76 and 86 percent through the study period. There was relatively wide variation when comparing estimates of TEE using the modified Harris Benedict equation versus indirect calorimetry. A multi-disciplinary approach to nutrition in ventilated patients with CSCI, incorporating indirect calorimetry, achieves target rates of nutrition. Our findings suggest that a hypermetabolic response may be common but variable in this population and subsequently both under and over feeding may be a risk if nutrition targets are not guided by indirect calorimetry. Further prospective research using protocoled indirect calorimetry measures would be beneficial to ascertain accurate energy requirements for this group of patients and also determine whether feeding to target influences weaning off the ventilator.

The ARTE index: Characterizing free‐living physical activity and indices of cardio‐metabolic health among postmenopausal women

PurposeThe doubly‐labeled water (DLW) technique is the gold‐standard used to objectively measure free‐living activity energy expenditure (AEE), however; it does not account for differences in body size or locomotion economy. Whereas the physical activity level (PAL) index, calculated from the ratio of total energy expenditure (TEE) and resting energy expenditure (REE), is employed to adjust for body size – it also does not account for variance in energy expenditure attributed to locomotion economy. Alternatively, the activity‐related time equivalent (ARTE) circumvents the limitations of AEE and PAL. In the present work, DLW was used to compare AEE, PAL, and variations of the ARTE index among a cohort of postmenopausal women dichotomized above/below the 50th percentile of normative data for body fat%. Correlations of AEE, PAL, and ARTE to measures of cardio‐metabolic health including arterial elasticity, body fat% and cardiorespiratory fitness (V̇O2max) were also performed.MethodsNinety‐two, healthy postmenopausal women (65+/−4 years) were recruited to measure free‐living AEE over a 14‐day period using DLW. TEE was reduced by 10% to account for the thermogenesis of feeding whereas AEE was calculated by subtracting REE from adjusted‐TEE. PAL was calculated from the ratio of TEE/REE. ARTE4act was calculated by dividing AEE by the average energy expenditure of non‐graded walking, graded walking, stair climbing, and a carrying task. AEE divided by the average energy expenditure of non‐graded walking was used to calculate ARTEwalk. Arterial elasticity was performed using pulse contour analysis from the radial artery. Dual‐energy X‐ray absorptiometry was used to estimate body fat% whereas a modified‐Balke protocol was used to measure V̇O2max. Between‐group comparisons were performed using independent t‐tests and Pearson’s correlation were used to evaluate relationships.ResultsBetween‐group differences were not detected for AEE, PAL, or the ARTE4act. However, women with less percent body fat (i.e., &lt; 50th percentile) exhibited greater activity as evidenced by the ARTEwalk (min·day−1) (255+/−154 vs. 193+/−130; p &lt; 0.05). Though AEE and PAL did not correlate with any cardio‐metabolic variables, ARTE4act was related to arterial elasticity (r = 0.24) and V̇O2max (r = 0.27) while ARTEwalk was related to arterial elasticity (r = 0.27), body fat% (r = −0.24), and V̇O2max (r = 0.32).ConclusionsConsistent with the ARTEwalk, adjustments for energetic cost of non‐graded walking may improve the sensitivity of AEE for detecting differences in free‐living physical activity and parameters of cardio‐metabolic health – known to be critical for overall well‐being.Support or Funding InformationThis investigation was supported by the following grants from the National Institutes of Health: R01AG027084‐01, R01AG027084‐S, P30DK056336, P60DK079626, and UL1RR025777.