Maximal sustainable energy intake during transatlantic ocean rowing is insufficient for total energy expenditure and skeletal muscle mass maintenance.

Studies of extreme endurance have suggested that there is an alimentary limit to energy intake (EI) of ∼2.5 × resting metabolic rate (RMR). To gain further insight, this study aimed to simultaneously measure EI, total energy expenditure (TEE) body mass and muscle mass in a large cohort of males and females of varying ages during a transatlantic rowing race. Forty-nine competitors (m = 32, f = 17; age 24-67 years; time at sea 46 ± 7 days) in the 2020 and 2021 Talisker Whisky Atlantic Challenge rowed 12-18 hday-1 for ∼3000 miles. TEE was assessed in the final week of the row using 2 H2 18 O doubly labelled water, and EI was analysed from daily ration packs over this period. Thickness of relatively active (vastus lateralis, intermedius, biceps brachaii and rectus abdominus) and inactive (gastrocnemius, soleus and triceps) muscles was measured pre (<7 days) and post (<24 h) row using ultrasound. Body mass was measured and used to calculate RMR from standard equations. There were no sex differences in males and females in EI (2.5 ± 0.5 and 2.3 ± 0.4 × RMR, respectively, P = 0.3050), TEE (2.5 ± 1.0 and 2.3 ± 0.4 × RMR, respectively, P = 0.5170), or body mass loss (10.2 ± 3.1% and 10.0 ± 3.0%, respectively, P = 0.8520), and no effect of age on EI (P = 0.5450) or TEE (P = 0.9344). Muscle loss occurred exclusively in the calf (15.7% ± 11.4% P < 0.0001), whilst other muscles remained unchanged. After 46 days of prolonged ultra-endurance ocean rowing incurring 10% body mass loss, maximal sustainable EI of ∼2.5 × RMR was unable to meet total TEE suggesting that there is indeed a physiological capacity to EI.

Validation of an web-based dietary assessment tool (RiksmatenFlex) against doubly labelled water and 24 h dietary recalls in pregnant women.

INTRODUCTION: Digital technologies have enabled new possibilities to assess dietary intake and have shown promise in terms of decreased participant burden, improved accuracy and lower costs. However, their potential and validity in pregnant populations are scarcely explored. OBJECTIVES: This study aimed to (a) validate energy intakes obtained from a web-based dietary recall method developed for national surveys (RiksmatenFlex) against total energy expenditure (TEE) by means of the doubly labelled water (DLW) method, and (b) to compare intakes of macronutrients, key unhealthy and healthy foods as well as adherence to food-based dietary guidelines between RiksmatenFlex and repeated 24 h telephone dietary recalls in healthy Swedish pregnant women. METHODS: This study was conducted as a nested validation within the HealthyMoms trial. Intakes of foods, macronutrients and energy were assessed during three days through RiksmatenFlex and 24 h telephone dietary recalls, and Swedish Healthy Eating Index (SHEI) scores were also calculated for both methods (n = 52). For 24 women, TEE was also assessed through the DLW method. Paired Samples T-tests and Wilcoxon Signed Ranks Tests were used to identify differences between means for foods, macronutrients, energy and SHEI scores. Pearson correlation coefficient or Spearman's rho were performed to identify relationships between variables. To compare energy intake (RiksmatenFlex) with TEE (DLW method) and 24 h telephone dietary recalls, Bland and Altman plots were constructed. RESULTS: Average energy intake from RiksmatenFlex (10,015 [SD 2004] kJ) was not statistically different from TEE (10,252 [SD 1197] kJ) (p = 0.596) (mean difference: -237 kJ/24 h). Correspondingly, there were small mean differences between average intakes of key unhealthy and healthy foods and average SHEI scores between RiksmatenFlex and 24 h telephone dietary recalls. However, the Bland and Altman plots showed wide limits of agreement for all dietary variables (e.g., for energy intake using RiksmatenFlex versus TEE: ±4239 kJ/24 h). High correlations between the investigated dietary variables for the two dietary methods were observed (r = 0.751 to 0.931; all p < 0.001). CONCLUSION: RiksmatenFlex captured average intakes of energy, unhealthy and healthy food groups and adherence to food-based dietary guidelines in a comparable way to 24 h telephone dietary recalls and the DLW method. Our results support the validity of RiksmatenFlex as a web-based dietary assessment method for future use in pregnancy for intervention studies and national dietary surveys.

Energy expenditure and dietary intake in professional female football players in the Dutch Women's League: Implications for nutritional counselling.

In contrast to male football players, research on the nutritional requirements of female football players is limited. This study aimed to assess total daily energy expenditure (TDEE) in professional female football players, along with body composition, physical activity and dietary intake. This observational study included 15 professional football players playing in the highest Dutch Women's League. TDEE was assessed by doubly labelled water over 14 days, along with resting metabolic rate (RMR; ventilated hood), fat-free mass (FFM; dual-energy x-ray absorptiometry), and dietary intake (24-h recalls). Physical activity energy expenditure (PAEE) was derived from subtracting RMR and estimated diet-induced thermogenesis (10%) from TDEE. TDEE was 2882 ± 278 kcal/day (58 ± 5 kcal/kg FFM) and significantly (p < 0.05) correlated with FFM (r = 0.62). PAEE was 1207 ± 213 kcal/d. Weighted energy intake was 2344 kcal [2023-2589]. Carbohydrate intakes were 3.2 ± 0.7, 4.4 ± 1.1 and 5.3 ± 1.9 g/kg body mass for rest, training and match days, respectively, while weighted mean protein intake was 1.9 ± 0.4 g/kg body mass. In conclusion, the energy requirements of professional female football players are moderate to high and can be explained by the substantial PAEE. To fuel these requirements, sports nutritionists should consider shifting the players' focus towards prioritizing adequate carbohydrate intakes, rather than emphasizing high protein consumption.

Total daily energy expenditure and elevated water turnover in a small-scale semi-nomadic pastoralist society from Northern Kenya.

BACKGROUND: Pastoralists live in challenging environments, which may be accompanied by unique activity, energy, and water requirements. AIM: Few studies have examined whether the demands of pastoralism contribute to differences in total energy expenditure (TEE) and water turnover (WT) compared to other lifestyles. SUBJECTS AND METHODS: Accelerometer-derived physical activity, doubly labelled water-derived TEE and WT, and anthropometric data were collected for 34 semi-nomadic Daasanach adults from three northern Kenyan communities with different levels of pastoralist activity. Daasanach TEEs and WTs were compared to those of other small-scale and industrialised populations. RESULTS: When modelled as a function of fat-free-mass, fat-mass, age, and sex, TEE did not differ between Daasanach communities. Daasanach TEE (1564-4172 kcal/day) was not significantly correlated with activity and 91% of TEEs were within the range expected for individuals from comparison populations. Mean WT did not differ between Daasanach communities; Daasanach absolute (7.54 litres/day men; 7.46 litres/day women), mass-adjusted, and TEE-adjusted WT was higher than most populations worldwide. CONCLUSIONS: The similar mass-adjusted TEE of Daasanach and industrialised populations supports the hypothesis that habitual TEE is constrained, with physically demanding lifestyles necessitating trade-offs in energy allocation. Elevated WT in the absence of elevated TEE likely reflects a demanding active lifestyle in a hot, arid climate.

Determining energy expenditure in a large seabird using accelerometry.

The trade off between energy gained and expended is the foundation of understanding how, why and when animals perform any activity. Based on the concept that animal movements have an energetic cost, accelerometry is increasingly being used to estimate energy expenditure. However, validation of accelerometry as an accurate proxy for field metabolic rate in free-ranging species is limited. In the present study, Australasian gannets (Morus serrator) from the Pope's Eye colony (38°16'42″S 144°41'48″E), south-eastern Australia, were equipped with GPS and tri-axial accelerometers and dosed with doubly labelled water (DLW) to measure energy expenditure during normal behaviour for 3-5 days. The correlation between daily energy expenditure from the DLW and vectorial dynamic body acceleration (VeDBA) was high for both a simple correlation and activity-specific approaches (R2=0.75 and 0.80, respectively). Varying degrees of success were observed for estimating at-sea metabolic rate from accelerometry when removing time on land using published energy expenditure constants (R2=0.02) or activity-specific approaches (R2=0.42). The predictive capacity of energy expenditure models for total and at-sea periods was improved by the addition of total distance travelled and proportion of the sampling period spent at sea during the night, respectively (R2=0.61-0.82). These results indicate that accelerometry can be used to estimate daily energy expenditure in free-ranging gannets and its accuracy may depend on the inclusion of movement parameters not detected by accelerometry.

Total Energy Expenditure in Healthy Ambulatory Older Adults Aged ≥80 Years: A Doubly Labelled Water Study.

INTRODUCTION: The life expectancy of older adults continues to increase; however, knowledge regarding their total energy requirements is lacking. This study aimed to compare the total energy expenditure (TEE) of older adults ≥80 years measured using doubly labelled water (DLW), with estimated TEE. The hypothesis was that the Mifflin, Ikeda, and Livingston equations will more closely estimate energy requirements than the commonly used Schofield equation. METHODS: Resting metabolic rate (RMR) and TEE were measured using the reference methods of indirect calorimetry and DLW, respectively. Bland-Altman plots compared measured RMR and TEE with predicted RMR using equations (Mifflin, Ikeda, Livingston, Schofield) and predicted TEE (predicted RMR × physical activity level). RESULTS: Twenty-one older adults (age range 80.7-90.1 years, BMI 26.1 ± 5.5 kg/m2) were included. The Schofield equation demonstrated the greatest bias from measured RMR, overestimating approximately up to double the mean difference (865 ± 662 kJ/day) compared with the three other equations. The Schofield equation exhibited the greatest bias (overestimation of 641 ± 1,066 kJ/day) compared with measured TEE. The other three equations underestimated TEE, with the least bias from Ikeda (37 ± 1,103 kJ/day), followed by Livingston (251 ± 1,108 kJ/day), and Mifflin (354 ± 1,140 kJ/day). Data are mean ± SD. CONCLUSIONS: In older adults ≥80 years, the Ikeda, Mifflin, and Livingston equations provide closer estimates of TEE than the widely used Schofield equation. The development of nutrition guidelines therefore should consider the utilization of equations which more accurately reflect age-specific requirements.

Is the energy balance explanation of the obesity epidemic wrong?

There is a striking discrepancy in both U.S and the U.K data between obesity rates, which are increasing, and self-reported food consumption rates, which are decreasing. There are two possible explanations for this discrepancy, namely that the widely accepted energy balance interpretation of obesity is wrong or that food consumption data are somehow biased. In a comment entitled "Obesity-an unexplained epidemic", Mozaffarian (2022) challenged the Energy Balance Model (EBM) and argued for a need to replace it with a novel biological theory. This challenge is premature, because there are psychological explanations for this discrepancy, namely that individuals with overweight and obesity underreport their food consumption and that this tendency has increased in recent years. To support these hypotheses, U.S and U.K data are reviewed that used the Doubly Labelled Water method (DLW), which is the gold standard for estimating energy expenditure. Such studies find not only consistent evidence of underreporting, but also that the discrepancy between measured energy expenditure and reported calorie consumption increased over time. Two psychological explanations for this pattern are discussed.

Daily energy requirements of male academy soccer players are greater than age-matched non-academy soccer players: A doubly labelled water investigation.

This study aimed to test the hypothesis that the total daily energy expenditure (TDEE) of male academy soccer players is greater than players not enrolled on a formalised academy programme. English Premier League academy (ACAD: n = 8, 13 years, 50 ± 6 kg, 88 ± 3% predicted adult stature, PAS) and non-academy players (NON-ACAD: n = 6, 13 years, 53 ± 12 kg, 89 ± 3% PAS) were assessed for TDEE (via doubly labelled water) during a 14-day in-season period. External loading was evaluated during training (ACAD: 8 sessions, NON-ACAD: 2 sessions) and games (2 games for both ACAD and NON-ACAD) via GPS, and daily physical activity was evaluated using triaxial accelerometry. Accumulative duration of soccer activity (ACAD: 975 ± 23 min, NON-ACAD: 397 ± 2 min; p < 0.01), distance covered (ACAD: 54.2 ± 8.3 km, NON-ACAD: 21.6 ± 4.7 km; p < 0.05) and time engaged in daily moderate-to-vigorous (ACAD: 124 ± 17 min, NON-ACAD: 79 ± 18 min; p < 0.01) activity was greater in academy players. Academy players displayed greater absolute (ACAD: 3380 ± 517 kcal · d-1, NON-ACAD: 2641 ± 308 kcal · d-1; p < 0.05) and relative TDEE (ACAD: 66 ± 6 kcal · kg · d-1, NON-ACAD: 52 ± 10 kcal · kg · d-1; p < 0.05) versus non-academy players. Given the injury risk associated with high training volumes during growth and maturation, data demonstrate the requirement for academy players to consume sufficient energy (and carbohydrate) intake to support the enhanced energy cost of academy programmes.

Comparison of total and activity energy expenditure estimates from physical activity questionnaires and doubly labelled water: a systematic review and meta-analysis.

Physical activity questionnaires (PAQ) could be suitable tools in free-living people for measures of physical activity, total and activity energy expenditure (TEE and AEE). This meta-analysis was performed to determine valid PAQ for estimating TEE and AEE using doubly labelled water (DLW). We identified data from relevant studies by searching Google Scholar, PubMed and Scopus databases. This revealed thirty-eight studies that had validated PAQ with DLW and reported the mean differences between PAQ and DLW measures of TEE (TEEDLW - TEEPAQ) and AEE (AEEDLW - AEEPAQ). We assessed seventy-eight PAQ consisting of fifty-nine PAQ that assessed TEE and thirty-five PAQ that examined AEE. There was no significant difference between TEEPAQ and TEEDLW with a weighted mean difference of -243·3 and a range of -841·4 to 354·6 kJ/d, and a significant weighted mean difference of AEEDLW - AEE PAQ 414·6 and a range of 78·7-750·5. To determine whether any PAQ was a valid tool for estimating TEE and AEE, we carried out a subgroup analysis by type of PAQ. Only Active-Q, administered in two seasons, and 3-d PA diaries were correlated with TEE by DLW at the population level; however, these two PAQ did not demonstrate an acceptable limit of agreement at individual level. For AEE, no PAQ was correlated with DLW either at the population or at the individual levels. Active-Q and 3-d PA diaries were identified as the only valid PAQ for TEE estimation. Further well-designed studies are needed to verify this result and identify additional valid PAQ.

Doubly labelled water-calibration approach attenuates the underestimation of energy intake calculated from self-reported dietary assessment data in Japanese older adults.

OBJECTIVE: Self-reported energy intake (EI) estimation may incur systematic errors that could be attenuated through biomarker calibration. We aimed to confirm whether calibrated EI was comparable to total energy expenditure (TEE) measured using the doubly labelled water (DLW) technique. DESIGN: Cross-sectional study. SETTING: General older population from the Kyoto-Kameoka Study, Japan. PARTICIPANTS: This study included sub- and main cohorts of 72 and 8058 participants aged≥ 65 years, respectively. EI was evaluated using a validated FFQ, and calibrated EI was obtained using a previously developed equation based on the DLW method. TEE was considered representative of true EI and also measured using the DLW method. We used a Wilcoxon signed-rank test and correlation analysis to compare the uncalibrated and calibrated EI with TEE. RESULTS: In the sub-cohort, the median TEE, uncalibrated EI and calibrated EI were 8559 kJ, 7088 kJ and 9269 kJ, respectively. The uncalibrated EI was significantly lower than the TEE (median difference = -1847 kJ; interquartile range (IQR): -2785 to -1096), although the calibrated EI was not (median difference = 463 kJ; IQR: -330 to 1541). The uncalibrated (r = 0·275) and calibrated EI (r = 0·517) significantly correlated with TEE. The reproducibility was higher for calibrated EI (interclass correlation coefficient (ICC) = 0·982) than for uncalibrated EI (ICC = 0·637). Similar findings were observed when stratifying the sample by sex. For medians, uncalibrated EI was lower (about 17 %) than calibrated EI in the main cohort. CONCLUSIONS: Biomarker calibration may improve the accuracy of self-reported dietary intake estimation.

Comparison of energy intake assessed by image-assisted food records to doubly labelled water in adolescents with intellectual and developmental disabilities: a feasibility study.

BACKGROUND: There are currently no validated methods for energy intake assessment in adolescents with intellectual and developmental disabilities (IDD). The purpose of this study was to determine the feasibility of collecting 3-day image-assisted food records (IARs) and doubly labelled water (TDEEDLW ) data in adolescents with IDD and to obtain preliminary estimates of validity and reliability for energy intake estimated by IAR. METHODS: Adolescents with IDD completed a 14-day assessment of mean daily energy expenditure using doubly labelled water. Participants were asked to complete 3-day IARs twice during the 14-day period. To complete the IAR, participants were asked to fill out a hard copy food record over three consecutive days (two weekdays/one weekend day) and to take before and after digital images of all foods and beverages consumed using an iPad tablet provided by the study. Energy intake from the IAR was calculated using Nutrition Data System for Research. Mean differences, intraclass correlations and Bland-Altman limits of agreement were performed. RESULTS: Nineteen adolescents with IDD, mean age 15.1 years, n = 6 (31.6%) female and n = 6 (31.6%) ethnic/racial minorities, enrolled in the trial. Participants successfully completed their 3-day food records and self-collected doubly labelled water urine samples for 100% of required days. Images were captured for 67.4 ± 30.1% of all meals recorded at assessment 1 and 72.3 ± 29.5% at assessment 2. The energy intake measured by IAR demonstrated acceptable test-retest reliability (intraclass correlation = 0.70). On average, IAR underestimated total energy intake by -299 ± 633 kcal/day (mean per cent error = -9.6 ± 22.2%); however, there was a large amount of individual variability in differences between the IAR and TDEEDLW (range = -1703 to 430). CONCLUSIONS: The collection of IAR and TDEEDLW is feasible in adolescents with IDD. While future validation studies are needed, the preliminary estimates obtained by this study suggest that in adolescents with IDD, the IAR method has acceptable reliability and may underestimate energy intake by ~9%.

Estimating physical activity from self-reported behaviours in large-scale population studies using network harmonisation: findings from UK Biobank and associations with disease outcomes.

BACKGROUND: UK Biobank is a large prospective cohort study containing accelerometer-based physical activity data with strong validity collected from 100,000 participants approximately 5 years after baseline. In contrast, the main cohort has multiple self-reported physical behaviours from > 500,000 participants with longer follow-up time, offering several epidemiological advantages. However, questionnaire methods typically suffer from greater measurement error, and at present there is no tested method for combining these diverse self-reported data to more comprehensively assess the overall dose of physical activity. This study aimed to use the accelerometry sub-cohort to calibrate the self-reported behavioural variables to produce a harmonised estimate of physical activity energy expenditure, and subsequently examine its reliability, validity, and associations with disease outcomes. METHODS: We calibrated 14 self-reported behavioural variables from the UK Biobank main cohort using the wrist accelerometry sub-cohort (n = 93,425), and used published equations to estimate physical activity energy expenditure (PAEESR). For comparison, we estimated physical activity based on the scoring criteria of the International Physical Activity Questionnaire, and by summing variables for occupational and leisure-time physical activity with no calibration. Test-retest reliability was assessed using data from the UK Biobank repeat assessment (n = 18,905) collected a mean of 4.3 years after baseline. Validity was assessed in an independent validation study (n = 98) with estimates based on doubly labelled water (PAEEDLW). In the main UK Biobank cohort (n = 374,352), Cox regression was used to estimate associations between PAEESR and fatal and non-fatal outcomes including all-cause, cardiovascular diseases, respiratory diseases, and cancers. RESULTS: PAEESR explained 27% variance in gold-standard PAEEDLW estimates, with no mean bias. However, error was strongly correlated with PAEEDLW (r = -.98; p < 0.001), and PAEESR had narrower range than the criterion. Test-retest reliability (Λ = .67) and relative validity (Spearman = .52) of PAEESR outperformed two common approaches for processing self-report data with no calibration. Predictive validity was demonstrated by associations with morbidity and mortality, e.g. 14% (95%CI: 11-17%) lower mortality for individuals meeting lower physical activity guidelines. CONCLUSIONS: The PAEESR variable has good reliability and validity for ranking individuals, with no mean bias but correlated error at individual-level. PAEESR outperformed uncalibrated estimates and showed stronger inverse associations with disease outcomes.

Estimates for energy expenditure in free-living animals using acceleration proxies: A reappraisal.

It is fundamentally important for many animal ecologists to quantify the costs of animal activities, although it is not straightforward to do so. The recording of triaxial acceleration by animal-attached devices has been proposed as a way forward for this, with the specific suggestion that dynamic body acceleration (DBA) be used as a proxy for movement-based power. Dynamic body acceleration has now been validated frequently, both in the laboratory and in the field, although the literature still shows that some aspects of DBA theory and practice are misunderstood. Here, we examine the theory behind DBA and employ modelling approaches to assess factors that affect the link between DBA and energy expenditure, from the deployment of the tag, through to the calibration of DBA with energy use in laboratory and field settings. Using data from a range of species and movement modes, we illustrate that vectorial and additive DBA metrics are proportional to each other. Either can be used as a proxy for energy and summed to estimate total energy expended over a given period, or divided by time to give a proxy for movement-related metabolic power. Nonetheless, we highlight how the ability of DBA to predict metabolic rate declines as the contribution of non-movement-related factors, such as heat production, increases. Overall, DBA seems to be a substantive proxy for movement-based power but consideration of other movement-related metrics, such as the static body acceleration and the rate of change of body pitch and roll, may enable researchers to refine movement-based metabolic costs, particularly in animals where movement is not characterized by marked changes in body acceleration.

The allometry of daily energy expenditure in hummingbirds: An energy budget approach.

Within-clade allometric relationships represent standard laws of scaling between energy and size, and their outliers provide new avenues for physiological and ecological research. According to the metabolic-level boundaries hypothesis, metabolic rates as a function of mass are expected to scale closer to 0.67 when driven by surface-related processes (e.g. heat or water flux), while volume-related processes (e.g. activity) generate slopes closer to one. In birds, daily energy expenditure (DEE) scales with body mass (M) in the relationship logDEE=2.35+0.68×logM , consistent with surface-level processes driving the relationship. However, taxon-specific patterns differ from the scaling slope of all birds. Hummingbirds have the highest mass-specific metabolic rates among all vertebrates. Previous studies on a few hummingbird species, without accounting for the phylogeny, estimated that the DEE-body mass relationship for hummingbirds was logDEE=1.72+1.21×logM . In Contrast to the theoretical expectations, this slope >1 indicates that larger hummingbirds are less metabolically efficient than smaller hummingbirds. We collected DEE and mass data for 12 hummingbird species, which, combined with published data, represented 17 hummingbird species in eight of nine hummingbird clades over a sixfold size range of body size (2.7-17.5 g). After accounting for phylogenetic relatedness, we found DEE scales with body mass as logDEE=2.04+0.95×logM . This slope of 0.95 is lower than previously estimated for hummingbirds, but much higher than the slope for all birds (0.68). The high slopes of torpor, hovering and flight potentially explain the high interspecific DEE slope for hummingbirds compared to other endotherms.

Comparing saliva and urine samples for measuring breast milk intake with the 2H oxide dose-to-mother technique among children 2-4 months old.

Saliva and urine are the two main body fluids sampled when breast milk intake is measured with the 2H oxide dose-to-mother technique. However, these two body fluids may generate different estimates of breast milk intake due to differences in isotope enrichment. Therefore, we aimed to assess how the estimated amount of breast milk intake differs when based on saliva and urine samples and to explore whether the total energy expenditure of the mothers is related to breast milk output. We used a convenience sample of thirteen pairs of mothers and babies aged 2-4 months, who were exclusively breastfed and apparently healthy. To assess breast milk intake, we administered doubly labelled water to the mothers and collected saliva samples from them, while simultaneously collecting both saliva and urine from their babies over a 14-d period. Isotope ratio MS was used to analyse the samples for 2H and 18O enrichments. Mean breast milk intake based on saliva samples was significantly higher than that based on urine samples (854·5 v. 812·8 g/d, P = 0·029). This can be attributed to slightly higher isotope enrichments in saliva and to a poorer model fit for urine samples as indicated by a higher square root of the mean square error (14·6 v. 10·4 mg/kg, P = 0·001). Maternal energy expenditure was not correlated with breast milk output. Our study suggests that saliva sampling generates slightly higher estimates of breast milk intake and is more precise as compared with urine and that maternal energy expenditure does not influence breast milk output.

Gut microbiota diversity is associated with cardiorespiratory fitness in post-primary treatment breast cancer survivors.

NEW FINDINGS: What is the central question of this study? Does the link between cardiorespiratory fitness and gut microbiota diversity persist after adjusting for the potential effects of percentage body fat and activity-related energy expenditure (AEE)? What is the main finding and its importance? This is the first study to examine the link between cardiorespiratory fitness and gut microbiota diversity while accounting for the underlying effects of percentage body fat and free-living AEE. Results from the present work suggest that cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity among post-primary treatment, non-metastatic breast cancer survivors. ABSTRACT: Cancer treatment uniquely triggers multiple physiological shifts detrimental to overall health. Although previous research indicates a link between the gut microbiota and cardiorespiratory fitness, it is unclear whether these findings are attributable to potential underlying effects of percentage body fat or free-living activity energy expenditure (AEE). The microbe composition of faecal specimens from 37 breast cancer survivors was determined using 16S microbiome analyses. Individual-sample microbiota diversity (α-diversity) and between-sample community differences (ß-diversity) were examined. Peak oxygen uptake ( V̇O2peak ) was estimated from a graded exercise test consistent with the modified Naughton protocol, in which exercise terminates at 85% of age-predicted maximal heart rate. The AEE was measured over 10 days using doubly labelled water, wherein the percentage body fat was calculated from total body water. Pearson correlations revealed α-diversity indices (Chao1, observed species, PD whole tree and Shannon) to be positively associated with V̇O2peak (r = 0.34-0.51; P < 0.05), whereas the percentage of maximal heart rate during stages 1-4 of the graded exercise test (r = -0.34 to -0.50; P < 0.05) and percentage body fat (r = -0.32 to -0.41; P < 0.05) were negatively associated with the same α-diversity indices. Multiple linear regression models showed that V̇O2peak accounted for 22 and 26% of the variance in taxonomic richness (observed species) and phylogenic diversity after adjustment for percentage body fat and menopausal status. Unweighted UniFrac (ß-diversity) was significant for several outcomes involving cardiorespiratory fitness, and significant taxa comparisons were found. Associations between gut microbiota and free-living AEE were not found. Results from the present work suggest that cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity.

Agreement between the total energy expenditure calculated with accelerometry data and the BMR yielded by predictive equations v. the total energy expenditure obtained with doubly labelled water in low-income women with excess weight.

Low-income women are the group with the highest levels of obesity worldwide. In low-income settings, the use of predictive equations, which yield a measure of the individuals' BMR, is a feasible approach to estimate the individuals' total energy expenditure (TEE), using the factorial method (calculated-TEE = BMR × physical activity level), an important step of the obesity nutritional care. The present study aimed to identify the predictive equation that, in conjunction with metabolic equivalents of tasks (MET) data from accelerometers, yields the calculated-TEE with better agreement compared with the TEE measured by doubly labelled water (TEE-DLW). Forty-five women aged 19-45 years, with excess weight and mothers of undernourished children, were included. They received DLW to determine TEE (14 d); at the same time, they used triaxial accelerometers (7 d) to estimate their MET. The Bland-Altman method, paired-sample t tests, concordance correlation coefficient and root-mean-square error were used to assess the agreement. Maximum allowed differences were defined as 24 %, based on the within-variance coefficient of the energy intake of the sample. Eleven equations were studied. The calculated-TEE obtained by five equations showed non-significant bias: Dietary Reference Intake (Institute of Medicine (2005) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids), FAO/WHO/UNU ((2001) Food and Nutrition Technical Report Series), Harris & Benedict ((1919) Proc Natl Acad Sci USA4, 370-373), Henry & Rees ((1991) Eur J Clin Nutr45, 177-185) and Schofield ((1985) Hum Nutr Clin Nutr39, 5-41). The mean percentage differences were -1·5, -0·8, 2·2, -2·2 and 2·0 %, respectively. Considering all parameters, FAO/WHO/UNU ((2001) Food and Nutrition Technical Report Series) equation performed slightly better than the others; nevertheless, no equation in conjunction with the estimated-MET showed a calculated-TEE with its CI for the Bland-Altman limits of agreement inside the pre-defined acceptable range.

Metabolism, bioenergetics and thermal physiology: influences of the human intestinal microbiota.

The micro-organisms which inhabit the human gut (i.e. the intestinal microbiota) influence numerous human biochemical pathways and physiological functions. The present review focuses on two questions, 'Are intestinal microbiota effects measurable and meaningful?' and 'What research methods and variables are influenced by intestinal microbiota effects?'. These questions are considered with respect to doubly labelled water measurements of energy expenditure, heat balance calculations and models, measurements of RMR via indirect calorimetry, and diet-induced energy expenditure. Several lines of evidence suggest that the intestinal microbiota introduces measurement variability and measurement errors which have been overlooked in research studies involving nutrition, bioenergetics, physiology and temperature regulation. Therefore, we recommend that present conceptual models and research techniques be updated via future experiments, to account for the metabolic processes and regulatory influences of the intestinal microbiota.

The International Atomic Energy Agency International Doubly Labelled Water Database: Aims, Scope and Procedures.

BACKGROUND: The doubly labelled water (DLW) method is an isotope-based technique that quantifies total energy expenditure (TEE) over periods of 1-3 weeks from the differential elimination of stable isotopes of oxygen and hydrogen. The method was invented in the 1950s, but limited ability to measure low isotope enrichments combined with the high cost of isotopes meant it only became feasible to use in humans in the 1980s. It is still relatively expensive to use, and alone small samples are unable to tackle some of the important questions surrounding energy balance such as how have expenditures changed over time and how do expenditures differ with age, between sexes and in different environments? SUMMARY: By combining information across studies, answers to such questions may be possible. The International Atomic Energy Agency (IAEA) DLW database was established to pool DLW data across multiple studies. It was initiated by the main labs currently using the method and is hosted by the IAEA. At present, the database contains 6,621 measures of TEE by DLW from individuals in 23 countries, along with various additional data on the study participants. Key Messages: The IAEA DLW database is a key resource enabling future studies of energy demands.

Energy expenditure and dietary intake in professional football players in the Dutch Premier League: Implications for nutritional counselling.

Selecting effective dietary strategies for professional football players requires comprehensive information on their energy expenditure (EE) and dietary intake. This observational study aimed to assess EE and dietary intake over a 14-day period in a representative group (n = 41) of professional football players playing in the Dutch Premier League (Eredivisie). Daily EE, as assessed by doubly labelled water, was 13.8 ± 1.5 MJ/day, representing a physical activity level (PAL) of 1.75 ± 0.13. Weighted mean energy intake (EI), as assessed by three face-to-face 24-h recalls, was 11.1 ± 2.9 MJ/day, indicating 18 ± 15% underreporting of EI. Daily EI was higher on match days (13.1 ± 4.1 MJ) compared with training (11.1 ± 3.4 MJ; P < 0.01) and rest days (10.5 ± 3.1 MJ; P < 0.001). Daily carbohydrate intake was significantly higher during match days (5.1 ± 1.7 g/kg body mass (BM)) compared with training (3.9 ± 1.5 g/kg BM; P < 0.001) and rest days (3.7 ± 1.4 g/kg BM; P < 0.001). Weighted mean protein intake was 1.7 ± 0.5 g/kg BM. Daytime distribution of protein intake was skewed, with lowest intakes at breakfast and highest at dinner. In conclusion, daily EE and PAL of professional football players are modest. Daily carbohydrate intake should be increased to maximize performance and recovery. Daily protein intake seems more than adequate, but could be distributed more evenly throughout the day.