| 1. |
- Speakman, John R., et al.
(författare)
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Total daily energy expenditure has declined over the past three decades due to declining basal expenditure, not reduced activity expenditure
- 2023
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Ingår i: Nature Metabolism. - : NATURE PORTFOLIO. - 2522-5812. ; 5:4, s. 579-588
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Obesity is caused by a prolonged positive energy balance(1,2). Whether reduced energy expenditure stemming from reduced activity levels contributes is debated(3,4). Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased over time. We use the International Atomic Energy Agency Doubly Labelled Water database on energy expenditure of adults in the United States and Europe (n = 4,799) to explore patterns in total (TEE: n = 4,799), basal (BEE: n = 1,432) and physical activity energy expenditure (n = 1,432) over time. In males, adjusted BEE decreased significantly, but in females this did not reach significance. A larger dataset of basal metabolic rate (equivalent to BEE) measurements of 9,912 adults across 163 studies spanning 100 years replicates the decline in BEE in both sexes. We conclude that increasing obesity in the United States/Europe has probably not been fuelled by reduced physical activity leading to lowered TEE. We identify here a decline in adjusted BEE as a previously unrecognized factor.
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| 2. |
- Kaviani, Sepideh, et al.
(författare)
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Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique
- 2018
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Ingår i: Nutrition in Clinical Practice. - : Wiley. - 0884-5336. ; 33:2, s. 206-216
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Tidskriftsartikel (refereegranskat)abstract
- Background: Several indirect calorimetry (IC) instruments are commercially available, but comparative validity and reliability data are lacking. Existing data are limited by inconsistencies in protocols, subject characteristics, or single-instrument validation comparisons. The aim of this study was to compare accuracy and reliability of metabolic carts using methanol combustion as the cross-laboratory criterion. Methods: Eight 20-minute methanol burn trials were completed on 12 metabolic carts. Respiratory exchange ratio (RER) and percent O2 and CO2 recovery were calculated. Results: For accuracy, 1 Omnical, Cosmed Quark CPET (Cosmed), and both Parvos (Parvo Medics trueOne 2400) measured all 3 variables within 2% of the true value; both DeltaTracs and the Vmax Encore System (Vmax) showed similar accuracy in measuring 1 or 2, but not all, variables. For reliability, 8 instruments were shown to be reliable, with the 2 Omnicals ranking best (coefficient of variation [CV] < 1.26%). Both Cosmeds, Parvos, DeltaTracs, 1 Jaeger Oxycon Pro (Oxycon), Max-II Metabolic Systems (Max-II), and Vmax were reliable for at least 1 variable (CV ≤ 3%). For multiple regression, humidity and amount of combusted methanol were significant predictors of RER (R2 = 0.33, P <.001). Temperature and amount of burned methanol were significant predictors of O2 recovery (R2 = 0.18, P <.001); only humidity was a predictor for CO2 recovery (R2 = 0.15, P <.001). Conclusions: Omnical, Parvo, Cosmed, and DeltaTrac had greater accuracy and reliability. The small number of instruments tested and expected differences in gas calibration variability limits the generalizability of conclusions. Finally, humidity and temperature could be modified in the laboratory to optimize IC conditions.
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| 3. |
- Kaviani, Sepideh, et al.
(författare)
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Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique
- 2017
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Ingår i: The FASEB Journal. - 0892-6638 .- 1530-6860. ; 31:S1
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveThere are several indirect calorimetry (IC) instruments commercially available but validity and reliability data is lacking. Site-to-site inconsistencies in protocols and subject characteristics, and comparisons to a “gold standard” instrument or method which may no longer be accurate enough, have put restraints on drawing conclusions about instruments' performance.PurposeTo compare the accuracy and reliability of different metabolic carts using the methanol combustion technique as the criterion measure.MethodsA total of eight, 20-minute methanol burn trials were completed on 12 metabolic carts (2 Cosmed Quark CPET, 2 DeltaTrac II, 2 Parvo Medics TrueOne 2400, 2 Iaeger Oxycon Pros, 2 Omnicals, a Vmax Encore, and a Max-II Metabolic System) at 11 international study sites. Methanol tests were performed at 0700, 1000, 1300, and 1600 hours on 2 consecutive days. Respiratory Exchange Ratio (RER) and percent (%) recovery of O2 and CO2 were calculated after each test.ResultsAccuracy – 1 Omnical, Cosmed, and Parvo were accurate in measuring RER and % recovery O2, while 1 DeltaTrac was also accurate for % recovery O2. The same Cosmed and Parvo, and the other DeltaTrac were accurate in measuring % recovery CO2. Reliability – 8 instruments were shown to be reliable with the two Omnicals ranking best based on the smallest coefficient of variation (CV) (all CV(s) 1.26%). Both Cosmeds, Parvos, DeltaTracs and 1 Vmax were the reliable instruments for at least one variable (CV(s) 3%). Multiple Regression– Humidity, amount of methanol combusted, and temperature were tested as predictors of IC outcomes. Humidity and amount of combusted methanol were significant predictors of RER (F (2, 60) =10.91, p<0.001, R2=0.33). Temperature and amount of burned methanol were significant predictors of % recovery O2 (F (2, 60) =8.32, p<0.001, R2=0.18) while only humidity was a predictor for % recovery CO2 (F (1, 61) =21.10, p<0.001, R2=0.15).ConclusionOmnical, Cosmed, and Parvo showed superior accuracy and reliability; however, accuracy was only found at one of two study sites. Exogenous factors such as humidity and temperature may be influencing instrument performance and could be modified in the lab to optimize IC conditions.
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| 4. |
- Forsum, Elisabet, 1947-, et al.
(författare)
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Calculation of energy expenditure in women using the MET system
- 2006
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Ingår i: Medicine & Science in Sports & Exercise. - : Ovid Technologies (Wolters Kluwer Health). - 0195-9131 .- 1530-0315. ; 38:8, s. 1520-1525
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Interpretation of physical activity as energy expenditure requires adjustment for body size. This is usually accomplished by means of the MET system, which assumes a basal metabolic rate (BMR) of 4.184 kJ·kg -1·h-1 and, when the standard calculation is used, that the energy costs of different activities are proportional to BMR. These relationships may be altered by increases in percent total body fat (% TBF), and this paper examines relationships between % TBF and total energy expenditure (TEE) obtained using the standard and a proposed calculation. Methods: Published data regarding body composition, physical activity (heart rate recording), and BMR in 11 American women (before and after weight gain) and in 15 Swedish women (before and during pregnancy) were used to calculate TEE. Reference estimates of TEE were obtained using doubly labeled water. Results: In Swedish women, reference TEE minus standard TEE (MJ·24 h-1) was 1.37 ± 1.29 (P < 0.01) before and 1.03 ± 1.13 (P < 0.05) during pregnancy. For proposed TEE these differences were 0.43 ± 1.63 (P > 0.05) and 0.31 ± 1.28 (P > 0.05) (MJ·24 h-1), respectively. In American women before and after weight gain, reference TEE minus standard TEE (MJ·24 h-1) were 0.38 ± 1.79 (P > 0.05) and 1.39 ± 2.36 (P > 0.05), respectively, whereas the corresponding differences for proposed TEE (MJ·24 h-1) were -0.52 ± 2.20 (P > 0.05) and 0.21 ± 2.36 (P > 0.05), respectively. In Swedish women before pregnancy and American women after weight gain (N = 26, BMI = 18-39), significant (P < 0.001) relationships were found for standard TEE/proposed TEE (y) versus % TBF, (x, r = -0.65) and versus BMI (x, r = -0.70). Conclusions: In individuals with a TBF content typical for contemporary Western women, standard TEE is lower than proposed TEE. This bias increases as the TBF content of subjects increases. The results indicate that proposed TEE is more accurate than standard TEE, but this requires confirmation. Copyright © 2006 by the American College of Sports Medicine.
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