Measurement of metabolic rate in hyperoxia

1981 ◽  
Vol 51 (3) ◽  
pp. 725-731 ◽  
Author(s):  
H. G. Welch ◽  
P. K. Pedersen
Keyword(s):  
Metabolic Rate ◽  
Submaximal Exercise ◽  
Co2 Production ◽  
O2 Uptake ◽  
Vo2 Max ◽  
Conventional Calculation ◽  
Mixing Chamber ◽  
Douglas Bag ◽  
Douglas Bag Method ◽  
Fick Equation

The conventional Douglas bag calculation for estimating O2 uptake (VO2) during exercise in normoxia and hyperoxia, VO2 = VE . (FIO2 . FEN2/FIN2 - FEO2), was tested against two other valid calculations: the Fick equation, VO2 = VI . FIO2 - VE . FEO2, and the equation VO2 = VI - VE - VCO2 (VE and VI are expired and inspired ventilation, respectively; FEO2 and FIO2 are expired and inspired O2 contents, respectively; FEN2 and FIN2 are expired and inspired N2 contents, respectively; and VCO2 is CO2 production.). These calculations are based on different assumptions, in part, and are affected to a varying degree of errors in volume or gas fraction measurements. With the conventional Douglas bag technique, we found evidence of an overestimate of VO2 during hyperoxia. After the introduction of a mixing chamber for sampling expired air, the means of the three methods were not significantly different. The variability among the methods was least with the conventional calculation but increased with higher O2 fractions. The average VO2 for submaximal exercise in hyperoxia was not significantly different from that of normoxia. VO2 max was significantly higher in hyperoxia. The increased variability of the Douglas bag method in hyperoxia may lead to overestimates of VO2 max unless special precautions are taken.

Measurements of metabolic rate in rats: a comparison of techniques

1988 ◽  
Vol 65 (2) ◽  
pp. 964-970 ◽  
Author(s):  
T. I. Musch ◽  
A. Bruno ◽  
G. E. Bradford ◽  
A. Vayonis ◽  
R. L. Moore
Keyword(s):  
Metabolic Rate ◽  
Maximal Exercise ◽  
Ambient Air ◽  
Open Circuit ◽  
Submaximal Exercise ◽  
Co2 Production ◽  
Arterial Blood ◽  
In Series ◽  
Series Of Experiments ◽  
Four Levels

Two different open-circuit techniques of measuring metabolic rate were examined in rats at rest and during exercise. With one technique ambient air was drawn through a tightly fitting mask that was secured to the rat's head, whereas with the other technique the rat was placed into and ambient air was drawn through a Plexiglas box. Two series of experiments were performed. In series I, two groups were studied that consisted of rats that had received myocardial infarctions produced by coronary arterial ligations and rats that had received sham operations. In this series of experiments O2 uptake (VO2) and CO2 production (VCO2) were measured at rest, during four levels of submaximal exercise, and during maximal treadmill exercise in the same group of rats by use of both techniques in random order. VO2, VCO2, and the calculated respiratory exchange ratio (R) were similar at rest, during the highest level of submaximal exercise (20% grade, 37 m/min), and during maximal exercise; however, VO2 and VCO2 were significantly lower with the metabolic box technique compared with the mask technique during the three lowest work loads (5% grade, 19 m/min; 10% grade, 24 m/min; and 15% grade, 31 m/min). These differences appeared to be associated with a change in gait produced when the mask was worn. In series II, the arterial blood gas and acid-base responses to both submaximal and maximal exercise were measured using both techniques in a group of instrumented rats that had a catheter placed into the right carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)

The Ventilation-Corrected ParvoMedics TrueOne 2400 Provides a Valid and Reliable Assessment of Resting Metabolic Rate (RMR) in Athletes Compared With the Douglas Bag Method

2016 ◽  
Vol 26 (5) ◽  
pp. 454-463 ◽  
Author(s):  
Amy L. Woods ◽  
Laura A. Garvican-Lewis ◽  
Anthony J. Rice ◽  
Kevin G. Thompson
Keyword(s):  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Regression Equation ◽  
Reliable Measurement ◽  
Metabolic Cart ◽  
Typical Error ◽  
Reliable Assessment ◽  
Douglas Bag ◽  
Douglas Bag Method ◽  
The Difference

The aim of the current study was to determine if a single ParvoMedics TrueOne 2400 metabolic cart provides valid and reliable measurement of RMR in comparison with the criterion Douglas Bag method (DB). Ten endurance-trained participants completed duplicate RMR measurements on 2 consecutive days using the ParvoMedics system in exercise mode, with the same expirate analyzed using DB. Typical error (TE) in mean RMR between the systems was 578.9 kJ or 7.5% (p = .01). In comparison with DB, the ParvoMedics system over-estimated RMR by 946.7 ± 818.6 kJ. The bias between systems resulted from ParvoMedics VE(STPD) values. A regression equation was developed to correct the bias, which reduced the difference to -83.3 ± 631.9 kJ. TE for the corrected ParvoMedics data were 446.8 kJ or 7.2% (p = .70). On Day 1, intraday reliability in mean RMR for DB was 286.8 kJ or 4.3%, (p = .54) and for ParvoMedicsuncorrected, 359.3 kJ or 4.4%, (p = .35), with closer agreement observed on Day 2. Interday reliability for DB was 455.3 kJ or 6.6% (p = .61) and for ParvoMedicsuncorrected, 390.2 kJ or 6.3% (p = .54). Similar intraday and interday TE was observed between ParvoMedicsuncorrected and ParvoMedicscorrected data. The ParvoMedics TrueOne 2400 provided valid and reliable RMR values compared with DB when the VE(STPD) error was corrected. This will enable widespread monitoring of RMR using the ParvoMedics system in a range of field-based settings when DB is not available.

Increased exercise SaO2 independent of ventilatory acclimatization at 4,300 m

1989 ◽  
Vol 66 (6) ◽  
pp. 2733-2738 ◽  
Author(s):  
P. R. Bender ◽  
R. E. McCullough ◽  
R. G. McCullough ◽  
S. Y. Huang ◽  
P. D. Wagner ◽  
...  
Keyword(s):  
Time Course ◽  
Submaximal Exercise ◽  
Co2 Production ◽  
O2 Consumption ◽  
Moderate Exercise ◽  
O2 Uptake ◽  
Cycle Exercise ◽  
State Cycle ◽  
Arterial O2 Saturation ◽  
Male Subjects

Arterial O2 saturation (Sao2) decreases in hypoxia in the transition from rest to moderate exercise, but it is unknown whether other several weeks at high altitude SaO2 in submaximal exercise follows the same time course and pattern as that of ventilatory acclimatization in resting subjects. Ventilatory acclimatization is essentially complete after approximately 1 wk at 4,300 m, such that improvement in submaximal exercise SaO2 would then require other mechanisms. On days 2, 8, and 22 on Pikes Peak (4,300 m), 6 male subjects performed prolonged steady-state cycle exercise at 79% maximal O2 uptake (VO2 max). Resting SaO2 rose from day 1 (78.4 +/- 1.6%) to day 8 (87.5 +/- 1.4%) and then did not increase further by day 20 (86.4 +/- 0.6%). During exercise, SaO2 values (mean of 5-, 15-, and 30-min measurements) were 72.7% (day 2), 78.6% (day 8), and 82.3% (day 22), meaning that all of the increase in resting SaO2 occurred from day 1 to day 8, but exercise SaO2 increased from day 2 to day 8 (5.9%) and then increased further from day 8 to day 22 (3.7%). On day 22, the exercise SaO2 was higher than on day 8 despite an unchanged ventilation and O2 consumption. The increased exercise SaO2 was accompanied by decreased CO2 production. The mechanisms responsible for the increased exercise SaO2 require further investigation.

Comparison of indirect calorimetry and a new breath 13C/12C ratio method during strenuous exercise

1992 ◽  
Vol 263 (1) ◽  
pp. E64-E71 ◽  
Author(s):  
J. A. Romijn ◽  
E. F. Coyle ◽  
J. Hibbert ◽  
R. R. Wolfe
Keyword(s):  
Indirect Calorimetry ◽  
Fat Oxidation ◽  
Substrate Oxidation ◽  
Co2 Production ◽  
Strenuous Exercise ◽  
Ratio Method ◽  
O2 Uptake ◽  
Underlying Assumption ◽  
Oxidation Rates

A new stable isotope method for the determination of substrate oxidation rates in vivo is described and compared with indirect calorimetry at rest and during high-intensity exercise (30 min at 80-85% maximal O2 uptake capacity) in six well-trained cyclists. This method uses the absolute ratios of 13C/12C in expired air, endogenous glucose, fat, and protein in addition to O2 consumption and is independent of CO2 production (VCO2). Carbohydrate and fat oxidation rates at rest, calculated by both methods, were not significantly different. During exercise the breath 13C/12C ratio increased and reached a steady state after 15-20 min. Carbohydrate oxidation rates during exercise were 39.4 +/- 5.2 and 41.7 +/- 5.7 mg.kg-1.min-1 [not significant (NS)], and fat oxidation rates were 7.3 +/- 1.3 and 6.9 +/- 1.2 mg.kg-1.min-1 (NS), using indirect calorimetry, and the breath ratio method, respectively. We conclude that the breath 13C/12C ratio method can be used to calculate substrate oxidation under different conditions, such as the basal state and exercise. In addition, the results obtained by this new method support the validity of the underlying assumption that indirect calorimetry regards VCO2 as a reflection of tissue CO2 production, during exercise in trained subjects, even up to 80-85% maximal O2 uptake.

Endurance training in older men and women II. Blood lactate response to submaximal exercise

1984 ◽  
Vol 57 (4) ◽  
pp. 1030-1033 ◽  
Author(s):  
D. R. Seals ◽  
B. F. Hurley ◽  
J. Schultz ◽  
J. M. Hagberg
Keyword(s):  
Endurance Training ◽  
Blood Lactate ◽  
Respiratory Exchange Ratio ◽  
Submaximal Exercise ◽  
Older Individuals ◽  
O2 Uptake ◽  
Men And Women ◽  
Low Intensity ◽  
Older Men And Women ◽  
Intensity Training

Seven men and four women (age 63 +/- 2 yr, mean +/- SD, range 61–67 yr) participated in a 12-mo endurance training program to determine the effects of low-intensity (LI) and high-intensity (HI) training on the blood lactate response to submaximal exercise in older individuals. Maximal oxygen uptake (VO2max), blood lactate, O2 uptake (VO2), heart rate (HR), ventilation (VE), and respiratory exchange ratio (R) during three submaximal exercise bouts (65–90% VO2max) were determined before training, after 6 mo of LI training, and after an additional 6 mo of HI training. VO2max (ml X kg-1 X min-1) was increased 12% after LI training (P less than 0.05), while HI training induced a further increase of 18% (P less than 0.01). Lactate, HR, VE, and R were significantly lower (P less than 0.05) at the same absolute work rates after LI training, while HI training induced further but smaller reductions in these parameters (P greater than 0.05). In general, at the same relative work rates (ie., % of VO2max) after training, lactate was lower or unchanged, HR and R were unchanged, and VO2 and VE were higher. These findings indicate that LI training in older individuals results in adaptations in the response to submaximal exercise that are similar to those observed in younger populations and that additional higher intensity training results in further but less-marked changes.

Exercise recovery above and below anaerobic threshold following maximal work

1981 ◽  
Vol 51 (4) ◽  
pp. 840-844 ◽  
Author(s):  
B. A. Stamford ◽  
A. Weltman ◽  
R. Moffatt ◽  
S. Sady
Keyword(s):  
Blood Lactate ◽  
Anaerobic Threshold ◽  
Maximal Exercise ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Base Line ◽  
Exercise Recovery ◽  
O2 Uptake ◽  
Vo2 Max ◽  
Individual Subject

The purpose of this study was to determine the effects of resting and exercise recovery above [70% of maximum O2 uptake (VO2 max)] and below [40% of VO2 max] anaerobic threshold (AT) on blood lactate disappearance following maximal exercise. Blood lactate concentrations at rest (0.9 mM) and during exercise at 40% (1.3 mM) and 70% (3.5 mM) of VO2 max without preceding maximal exercise were determined on separate occasions and represented base lines for each condition. The rate of blood lactate disappearance from peak values was ascertained from single-component exponential curves fit for each individual subject for each condition using both the determined and resting base lines. When determined base lines were utilized, there were no significant differences in curve parameters between the 40 and 70% of VO2 max recoveries, and both were significantly different from the resting recovery. When a resting base line (0.9 mM) was utilized for all conditions, 40% of VO2 max demonstrated a significantly faster half time than either 70% of VO2 max or resting recovery. No differences were found between 70% of VO2 max and resting recovery. It was concluded that interpretation of the effectiveness of exercise recovery above and below AT with respect to blood lactate disappearance is influenced by the base-line blood lactate concentration utilized in the calculation of exponential half times.

Effects of acetazolamide on metabolic and respiratory responses to exercise at maximal O2 uptake

1990 ◽  
Vol 68 (2) ◽  
pp. 617-626 ◽  
Author(s):  
R. J. Rose ◽  
D. R. Hodgson ◽  
T. B. Kelso ◽  
L. J. McCutcheon ◽  
W. M. Bayly ◽  
...  
Keyword(s):  
Muscle Metabolism ◽  
Blood Gases ◽  
Co2 Production ◽  
O2 Uptake ◽  
Blood Temperature ◽  
Arterial Ph ◽  
Muscle Ph ◽  
Venous Pco2 ◽  
Total Body ◽  
Exercise Muscle

Changes in blood gases, ions, lactate, pH, hemoglobin, blood temperature, total body metabolism, and muscle metabolites were measured before and during exercise (except muscle), at fatigue, and during recovery in normal and acetazolamide-treated horses to test the hypothesis that an acetazolamide-induced acidosis would compromise the metabolism of the horse exercising at maximal O2 uptake. Acetazolamide-treated horses had a 13-mmol/l base deficit at rest, higher arterial Po2 at rest and during exercise, higher arterial and mixed venous Pco2 during exercise, and a 48-s reduction in run time. Arterial pH was lower during exercise but not in recovery after acetazolamide. Blood temperature responses were unaffected by acetazolamide administration. O2 uptake was similar during exercise and recovery after acetazolamide treatment, whereas CO2 production was lower during exercise. Muscle [glycogen] and pH were lower at rest, whereas heart rate, muscle pH and [lactate], and plasma [lactate] and [K+] were lower and plasma [Cl-] higher following exercise after acetazolamide treatment. These data demonstrate that acetazolamide treatment aggravates the CO2 retention and acidosis occurring in the horse during heavy exercise. This could negatively affect muscle metabolism and exercise capacity.

Intestinal capillary blood flow during metabolic hyperemia.

1979 ◽  
Vol 237 (6) ◽  
pp. E548 ◽  
Author(s):  
A P Shepherd
Keyword(s):  
Blood Flow ◽  
Metabolic Rate ◽  
Constant Pressure ◽  
Oxygen Demand ◽  
Capillary Density ◽  
Control Mechanisms ◽  
O2 Uptake ◽  
O2 Extraction ◽  
Circulatory Control ◽  
Parenchymal Cells

It has been postulated that local circulatory control mechanisms regulate the O2 flux to parenchymal cells by two vascular mechanisms: changes in blood flow that minimize capillary PO2 variations and changes in the density of the perfused capillary bed through which O2 extraction is regulated. To test this prediction, isolated loops of canine jejenum and ileum were perfused at either constant blood flow or constant pressure, and intraluminal glucose was used to increase metabolic rate. In the constant-flow series, glucose increased O2 extraction, O2 uptake, and rubidium extraction. Resistance fell when the metabolic rate was elevated. In the constant-pressure series, glucose increased blood flow, O2 extraction, O2 uptake, and capillary filtration coefficients. These results show that vascular resistance falls and that capillary density increases following an increase in oxygen demand. Thus, the glucose-stimulated gut loop seems to be a valid model of metabolic hyperemia, and its behavior would be difficult to reconcile with a purely myogenic theory of intestinal blood flow autoregulation.

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