Search PubMed⌕ Search

Biomedical subjects

E Adopo

Publications and source records attributed to E Adopo.

10 recordsLinked to original sources
PubMed1994

Effect of metabolic rate on the oxidation of ingested glucose and fructose during exercise.

The purpose of the present study was to describe the relationship between the metabolic rate (W.kg-1 b.m.) and the oxidation rate (mg.kg-1.min-1) of exogenous glucose and fructose during prolonged exercise in 18 healthy active male volunteers (VO2max = 43-71 ml.kg-1.min-1). Each subject performed three 120-min exercises at 60% VO2max (8.5-15.0 W.kg-1.min-1) on cycle ergometer while ingesting water only or 1.33 g.k-1 (97 +/- 9 g; mean +/- SE) of 13C-glucose or 13C-fructose in water (7%). The oxidation rate of exogenous glucose and fructose increased linearly with increasing metabolic rate (r = 0.71 and 0.70, respectively, p < 0.05), the amount of exogenous glucose oxidized being significantly higher than the amount of fructose oxidized (56.1 +/- 14.2 vs 35.7 +/- 9.2 g, respectively). The respective contributions of exogenous glucose and fructose oxidation to the energy yield remain remarkably similar over the range of metabolic rate studied (14.0 +/- 2.1 and 8.9 +/- 1.6%). These observations suggest that the rate of absorption of glucose and fructose and the rate of conversion of fructose into glucose by the liver are not limiting factors for their oxidation, which could simply follow the oxidation rate of circulating glucose. From a practical point of view, these results confirm that fructose is a less efficient energy supplement than exogenous glucose for any metabolic rate sustained.

Adult↗
PubMed1994

Respective oxidation of exogenous glucose and fructose given in the same drink during exercise.

We computed the respective amounts of exogenous glucose (G) and fructose (F), which are oxidized during exercise when ingested simultaneously, with the use of 13C labeling. Six subjects exercised for 2 h at 60.7 +/- 2.9% of maximal O2 uptake on a cycle ergometer while ingesting 50 or 100 g of G or F or a mixture of 50 g each of G and F in 500 ml of water. The amount of exogenous G oxidized increased from 37.8 +/- 2.2 to 58.3 +/- 8.1 g when the total amount ingested increased from 50 to 100 g. The amount of F oxidized was significantly lower (32.2 +/- 1.2 and 45.8 +/- 2.6 g for the 50 and 100 g ingested, respectively). When 50 g each of G and F were simultaneously ingested in the same drink, the amounts oxidized (39.5 +/- 4.8 and 34.1 +/- 1.5 g, respectively) were similar to those observed when 50 g of G or F were ingested separately. The cumulative amount of exogenous hexoses oxidized (73.6 +/- 6.6 g) was 21% larger than when 100 g of G were ingested. This finding could be due to the fact that the routes for absorption and metabolism of exogenous G and F are at least partly different, resulting in less competition for oxidation when a mixture of these two hexoses is ingested than when an isocaloric amount of G is ingested. From a practical point of view, these data may provide experimental support for using mixtures of carbohydrates in the energy supplements for endurance athletes.

Administration, Oral↗
PubMed1993

Exogenous 13C glucose oxidation during exercise: North American vs Western European studies.

The purpose of this study was to test the hypothesis that the well-documented changes in background 13C enrichment of expired CO2 observed in response to exercise and carbohydrate ingestion, in subjects living on a North American diet, are not present in subjects living on a Western European diet. The experimental protocol used by Pirnay et al. in 1977 and by Krzentowski et al. in 1984 in subjects living on a Western European diet (4 h of exercise on a treadmill at approximately 50% VO2max with ingestion of 100 g of glucose in 400 ml of water) was duplicated as closely as possible in six subjects living on a North American diet. The actual amounts of exogenous glucose oxidized, computed with a high artificial 13C enrichment of glucose (+189.7/1000 delta 13C PDB-1) which allows one to neglect the 1-2/1000 delta changes in 13C background, were [mean (SEM)] 54.7 (5.4) and 84.2 (3.4) g over 2 h and 4 h of exercise, respectively. These values compare well with data computed by Pirnay et al. [56.6 (13.1) and 94.9 (4.2) g] and by Krzentowski et al. [55.0 (6.2) and 88.0 (4.5) g] using a natural enrichment of glucose (-11.21 and -10.63/1000 delta 13C PDB-1, respectively) assuming no change in 13C background in their Western European subjects. Under the same assumption and using a natural enrichment of glucose (-11.30/1000 delta 13C PDB-1) the oxidation of exogenous glucose was overestimated by 30-40% in our North American subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Oxidation of ethanol at rest and during prolonged exercise in men.

The purpose of this study was to measure the oxidation of ethanol at rest and during prolonged moderate exercise with use of 13C labeling. Five healthy young males (22.4 +/- 2.7 yr; maximal O2 uptake = 56 +/- 6.6 ml.kg-1.min-1) performed three exercises (68.4 +/- 6.7% maximal O2 uptake; 90 min) on a cycle ergometer with ingestion of 0.4 (trial A) and 0.8 (trial B) g/kg body wt of [13C]ethanol (diluted in 770 +/- 72 ml of water) or water only (trial C). The subjects were also studied during a 90-min rest period after the ingestion of 0.8 g/kg body wt of [13C]ethanol (trial D). At rest, over the 90-min observation period, only 2.1 +/- 0.3 g of the 61.6 +/- 5.7 g of ethanol ingested were oxidized, providing 11.1 +/- 1.9% of the total energy expenditure. Over the 90 min of exercise, the amounts of ethanol oxidized were similar in trials A (9.5 +/- 2.0 g) and B (8.5 +/- 2.5 g). The contribution of ethanol represented 5.2 +/- 1.0% of the total energy expenditure, which is much lower than that previously reported for exogenous carbohydrates (8-18%) or medium-chain free fatty acids (7-14%). The small contribution of ethanol to energy metabolism did not significantly modify endogenous substrate oxidation.

Adult↗
PubMed1993

Method for computing the oxidation of two 13C-substrates ingested simultaneously during exercise.

This study presents a method for computing the respective amounts of two simultaneously ingested exogenous substrates (A and B) that are oxidized during a period of prolonged exercise by use of 13C labeling. This method is based on the observation that the total volume of 13CO2 produced (V13CO2tot) is the sum of 1) V13CO2 arising from the oxidation of endogenous substrates (V13CO2endo), 2) V13CO2 arising from the oxidation of substrate A (V13CO2A), and 3) V13CO2 arising from the oxidation of substrate B (V13CO2B). The equation, V13CO2tot = V13CO2endo+V13CO2A+V13CO2B, with three unknowns, can be solved from the results of three experiments conducted under the same conditions but with at least two values for the isotopic composition of A and B. This method has been used on five healthy male subjects to compute the amounts of glucose and fructose oxidized when a mixture of 15 g of glucose and 15 g of fructose is ingested (in 300 ml of water) over 60 min of cycle ergometer exercise at 65% of maximal O2 uptake. Results from three experiments indicated that 9.8 +/- 3.1 and 5.7 +/- 2.1 g of glucose and fructose, respectively, were oxidized. The total amount of exogenous carbohydrates oxidized (15.5 +/- 4.3 g) is in agreement with the oxidation rates of exogenous glucose computed in similar conditions when 30 g of glucose were ingested (13 g; Péronnet et al. Med. Sci. Sports Exercise 25: 297-302, 1993). The difference between the oxidation rates of exogenous glucose and fructose is also in line with data from the literature.

Adult↗
PubMed1993

Comparison of two methods for computing exogenous substrate oxidation using 13C-labeling.

With 13C stable isotope as tracer, the purposes of this study were to measure the oxidation rates of exogenous glucose by using two computation procedures that take into account changes in isotopic composition of CO2 arising from oxidation of endogenous substrates (Rendo) and compare these results with studies using 14C-glucose. Two different low levels of 13C-enrichment were used in the first procedure, while a very high level of enrichment was used in the second one. Each of the eight subjects completed four exercises (68 +/- 5% VO2max; 90 min) on cycle ergometer, at 7-d intervals. After 30 min of exercise, the subjects ingested in a single bolus of 30 g of 13C-glucose, dissolved in 300 ml of water, enriched at three different levels (trials A and B = -10.9 and +2.5; trial C = +291.9/1000 delta 13C-PDB-1), or water only. The metabolic and endocrine state at rest and its response to exercise with or without glucose ingestion were similar in the four trials, with the exception of FFA and glycerol, which were blunted by the ingestion of glucose. As expected, Rendo significantly increased from rest (-22.7 +/- 0.7/1000 delta 13C-PDB-1) to the beginning of exercise without glucose ingestion (-21.2 +/- 0.5/1000 delta 13C-PDB-1). The amounts of exogenous glucose oxidized over the last hour of exercise and computed from trials A and B and from trial C were 14.9 +/- 4.4 and 13.0 +/- 4.2 g, representing 7.4 and 6.3% of the total energy requirement, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Metabolic availability of oral glucose during exercise: a reassessment.

The purpose of this study was to reassess the metabolic availability of oral glucose during prolonged exercise in man, using 13C-labeling and a computation procedure (J Appl Physiol 69:1047-1052, 1990) that correctly takes into account changes in isotopic composition of CO2 arising from oxidation of endogenous substrates (Rendo). These changes are due to glucose ingestion associated with exercise. Each of the seven subjects completed three 2-hour periods of exercise at 67% maximum oxygen consumption (VO2max) on an ergocycle, with ingestion of water (1,000 mL) or 60 g (in 1,000 mL water) of 13C-labeled glucose at two levels of enrichment (13C/12C = 1.11482% and 1.13303%). As expected, Rendo significantly increased from rest to exercise with water ingestion (1.09888% +/- .00196% to 1.09970% +/- .00175%) and with glucose ingestion (1.10002% +/- .00159%) due to changes in the respective contributions of endogenous carbohydrates and fat to energy requirements as assessed by the respiratory exchange ratio (RER). When changes in Rendo were taken into account, the estimated amount of exogenous glucose oxidized was 38.8 +/- 10.3 g. Much higher values were found when Rendo at rest or during exercise with water ingestion were used in the computation (42.3 +/- 10.3 to 65.1 +/- 20.5 g) according to the commonly used method. Examination of data in the literature indicates that the reported oxidation rate of exogenous glucose (g/min) is significantly related to oxygen consumption (VO2) (L/min; r = .592) and that exogenous glucose contributes approximately 14% to 17% to the energy requirement.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Exogenous substrate oxidation during exercise: studies using isotopic labelling.

This presentation summarizes the experimental data on the oxidation of exogenous substrates using isotopic labelling: glucose, fructose, maltodextrins, glucose polymers, starch and FFA. The two main determining factors for the oxidation of exogenous substrates are in this order: power output and amount of ingested substrates. The largest oxidation of exogenous substrate is observed for glucose, maltodextrins, Polycose, and starch. For exercises of one hour duration or more, the average rate of oxidation of these compounds can reach up to 0.5 g/min, which agrees with the indirect estimation of Coyle et al. Fructose is oxidized at a lower rate, except when it is taken before the exercise period. FFA are only oxidized to a small extent.

Carbon Isotopes↗