Effect of glucose ingestion on energy substrate utilization during prolonged muscular exercise

Pirnay, F; Lacroix, M.; Mosora, F.; Luyckx, A; Lefèbvre, Pierre

doi:10.1007/bf00423050

Cited by 50 publications

(52 citation statements)

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“…In the current studies, the low-and high-intensity exercise protocols were well defined, based on each individual's lactate threshold, and represented distinctly different states of skeletal muscle metabolism (1)(2)(3)(4)(5)(6)(7). Low-intensity exercise was easily maintained for 60 min, without a change in blood lactate concentration.…”

Section: Discussionmentioning

confidence: 99%

“…When constant-load exercise is performed at a low intensity (< 35-45% of maximal oxygen consumption), there is an increase in both the plasma concentration and uptake of free fatty acids by exercising muscle (1,2). As free fatty acids become the major substrate for energy metabolism, there is a fall in the plasma concentrations of insulin and glucose (3)(4)(5). With low-intensity exercise, blood lactate concentration does not increase, and oxygen uptake kinetics remain at a steady state (1,(4)(5)(6).…”

Section: Introductionmentioning

confidence: 99%

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Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Hiatt¹,

Regensteiner²,

Wolfel³

et al. 1989

J. Clin. Invest.

126

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Carnitine metabolism has been previously shown to change with exercise in normal subjects, and in patients with ischemic muscle diseases. To characterize carnitine metabolism further during exercise, six normal male subjects performed constantload exercise on a bicycle ergometer on two separate occasions. Low-intensity exercise was performed for 60 min at a work load equal to 50% of the lactate threshold, and high-intensity exercise was performed for 30 min at a work load between the lactate threshold and maximal work capacity for the individual. Low-intensity exercise was not associated with a change in muscle (vastus lateralis) carnitine metabolism. In contrast, from rest to 10 min of high-intensity exercise, muscle shortchain acylcarnitine content increased 5.5-fold while free carnitine content decreased 66%, and muscle total carnitine content decreased by 19% (all P < 0.01). These changes in skeletal muscle carnitine metabolism were present at the completion of 30 min of high-intensity exercise, and persisted through a 60-min recovery period. With 30 min of high-intensity exercise, plasma short-chain and long-chain acylcarnitine concentrations increased by 46% and 23%, respectively. Neither exercise state was associated with a change in the urine excretion rates of free carnitine or acylcarnitines. Thus, alterations in skeletal muscle carnitine metabolism, characterized by an increase in acylcarnitines and a decrease in free and total carnitine, are dependent on the work load and, therefore, the metabolic state associated with the exercise, and are poorly reflected in the plasma and urine carnitine pools.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Hiatt¹,

Regensteiner²,

Wolfel³

et al. 1989

J. Clin. Invest.

126

View full text Add to dashboard Cite

show abstract

“…7 It was only after the late 1970's and early 1980's that 13c and 14c labelling techniques were used to calculate rates of ingested CHO oxidation during exercise (Lefebvre et al 1975;Lefebvre et al 1979;Pirnay et al 1977aPirnay et al , 1977bPirnay et al , 1982Jandrain et al 1984Jandrain et al , 1989Krzentowski et al 1984;Massicotte et al 1986Massicotte et al , 1989Massicotte et al , 1990Pallikarakis et al 1986;Peronnet et al 1990;Hawley et al 1992a;Moodley et al 1992). Such studies were, on the whole performed on cyclists, possibly because it is easier to take blood from a cyclist on a stationary ergometer that from a runner on a treadmill.…”

Section: Introduction and Historical Overviewmentioning

confidence: 99%

Fuel kinetics during intense running and cycling when fed carbohydrate

Derman

Hawley

Noakes

et al. 1996

Europ. J. Appl. Physiol.

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“…Le signe de la valeur de δ 13 C indique si l'échantillon a un rapport 13 (Pirnay et al, 1977a). De plus, dans l'article publié dans le…”

Section: Duréeunclassified

Sélection des substrats lors de l’exercice prolongé avec ingestion de glucides : études par traçage au ¹³C

Tremblay¹

2011

Appl. Physiol. Nutr. Metab.

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cides et davantage de lipides que les hommes. Les effets séparés d'une alimentation riche v en glucides ou de l'ingestion de glucose pendant l'exercice sur la sélection des substrats furent pourtant similaires chez les deux sexes. L'effet combiné des deux procédures de supplémentation est toutefois plus important chez la femme que chez l'homme, soutenant l'hypothèse qu'un léger déficit en glucides soit présent chez les femmes.Dans la troisième étude, l'oxydation des substrats et particulièrement celle d'amidon exogène au cours d'une marche prolongée à une faible puissance de travail a été décrite.Les individus qui pratiquent des activités physiques prolongées à des intensités faibles (< 40 %VO 2 max) sont encouragés à ingérer des glucides et de l'eau pendant l'effort, mais la contribution de leur oxydation à la fourniture d'énergie est relativement peu connue.Nous avons montré que, contrairement aux observations précédemment effectuées à jeun sans ingestion de glucides pendant l'effort, les glucides (incluant de source exogène) peuvent fournir une très grande partie de l'énergie lorsqu'ils sont ingérés à des intervalles réguliers au cours de l'exercice prolongé.Dans l'ensemble, les résultats des études expérimentales présentées dans cette thèse montrent que les glucides ingérés peuvent fournir une grande proportion de l'énergie pendant l'exercice prolongé. Toutefois, le mode d'exercice, le sexe et la puissance de travail mènent à des variations qui sont en grande partie liées à une dépense énergé-tique variable selon les conditions et les groupes d'individus ayant des caractéristiques différentes.Mots clés: calorimétrie indirecte respiratoire, sexe, mode d'exercice, marche. ABSTRACTThe main substrates oxidized during prolonged exercise, whether carbohydrates, fats or proteins, do not contribute equally to the energy supply. In addition, glucose can originate from different endogenous (muscle, liver) and exogenous sources. Many factors can affect their respective contribution including: active muscle mass, training, sex, nutritional state and environmental conditions. The use of stable isotopes, such as carbon 13 ( 13 C), combined with indirect respiratory calorimetry corrected for urea excretion in urine and sweat, allows the differentiation of endogenous and exogenous substrates and the estimation of their contribution to the energy yield.These methods, allowing the measurement of fuel selection during prolonged exercise with glucose ingestion, enabled the comparisons found in the three experimental studies part of this thesis. In the first study, fuel selection was compared during prolonged upper-and lower-body exercise with or without glucose ingestion. The difference in fuel selection between upper-and lower-body exercise when water was ingested was modest with a slightly higher reliance on carbohydrate oxidation during upper-body exercise. The amount of exogenous glucose oxidized was lower but its contribution to the energy yield was higher during upper-body exercise due to the lower energy expenditure.In t...

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Effect of glucose ingestion on energy substrate utilization during prolonged muscular exercise

Cited by 50 publications

References 21 publications

Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Fuel kinetics during intense running and cycling when fed carbohydrate

Sélection des substrats lors de l’exercice prolongé avec ingestion de glucides : études par traçage au ¹³C

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Effect of glucose ingestion on energy substrate utilization during prolonged muscular exercise

Cited by 50 publications

References 21 publications

Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Carnitine and acylcarnitine metabolism during exercise in humans. Dependence on skeletal muscle metabolic state.

Fuel kinetics during intense running and cycling when fed carbohydrate

Sélection des substrats lors de l’exercice prolongé avec ingestion de glucides : études par traçage au 13C

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Sélection des substrats lors de l’exercice prolongé avec ingestion de glucides : études par traçage au ¹³C