Progressive effect of endurance training on metabolic adaptations in working skeletal muscle

Phillips, Stuart M.; Green, H. J.; Tarnopolsky, Mark A.; Heigenhauser, George J. F.; Grant, Susan

doi:10.1152/ajpendo.1996.270.2.e265

Cited by 142 publications

(184 citation statements)

References 16 publications

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“…Given the acute reductions observed for some enzymes, such as COX and hexokinase during exercise, it is clear that the reductions are transitory, recovering between exercise days (hexokinase) or by the 2nd day of inactivity. The failure to find increases in the maximal activities of the CAC and the rate-limiting enzymes of glycogenolysis and glycolysis during the recovery days was not surprising, given the results of several previous experiments that have reported no change in response to several sessions of exercise (21,61). To our knowledge, decreases in COX have not been reported with either exercise or short-term training.…”

Section: Discussionmentioning

confidence: 70%

“…These studies indicate that training-like adaptations can be observed within the first few sessions of regular exercise in the absence of increases in V max of a range of mitochondrial enzymes (21,28,61). Current evidence indicates that the metabolic adaptations are mediated by events outside of the muscle, namely, increased V O 2 kinetics during the nonsteady rate (60), which occurs secondary to a more rapid adjustment in blood flow (71).…”

mentioning

confidence: 99%

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Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Green

Bombardier²,

Duhamel³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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AR, Ouyang J. Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery. Am J Physiol Regul Integr Comp Physiol 295: R1238 -R1250, 2008. First published July 23, 2008 doi:10.1152/ajpregu.00171.2008This study investigated the responses in substrate-and energy-based properties to repetitive days of prolonged submaximal exercise and recovery. Twelve untrained volunteers (V O 2peak ϭ 44.8 Ϯ 2.0 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 , mean Ϯ SE) cycled (ϳ60 V O2peak) on three consecutive days followed by 3 days of recovery. Tissue samples were extracted from the vastus lateralis both pre-and postexercise on day 1 (E1), day 3 (E3), and during recovery (R1, R2, R3) and were analyzed for changes in metabolism, substrate, and enzymatic and transporter responses. For the metabolic properties (mmol/kg Ϫ1 dry wt), exercise on E1 resulted in reductions (P Ͻ 0.05) in phosphocreatine (PCr; 80 Ϯ 1.9 vs. 41.2 Ϯ 3.0) and increases (P Ͻ 0.05) in inosine monophosphate (IMP; 0.13 Ϯ 0.01 vs. 0.61 Ϯ 0.2) and lactate (3.1 Ϯ 0.4 vs. 19.2 Ϯ 4.3). At E3, both IMP and lactate were lower (P Ͻ 0.05) during exercise. For the transporters, the experimental protocol resulted in a decrease (P Ͻ 0.05) in glucose transporter-1 (GLUT1; 29% by R1), an increase in GLUT4 (29% by E3), and increases (P Ͻ 0.05) for both monocarboxylate transporters (MCT) (for MCT1, 23% by R2 and for MCT4, 18% by R1). Of the mitochondrial and cytosolic enzyme activities examined, cytochrome c oxidase (COX), and hexokinase were both reduced (P Ͻ 0.05) by exercise at E1 and in the case of hexokinase and phosphorylase by exercise on E3. With the exception at COX, which was lower (P Ͻ 0.05) at R1, no differences in enzyme activities existed at rest between E, E3, and recovery days. Results suggest that the glucose and lactate transporters are among the earliest adaptive responses of substrate and metabolic properties studied to the sudden onset of regular lowintensity exercise. contractile activity; glucose; lactate; transporters; vastus lateralis; glycogen; energy metabolism; enzyme activity IN WORKING SKELETAL MUSCLE, regular submaximal contractile activity promotes a better matching between ATP supply and ATP utilization, resulting in less of a disturbance in phosphorylation potential, increased delivery of fuels, such as carbohydrate (CHO) to the metabolic pathways so as not to be limiting to pathway flux, and attenuation of the by-products of metabolism, such as lactic acid, thereby minimizing their potentially disruptive effects (38,39,46,56,68).It has also been reported that these altered responses depend on a series of adaptations that increase the abundance of a multitude of proteins and protein isoforms that are involved in oxidative phosphorylation (OXPHOS), substrate availability, and metabolic by-product management. The tighter metabolic coupling, as an example, has been attributed to the increase in the potential for OXPHOS, which is believed to occur as a result of increases in mitochondrial density and the maximal ac...

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Section: Discussionmentioning

confidence: 70%

mentioning

confidence: 99%

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Green

Bombardier²,

Duhamel³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The effects of exercise training on TG m content in healthy subjects are equivocal, with some studies reporting an increase [11,24,25], decrease [26] or no [9,10,27] after short-term (6-12 weeks) endurance exercise. In our investigation, exercise training had little effect on TG m concentrations in control subjects, but resulted in a substantial overall decrease in patients with Type 2 diabetes.…”

Section: Discussionmentioning

confidence: 99%

“…It is well known that endurance training elicits an increase in the oxidative capacity of skeletal muscle from healthy, insulin-sensitive subjects [25,36,37]. Thus, regular exercise training might be therapeutic in overcoming derangements in lipid metabolism observed in Type 2 diabetes.…”

Section: Discussionmentioning

confidence: 99%

Disassociation of muscle triglyceride content and insulin sensitivity after exercise training in patients with Type 2 diabetes

et al. 2004

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Aim/hypothesis. We determined the effect of exercise training on insulin sensitivity and muscle lipids (triglyceride [TG m ] and long-chain fatty acyl CoA [LCACoA] concentration) in patients with Type 2 diabetes. Methods. Seven patients with Type 2 diabetes and six healthy control subjects who were matched for age, BMI, % body fat and VO 2 peak participated in a 3 days per week training program for 8 weeks. Insulin sensitivity was determined pre-and post-training during a 120 min euglycaemic-hyperinsulinaemic clamp and muscle biopsies were obtained before and after each clamp. Oxidative enzyme activities [citrate synthase (CS), β-hydroxy-acyl-CoA (β-HAD)] and TG m were determined from basal muscle samples pre-and post training, while total LCACoA content was measured in samples obtained before and after insulinstimulation, pre-and post training. Results. The training-induced increase in VO 2 peak (~20%, p<0.01) was similar in both groups. Compared with control subjects, insulin sensitivity was lower in the diabetic patients before and after training (~60%; p<0.05), but was increased to the same extent in both groups with training (~30%; p<0.01). TG m was increased in patients with Type 2 diabetes (170%; p<0.05) before, but was normalized to levels observed in control subjects after training. Basal LCACoA content was similar between groups and was unaltered by training. Insulin-stimulation had no detectable effect on LCACoA content. CS and β-HAD activity were increased to the same extent in both groups in response to training (p<0.001). Conclusion/interpretation. We conclude that the enhanced insulin sensitivity observed after short-term exercise training was associated with a marked decrease in TG m content in patients with Type 2 diabetes. However, despite the normalization of TG m to levels observed in healthy individuals, insulin resistance was not completely reversed in the diabetic patients. Type 2 diabetes is characterized by skeletal muscle insulin resistance and impaired glucose metabolism. In addition to disturbances in glucose homeostasis, individuals with Type 2 diabetes have an impaired lipid metabolism, reflected by increased circulating free fatty acids [1], reduced rates of whole body fat oxidation [2] and excessive deposition of lipids in various tissues including skeletal muscle [3]. With regard to muscle lipid status, there is evidence in humans that increased trigacylglycerol (TG m ) concentration [3,4,5,6,7] and increased long-chain fatty acyl CoA (LCACoA) content are negatively associated with whole body insulin action [8]. Considering the rela-

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“…No entanto, a entrada de AG no plasma é similar à taxa de oxidação no mesmo período. Alguns pesquisadores sugerem que outra fonte de lipídios, além dos AG provenientes do tecido adiposo, provavelmente plasmático ou TGIM, é também oxidada pelo músculo (18,19).…”

Section: Metabolismo Dos Triacilgliceróis Intramusculares (Tgim)unclassified

Ciclo de Krebs como fator limitante na utilização de ácidos graxos durante o exercício aeróbico

Curi

Lagranha

Rodrigues

et al. 2003

Arq Bras Endocrinol Metab

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RESUMOOs ácidos graxos (AG) representam uma fonte importante de energia durante exercícios de intensidade leve ou moderada, e principalmente naqueles de duração prolongada. A utilização dos AG pelos músculos esqueléticos depende de passos importantes como a mobilização, transporte via corrente sangüínea, passagem pelas membranas plasmática e mitocôndrial, β-oxidação e, finalmente, a oxidação no ciclo de Krebs e atividade da cadeia respiratória. O exercício agudo e o treinamento induzem adaptações que possibilitam maior aproveitamento dos AG como fonte de energia, ao mesmo tempo em que o glicogênio muscular é preservado. Contudo, as tentativas de manipulação da dieta e suplementação com agentes ativos para aumentar a mobilização e utilização dos AG durante o exercício não apresentam resultados conclusivos. Nesse trabalho, a hipótese de que o ciclo de Krebs é o fator limitante da utilização de ácidos graxos pelo tecido muscular no exercício prolongado é apresentada. ABSTRACTThe Krebs Cycle as Limiting Factor for Fatty Acids Utilization During Aerobic Exercise. Fatty acids are important fuels for muscle during moderate and prolonged exercise. The utilization of fatty acids by skeletal muscle depends on important key steps such as lipolysis in the adipose tissue, plasma fatty acids transport, and passage through plasma and mitochondrial membranes, β-oxidation, and finally oxidation through the Krebs cycle and respiratory chain activity. Acute exercise and exercise training induce adaptations that lead to an increase in fatty acid oxidation. As a result muscle glycogen is preserved. Nevertheless, diet manipulation and supplementation with lipolytic agents that raise fatty acids mobilization and oxidation during exercise failed to show beneficial results on exercise performance. The hypothesis that Krebs cycle is a limiting factor for fatty acid oxidation by the skeletal muscle during prolonged exercise is presented herein.

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Progressive effect of endurance training on metabolic adaptations in working skeletal muscle

Cited by 142 publications

References 16 publications

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Metabolic, enzymatic, and transporter responses in human muscle during three consecutive days of exercise and recovery

Disassociation of muscle triglyceride content and insulin sensitivity after exercise training in patients with Type 2 diabetes

Ciclo de Krebs como fator limitante na utilização de ácidos graxos durante o exercício aeróbico

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