More than a store: regulatory roles for glycogen in skeletal muscle adaptation to exercise

2012 ◽  
Vol 302 (11) ◽  
pp. E1343-E1351 ◽  
Author(s):  
Andrew Philp ◽  
Mark Hargreaves ◽  
Keith Baar

The glycogen content of muscle determines not only our capacity for exercise but also the signaling events that occur in response to exercise. The result of the shift in signaling is that frequent training in a low-glycogen state results in improved fat oxidation during steady-state submaximal exercise. This review will discuss how the amount or localization of glycogen particles can directly or indirectly result in this differential response to training. The key direct effect discussed is carbohydrate binding, whereas the indirect effects include the metabolic shift toward fat oxidation, the increase in catecholamines, and osmotic stress. Although our understanding of the role of glycogen in response to training has expanded exponentially over the past 5 years, there are still many questions remaining as to how stored carbohydrate affects the muscular adaptation to exercise.

1999 ◽  
Vol 11 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Glen E. Duncan ◽  
Edward T. Howley

This review addresses issues related to substrate metabolism in children and how this information compares and contrasts to that of adults. The relative percent of fat and carbohydrate (CHO) utilized by an individual can be estimated from respiratory exchange ratio (RER) values between 0.7 (100% fat, 0% CHO) and 1.0 (100% CHO, 0% fat). The rise in RER towards 1.0 in relation to increased exercise intensity demonstrates the augmented role of CHO as an energy source for muscle; however, fat oxidation also represents a major source of energy during exercise of moderate-to-heavy intensity. Preliminary reports suggest that children demonstrate patterns of fat and CHO use in response to exercise intensity similar to those of adults and also show a reduction in RER at submaximal exercise intensities after training. The use of the “crossover concept" may simplify the presentation of how metabolism is affected by exercise intensity and training.


1990 ◽  
Vol 258 (2) ◽  
pp. E382-E389 ◽  
Author(s):  
R. R. Wolfe ◽  
S. Klein ◽  
F. Carraro ◽  
J. M. Weber

We have investigated the role of triglyceride-fatty acid cycling in amplifying control of the net flux of fatty acids in response to exercise and in recovery from exercise. Five normal volunteers were infused with [1-13C]palmitate and D-5-glycerol throughout rest, 4 h of treadmill exercise at 40% maximum O2 consumption, and 2 h of recovery. Total fat oxidation was quantified by indirect calorimetry. Lipolysis (rate of appearance of glycerol) increased from 2.1 +/- 0.3 to 6.0 +/- 1.2 mumol.kg-1.min-1 after 30 min of exercise and progressively increased thereafter to a value of 10.5 +/- 0.8 mumol.kg-1.min-1 after 4 h. Lipolysis decreased rapidly during the first 20 min of recovery, but it was still significantly elevated after 2 h of recovery. The rate of appearance of free fatty acids followed the same pattern of response. Seventy percent of released fatty acids were reesterified at rest, and this value decreased to 25% within the first 30 min of exercise. Reesterification remained less than 35% of lipolysis until the start of recovery, at which time the value rose to 90%. In exercise, more than one-half the increase in fat oxidation could be attributed to the reduction in the percent reesterification. Most of the change in percent reesterification during exercise and recovery was caused by changes in extracellular cycling of fatty acids released into plasma. We conclude that triglyceride-fatty acid cycling plays an important role in enabling a rapid response of fatty acid metabolism to major changes in energy metabolism.


2020 ◽  
Vol 9 (2) ◽  
pp. 562 ◽  
Author(s):  
Charline Pegon ◽  
Emmanuelle Rochette ◽  
Nadège Rouel ◽  
Bruno Pereira ◽  
Eric Doré ◽  
...  

Background: Leukemia is the most common cancer in pediatrics, with many late effects such as higher risk of dyslipidemia, insulin resistance, obesity, and metabolic syndrome. The objective of this work was to investigate substrate oxidation during submaximal exercise in survivors of childhood acute leukemia. Methods: A total of 20 leukemia survivors and 20 healthy children were matched by sex, age, and Tanner stage. They all took a submaximal incremental exercise test to determine fat and carbohydrate oxidation rates. Results: Cardiorespiratory fitness was significantly lower in leukemia survivors, with lower relative VO2 peaks (p < 0.001), lower heart rate values (p = 0.02), and lower exercise power (p = 0.012), whereas rest metabolism and body mass index did not differ between the two groups. During exercise, upward of heart rate relative to VO2 peak was significantly higher (p < 0.001) in childhood leukemia survivors. We found lower carbohydrate and fat oxidation rates (p = 0.07) in leukemia survivors compared with healthy children, and also a significantly lower relative maximal fat oxidation rate (p = 0.014). Conclusion: Despite impaired physical fitness and metabolic response to exercise, childhood leukemia survivors remained sensitive to physical activity interventions, and could readily adapt to submaximal exercise intensity.


Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.


1968 ◽  
Vol 11 (4) ◽  
pp. 767-776 ◽  
Author(s):  
B. Don Franks ◽  
Elizabeth B. Franks

Eight college students enrolled in group therapy for stuttering were divided into two equal groups for 20 weeks. The training group supplemented therapy with endurance running and calisthenics three days per week. The subjects were tested prior to and at the conclusion of the training on a battery of stuttering tests and cardiovascular measures taken at rest, after stuttering, and after submaximal exercise. There were no significant differences (0.05 level) prior to training. At the conclusion of training, the training group was significandy better in cardiovascular response to exercise and stuttering. Although physical training did not significantly aid the reduction of stuttering as measured in this study, training did cause an increased ability to adapt physiologically to physical stress and to the stress of stuttering.


2019 ◽  
pp. 121-143
Author(s):  
Riccardo Resciniti ◽  
Federica De Vanna

The rise of e-commerce has brought considerable changes to the relationship between firms and consumers, especially within international business. Hence, understanding the use of such means for entering foreign markets has become critical for companies. However, the research on this issue is new and so it is important to evaluate what has been studied in the past. In this study, we conduct a systematic review of e-commerce and internationalisation studies to explicate how firms use e-commerce to enter new markets and to export. The studies are classified by theories and methods used in the literature. Moreover, we draw upon the internationalisation decision process (antecedents-modalities-consequences) to propose an integrative framework for understanding the role of e-commerce in internationalisation


2020 ◽  
Vol 28 (1) ◽  
pp. 106-121
Author(s):  
Kato Gogo Kingston

Financial crime in Nigeria – including money laundering – is ravaging Nigeria's economic growth. In the past few years, the Nigerian government has made efforts to tackle money laundering by enacting laws and setting up several agencies to enforce the laws. However, there are substantial loopholes in the regulatory and enforcement regimes. This article seeks to unravel the involvement of the churches as key drivers in money laundering crimes in Nigeria. It concludes that the permissive secrecy which enables churches to conceal the names of their financiers and donors breeds criminality on an unimaginable scale.


2020 ◽  
Vol 28 (2) ◽  
pp. 298-318
Author(s):  
Roman Girma Teshome

The effectiveness of human rights adjudicative procedures partly, if not most importantly, hinges upon the adequacy of the remedies they grant and the implementation of those remedies. This assertion also holds water with regard to the international and regional monitoring bodies established to receive individual complaints related to economic, social and cultural rights (hereinafter ‘ESC rights’ or ‘socio-economic rights’). Remedies can serve two major functions: they are meant, first, to rectify the pecuniary and non-pecuniary damage sustained by the particular victim, and second, to resolve systematic problems existing in the state machinery in order to ensure the non-repetition of the act. Hence, the role of remedies is not confined to correcting the past but also shaping the future by providing reforming measures a state has to undertake. The adequacy of remedies awarded by international and regional human rights bodies is also assessed based on these two benchmarks. The present article examines these issues in relation to individual complaint procedures that deal with the violation of ESC rights, with particular reference to the case laws of the three jurisdictions selected for this work, i.e. the United Nations, Inter-American and African Human Rights Systems.


Somatechnics ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 288-303
Author(s):  
Michael Connors Jackman

This article investigates the ways in which the work of The Body Politic (TBP), the first major lesbian and gay newspaper in Canada, comes to be commemorated in queer publics and how it figures in the memories of those who were involved in producing the paper. In revisiting a critical point in the history of TBP from 1985 when controversy erupted over race and racism within the editorial collective, this discussion considers the role of memory in the reproduction of whiteness and in the rupture of standard narratives about the past. As the controversy continues to haunt contemporary queer activism in Canada, the productive work of memory must be considered an essential aspect of how, when and for what reasons the work of TBP comes to be commemorated. By revisiting the events of 1985 and by sifting through interviews with individuals who contributed to the work of TBP, this article complicates the narrative of TBP as a bluntly racist endeavour whilst questioning the white privilege and racially-charged demands that undergird its commemoration. The work of producing and preserving queer history is a vital means of challenging the intentional and strategic erasure of queer existence, but those who engage in such efforts must remain attentive to the unequal terrain of social relations within which remembering forms its objects.


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