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Sabharwal A, Gupta V, Kv S, Kumar Manokaran R, Verma A, Mishra A, Bhoyar RC, Jain A, Sivadas A, Rawat S, Jolly B, Mohanty S, Gulati S, Gupta N, Kabra M, Scaria V, Sivasubbu S. Whole genome sequencing followed by functional analysis of genomic deletion encompassing ERCC8 and NDUFAF2 genes in a non-consanguineous Indian family reveals dysfunctional mitochondrial bioenergetics leading to infant mortality. Mitochondrion 2024; 75:101844. [PMID: 38237647 DOI: 10.1016/j.mito.2024.101844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 12/07/2023] [Accepted: 01/14/2024] [Indexed: 01/26/2024]
Abstract
Genomic investigations on an infant who presented with a putative mitochondrial disorder led to identification of compound heterozygous deletion with an overlapping region of ∼142 kb encompassing two nuclear encoded genes namely ERCC8 and NDUFAF2. Investigations on fetal-derived fibroblast culture demonstrated impaired bioenergetics and mitochondrial dysfunction, which explains the phenotype and observed infant mortality in the present study. The genetic findings from this study extended the utility of whole-genome sequencing as it led to development of a MLPA-based assay for carrier screening in the extended family and the prenatal testing aiding in the birth of two healthy children.
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Affiliation(s)
- Ankit Sabharwal
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; Department of Pediatrics, Dell Medical School, The University of Texas at Austin, Austin, Texas, United States.
| | - Vishu Gupta
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Shamsudheen Kv
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | | | - Ankit Verma
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
| | - Anushree Mishra
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Rahul C Bhoyar
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
| | - Abhinav Jain
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Ambily Sivadas
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sonali Rawat
- Stem Cell Facility, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Bani Jolly
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sujata Mohanty
- Stem Cell Facility, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Sheffali Gulati
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Neerja Gupta
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India
| | - Madhulika Kabra
- Department of Pediatrics, All India Institute of Medical Sciences (AIIMS), Delhi, India.
| | - Vinod Scaria
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
| | - Sridhar Sivasubbu
- CSIR Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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2
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Homer KA, Cross MR, Helms ER. Peak Week Carbohydrate Manipulation Practices in Physique Athletes: A Narrative Review. SPORTS MEDICINE - OPEN 2024; 10:8. [PMID: 38218750 PMCID: PMC10787737 DOI: 10.1186/s40798-024-00674-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024]
Abstract
BACKGROUND Physique athletes are ranked by a panel of judges against the judging criteria of the corresponding division. To enhance on-stage presentation and performance, competitors in certain categories (i.e. bodybuilding and classic physique) achieve extreme muscle size and definition aided by implementing acute "peaking protocols" in the days before competition. Such practices can involve manipulating nutrition and training variables to increase intramuscular glycogen and water while minimising the thickness of the subcutaneous layer. Carbohydrate manipulation is a prevalent strategy utilised to plausibly induce muscle glycogen supercompensation and subsequently increase muscle size. The relationship between carbohydrate intake and muscle glycogen saturation was first examined in endurance event performance and similar strategies have been adopted by physique athletes despite the distinct physiological dissimilarities and aims between the sports. OBJECTIVES The aim of this narrative review is to (1) critically examine and appraise the existing scientific literature relating to carbohydrate manipulation practices in physique athletes prior to competition; (2) identify research gaps and provide direction for future studies; and (3) provide broad practical applications based on the findings and physiological reasoning for coaches and competitors. FINDINGS The findings of this review indicate that carbohydrate manipulation practices are prevalent amongst physique athletes despite a paucity of experimental evidence demonstrating the efficacy of such strategies on physique performance. Competitors have also been observed to manipulate water and electrolytes in conjunction with carbohydrate predicated on speculative physiological mechanisms which may be detrimental for performance. CONCLUSIONS Further experimental evidence which closely replicates the nutritional and training practices of physique athletes during peak week is required to make conclusions on the efficacy of carbohydrate manipulation strategies. Quasi-experimental designs may be a feasible alternative to randomised controlled trials to examine such strategies due to the difficulty in recruiting the population of interest. Finally, we recommend that coaches and competitors manipulate as few variables as possible, and experiment with different magnitudes of carbohydrate loads in advance of competition if implementing a peaking strategy.
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Affiliation(s)
- Kai A Homer
- Sport Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, 17 Antares Place, Rosedale, Auckland, 0632, New Zealand.
| | - Matt R Cross
- Sport Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, 17 Antares Place, Rosedale, Auckland, 0632, New Zealand
| | - Eric R Helms
- Sport Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, 17 Antares Place, Rosedale, Auckland, 0632, New Zealand
- Department of Exercise Science and Health Promotion, Muscle Physiology Laboratory, Florida Atlantic University, Boca Raton, FL, USA
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3
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Thorsteinsson H, Vigh-Larsen JF, Panduro J, Fristrup B, Kruse DZ, Gliemann L, Egeland M, Olesen JL, Aagaard P, Randers MB, Krustrup P, Nybo L, Overgaard K, Mohr M. The recovery of muscle function and glycogen levels following game-play in young elite male ice hockey players. Scand J Med Sci Sports 2023; 33:2457-2469. [PMID: 37668421 DOI: 10.1111/sms.14485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/10/2023] [Accepted: 08/18/2023] [Indexed: 09/06/2023]
Abstract
Despite the frequent occurrence of congested game fixtures in elite ice hockey, the postgame recovery pattern has not previously been investigated. The purpose of the present study was therefore to evaluate the acute decrements and subsequent recovery of skeletal muscle glycogen levels, muscle function and repeated-sprint ability following ice hockey game-play. Sixteen male players from the Danish U20 national team completed a training game with muscle biopsies obtained before, postgame and following ~38 h of recovery (day 2). On-ice repeated-sprint ability and muscle function (maximal voluntary isometric [MVIC] and electrically induced low- (20 Hz) and high-frequency (50 Hz) knee-extensor contractions) were assessed at the same time points, as well as ~20 h into recovery (day 1). Muscle glycogen decreased 31% (p < 0.001) postgame and had returned to pregame levels on day 2. MVIC dropped 11%, whereas 50 and 20 Hz torque dropped 21% and 29% postgame, respectively, inducing a 10% reduction in the 20/50 Hz torque ratio indicative of low-frequency force depression (all p < 0.001). While MVIC torque returned to baseline on day 1, 20 and 50 Hz torque remained depressed by 9%-11% (p = 0.010-0.040), hence restoring the pre-exercise 20/50 Hz ratio. Repeated-sprint ability was only marginally reduced by 1% postgame (p = 0.041) and fully recovered on day 1. In conclusion, an elite youth ice hockey game induces substantial reductions in muscle glycogen content and muscle function, but only minor reductions in repeated-sprint ability and with complete recovery of all parameters within 1-2 days postgame.
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Affiliation(s)
- Hallur Thorsteinsson
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
| | - Jeppe F Vigh-Larsen
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
- Department of Public Health, Section of Sport Science, Aarhus University, Aarhus, Denmark
| | - Jeppe Panduro
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
| | - Bjørn Fristrup
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
| | - Daniel Zornow Kruse
- Department of Public Health, Section of Sport Science, Aarhus University, Aarhus, Denmark
| | - Lasse Gliemann
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Marte Egeland
- Department of Anesthesia, Centre and Head and Orthopedics, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens L Olesen
- Department of Clinical Medicine, The Faculty of Medicine, Aalborg University, Aalborg, Denmark
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
| | - Morten B Randers
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
- School of Sport Sciences, Faculty of Health Sciences, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Peter Krustrup
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
- Danish Institute for Advanced Study (DIAS), University of Southern Denmark, Odense, Denmark
- Sport and Health Sciences, University of Exeter, Exeter, UK
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Overgaard
- Department of Public Health, Section of Sport Science, Aarhus University, Aarhus, Denmark
| | - Magni Mohr
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark
- Centre of Health Science, Faculty of Health, University of the Faroe Islands, Tórshavn, Faroe Islands
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4
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Renaud JM, Ørtenblad N, McKenna MJ, Overgaard K. Exercise and fatigue: integrating the role of K +, Na + and Cl - in the regulation of sarcolemmal excitability of skeletal muscle. Eur J Appl Physiol 2023; 123:2345-2378. [PMID: 37584745 PMCID: PMC10615939 DOI: 10.1007/s00421-023-05270-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
Perturbations in K+ have long been considered a key factor in skeletal muscle fatigue. However, the exercise-induced changes in K+ intra-to-extracellular gradient is by itself insufficiently large to be a major cause for the force decrease during fatigue unless combined to other ion gradient changes such as for Na+. Whilst several studies described K+-induced force depression at high extracellular [K+] ([K+]e), others reported that small increases in [K+]e induced potentiation during submaximal activation frequencies, a finding that has mostly been ignored. There is evidence for decreased Cl- ClC-1 channel activity at muscle activity onset, which may limit K+-induced force depression, and large increases in ClC-1 channel activity during metabolic stress that may enhance K+ induced force depression. The ATP-sensitive K+ channel (KATP channel) is also activated during metabolic stress to lower sarcolemmal excitability. Taking into account all these findings, we propose a revised concept in which K+ has two physiological roles: (1) K+-induced potentiation and (2) K+-induced force depression. During low-moderate intensity muscle contractions, the K+-induced force depression associated with increased [K+]e is prevented by concomitant decreased ClC-1 channel activity, allowing K+-induced potentiation of sub-maximal tetanic contractions to dominate, thereby optimizing muscle performance. When ATP demand exceeds supply, creating metabolic stress, both KATP and ClC-1 channels are activated. KATP channels contribute to force reductions by lowering sarcolemmal generation of action potentials, whilst ClC-1 channel enhances the force-depressing effects of K+, thereby triggering fatigue. The ultimate function of these changes is to preserve the remaining ATP to prevent damaging ATP depletion.
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Affiliation(s)
- Jean-Marc Renaud
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON, K1H 8M5, Canada.
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- College of Physical Education, Southwest University, Chongqing, China
- College of Sport Science, Zhuhai College of Science and Technology, Zhuhai, China
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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5
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Harrylal CA, Lensink AV, Gupta SK, Aire TA. The ultrastructural features of the infundibulum of the green iguana, Iguana iguana. J Morphol 2023; 284:e21644. [PMID: 37856278 DOI: 10.1002/jmor.21644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023]
Abstract
The purpose of this study is to describe, in detail, the ultrastructure of the infundibulum of the sexually mature and active female green iguana, Iguana iguana. The infundibulum of five iguanas was remarkably distinct from the uterus, and was also clearly demarcated into cranial (expanded v-shaped) and caudal (tubular) divisions. Tissue samples obtained from five portions (three from the cranial division and two from the caudal division) of the infundibulum were processed conventionally for light and electron microscopy. The epithelial lining of the most anterior, middle, and posterior, parts of the cranial division displayed nonciliated cells predominantly, and occasionally ciliated cells. The numerous secretory granules in nonciliated type 1 cell found in the fimbrial aspect of the infundibulum were homogenous and deeply electron-dense, but those in the other two regions were variants of this cell type because they contained variably electron-dense secretory granules. Two main types of nonciliated cells (type 2 and its variant, type 3, as well as type 4) occurred in the epithelial lining of the caudal division of the infundibulum, but they, clearly, showed no dense secretory granules. Whereas the nonciliated type 2 cell and its variant (type 3 cell) contained large glycogen deposits, the type 4 cell lacked these deposits but its apical part contained large lipid-like droplets and, remarkably, blebbed into the duct lumen. The nonciliated cells lining the mucosal tubular glands contained highly electron-dense secretory granules, which were similar to those found in the nonciliated type 1 cell in the epithelial lining of the fimbrial part of the cranial division of the infundibulum.
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Affiliation(s)
- Crissy-Ann Harrylal
- Department of Anatomy, Physiology, and Pharmacology School of Veterinary Medicine, St. George's University, True Blue, Grenada
| | - Antoinette V Lensink
- Electron Microscope Unit, Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Sunil K Gupta
- Department of Anatomy, Physiology, and Pharmacology School of Veterinary Medicine, St. George's University, True Blue, Grenada
| | - Tom A Aire
- Department of Anatomy, Physiology, and Pharmacology School of Veterinary Medicine, St. George's University, True Blue, Grenada
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6
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El-Kurd OB, Bialy P, Kirkes M. What about hybrids? Supplemental methods for skeletal muscle fibre typing. J Physiol 2023; 601:251-252. [PMID: 36448550 DOI: 10.1113/jp284038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Affiliation(s)
- Omar B El-Kurd
- Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University, San Francisco, CA, USA
| | - Patrick Bialy
- Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University, San Francisco, CA, USA
| | - Maty Kirkes
- Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University, San Francisco, CA, USA
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7
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Qiu F, Yuan Y, Luo W, Gong YS, Zhang ZM, Liu ZM, Gao L. Asiatic acid alleviates ischemic myocardial injury in mice by modulating mitophagy- and glycophagy-based energy metabolism. Acta Pharmacol Sin 2022; 43:1395-1407. [PMID: 34522006 PMCID: PMC9160258 DOI: 10.1038/s41401-021-00763-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 08/10/2021] [Indexed: 02/07/2023] Open
Abstract
Myocardial infarction (MI) causes disturbances in myocardial energy metabolism, ultimately leading to a poor prognosis. Cytosolic glycogen autophagy (glycophagy) and mitochondrial autophagy (mitophagy) are upregulated in MI to optimize energy metabolism but to a limited extent. Asiatic acid (AA), a pentacyclic triterpene derived from the traditional Chinese herb Centella asiatica, displays anti-inflammatory, antioxidant, and antiapoptotic activities. AA has been found to alleviate focal cerebral and liver ischemic injury by reversing mitochondrial dysfunction. In this study, we investigated whether AA exerted cardioprotective effects against MI by activating glycophagy and mitophagy to improve the energy balance. In vitro cardioprotective effects were examined in neonatal mouse cardiomyocytes subjected to oxygen-glucose deprivation for 12 h. Treatment with AA (2-50 μM) significantly increased cell viability and improved the energy metabolism evidenced by increased ATP level and phosphocreatine/ATP ratio. In vivo cardioprotective effects were studied in a mouse model of MI. Administration of AA (5-125 mg·kg-1·d-1, ig) significantly reduced infarct size and ischemic myocardial injury, and improved cardiac function. AA treatment also promoted mitophagy and relieved mitochondrial edema evidenced by increased number of mitophagosomes in ischemic myocardium in vivo and increased mitochondria-light chain 3 (LC3)-II colocalization in ODG-treated cardiomyocytes in vitro. Mitophagy activation was accompanied by activation of the AMPK signaling pathway. Knockdown of AMPK abolished AA-activated mitophagy. Furthermore, we showed that glycophagy was upregulated in OGD cardiomyocytes evidenced by increased starch binding domain protein 1 (STBD1)-GABA type A receptor-associated protein-like 1(GABARAPL1) interaction and extracellular acidification rate, whereas AA treatment further promoted glycophagy accompanied by PI3K/Akt activation. PI3K inhibitor LY294002 or Akt inhibitor GSK690693 blocked the effects of AA on glycophagy and glycolysis. Finally, simultaneous inhibition of glycophagy and mitophagy abolished the cardioprotective effects and energy regulation of AA. These results demonstrate that AA protects ischemic cardiomyocytes by modulating glycophagy- and mitophagy-based energy metabolism through the PI3K/Akt and AMPK pathways.
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Affiliation(s)
- Fan Qiu
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China ,grid.452753.20000 0004 1799 2798Department of Cardiovascular and Thoracic Surgery, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Yi Yuan
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China
| | - Wei Luo
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China ,grid.452753.20000 0004 1799 2798Department of Cardiovascular and Thoracic Surgery, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Yan-shan Gong
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China
| | - Zhong-ming Zhang
- grid.413389.40000 0004 1758 1622Department of Cardiovascular and Thoracic Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221006, China
| | - Zhong-min Liu
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China ,grid.452753.20000 0004 1799 2798Department of Cardiovascular and Thoracic Surgery, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China ,grid.452753.20000 0004 1799 2798Shanghai Institute of Stem Cell Research and Clinical translation, Shanghai East Hospital, Tongji University, Shanghai 200120, China ,Shanghai Engineering Research Center for Stem Cell Clinical Treatment, Shanghai 200123, China
| | - Ling Gao
- grid.452753.20000 0004 1799 2798Translational Medical Center for Stem Cell Therapy & Institute for Regenerative Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China ,grid.452753.20000 0004 1799 2798Shanghai Institute of Stem Cell Research and Clinical translation, Shanghai East Hospital, Tongji University, Shanghai 200120, China ,Shanghai Engineering Research Center for Stem Cell Clinical Treatment, Shanghai 200123, China
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8
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Janzen NR, Whitfield J, Murray-Segal L, Kemp BE, Hawley JA, Hoffman NJ. Disrupting AMPK-Glycogen Binding in Mice Increases Carbohydrate Utilization and Reduces Exercise Capacity. Front Physiol 2022; 13:859246. [PMID: 35392375 PMCID: PMC8980720 DOI: 10.3389/fphys.2022.859246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
The AMP-activated protein kinase (AMPK) is a central regulator of cellular energy balance and metabolism and binds glycogen, the primary storage form of glucose in liver and skeletal muscle. The effects of disrupting whole-body AMPK-glycogen interactions on exercise capacity and substrate utilization during exercise in vivo remain unknown. We used male whole-body AMPK double knock-in (DKI) mice with chronic disruption of AMPK-glycogen binding to determine the effects of DKI mutation on exercise capacity, patterns of whole-body substrate utilization, and tissue metabolism during exercise. Maximal treadmill running speed and whole-body energy utilization during submaximal running were determined in wild type (WT) and DKI mice. Liver and skeletal muscle glycogen and skeletal muscle AMPK α and β2 subunit content and signaling were assessed in rested and maximally exercised WT and DKI mice. Despite a reduced maximal running speed and exercise time, DKI mice utilized similar absolute amounts of liver and skeletal muscle glycogen compared to WT. DKI skeletal muscle displayed reduced AMPK α and β2 content versus WT, but intact relative AMPK phosphorylation and downstream signaling at rest and following exercise. During submaximal running, DKI mice displayed an increased respiratory exchange ratio, indicative of greater reliance on carbohydrate-based fuels. In summary, whole-body disruption of AMPK-glycogen interactions reduces maximal running capacity and skeletal muscle AMPK α and β2 content and is associated with increased skeletal muscle glycogen utilization. These findings highlight potential unappreciated roles for AMPK in regulating tissue glycogen dynamics and expand AMPK’s known roles in exercise and metabolism.
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Affiliation(s)
- Natalie R. Janzen
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Jamie Whitfield
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Lisa Murray-Segal
- St Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VIC, Australia
| | - Bruce E. Kemp
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
- St Vincent’s Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VIC, Australia
| | - John A. Hawley
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
| | - Nolan J. Hoffman
- Exercise and Nutrition Research Program, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC, Australia
- *Correspondence: Nolan J. Hoffman,
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9
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Hostrup M, Cairns SP, Bangsbo J. Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance. Compr Physiol 2021; 11:1895-1959. [PMID: 34190344 DOI: 10.1002/cphy.c190024] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise causes major shifts in multiple ions (e.g., K+ , Na+ , H+ , lactate- , Ca2+ , and Cl- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K+ , Na+ , and Ca2+ during fatiguing exercise, while changes in gradients for Cl- and Cl- conductance may exert either protective or detrimental effects on fatigue. Myocellular H+ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca2+ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na+ /K+ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K+ and Cl- , respectively via metabolic regulation of the ATP-sensitive K+ channel (KATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.
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Affiliation(s)
- Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Simeon Peter Cairns
- SPRINZ, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand.,Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand
| | - Jens Bangsbo
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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10
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Krustrup P, Mohr M, Nybo L, Draganidis D, Randers MB, Ermidis G, Ørntoft C, Røddik L, Batsilas D, Poulios A, Ørtenblad N, Loules G, Deli CK, Batrakoulis A, Nielsen JL, Jamurtas AZ, Fatouros IG. Muscle metabolism and impaired sprint performance in an elite women's football game. Scand J Med Sci Sports 2021; 32 Suppl 1:27-38. [PMID: 34171140 DOI: 10.1111/sms.13970] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/01/2021] [Accepted: 04/05/2021] [Indexed: 01/12/2023]
Abstract
The present study examined skeletal muscle metabolism and changes in repeated sprint performance during match play for n = 20 competitive elite women outfield players. We obtained musculus vastus lateralis biopsies and blood samples before, after, and following intense periods in each half of a friendly match, along with 5 × 30-meter sprint tests and movement pattern analyses (10-Hz S5 Global Positioning System [GPS]). Muscle glycogen decreased by 39% and 42% after an intense period of the second half and after the match, respectively, compared to baseline (p < 0.05). Post-match, 80% type I fibers and 69% type II fibers were almost empty or completely empty of glycogen. Muscle lactate was higher (p < 0.05) after the intense period of the first half and post-match compared to baseline (14.3 ± 4.6 (±SEM) and 12.9 ± 5.7 vs. 6.4 ± 3.7 mmol/kg d.w.). Muscle phosphocreatine was reduced (p < 0.05) by 16% and 12%, respectively, after an intense period in the first and second half compared to baseline. Blood lactate and glucose increased during the match and peaked at 8.4 ± 2.0 and 7.9 ± 1.2 mmol/L, respectively. Mean 5 × 30 m sprint time declined by 3.2 ± 1.7 and 7.0 ± 2.1% after the first and second half, respectively, and 4.7 ± 1.6% (p < 0.05) after an intense period in the first half compared to baseline. In conclusion, match play in elite female football players resulted in marked glycogen depletion in both fiber types, which may explain fatigue at the end of a match. Repeated sprint ability was impaired after intense periods in the first half and after both halves, which may be associated with the observed muscle metabolite perturbations.
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Affiliation(s)
- Peter Krustrup
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,Danish Institute for Advanced Study (DIAS), University of Southern Denmark, Odense, Denmark.,Sport and Health Sciences, Faculty of Life and Environmental Sciences, University of Exeter, Exeter, UK.,Shanghai University of Sport, Shanghai, China
| | - Magni Mohr
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,Center of Health Science, Faculty of Health Sciences, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen N, Denmark
| | - Dimitrios Draganidis
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Morten B Randers
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,School of Sport Sciences, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Georgios Ermidis
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,Department of Movement Sciences and Wellness, "Parthenope" University of Naples, Naples, Italy
| | - Christina Ørntoft
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,Team Danmark, Brøndby, Denmark
| | - Line Røddik
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark
| | - Dimitrios Batsilas
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Athanasios Poulios
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Georgios Loules
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Charikleia K Deli
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Alexios Batrakoulis
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Jakob L Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Athanasios Z Jamurtas
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
| | - Ioannis G Fatouros
- School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece
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11
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Escalante G, Stevenson SW, Barakat C, Aragon AA, Schoenfeld BJ. Peak week recommendations for bodybuilders: an evidence based approach. BMC Sports Sci Med Rehabil 2021; 13:68. [PMID: 34120635 PMCID: PMC8201693 DOI: 10.1186/s13102-021-00296-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 06/02/2021] [Indexed: 01/10/2023]
Abstract
Bodybuilding is a competitive endeavor where a combination of muscle size, symmetry, "conditioning" (low body fat levels), and stage presentation are judged. Success in bodybuilding requires that competitors achieve their peak physique during the day of competition. To this end, competitors have been reported to employ various peaking interventions during the final days leading to competition. Commonly reported peaking strategies include altering exercise and nutritional regimens, including manipulation of macronutrient, water, and electrolyte intake, as well as consumption of various dietary supplements. The primary goals for these interventions are to maximize muscle glycogen content, minimize subcutaneous water, and reduce the risk abdominal bloating to bring about a more aesthetically pleasing physique. Unfortunately, there is a dearth of evidence to support the commonly reported practices employed by bodybuilders during peak week. Hence, the purpose of this article is to critically review the current literature as to the scientific support for pre-contest peaking protocols most commonly employed by bodybuilders and provide evidence-based recommendations as safe and effective strategies on the topic.
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Affiliation(s)
- Guillermo Escalante
- Department of Kinesiology, California State University- San Bernardino, CA San Bernardino, USA
| | | | - Christopher Barakat
- Competitive Breed LLC, FL Tampa, USA
- Human Performance Laboratory, The University of Tampa, FL Tampa, USA
| | - Alan A. Aragon
- Department of Family and Consumer Sciences, California State University- Northridge, Los Angeles, CA USA
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12
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Muscle Glycogen Metabolism and High-Intensity Exercise Performance: A Narrative Review. Sports Med 2021; 51:1855-1874. [PMID: 33900579 DOI: 10.1007/s40279-021-01475-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2021] [Indexed: 02/06/2023]
Abstract
Muscle glycogen is the main substrate during high-intensity exercise and large reductions can occur after relatively short durations. Moreover, muscle glycogen is stored heterogeneously and similarly displays a heterogeneous and fiber-type specific depletion pattern with utilization in both fast- and slow-twitch fibers during high-intensity exercise, with a higher degradation rate in the former. Thus, depletion of individual fast- and slow-twitch fibers has been demonstrated despite muscle glycogen at the whole-muscle level only being moderately lowered. In addition, muscle glycogen is stored in specific subcellular compartments, which have been demonstrated to be important for muscle function and should be considered as well as global muscle glycogen availability. In the present review, we discuss the importance of glycogen metabolism for single and intermittent bouts of high-intensity exercise and outline possible underlying mechanisms for a relationship between muscle glycogen and fatigue during these types of exercise. Traditionally this relationship has been attributed to a decreased ATP resynthesis rate due to inadequate substrate availability at the whole-muscle level, but emerging evidence points to a direct coupling between muscle glycogen and steps in the excitation-contraction coupling including altered muscle excitability and calcium kinetics.
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13
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Hokken R, Laugesen S, Aagaard P, Suetta C, Frandsen U, Ørtenblad N, Nielsen J. Subcellular localization- and fibre type-dependent utilization of muscle glycogen during heavy resistance exercise in elite power and Olympic weightlifters. Acta Physiol (Oxf) 2021; 231:e13561. [PMID: 32961628 DOI: 10.1111/apha.13561] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 12/16/2022]
Abstract
AIM Glycogen particles are found in different subcellular localizations, which are utilized heterogeneously in different fibre types during endurance exercise. Although resistance exercise typically involves only a moderate use of mixed muscle glycogen, the hypothesis of the present study was that high-volume heavy-load resistance exercise would mediate a pattern of substantial glycogen depletion in specific subcellular localizations and fibre types. METHODS 10 male elite weightlifters performed resistance exercise consisting of four sets of five (4 × 5) repetitions at 75% of 1RM back squats, 4 × 5 at 75% of 1RM deadlifts and 4 × 12 at 65% of 1RM rear foot elevated split squats. Muscle biopsies (vastus lateralis) were obtained before and after the exercise session. The volumetric content of intermyofibrillar (between myofibrils), intramyofibrillar (within myofibrils) and subsarcolemmal glycogen was assessed by transmission electron microscopy. RESULTS After exercise, biochemically determined muscle glycogen decreased by 38 (31:45)%. Location-specific glycogen analyses revealed in type 1 fibres a large decrement in intermyofibrillar glycogen, but no or only minor changes in intramyofibrillar or subsarcolemmal glycogen. In type 2 fibres, large decrements in glycogen were observed in all subcellular localizations. Notably, a substantial fraction of the type 2 fibres demonstrated near-depleted levels of intramyofibrillar glycogen after the exercise session. CONCLUSION Heavy resistance exercise mediates a substantial utilization of glycogen from all three subcellular localization in type 2 fibres, while mostly taxing intermyofibrillar glycogen stores in type 1 fibres. Thus, a better understanding of the impact of resistance training on myocellular metabolism and performance requires a focus on compartmentalized glycogen utilization.
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Affiliation(s)
- Rune Hokken
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Simon Laugesen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Charlotte Suetta
- Geriatric Research Unit Department of Geriatrics Bispebjerg‐Frederiksberg and Herlev‐Gentofte HospitalsUniversity of Copenhagen Kobenhavn Denmark
| | - Ulrik Frandsen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
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14
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Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients 2020; 12:E1367. [PMID: 32403259 PMCID: PMC7284742 DOI: 10.3390/nu12051367] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 12/17/2022] Open
Abstract
Background-exercise-induced muscle damage (EIMD) and internal exercise load are increased after competing in ultraendurance events such as mountain marathons. Adequate carbohydrate (CHO) intake during exercise optimizes athletic performance and could limit EIMD, reduce internal exercise load and, thus, improve recovery. Therefore, the aim of this study was to research into and compare the effects of high CHO intake (120 g/h) in terms of CHO intake recommendation (90 g/h) and regular CHO intake performed by ultraendurance athletes (60 g/h) during a mountain marathon, on exercise load and EIMD markers (creatine kinase (CK), lactate dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT), urea and creatinine). Materials and Methods-a randomized trial was carried out on 20 male elite runners who had previously undertaken nutritional and gut training, and who consumed different CHO dosages according to experimental (EXP-120 g/h), control (CON-90 g/h) and low CHO intake (LOW-60 g/h) groups during a ~4000 m cumulative slope mountain marathon. EIMD markers were analyzed before the race and 24 h afterwards. Internal exercise load was calculated based on rate of perceived exertion (RPE) during and after the marathon event. Results-internal exercise load during the mountain marathon was significantly lower (p = 0.019; η2p = 0.471) in EXP (3805 ± 281 AU) compared to LOW (4688 ± 705 AU) and CON (4692 ± 716 AU). Moreover, results revealed that the EXP group evidenced significantly lower CK (p = 0.019; η2p = 0.373), LDH (p < 0.001; η2p = 0.615) and GOT (p = 0.003; η2p = 0.500) values 24 h after the mountain marathon race compared to LOW and CON. Along these lines, EIMD and exercise load evidenced a close correlation (R = 0.742; p < 0.001). Conclusion: High CHO intake (120 g/h) during a mountain marathon could limit the EIMD observed by CK, LDH and GOT and internal exercise load compared to CHO ingestion of 60 and 90 g/h.
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Affiliation(s)
- Aitor Viribay
- Glut4Science, Physiology, Nutrition and Sport, 01004 Vitoria-Gasteiz, Spain;
| | - Soledad Arribalzaga
- Institute of Biomedicine (IBIOMED), Physiotherapy Department, University of Leon, Campus de Vegazana, 24071 Leon, Spain;
| | - Juan Mielgo-Ayuso
- Department of Biochemistry Molecular Biology and Physiology, Faculty of Health Sciences, University of Valladolid, 42004 Soria, Spain;
| | - Arkaitz Castañeda-Babarro
- Health, Physical Activity and Sports Science Laboratory, Department of Physical Activity and Sports, Faculty of Psychology and Education, University of Deusto, 48007 Bizkaia, Spain;
| | - Jesús Seco-Calvo
- Institute of Biomedicine (IBIOMED), Physiotherapy Department, University of Leon, Researcher at the Basque Country University, Campus de Vegazana, 24071 Leon, Spain;
| | - Aritz Urdampilleta
- Centro de Investigacion y de Formación ElikaEsport, 08290 Cerdanyola del Valles, Barcelona, Spain
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15
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Vanden Hole C, Ayuso M, Aerts P, Prims S, Van Cruchten S, Van Ginneken C. Glucose and glycogen levels in piglets that differ in birth weight and vitality. Heliyon 2019; 5:e02510. [PMID: 31687599 PMCID: PMC6819853 DOI: 10.1016/j.heliyon.2019.e02510] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 11/19/2022] Open
Abstract
In the pig, intrauterine crowding can greatly affect postnatal characteristics, among which birth weight and locomotion. In a previous study, we discovered that piglets with a low birth weight/low vitality (L piglets) have a reduced motor performance compared to piglets with a normal birth weight/normal vitality (N piglets). A possible explanation is that L piglets lack the energy to increase their motor performance to the level of that of N piglets. Blood glucose levels (GLU) and glycogen concentrations in skeletal muscle of the front (GLYFRONT) and hind leg (GLYHIND) and the liver (GLYLIVER) at birth and during the first 96 h postpartum were compared between L and N piglets. GLU at birth was the same for both groups. After birth, GLU immediately increased in N piglets, whereas it only increased after 8 h in L piglets. L piglets showed a lower GLYHIND at birth and did not use this glycogen during the first 8 h postpartum, while N piglets showed a gradual depletion. GLYLIVER at birth was 50% lower for L piglets and was unused during the studied period while N piglets consumed half of their GLYLIVER during the first 8 h. Based on these results, it is possible that lower glycogen concentrations at birth, the delayed increase in GLU and the lower use of glycogen during the first 8 h after birth negatively affect motor performance in L piglets. However, based on this study, it is unclear whether the low mobilization of glycogen by L piglets is a consequence, rather than a cause of their lower motor performance.
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Affiliation(s)
- Charlotte Vanden Hole
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium
| | - Miriam Ayuso
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium
| | - Peter Aerts
- Laboratory of Functional Morphology, Department of Biology, Faculty of Sciences, Universiteitsplein 1, University of Antwerp, Wilrijk, Belgium
- Department of Movement and Sports Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185 (3K3), Ghent, Belgium
| | - Sara Prims
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium
| | - Steven Van Cruchten
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium
| | - Chris Van Ginneken
- Laboratory of Applied Veterinary Morphology, Department of Veterinary Sciences, Faculty of Biomedical, Pharmaceutical and Veterinary Sciences, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium
- Corresponding author.
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16
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Interactive Roles for AMPK and Glycogen from Cellular Energy Sensing to Exercise Metabolism. Int J Mol Sci 2018; 19:ijms19113344. [PMID: 30373152 PMCID: PMC6274970 DOI: 10.3390/ijms19113344] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Accepted: 10/23/2018] [Indexed: 12/12/2022] Open
Abstract
The AMP-activated protein kinase (AMPK) is a heterotrimeric complex with central roles in cellular energy sensing and the regulation of metabolism and exercise adaptations. AMPK regulatory β subunits contain a conserved carbohydrate-binding module (CBM) that binds glycogen, the major tissue storage form of glucose. Research over the past two decades has revealed that the regulation of AMPK is impacted by glycogen availability, and glycogen storage dynamics are concurrently regulated by AMPK activity. This growing body of research has uncovered new evidence of physical and functional interactive roles for AMPK and glycogen ranging from cellular energy sensing to the regulation of whole-body metabolism and exercise-induced adaptations. In this review, we discuss recent advancements in the understanding of molecular, cellular, and physiological processes impacted by AMPK-glycogen interactions. In addition, we appraise how novel research technologies and experimental models will continue to expand the repertoire of biological processes known to be regulated by AMPK and glycogen. These multidisciplinary research advances will aid the discovery of novel pathways and regulatory mechanisms that are central to the AMPK signaling network, beneficial effects of exercise and maintenance of metabolic homeostasis in health and disease.
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17
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Cholewa JM, Newmire DE, Zanchi NE. Carbohydrate restriction: Friend or foe of resistance-based exercise performance? Nutrition 2018; 60:136-146. [PMID: 30586657 DOI: 10.1016/j.nut.2018.09.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 09/29/2018] [Indexed: 12/17/2022]
Abstract
It is commonly accepted that adequate carbohydrate availability is necessary for optimal endurance performance. However, for strength- and physique-based athletes, sports nutrition research and recommendations have focused on protein ingestion, with far less attention given to carbohydrates. Varying resistance exercise protocols, such as differences in intensity, volume, and intraset rest prescriptions between strength-training and physique-training goals elicit different metabolic responses, which may necessitate different carbohydrate needs. The results of several acute and chronic training studies suggest that although severe carbohydrate restriction may not impair strength adaptations during a resistance training program, consuming an adequate amount of carbohydrate in the days leading up to testing may enhance maximal strength and strength-endurance performance. Although several molecular studies demonstrate no additive increases in postexercise mammalian target of rapamycin 1 phosphorylation with carbohydrate and protein compared with protein ingestion alone, the effects of chronic resistance training with carbohydrate restriction on muscle hypertrophy are conflicting and require further research to determine a minimal carbohydrate threshold necessary to optimize muscle hypertrophy. This review summarizes the current knowledge regarding carbohydrate availability and resistance training outcomes and poses new research questions that will better help guide carbohydrate recommendations for strength and physique athletes. In addition, given that success in physique sports is based on subjective appearance, and not objective physical performance, we also review the effects of subchronic carbohydrate ingestion during contest preparation on aesthetic appearance.
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Affiliation(s)
- Jason M Cholewa
- Department of Kinesiology, Coastal Carolina University, Conway, South Carolina, USA.
| | - Daniel E Newmire
- Department of Kinesiology and Military Science, University of Texas A&M, Corpus Christi, Texas, USA
| | - Nelo Eidy Zanchi
- Department of Physical Education, Federal University of Maranhão, São Luís, Brazil; Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME), São Luís, Brazil
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18
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Abstract
The ability of athletes to train day after day depends in large part on adequate restoration of muscle glycogen stores, a process that requires the consumption of sufficient dietary carbohydrates and ample time. Providing effective guidance to athletes and others wishing to enhance training adaptations and improve performance requires an understanding of the normal variations in muscle glycogen content in response to training and diet; the time required for adequate restoration of glycogen stores; the influence of the amount, type, and timing of carbohydrate intake on glycogen resynthesis; and the impact of other nutrients on glycogenesis. This review highlights the practical implications of the latest research related to glycogen metabolism in physically active individuals to help sports dietitians, coaches, personal trainers, and other sports health professionals gain a fundamental understanding of glycogen metabolism, as well as related practical applications for enhancing training adaptations and preparing for competition.
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Affiliation(s)
- Bob Murray
- Sports Science Insights, LLC, Crystal Lake, Illinois, USA
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19
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Restoration of Muscle Glycogen and Functional Capacity: Role of Post-Exercise Carbohydrate and Protein Co-Ingestion. Nutrients 2018; 10:nu10020253. [PMID: 29473893 PMCID: PMC5852829 DOI: 10.3390/nu10020253] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 02/11/2018] [Accepted: 02/15/2018] [Indexed: 12/31/2022] Open
Abstract
The importance of post-exercise recovery nutrition has been well described in recent years, leading to its incorporation as an integral part of training regimes in both athletes and active individuals. Muscle glycogen depletion during an initial prolonged exercise bout is a main factor in the onset of fatigue and so the replenishment of glycogen stores may be important for recovery of functional capacity. Nevertheless, nutritional considerations for optimal short-term (3–6 h) recovery remain incompletely elucidated, particularly surrounding the precise amount of specific types of nutrients required. Current nutritional guidelines to maximise muscle glycogen availability within limited recovery are provided under the assumption that similar fatigue mechanisms (i.e., muscle glycogen depletion) are involved during a repeated exercise bout. Indeed, recent data support the notion that muscle glycogen availability is a determinant of subsequent endurance capacity following limited recovery. Thus, carbohydrate ingestion can be utilised to influence the restoration of endurance capacity following exhaustive exercise. One strategy with the potential to accelerate muscle glycogen resynthesis and/or functional capacity beyond merely ingesting adequate carbohydrate is the co-ingestion of added protein. While numerous studies have been instigated, a consensus that is related to the influence of carbohydrate-protein ingestion in maximising muscle glycogen during short-term recovery and repeated exercise capacity has not been established. When considered collectively, carbohydrate intake during limited recovery appears to primarily determine muscle glycogen resynthesis and repeated exercise capacity. Thus, when the goal is to optimise repeated exercise capacity following short-term recovery, ingesting carbohydrate at an amount of ≥1.2 g kg body mass−1·h−1 can maximise muscle glycogen repletion. The addition of protein to carbohydrate during post-exercise recovery may be beneficial under circumstances when carbohydrate ingestion is sub-optimal (≤0.8 g kg body mass−1·h−1) for effective restoration of muscle glycogen and repeated exercise capacity.
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20
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Muscle fatigue: general understanding and treatment. Exp Mol Med 2017; 49:e384. [PMID: 28983090 PMCID: PMC5668469 DOI: 10.1038/emm.2017.194] [Citation(s) in RCA: 274] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 05/20/2017] [Accepted: 05/23/2017] [Indexed: 12/19/2022] Open
Abstract
Muscle fatigue is a common complaint in clinical practice. In humans, muscle fatigue can be defined as exercise-induced decrease in the ability to produce force. Here, to provide a general understanding and describe potential therapies for muscle fatigue, we summarize studies on muscle fatigue, including topics such as the sequence of events observed during force production, in vivo fatigue-site evaluation techniques, diagnostic markers and non-specific but effective treatments.
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21
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Rydahl MG, Krac Un SK, Fangel JU, Michel G, Guillouzo A, Génicot S, Mravec J, Harholt J, Wilkens C, Motawia MS, Svensson B, Tranquet O, Ralet MC, Jørgensen B, Domozych DS, Willats WGT. Development of novel monoclonal antibodies against starch and ulvan - implications for antibody production against polysaccharides with limited immunogenicity. Sci Rep 2017; 7:9326. [PMID: 28839196 PMCID: PMC5570955 DOI: 10.1038/s41598-017-04307-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/12/2017] [Indexed: 02/06/2023] Open
Abstract
Monoclonal antibodies (mAbs) are widely used and powerful research tools, but the generation of mAbs against glycan epitopes is generally more problematic than against proteins. This is especially significant for research on polysaccharide-rich land plants and algae (Viridiplantae). Most antibody production is based on using single antigens, however, there are significant gaps in the current repertoire of mAbs against some glycan targets with low immunogenicity. We approached mAb production in a different way and immunised with a complex mixture of polysaccharides. The multiplexed screening capability of carbohydrate microarrays was then exploited to deconvolute the specificities of individual mAbs. Using this strategy, we generated a set of novel mAbs, including one against starch (INCh1) and one against ulvan (INCh2). These polysaccharides are important storage and structural polymers respectively, but both are generally considered as having limited immunogenicity. INCh1 and INCh2 therefore represent important new molecular probes for Viridiplantae research. Moreover, since the α-(1-4)-glucan epitope recognised by INCh1 is also a component of glycogen, this mAb can also be used in mammalian systems. We describe the detailed characterisation of INCh1 and INCh2, and discuss the potential of a non-directed mass-screening approach for mAb production against some glycan targets.
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Affiliation(s)
- Maja G Rydahl
- Department of Plant and Environmental Sciences, DK-1871, Frederiksberg, Denmark.
| | - Stjepan K Krac Un
- Department of Plant and Environmental Sciences, DK-1871, Frederiksberg, Denmark
| | - Jonatan U Fangel
- Carlsberg Research Laboratory, J.C. Jacobsens Gade 4, DK-1799, Copenhagen V, Denmark
| | - Gurvan Michel
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff, Bretagne, France
| | - Alexia Guillouzo
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff, Bretagne, France
| | - Sabine Génicot
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff, Bretagne, France
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, DK-1871, Frederiksberg, Denmark
| | - Jesper Harholt
- Carlsberg Research Laboratory, J.C. Jacobsens Gade 4, DK-1799, Copenhagen V, Denmark
| | - Casper Wilkens
- Department of Biotechnology and Biomedicine, Technical University of Denmark, DK-2800, Lyngby, Denmark
| | | | - Birte Svensson
- Department of Biotechnology and Biomedicine, Technical University of Denmark, DK-2800, Lyngby, Denmark
| | - Olivier Tranquet
- UR1268 Biopolymeres, Interactions et Assemblages, Institut National de la Recherche Agronomique, Rue de la Géraudière, BP 71627, F-44316, Nantes, France
| | - Marie-Christine Ralet
- UR1268 Biopolymeres, Interactions et Assemblages, Institut National de la Recherche Agronomique, Rue de la Géraudière, BP 71627, F-44316, Nantes, France
| | - Bodil Jørgensen
- Department of Plant and Environmental Sciences, DK-1871, Frederiksberg, Denmark
| | - David S Domozych
- Biology Department, Skidmore College, Saratoga Springs, NY, 12866, USA
| | - William G T Willats
- School of Agriculture, Food and Rural Development, Newcastle University, NE1 7RU, Newcastle upon Tyne, UK.
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22
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Kent JA, Ørtenblad N, Hogan MC, Poole DC, Musch TI. No Muscle Is an Island: Integrative Perspectives on Muscle Fatigue. Med Sci Sports Exerc 2017; 48:2281-2293. [PMID: 27434080 DOI: 10.1249/mss.0000000000001052] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Muscle fatigue has been studied with a variety approaches, tools and technologies. The foci of these studies have ranged tremendously, from molecules to the entire organism. Single cell and animal models have been used to gain mechanistic insight into the fatigue process. The theme of this review is the concept that the mechanisms of muscle fatigue do not occur in isolation in vivo: muscular work is supported by many complex physiological systems, any of which could fail during exercise and thus contribute to fatigue. To advance our overall understanding of fatigue, a combination of models and approaches is necessary. In this review, we examine the roles that neuromuscular properties, intracellular glycogen, oxygen metabolism, and blood flow play in the fatigue process during exercise and pathological conditions.
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Affiliation(s)
- Jane A Kent
- 1Department of Kinesiology, University of Massachusetts, Amherst MA; 2Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DENMARK; 3Department of Health Sciences, Mid Sweden University, Östersund, SWEDEN; 4Department of Medicine, University of California, San Diego, CA; and 5Department of Kinesiology, Kansas State University, Manhattan, KS
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23
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Burke LM, van Loon LJC, Hawley JA. Postexercise muscle glycogen resynthesis in humans. J Appl Physiol (1985) 2017; 122:1055-1067. [DOI: 10.1152/japplphysiol.00860.2016] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/12/2016] [Accepted: 10/23/2016] [Indexed: 11/22/2022] Open
Abstract
Since the pioneering studies conducted in the 1960s in which glycogen status was investigated using the muscle biopsy technique, sports scientists have developed a sophisticated appreciation of the role of glycogen in cellular adaptation and exercise performance, as well as sites of storage of this important metabolic fuel. While sports nutrition guidelines have evolved during the past decade to incorporate sport-specific and periodized manipulation of carbohydrate (CHO) availability, athletes attempt to maximize muscle glycogen synthesis between important workouts or competitive events so that fuel stores closely match the demands of the prescribed exercise. Therefore, it is important to understand the factors that enhance or impair this biphasic process. In the early postexercise period (0–4 h), glycogen depletion provides a strong drive for its own resynthesis, with the provision of CHO (~1 g/kg body mass) optimizing this process. During the later phase of recovery (4–24 h), CHO intake should meet the anticipated fuel needs of the training/competition, with the type, form, and pattern of intake being less important than total intake. Dietary strategies that can enhance glycogen synthesis from suboptimal amounts of CHO or energy intake are of practical interest to many athletes; in this scenario, the coingestion of protein with CHO can assist glycogen storage. Future research should identify other factors that enhance the rate of synthesis of glycogen storage in a limited time frame, improve glycogen storage from a limited CHO intake, or increase muscle glycogen supercompensation.
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Affiliation(s)
- Louise M. Burke
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
- Department of Sport Nutrition, Australian Institute of Sport, Belconnen, Australia
| | - Luc J. C. van Loon
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands; and
| | - John A. Hawley
- Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, Australia
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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24
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Ørtenblad N, Nielsen J. Muscle glycogen and cell function - Location, location, location. Scand J Med Sci Sports 2015; 25 Suppl 4:34-40. [DOI: 10.1111/sms.12599] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2015] [Indexed: 11/28/2022]
Affiliation(s)
- N. Ørtenblad
- Department of Sports Science and Clinical Biomechanics; SDU Muscle Research Cluster; University of Southern Denmark; Odense Denmark
- Swedish Winter Sports Research Centre; Department of Health Sciences; Mid Sweden University; Sweden
| | - J. Nielsen
- Department of Sports Science and Clinical Biomechanics; SDU Muscle Research Cluster; University of Southern Denmark; Odense Denmark
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25
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Santalla A, Nogales-Gadea G, Ørtenblad N, Brull A, de Luna N, Pinós T, Lucia A. McArdle disease: a unique study model in sports medicine. Sports Med 2015; 44:1531-44. [PMID: 25028051 DOI: 10.1007/s40279-014-0223-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
McArdle disease is arguably the paradigm of exercise intolerance in humans. This disorder is caused by inherited deficiency of myophosphorylase, the enzyme isoform that initiates glycogen breakdown in skeletal muscles. Because patients are unable to obtain energy from their muscle glycogen stores, this disease provides an interesting model of study for exercise physiologists, allowing insight to be gained into the understanding of glycogen-dependent muscle functions. Of special interest in the field of muscle physiology and sports medicine are also some specific (if not unique) characteristics of this disorder, such as the so-called 'second wind' phenomenon, the frequent exercise-induced rhabdomyolysis and myoglobinuria episodes suffered by patients (with muscle damage also occurring under basal conditions), or the early appearance of fatigue and contractures, among others. In this article we review the main pathophysiological features of this disorder leading to exercise intolerance as well as the currently available therapeutic possibilities. Patients have been traditionally advised by clinicians to refrain from exercise, yet sports medicine and careful exercise prescription are their best allies at present because no effective enzyme replacement therapy is expected to be available in the near future. As of today, although unable to restore myophosphorylase deficiency, the 'simple' use of exercise as therapy seems probably more promising and practical for patients than more 'complex' medical approaches.
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26
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Nielsen J, Farup J, Rahbek SK, de Paoli FV, Vissing K. Enhanced Glycogen Storage of a Subcellular Hot Spot in Human Skeletal Muscle during Early Recovery from Eccentric Contractions. PLoS One 2015; 10:e0127808. [PMID: 25996774 PMCID: PMC4440641 DOI: 10.1371/journal.pone.0127808] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 04/18/2015] [Indexed: 12/22/2022] Open
Abstract
Unaccustomed eccentric exercise is accompanied by muscle damage and impaired glucose uptake and glycogen synthesis during subsequent recovery. Recently, it was shown that the role and regulation of glycogen in skeletal muscle are dependent on its subcellular localization, and that glycogen synthesis, as described by the product of glycogen particle size and number, is dependent on the time course of recovery after exercise and carbohydrate availability. In the present study, we investigated the subcellular distribution of glycogen in fibers with high (type I) and low (type II) mitochondrial content during post-exercise recovery from eccentric contractions. Analysis was completed on five male subjects performing an exercise bout consisting of 15 x 10 maximal eccentric contractions. Carbohydrate-rich drinks were subsequently ingested throughout a 48 h recovery period and muscle biopsies for analysis included time points 3, 24 and 48 h post exercise from the exercising leg, whereas biopsies corresponding to prior to and at 48 h after the exercise bout were collected from the non-exercising, control leg. Quantitative imaging by transmission electron microscopy revealed an early (post 3 and 24 h) enhanced storage of intramyofibrillar glycogen (defined as glycogen particles located within the myofibrils) of type I fibers, which was associated with an increase in the number of particles. In contrast, late in recovery (post 48 h), intermyofibrillar, intramyofibrillar and subsarcolemmal glycogen in both type I and II fibers were lower in the exercise leg compared with the control leg, and this was associated with a smaller size of the glycogen particles. We conclude that in the carbohydrate-supplemented state, the effect of eccentric contractions on glycogen metabolism depends on the subcellular localization, muscle fiber’s oxidative capacity, and the time course of recovery. The early enhanced storage of intramyofibrillar glycogen after the eccentric contractions may entail important implications for muscle function and fatigue resistance.
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Affiliation(s)
- Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense M, Denmark
- Department of Pathology, SDU Muscle Research Cluster (SMRC), Odense University Hospital, Odense C, Denmark
- * E-mail:
| | - Jean Farup
- Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark
| | - Stine Klejs Rahbek
- Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark
| | | | - Kristian Vissing
- Section of Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark
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27
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Delbridge LMD, Mellor KM, Taylor DJR, Gottlieb RA. Myocardial autophagic energy stress responses--macroautophagy, mitophagy, and glycophagy. Am J Physiol Heart Circ Physiol 2015; 308:H1194-204. [PMID: 25747748 DOI: 10.1152/ajpheart.00002.2015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 03/02/2015] [Indexed: 12/26/2022]
Abstract
An understanding of the role of autophagic processes in the management of cardiac metabolic stress responses is advancing rapidly and progressing beyond a conceptualization of the autophagosome as a simple cell recycling depot. The importance of autophagy dysregulation in diabetic cardiomyopathy and in ischemic heart disease - both conditions comprising the majority of cardiac disease burden - has now become apparent. New findings have revealed that specific autophagic processes may operate in the cardiomyocyte, specialized for selective recognition and management of mitochondria and glycogen particles in addition to protein macromolecular structures. Thus mitophagy, glycophagy, and macroautophagy regulatory pathways have become the focus of intensive experimental effort, and delineating the signaling pathways involved in these processes offers potential for targeted therapeutic intervention. Chronically elevated macroautophagic activity in the diabetic myocardium is generally observed in association with structural and functional cardiomyopathy; yet there are also numerous reports of detrimental effect of autophagy suppression in diabetes. Autophagy induction has been identified as a key component of protective mechanisms that can be recruited to support the ischemic heart, but in this setting benefit may be mitigated by adverse downstream autophagic consequences. Recent report of glycophagy upregulation in diabetic cardiomyopathy opens up a novel area of investigation. Similarly, a role for glycogen management in ischemia protection through glycophagy initiation is an exciting prospect under investigation.
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Affiliation(s)
- Lea M D Delbridge
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia;
| | - Kimberley M Mellor
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia; Department of Physiology, University of Auckland, New Zealand; and
| | - David J R Taylor
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
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28
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Free glycogen in vaginal fluids is associated with Lactobacillus colonization and low vaginal pH. PLoS One 2014; 9:e102467. [PMID: 25033265 PMCID: PMC4102502 DOI: 10.1371/journal.pone.0102467] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 06/17/2014] [Indexed: 11/23/2022] Open
Abstract
Objective Lactobacillus dominates the lower genital tract microbiota of many women, producing a low vaginal pH, and is important for healthy pregnancy outcomes and protection against several sexually transmitted pathogens. Yet, factors that promote Lactobacillus remain poorly understood. We hypothesized that the amount of free glycogen in the lumen of the lower genital tract is an important determinant of Lactobacillus colonization and a low vaginal pH. Methods Free glycogen in lavage samples was quantified. Pyrosequencing of the 16S rRNA gene was used to identify microbiota from 21 African American women collected over 8–11 years. Results Free glycogen levels varied greatly between women and even in the same woman. Samples with the highest free glycogen had a corresponding median genital pH that was significantly lower (pH 4.4) than those with low glycogen (pH 5.8; p<0.001). The fraction of the microbiota consisting of Lactobacillus was highest in samples with high glycogen versus those with low glycogen (median = 0.97 vs. 0.05, p<0.001). In multivariable analysis, having 1 vs. 0 male sexual partner in the past 6 months was negatively associated, while BMI ≥30 was positively associated with glycogen. High concentrations of glycogen corresponded to higher levels of L. crispatus and L. jensenii, but not L. iners. Conclusion These findings show that free glycogen in genital fluid is associated with a genital microbiota dominated by Lactobacillus, suggesting glycogen is important for maintaining genital health. Treatments aimed at increasing genital free glycogen might impact Lactobacillus colonization.
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29
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Nielsen J, Cheng AJ, Ørtenblad N, Westerblad H. Subcellular distribution of glycogen and decreased tetanic Ca2+ in fatigued single intact mouse muscle fibres. J Physiol 2014; 592:2003-12. [PMID: 24591577 DOI: 10.1113/jphysiol.2014.271528] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In skeletal muscle fibres, glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); and (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator of sarcoplasmic reticulum Ca(2+) release. The aim of the present study was to test directly how the decrease in cytoplasmic free Ca(2+) ([Ca(2+)]i) during repeated tetanic contractions relates to the subcellular glycogen distribution. Single fibres of mouse flexor digitorum brevis muscles were fatigued with 70 Hz, 350 ms tetani given at 2 s (high-intensity fatigue, HIF) or 10 s (low-intensity fatigue, LIF) intervals, while force and [Ca(2+)]i were measured. Stimulation continued until force decreased to 30% of its initial value. Fibres were then prepared for analyses of subcellular glycogen distribution by transmission electron microscopy. At fatigue, tetanic [Ca(2+)]i was reduced to 70 ± 4% and 54 ± 4% of the initial in HIF (P < 0.01, n = 9) and LIF (P < 0.01, n = 5) fibres, respectively. At fatigue, the mean inter- and intramyofibrillar glycogen content was 60-75% lower than in rested control fibres (P < 0.05), whereas subsarcolemmal glycogen was similar to control. Individual fibres showed a good correlation between the fatigue-induced decrease in tetanic [Ca(2+)]i and the reduction in intermyofibrillar (P = 0.051) and intramyofibrillar (P = 0.0008) glycogen. In conclusion, the fatigue-induced decrease in tetanic [Ca(2+)]i, and hence force, is accompanied by major reductions in inter- and intramyofibrillar glycogen. The stronger correlation between decreased tetanic [Ca(2+)]i and reduced intramyofibrillar glycogen implies that sarcoplasmic reticulum Ca(2+) release critically depends on energy supply from the intramyofibrillar glycogen pool.
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30
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Müller MS, Fox R, Schousboe A, Waagepetersen HS, Bak LK. Astrocyte glycogenolysis is triggered by store-operated calcium entry and provides metabolic energy for cellular calcium homeostasis. Glia 2014; 62:526-34. [PMID: 24464850 DOI: 10.1002/glia.22623] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/11/2013] [Accepted: 12/16/2013] [Indexed: 01/14/2023]
Abstract
Astrocytic glycogen, the only storage form of glucose in the brain, has been shown to play a fundamental role in supporting learning and memory, an effect achieved by providing metabolic support for neurons. We have examined the interplay between glycogenolysis and the bioenergetics of astrocytic Ca(2+) homeostasis, by analyzing interdependency of glycogen and store-operated Ca(2+) entry (SOCE), a mechanism in cellular signaling that maintains high endoplasmatic reticulum (ER) Ca(2+) concentration and thus provides the basis for store-dependent Ca(2+) signaling. We stimulated SOCE in primary cultures of murine cerebellar and cortical astrocytes, and determined glycogen content to investigate the effects of SOCE on glycogen metabolism. By blocking glycogenolysis, we tested energetic dependency of SOCE-related Ca(2+) dynamics on glycogenolytic ATP. Our results show that SOCE triggers astrocytic glycogenolysis. Upon inhibition of adenylate cyclase with 2',5'-dideoxyadenosine, glycogen content was no longer significantly different from that in unstimulated control cells, indicating that SOCE triggers astrocytic glycogenolysis in a cAMP-dependent manner. When glycogenolysis was inhibited in cortical astrocytes by 1,4-dideoxy-1,4-imino-D-arabinitol, the amount of Ca(2+) loaded into ER via sarco/endoplasmic reticulum Ca(2)-ATPase (SERCA) was reduced, which suggests that SERCA pumps preferentially metabolize glycogenolytic ATP. Our study demonstrates SOCE as a novel pathway in stimulating astrocytic glycogenolysis. We also provide first evidence for a new functional role of brain glycogen, in providing local ATP to SERCA, thus establishing the bioenergetic basis for astrocytic Ca(2+) signaling. This mechanism could offer a novel explanation for the impact of glycogen on learning and memory.
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Affiliation(s)
- Margit S Müller
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100, Copenhagen, Denmark
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31
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Abstract
Studies performed at the beginning of the last century revealed the importance of carbohydrate as a fuel during exercise, and the importance of muscle glycogen on performance has subsequently been confirmed in numerous studies. However, the link between glycogen depletion and impaired muscle function during fatigue is not well understood and a direct cause-and-effect relationship between glycogen and muscle function remains to be established. The use of electron microscopy has revealed that glycogen is not homogeneously distributed in skeletal muscle fibres, but rather localized in distinct pools. Furthermore, each glycogen granule has its own metabolic machinery with glycolytic enzymes and regulating proteins. One pool of such glycogenolytic complexes is localized within the myofibrils in close contact with key proteins involved in the excitation-contraction coupling and Ca2+ release from the sarcoplasmic reticulum (SR). We and others have provided experimental evidence in favour of a direct role of decreased glycogen, localized within the myofibrils, for the reduction in SR Ca2+ release during fatigue. This is consistent with compartmentalized energy turnover and distinctly localized glycogen pools being of key importance for SR Ca2+ release and thereby affecting muscle contractility and fatigability.
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Affiliation(s)
- Niels Ørtenblad
- N. Ørtenblad: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DK-5230 Odense M, Denmark.
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