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McKenna MJ, Renaud JM, Ørtenblad N, Overgaard K. A century of exercise physiology: effects of muscle contraction and exercise on skeletal muscle Na +,K +-ATPase, Na + and K + ions, and on plasma K + concentration-historical developments. Eur J Appl Physiol 2024; 124:681-751. [PMID: 38206444 PMCID: PMC10879387 DOI: 10.1007/s00421-023-05335-9] [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: 02/02/2023] [Accepted: 09/27/2023] [Indexed: 01/12/2024]
Abstract
This historical review traces key discoveries regarding K+ and Na+ ions in skeletal muscle at rest and with exercise, including contents and concentrations, Na+,K+-ATPase (NKA) and exercise effects on plasma [K+] in humans. Following initial measures in 1896 of muscle contents in various species, including humans, electrical stimulation of animal muscle showed K+ loss and gains in Na+, Cl- and H20, then subsequently bidirectional muscle K+ and Na+ fluxes. After NKA discovery in 1957, methods were developed to quantify muscle NKA activity via rates of ATP hydrolysis, Na+/K+ radioisotope fluxes, [3H]-ouabain binding and phosphatase activity. Since then, it became clear that NKA plays a central role in Na+/K+ homeostasis and that NKA content and activity are regulated by muscle contractions and numerous hormones. During intense exercise in humans, muscle intracellular [K+] falls by 21 mM (range - 13 to - 39 mM), interstitial [K+] increases to 12-13 mM, and plasma [K+] rises to 6-8 mM, whilst post-exercise plasma [K+] falls rapidly, reflecting increased muscle NKA activity. Contractions were shown to increase NKA activity in proportion to activation frequency in animal intact muscle preparations. In human muscle, [3H]-ouabain-binding content fully quantifies NKA content, whilst the method mainly detects α2 isoforms in rats. Acute or chronic exercise affects human muscle K+, NKA content, activity, isoforms and phospholemman (FXYD1). Numerous hormones, pharmacological and dietary interventions, altered acid-base or redox states, exercise training and physical inactivity modulate plasma [K+] during exercise. Finally, historical research approaches largely excluded female participants and typically used very small sample sizes.
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Affiliation(s)
- 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.
| | - Jean-Marc Renaud
- Department of Cellular and Molecular Medicine, Neuromuscular Research Center, University of Ottawa, Ottawa, ON, Canada
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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2
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Effect of sample fractionation and normalization when immunoblotting for human muscle Na +/K +-ATPase subunits and glycogen synthase. Anal Biochem 2023; 666:115071. [PMID: 36736987 DOI: 10.1016/j.ab.2023.115071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 01/03/2023] [Accepted: 02/01/2023] [Indexed: 02/04/2023]
Abstract
Immunoblotting is widely used in muscle physiology to determine protein regulation and abundance. However, research groups use different protocols, which may result in differential outcomes. Herein, we investigated the effect of various homogenization procedures on determination of protein abundance in human m. vastus lateralis biopsies. Furthermore, we investigated differences in abundance between young healthy males (n = 12) and type-2 diabetics (n = 4), and the effect of data normalization. Fractionated lysates had the lowest variation in total protein determination as compared to non-fractionated homogenates. Abundance of NKAα2, NKAβ1, FXYD1, and glycogen synthase was higher (P < 0.05) in young healthy than in type-2 diabetics determined in both fractionated and non-fractionated samples for which normalization to the stain-free signal and/or standard curve did not affect outcomes. Precision and reliability of protein abundance determination between sample types showed a moderate to good reliability for these proteins, whereas the commonly used house-keeping protein, actin, showed poor reliability. In conclusion, fractionated and non-fractionated immunoblotting samples yield similar data for several sarcolemmal and cytosolic proteins, except for actin, which, therefore appears inappropriate for data normalization in immunoblotting of human skeletal muscle. Thus, fractionation does not seem to be a major source of bias when immunoblotting for NKA subunits and GS.
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Mckee JR, Girard O, Peiffer JJ, Scott BR. Repeated-Sprint Training With Blood Flow Restriction: A Novel Approach to Improve Repeated-Sprint Ability? Strength Cond J 2023. [DOI: 10.1519/ssc.0000000000000771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Pan J, Purev C, Zhao H, Zhang Z, Wang F, Wendoule N, Qi G, Liu Y, Zhou H. Discovery of exercise-related genes and pathway analysis based on comparative genomes of Mongolian originated Abaga and Wushen horse. Open Life Sci 2022; 17:1269-1281. [PMID: 36249530 PMCID: PMC9518662 DOI: 10.1515/biol-2022-0487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/21/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
The Mongolian horses have excellent endurance and stress resistance to adapt to the cold and harsh plateau conditions. Intraspecific genetic diversity is mainly embodied in various genetic advantages of different branches of the Mongolian horse. Since people pay progressive attention to the athletic performance of horse, we expect to guide the exercise-oriented breeding of horses through genomics research. We obtained the clean data of 630,535,376,400 bp through the entire genome second-generation sequencing for the whole blood of four Abaga horses and ten Wushen horses. Based on the data analysis of single nucleotide polymorphism, we severally detected that 479 and 943 positively selected genes, particularly exercise related, were mainly enriched on equine chromosome 4 in Abaga horses and Wushen horses, which implied that chromosome 4 may be associated with the evolution of the Mongolian horse and athletic performance. Four hundred and forty genes of positive selection were enriched in 12 exercise-related pathways and narrowed in 21 exercise-related genes in Abaga horse, which were distinguished from Wushen horse. So, we speculated that the Abaga horse may have oriented genes for the motorial mechanism and 21 exercise-related genes also provided a molecular genetic basis for exercise-directed breeding of the Mongolian horse.
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Affiliation(s)
- Jing Pan
- Faculty of Life Sciences, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
- Department of Reproductive Medicine, Inner Mongolia Maternal and Child Health Care Hospitaly, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
| | - Chimge Purev
- Mongolia-China Joint Laboratory of Applied Molecular Biology, “Administration of the Science Park” CSTI, Ulaanbaatar, Mongolia
| | - Hongwei Zhao
- Beijing 8omics Gene Technology Co. Ltd, Beijing, People’s Republic of China
| | - Zhipeng Zhang
- Faculty of Life Sciences, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
| | - Feng Wang
- Faculty of Life Sciences, Nankai University, Tianjin, People’s Republic of China
| | - Nashun Wendoule
- Animal Husbandry Workstation of Ewenki Autonomous County, Hulun Buir, Inner Mongolia Autonomous Region, People’s Republic of China
| | - Guichun Qi
- Bayanta Village of Animal Husbandry and Veterinary Station of Ewenki Autonomous County, Hulun Buir, Inner Mongolia Autonomous Region, People’s Republic of China
| | - Yongbin Liu
- Sheep Collaboration and Innovation Center, Inner Mongolia Universityy, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
| | - Huanmin Zhou
- Faculty of Life Sciences, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
- Sheep Collaboration and Innovation Center, Inner Mongolia Universityy, Hohhot, Inner Mongolia Autonomous Region, People’s Republic of China
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5
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Sostaric S, Petersen AC, Goodman CA, Gong X, Aw TJ, Brown MJ, Garnham A, Steward CH, Murphy KT, Carey KA, Leppik J, Fraser SF, Cameron-Smith D, Krum H, Snow RJ, McKenna MJ. Oral digoxin effects on exercise performance, K + regulation and skeletal muscle Na + ,K + -ATPase in healthy humans. J Physiol 2022; 600:3749-3774. [PMID: 35837833 PMCID: PMC9541254 DOI: 10.1113/jp283017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/08/2022] [Indexed: 11/30/2022] Open
Abstract
Abstract We investigated whether digoxin lowered muscle Na+,K+‐ATPase (NKA), impaired muscle performance and exacerbated exercise K+ disturbances. Ten healthy adults ingested digoxin (0.25 mg; DIG) or placebo (CON) for 14 days and performed quadriceps strength and fatiguability, finger flexion (FF, 105%peak‐workrate, 3 × 1 min, fourth bout to fatigue) and leg cycling (LC, 10 min at 33% VO2peak and 67% VO2peak, 90% VO2peak to fatigue) trials using a double‐blind, crossover, randomised, counter‐balanced design. Arterial (a) and antecubital venous (v) blood was sampled (FF, LC) and muscle biopsied (LC, rest, 67% VO2peak, fatigue, 3 h after exercise). In DIG, in resting muscle, [3H]‐ouabain binding site content (OB‐Fab) was unchanged; however, bound‐digoxin removal with Digibind revealed total ouabain binding (OB+Fab) increased (8.2%, P = 0.047), indicating 7.6% NKA–digoxin occupancy. Quadriceps muscle strength declined in DIG (−4.3%, P = 0.010) but fatiguability was unchanged. During LC, in DIG (main effects), time to fatigue and [K+]a were unchanged, whilst [K+]v was lower (P = 0.042) and [K+]a‐v greater (P = 0.004) than in CON; with exercise (main effects), muscle OB‐Fab was increased at 67% VO2peak (per wet‐weight, P = 0.005; per protein P = 0.001) and at fatigue (per protein, P = 0.003), whilst [K+]a, [K+]v and [K+]a‐v were each increased at fatigue (P = 0.001). During FF, in DIG (main effects), time to fatigue, [K+]a, [K+]v and [K+]a‐v were unchanged; with exercise (main effects), plasma [K+]a, [K+]v, [K+]a‐v and muscle K+ efflux were all increased at fatigue (P = 0.001). Thus, muscle strength declined, but functional muscle NKA content was preserved during DIG, despite elevated plasma digoxin and muscle NKA–digoxin occupancy, with K+ disturbances and fatiguability unchanged.
![]() Key points The Na+,K+‐ATPase (NKA) is vital in regulating skeletal muscle extracellular potassium concentration ([K+]), excitability and plasma [K+] and thereby also in modulating fatigue during intense contractions.
NKA is inhibited by digoxin, which in cardiac patients lowers muscle functional NKA content ([3H]‐ouabain binding) and exacerbates K+ disturbances during exercise. In healthy adults, we found that digoxin at clinical levels surprisingly did not reduce functional muscle NKA content, whilst digoxin removal by Digibind antibody revealed an ∼8% increased muscle total NKA content. Accordingly, digoxin did not exacerbate arterial plasma [K+] disturbances or worsen fatigue during intense exercise, although quadriceps muscle strength was reduced. Thus, digoxin treatment in healthy participants elevated serum digoxin, but muscle functional NKA content was preserved, whilst K+ disturbances and fatigue with intense exercise were unchanged. This resilience to digoxin NKA inhibition is consistent with the importance of NKA in preserving K+ regulation and muscle function.
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Affiliation(s)
- Simon Sostaric
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Aaron C Petersen
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Craig A Goodman
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Centre for Muscle Research, Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Xiaofei Gong
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Tai-Juan Aw
- Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Australia
| | - Malcolm J Brown
- Department of Biochemistry and Pharmacology, University of Melbourne, Melbourne, Australia
| | - Andrew Garnham
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Collene H Steward
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Kate T Murphy
- Institute for Health and Sport, Victoria University, Melbourne, Australia.,Centre for Muscle Research, Department of Anatomy and Physiology, University of Melbourne, Parkville, Australia
| | - Kate A Carey
- School of Women's and Children's Health, University of New South Wales, Sydney, Australia
| | - James Leppik
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Steve F Fraser
- Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia
| | - David Cameron-Smith
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore
| | - Henry Krum
- Department of Epidemiology and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Australia
| | - Rodney J Snow
- Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Australia
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Huang Y, Zhang Z, Wang J, Shen S, Yao T, Xu Y, Chen Z, Fang B, Ma J. circSPG21 protects against intervertebral disc disease by targeting miR-1197/ATP1B3. Exp Mol Med 2021; 53:1547-1558. [PMID: 34611269 PMCID: PMC8568895 DOI: 10.1038/s12276-021-00674-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/24/2021] [Accepted: 07/29/2021] [Indexed: 12/15/2022] Open
Abstract
The abnormal expression of circular RNAs (circRNAs) is associated with numerous human diseases. This study investigated the mechanism by which circRNA acts as competitive endogenous RNA in the regulation of degenerative intervertebral disc disease (IVDD). Decreased expression of circSPG21 was detected in degenerated nucleus pulposus cells (NPCs), the function of circSPG21 in NPCs was explored and verified, and the downstream target of circSPG21 was investigated. The interaction between circSPG21 and miR-1197 and its target gene (ATP1B3) was studied by online database prediction and molecular biological verification. Finally, the circSPG21/miR-1197/ATP1B3 axis was verified in the mouse tail-looping model. The expression of circSPG21 in the nucleus pulposus in IVDD was directly related to an imbalance of anabolic and catabolic factors, which affected cell senescence. circSPG21 was found to play a role in human NPCs by acting as a sponge of miR-1197 and thereby affecting ATP1B3. The regulation of circSPG21 provides a potentially effective therapeutic strategy for IVDD.
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Affiliation(s)
- Yizhen Huang
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Zhenlei Zhang
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Jianle Wang
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Shuying Shen
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Teng Yao
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Yining Xu
- grid.412551.60000 0000 9055 7865Shaoxing University School of Medicine, Shaoxing, China
| | - Zizheng Chen
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
| | - Bin Fang
- grid.412449.e0000 0000 9678 1884Department of Spine Surgery, Shaoxing Central Hospital, China Medical University, Shaoxing, China
| | - Jianjun Ma
- grid.13402.340000 0004 1759 700XDepartment of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China ,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang Province, Zhejiang, China
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Timing of Creatine Supplementation around Exercise: A Real Concern? Nutrients 2021; 13:nu13082844. [PMID: 34445003 PMCID: PMC8401986 DOI: 10.3390/nu13082844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 01/21/2023] Open
Abstract
Creatine has been considered an effective ergogenic aid for several decades; it can help athletes engaged in a variety of sports and obtain performance gains. Creatine supplementation increases muscle creatine stores; several factors have been identified that may modify the intramuscular increase and subsequent performance benefits, including baseline muscle Cr content, type II muscle fibre content and size, habitual dietary intake of Cr, aging, and exercise. Timing of creatine supplementation in relation to exercise has recently been proposed as an important consideration to optimise muscle loading and performance gains, although current consensus is lacking regarding the ideal ingestion time. Research has shifted towards comparing creatine supplementation strategies pre-, during-, or post-exercise. Emerging evidence suggests greater benefits when creatine is consumed after exercise compared to pre-exercise, although methodological limitations currently preclude solid conclusions. Furthermore, physiological and mechanistic data are lacking, in regard to claims that the timing of creatine supplementation around exercise moderates gains in muscle creatine and exercise performance. This review discusses novel scientific evidence on the timing of creatine intake, the possible mechanisms that may be involved, and whether the timing of creatine supplementation around exercise is truly a real concern.
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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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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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González-Hernández JM, García-Ramos A, Colomer-Poveda D, Tvarijonaviciute A, Cerón J, Jiménez-Reyes P, Márquez G. Resistance Training to Failure vs. Not to Failure: Acute and Delayed Markers of Mechanical, Neuromuscular, and Biochemical Fatigue. J Strength Cond Res 2021; 35:886-893. [PMID: 33306589 DOI: 10.1519/jsc.0000000000003921] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ABSTRACT González-Hernández, JM, García-Ramos, A, Colomer-Poveda, D, Tvarijonaviciute, A, Cerón, J, Jiménez-Reyes, P, and Márquez, G. Resistance training to failure vs. not to failure: acute and delayed markers of mechanical, neuromuscular, and biochemical fatigue. J Strength Cond Res 35(4): 886-893, 2021-This study aimed to compare acute and delayed markers of mechanical, neuromuscular, and biochemical fatigue between resistance training sessions leading to or not to failure. Twelve resistance-trained men completed 2 sessions that consisted of 6 sets of the full-squat exercise performed against the 10 repetitions maximum load. In a randomized order, in one session the sets were performed to failure and in the other session the sets were not performed to failure (5 repetitions per set). Mechanical fatigue was quantified through the recording of the mean velocity during all repetitions. The neuromuscular function of the knee extensors was assessed through a maximal voluntary contraction and the twitch interpolation technique before training, immediately after each set, and 1, 24, and 48 hours post-training. Serum creatine kinase (CK) and aspartate aminotransferase (AST) were measured before training and 1, 24, and 48 hours post-training to infer muscle damage. Alpha was set at a level of 0.05. A higher velocity loss between sets was observed during the failure protocol (-21.7%) compared with the nonfailure protocol (-3.5%). The markers of peripheral fatigue were generally higher and long lasting for the failure protocol. However, the central fatigue assessed by the voluntary activation was comparable for both protocols and remained depressed up to 48 hours post-training. The concentrations of CK and AST were higher after the failure protocol revealing higher muscle damage compared with the nonfailure protocol. These results support the nonfailure protocol to reduce peripheral fatigue and muscle damage, whereas the central fatigue does not seem to be affected by the set configuration.
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Affiliation(s)
- Jorge M González-Hernández
- Faculty of Health Science, European University of Canarias, Tenerife, Spain.,Department of Physical Education and Sport, Faculty of Sport Sciences, Catholic University of Murcia (UCAM), Murcia, Spain
| | - Amador García-Ramos
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain.,Department of Sports Sciences and Physical Conditioning, Faculty of Education, Catholic University of the Most Holy Concepcion, Concepción, Chile
| | - David Colomer-Poveda
- Department of Physical Education and Sport, Faculty of Sport Sciences, Catholic University of Murcia (UCAM), Murcia, Spain
| | - Asta Tvarijonaviciute
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | - José Cerón
- Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Regional Campus of International Excellence "Campus Mare Nostrum," University of Murcia, Murcia, Spain
| | | | - Gonzalo Márquez
- Department of Physical Education and Sport, Faculty of Sport Sciences, Catholic University of Murcia (UCAM), Murcia, Spain.,Department of Physical Education, Faculty of Sport Sciences and Physical Education, University of A Coruña, A Coruña, Spain
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11
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Resistance training upregulates skeletal muscle Na +, K +-ATPase content, with elevations in both α 1 and α 2, but not β isoforms. Eur J Appl Physiol 2020; 120:1777-1785. [PMID: 32500280 DOI: 10.1007/s00421-020-04408-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 05/25/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE The Na+, K+-ATPase (NKA) is important in regulating trans-membrane ion gradients, cellular excitability and muscle function. We investigated the effects of resistance training in healthy young adults on the adaptability of NKA content and of the specific α and β isoforms in human skeletal muscle. METHODS Twenty-one healthy young males (22.9 ± 4.6 year; 1.80 ± 0.70 m, 85.1 ± 17.8 kg, mean ± SD) underwent 7 weeks of resistance training, training three times per week (RT, n = 16) or control (CON, n = 5). The training program was effective with a 39% gain in leg press muscle strength (p = 0.001). A resting vastus lateralis muscle biopsy was taken before and following RT or CON and assayed for NKA content ([3H]ouabain binding site content) and NKA isoform (α1, α2, β1, β2) abundances. RESULTS After RT, each of NKA content (12%, 311 ± 76 vs 349 ± 76 pmol g wet weight-1, p = 0.01), NKA α1 (32%, p = 0.01) and α2 (10%, p < 0.01) isoforms were increased, whereas β1 (p = 0.18) and β2 (p = 0.22) isoforms were unchanged. NKA content and isoform abundances were unchanged during CON. CONCLUSIONS Resistance training increased muscle NKA content through upregulation of both α1 and α2 isoforms, which were independent of β isoform changes. In animal models, modulations in α1 and α2 isoform abundances in skeletal muscle may affect fatigue resistance during exercise, muscle hypertrophy and strength. Whether similar in-vivo functional benefits of these NKA isoform adaptations occurs in human muscle with resistance training remains to be determined.
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12
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Wyckelsma VL, Perry BD, Bangsbo J, McKenna MJ. Inactivity and exercise training differentially regulate abundance of Na +-K +-ATPase in human skeletal muscle. J Appl Physiol (1985) 2019; 127:905-920. [PMID: 31369327 DOI: 10.1152/japplphysiol.01076.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Physical inactivity is a global health risk that can be addressed through application of exercise training suitable for an individual's health and age. People's willingness to participate in physical activity is often limited by an initially poor physical capability and early onset of fatigue. One factor associated with muscle fatigue during intense contractions is an inexcitability of skeletal muscle cells, reflecting impaired transmembrane Na+/K+ exchange and membrane depolarization, which are regulated via the transmembranous protein Na+-K+-ATPase (NKA). This short review focuses on the plasticity of NKA in skeletal muscle in humans after periods of altered usage, exploring NKA upregulation with exercise training and downregulation with physical inactivity. In human skeletal muscle, the NKA content quantified by [3H]ouabain binding site content shows robust, yet tightly constrained, upregulation of 8-22% with physical training, across a broad range of exercise training types. Muscle NKA content in humans undergoes extensive downregulation with injury that involves substantial muscular inactivity. Surprisingly, however, no reduction in NKA content was found in the single study that investigated short-term disuse. Despite clear findings that exercise training and injury modulate NKA content, the adaptability of the individual NKA isoforms in muscle (α1-3 and β1-3) and of the accessory and regulatory protein FXYD1 are surprisingly inconsistent across studies, for exercise training as well as for injury/disuse. Potential reasons for this are explored. Finally, we provide suggestions for future studies to provide greater understanding of NKA regulation during exercise training and inactivity in humans.
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Affiliation(s)
- V L Wyckelsma
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - B D Perry
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia.,School of Science and Health, Western Sydney University, Penrith, New South Wales, Australia
| | - J Bangsbo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
| | - M J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
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13
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Christiansen D. Molecular stressors underlying exercise training-induced improvements in K + regulation during exercise and Na + ,K + -ATPase adaptation in human skeletal muscle. Acta Physiol (Oxf) 2019; 225:e13196. [PMID: 30288889 DOI: 10.1111/apha.13196] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/12/2018] [Accepted: 09/28/2018] [Indexed: 12/28/2022]
Abstract
Despite substantial progress made towards a better understanding of the importance of skeletal muscle K+ regulation for human physical function and its association with several disease states (eg type-II diabetes and hypertension), the molecular basis underpinning adaptations in K+ regulation to various stimuli, including exercise training, remains inadequately explored in humans. In this review, the molecular mechanisms essential for enhancing skeletal muscle K+ regulation and its key determinants, including Na+ ,K+ -ATPase function and expression, by exercise training are examined. Special attention is paid to the following molecular stressors and signaling proteins: oxygenation, redox balance, hypoxia, reactive oxygen species, antioxidant function, Na+ ,K+ , and Ca2+ concentrations, anaerobic ATP turnover, AMPK, lactate, and mRNA expression. On this basis, an update on the effects of different types of exercise training on K+ regulation in humans is provided, focusing on recent discoveries about the muscle fibre-type-dependent regulation of Na+ ,K+ -ATPase-isoform expression. Furthermore, with special emphasis on blood-flow-restricted exercise as an exemplary model to modulate the key molecular mechanisms identified, it is discussed how training interventions may be designed to maximize improvements in K+ regulation in humans. The novel insights gained from this review may help us to better understand how exercise training and other strategies, such as pharmacological interventions, may be best designed to enhance K+ regulation and thus the physical function in humans.
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Affiliation(s)
- Danny Christiansen
- Department of Nutrition, Exercise and Sports (NEXS) University of Copenhagen Copenhagen Denmark
- Institute for Health and Sport (IHES) Victoria University Melbourne Victoria Australia
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14
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Christiansen D, Murphy RM, Bangsbo J, Stathis CG, Bishop DJ. Increased FXYD1 and PGC-1α mRNA after blood flow-restricted running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle. Acta Physiol (Oxf) 2018; 223:e13045. [PMID: 29383885 PMCID: PMC5969286 DOI: 10.1111/apha.13045] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 01/01/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022]
Abstract
Aim This study explored the effects of blood flow restriction (BFR) on mRNA responses of PGC‐1α (total, 1α1, and 1α4) and Na+,K+‐ATPase isoforms (NKA; α1‐3, β1‐3, and FXYD1) to an interval running session and determined whether these effects were related to increased oxidative stress, hypoxia, and fibre type‐specific AMPK and CaMKII signalling, in human skeletal muscle. Methods In a randomized, crossover fashion, 8 healthy men (26 ± 5 year and 57.4 ± 6.3 mL kg−1 min−1) completed 3 exercise sessions: without (CON) or with blood flow restriction (BFR), or in systemic hypoxia (HYP, ~3250 m). A muscle sample was collected before (Pre) and after exercise (+0 hour, +3 hours) to quantify mRNA, indicators of oxidative stress (HSP27 protein in type I and II fibres, and catalase and HSP70 mRNA), metabolites, and α‐AMPK Thr172/α‐AMPK, ACC Ser221/ACC, CaMKII Thr287/CaMKII, and PLBSer16/PLB ratios in type I and II fibres. Results Muscle hypoxia (assessed by near‐infrared spectroscopy) was matched between BFR and HYP, which was higher than CON (~90% vs ~70%; P < .05). The mRNA levels of FXYD1 and PGC‐1α isoforms (1α1 and 1α4) increased in BFR only (P < .05) and were associated with increases in indicators of oxidative stress and type I fibre ACC Ser221/ACC ratio, but dissociated from muscle hypoxia, lactate, and CaMKII signalling. Conclusion Blood flow restriction augmented exercise‐induced increases in muscle FXYD1 and PGC‐1α mRNA in men. This effect was related to increased oxidative stress and fibre type‐dependent AMPK signalling, but unrelated to the severity of muscle hypoxia, lactate accumulation, and modulation of fibre type‐specific CaMKII signalling.
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Affiliation(s)
- D. Christiansen
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - R. M. Murphy
- Department of Biochemistry and Genetics; La Trobe Institute for Molecular Science; La Trobe University; Melbourne Vic. Australia
| | - J. Bangsbo
- Department of Nutrition, Exercise and Sports (NEXS); University of Copenhagen; Copenhagen N Denmark
| | - C. G. Stathis
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
| | - D. J. Bishop
- Institute of Sport, Exercise and Active Living (ISEAL); Victoria University; Melbourne Vic. Australia
- School of Medical and Health Sciences; Edith Cowan University; Perth WA Australia
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15
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Christiansen D, Bishop DJ, Broatch JR, Bangsbo J, McKenna MJ, Murphy RM. Cold-water immersion after training sessions: effects on fiber type-specific adaptations in muscle K + transport proteins to sprint-interval training in men. J Appl Physiol (1985) 2018; 125:429-444. [PMID: 29745801 DOI: 10.1152/japplphysiol.00259.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Effects of regular use of cold-water immersion (CWI) on fiber type-specific adaptations in muscle K+ transport proteins to intense training, along with their relationship to changes in mRNA levels after the first training session, were investigated in humans. Nineteen recreationally active men (24 ± 6 yr, 79.5 ± 10.8 kg, 44.6 ± 5.8 ml·kg-1·min-1) completed six weeks of sprint-interval cycling, either without (passive rest; CON) or with training sessions followed by CWI (15 min at 10°C; COLD). Muscle biopsies were obtained before and after training to determine abundance of Na+, K+-ATPase isoforms (α1-3, β1-3) and phospholemman (FXYD1) and after recovery treatments (+0 h and +3 h) on the first day of training to measure mRNA content. Training increased ( P < 0.05) the abundance of α1 and β3 in both fiber types and β1 in type-II fibers and decreased FXYD1 in type-I fibers, whereas α2 and α3 abundance was not altered by training ( P > 0.05). CWI after each session did not influence responses to training ( P > 0.05). However, α2 mRNA increased after the first session in COLD (+0 h, P < 0.05) but not in CON ( P > 0.05). In both conditions, α1 and β3 mRNA increased (+3 h; P < 0.05) and β2 mRNA decreased (+3 h; P < 0.05), whereas α3, β1, and FXYD1 mRNA remained unchanged ( P > 0.05) after the first session. In summary, Na+,K+-ATPase isoforms are differently regulated in type I and II muscle fibers by sprint-interval training in humans, which, for most isoforms, do not associate with changes in mRNA levels after the first training session. CWI neither impairs nor improves protein adaptations to intense training of importance for muscle K+ regulation. NEW & NOTEWORTHY Although cold-water immersion (CWI) after training and competition has become a routine for many athletes, limited published evidence exists regarding its impact on training adaptation. Here, we show that CWI can be performed regularly without impairing training-induced adaptations at the fiber-type level important for muscle K+ handling. Furthermore, sprint-interval training invoked fiber type-specific adaptations in K+ transport proteins, which may explain the dissociated responses of whole-muscle protein levels and K+ transport function to training previously reported.
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Affiliation(s)
- Danny Christiansen
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.,Department of Nutrition, Exercise, and Sports, University of Copenhagen , Copenhagen , Denmark
| | - David J Bishop
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.,School of Medical and Health Sciences, Edith Cowan University , Perth, Western Australia , Australia
| | - James R Broatch
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Jens Bangsbo
- Department of Nutrition, Exercise, and Sports, University of Copenhagen , Copenhagen , Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Robyn M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University , Melbourne, Victoria , Australia
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16
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Wyckelsma VL, Levinger I, Murphy RM, Petersen AC, Perry BD, Hedges CP, Anderson MJ, McKenna MJ. Intense interval training in healthy older adults increases skeletal muscle [ 3H]ouabain-binding site content and elevates Na +,K +-ATPase α 2 isoform abundance in Type II fibers. Physiol Rep 2017; 5:5/7/e13219. [PMID: 28373411 PMCID: PMC5392511 DOI: 10.14814/phy2.13219] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 02/27/2017] [Indexed: 12/12/2022] Open
Abstract
Young adults typically adapt to intense exercise training with an increased skeletal muscle Na+,K+-ATPase (NKA) content, concomitant with reduced extracellular potassium concentration [K+] during exercise and enhanced exercise performance. Whether these changes with longitudinal training occur in older adults is unknown and was investigated here. Fifteen older adults (69.4 ± 3.5 years, mean ± SD) were randomized to either 12 weeks of intense interval training (4 × 4 min at 90-95% peak heart rate), 3 days/week (IIT, n = 8); or no exercise controls (n = 7). Before and after training, participants completed an incremental cycle ergometer exercise test until a rating of perceived exertion of 17 (very hard) on a 20-point scale was attained, with measures of antecubital venous [K+]v Participants underwent a resting muscle biopsy prior to and at 48-72 h following the final training session. After IIT, the peak exercise work rate (25%), oxygen uptake (16%) and heart rate (6%) were increased (P < 0.05). After IIT, the peak exercise plasma [K+]v tended to rise (P = 0.07), while the rise in plasma [K+]v relative to work performed (nmol.L-1J-1) was unchanged. Muscle NKA content increased by 11% after IIT (P < 0.05). Single fiber measurements, increased in NKA α2 isoform in Type II fibers after IIT (30%, P < 0.05), with no changes to the other isoforms in single fibers or homogenate. Thus, intense exercise training in older adults induced an upregulation of muscle NKA, with a fiber-specific increase in NKA α2 abundance in Type II fibers, coincident with increased muscle NKA content and enhanced exercise performance.
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Affiliation(s)
- Victoria L Wyckelsma
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia
| | - Itamar Levinger
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Victoria, Australia
| | - Aaron C Petersen
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia
| | - Ben D Perry
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia.,Renal Division, Department of Medicine, Emory University, Atlanta, Georgia
| | - Christopher P Hedges
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia
| | - Mitchell J Anderson
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia.,Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Michael J McKenna
- Clinical Exercise Science Research Program, Institute of Sport, Exercise and Active Living (ISEAL), Victoria, Australia
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17
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Skovgaard C, Almquist NW, Bangsbo J. The effect of repeated periods of speed endurance training on performance, running economy, and muscle adaptations. Scand J Med Sci Sports 2017; 28:381-390. [DOI: 10.1111/sms.12916] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2017] [Indexed: 12/30/2022]
Affiliation(s)
- C. Skovgaard
- Department of Nutrition; Exercise and Sports; Section of Integrated Physiology; University of Copenhagen; Copenhagen Denmark
- Team Danmark (Danish Elite Sports Organization); Copenhagen Denmark
| | - N. W. Almquist
- Department of Nutrition; Exercise and Sports; Section of Integrated Physiology; University of Copenhagen; Copenhagen Denmark
| | - J. Bangsbo
- Department of Nutrition; Exercise and Sports; Section of Integrated Physiology; University of Copenhagen; Copenhagen Denmark
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18
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Skovgaard C, Almquist NW, Bangsbo J. Effect of increased and maintained frequency of speed endurance training on performance and muscle adaptations in runners. J Appl Physiol (1985) 2017; 122:48-59. [DOI: 10.1152/japplphysiol.00537.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 10/05/2016] [Accepted: 11/07/2016] [Indexed: 01/04/2023] Open
Abstract
The aim of the study was, in runners accustomed to speed endurance training (SET), to examine the effect of increased and maintained frequency of SET on performance and muscular adaptations. After familiarization (FAM) to SET, 18 male ( n = 14) and female ( n = 4) runners (V̇o2max: 57.3 ± 3.4 ml/min; means ± SD) completed 20 sessions of maintained low-frequency (LF; every fourth day; n = 7) or high-frequency (HF; every second day; n = 11) SET. Before FAM as well as before and after an intervention period (INT), subjects completed a series of running tests and a biopsy from m. vastus lateralis was collected. Ten-kilometer performance improved ( P < 0.05) ~3.5% during FAM with no further change during INT. Time to exhaustion at 90% vV̇o2max was 15 and 22% longer ( P < 0.05) during FAM and a further 12 and 16% longer ( P < 0.05) during INT in HF and LF, respectively. During FAM, muscle expression of NHE1 and maximal activity of citrate synthase (CS) and phosphofructokinase (PFK) increased ( P < 0.05), running economy (RE) improved ( P < 0.05), and V̇o2max was unchanged. During INT, both HF and LF increased ( P < 0.05) muscle expression of NKAβ1, whereas maximal activity of CS and PFK, RE, and V̇o2max were unchanged. Furthermore, during INT, muscle expression of FXYD1 and SERCA1, and FXYD1 activity increased ( P < 0.05) in HF, while muscle expression of SERCA2 decreased ( P < 0.05) in LF. Thus increased or maintained frequency of SET leads to further improvements in short-term exercise capacity, but not in 10-km running performance. The better short-term exercise capacity may be associated with elevated expression of muscle proteins related to Na+/K+ transportation and Ca2+ reuptake. NEW & NOTEWORTHY Ten speed endurance training (SET) sessions improved short-term exercise capacity and 10-km performance, which was followed by further improved short-term exercise capacity, but unchanged 10-km performance after 20 SET sessions performed with either high frequency (4 per 8 days) or continued low frequency (2 per 8 days) in trained runners. The further gain in short-term exercise capacity was associated with changes in muscle expression of proteins of importance for the development of fatigue.
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Affiliation(s)
- Casper Skovgaard
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
- Team Danmark (Danish Elite Sports Organization), Copenhagen, Denmark
| | - Nicki Winfield Almquist
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
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19
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Hostrup M, Bangsbo J. Limitations in intense exercise performance of athletes - effect of speed endurance training on ion handling and fatigue development. J Physiol 2016; 595:2897-2913. [PMID: 27673449 DOI: 10.1113/jp273218] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/21/2016] [Indexed: 01/10/2023] Open
Abstract
Mechanisms underlying fatigue development and limitations for performance during intense exercise have been intensively studied during the past couple of decades. Fatigue development may involve several interacting factors and depends on type of exercise undertaken and training level of the individual. Intense exercise (½-6 min) causes major ionic perturbations (Ca2+ , Cl- , H+ , K+ , lactate- and Na+ ) that may reduce sarcolemmal excitability, Ca2+ release and force production of skeletal muscle. Maintenance of ion homeostasis is thus essential to sustain force production and power output during intense exercise. Regular speed endurance training (SET), i.e. exercise performed at intensities above that corresponding to maximum oxygen consumption (V̇O2, max ), enhances intense exercise performance. However, most of the studies that have provided mechanistic insight into the beneficial effects of SET have been conducted in untrained and recreationally active individuals, making extrapolation towards athletes' performance difficult. Nevertheless, recent studies indicate that only a few weeks of SET enhances intense exercise performance in highly trained individuals. In these studies, the enhanced performance was not associated with changes in V̇O2, max and muscle oxidative capacity, but rather with adaptations in muscle ion handling, including lowered interstitial concentrations of K+ during and in recovery from intense exercise, improved lactate- -H+ transport and H+ regulation, and enhanced Ca2+ release function. The purpose of this Topical Review is to provide an overview of the effect of SET and to discuss potential mechanisms underlying enhancements in performance induced by SET in already well-trained individuals with special emphasis on ion handling in skeletal muscle.
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Affiliation(s)
- Morten Hostrup
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.,Department of Respiratory Research, Bispebjerg University Hospital, Denmark
| | - Jens Bangsbo
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark
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20
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Pirkmajer S, Chibalin AV. Na,K-ATPase regulation in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 311:E1-E31. [PMID: 27166285 DOI: 10.1152/ajpendo.00539.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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21
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Whitty AG, Murphy AJ, Coutts AJ, Watsford ML. The effect of low- vs high-cadence interval training on the freely chosen cadence and performance in endurance-trained cyclists. Appl Physiol Nutr Metab 2016; 41:666-73. [PMID: 27175601 DOI: 10.1139/apnm-2015-0562] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to determine the effects of high- and low-cadence interval training on the freely chosen cadence (FCC) and performance in endurance-trained cyclists. Sixteen male endurance-trained cyclists completed a series of submaximal rides at 60% maximal power (Wmax) at cadences of 50, 70, 90, and 110 r·min(-1), and their FCC to determine their preferred cadence, gross efficiency (GE), rating of perceived exertion, and crank torque profile. Performance was measured via a 15-min time trial, which was preloaded with a cycle at 60% Wmax. Following the testing, the participants were randomly assigned to a high-cadence (HC) (20% above FCC) or a low-cadence (LC) (20% below FCC) group for 18 interval-based training sessions over 6 weeks. The HC group increased their FCC from 92 to 101 r·min(-1) after the intervention (p = 0.01), whereas the LC group remained unchanged (93 r·min(-1)). GE increased from 22.7% to 23.6% in the HC group at 90 r·min(-1) (p = 0.05), from 20.0% to 20.9% at 110 r·min(-1) (p = 0.05), and from 22.8% to 23.2% at their FCC. Both groups significantly increased their total distance and average power output following training, with the LC group recording a superior performance measure. There were minimal changes to the crank torque profile in both groups following training. This study demonstrated that the FCC can be altered with HC interval training and that the determinants of the optimal cycling cadence are multifactorial and not completely understood. Furthermore, LC interval training may significantly improve time-trial results of short duration as a result of an increase in strength development or possible neuromuscular adaptations.
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Affiliation(s)
- Anthony G Whitty
- a School of Exercise and Health Science, Australian Catholic University, Locked Bag 4115, Fitzroy, VIC, Australia.,b Faculty of Health, University of Technology Sydney, Moore Park, Australia
| | - Aron J Murphy
- b Faculty of Health, University of Technology Sydney, Moore Park, Australia.,c School of Science and Technology, University of New England, Armidale, Australia
| | - Aaron J Coutts
- b Faculty of Health, University of Technology Sydney, Moore Park, Australia
| | - Mark L Watsford
- b Faculty of Health, University of Technology Sydney, Moore Park, Australia
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22
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Río-Rodríguez D, Iglesias-Soler E, Fernández del Olmo M. Set Configuration in Resistance Exercise: Muscle Fatigue and Cardiovascular Effects. PLoS One 2016; 11:e0151163. [PMID: 26982500 PMCID: PMC4794235 DOI: 10.1371/journal.pone.0151163] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 02/24/2016] [Indexed: 12/03/2022] Open
Abstract
Purpose Cardiovascular responses of traditional resistance (TS) training have been extensively explored. However, the fatigue mechanisms associated with an intra-set rest configuration (ISR) have not been investigated. This study compares two modalities of set configurations for resistance exercise that equates work to rest ratios and measures the central and peripheral fatigue in combination with cortical, hemodynamic and cardiovascular measures. Methods 11 subjects performed two isometric knee extension training sessions using TS and ISR configurations. Voluntary activation (VA), single twitch amplitude, low frequency fatigue (LFF), Mwave, motor evoked potential (MEP), short intracortical inhibition (SICI), intracortical facilitation (ICF) and heart rate variability were evaluated before and after each training session. During each session beat to beat heart rate, blood pressure and rate pressure product (RPP) were also evaluated. Results After exercise VA decreased significantly for TS but not for ISR (P < 0.001), single twitch amplitude and LFF values were lower for TS than ISR (P < 0.004), and SICI was reduced only for the TS configuration (P = 0.049). During exercise RPP values were significantly higher for the TS than for ISR (P = 0.001). RPP correlated with VA for TS (r = -.85 P < 0.001) suggesting a relationship between central fatigue and cardiovascular stress. Conclusions We conclude that ISR induced lower central and peripheral fatigue as well as lower cardiovascular stress in comparison with TS configuration. Our study suggests that set configuration is a key factor in the regulation of the neuromuscular and cardiovascular responses of resistance training.
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Affiliation(s)
- Dan Río-Rodríguez
- Learning and Human Movement Control Group, Department of Physical Education and Sport Faculty of Sports Sciences and Physical Education, University of A Coruna, A Coruna, Spain
| | - Eliseo Iglesias-Soler
- Performance and Health Group, Department of Physical Education and Sport, Faculty of Sports Sciences and Physical Education, University of A Coruna, A Coruna, Spain
| | - Miguel Fernández del Olmo
- Learning and Human Movement Control Group, Department of Physical Education and Sport Faculty of Sports Sciences and Physical Education, University of A Coruna, A Coruna, Spain
- * E-mail:
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23
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Thomassen M, Gunnarsson TP, Christensen PM, Pavlovic D, Shattock MJ, Bangsbo J. Intensive training and reduced volume increases muscle FXYD1 expression and phosphorylation at rest and during exercise in athletes. Am J Physiol Regul Integr Comp Physiol 2016; 310:R659-69. [PMID: 26791827 DOI: 10.1152/ajpregu.00081.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 01/18/2016] [Indexed: 01/10/2023]
Abstract
The present study examined the effect of intensive training in combination with marked reduction in training volume on phospholemman (FXYD1) expression and phosphorylation at rest and during exercise. Eight well-trained cyclists replaced their regular training with speed-endurance training (10-12 × ∼30-s sprints) two or three times per week and aerobic high-intensity training (4-5 × 3-4 min at 90-95% of peak aerobic power output) 1-2 times per week for 7 wk and reduced the training volume by 70%. Muscle biopsies were obtained before and during a repeated high-intensity exercise protocol, and protein expression and phosphorylation were determined by Western blot analysis. Expression of FXYD1 (30%), actin (40%), mammalian target of rapamycin (mTOR) (12%), phospholamban (PLN) (16%), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) γ/δ (25%) was higher (P < 0.05) than before the training intervention. In addition, after the intervention, nonspecific FXYD1 phosphorylation was higher (P < 0.05) at rest and during exercise, mainly achieved by an increased FXYD1 Ser-68 phosphorylation, compared with before the intervention. CaMKII, Thr-287, and eukaryotic elongation factor 2 Thr-56 phosphorylation at rest and during exercise, overall PKCα/β, Thr-638/641, and mTOR Ser-2448 phosphorylation during repeated intense exercise as well as resting PLN Thr-17 phosphorylation were also higher (P < 0.05) compared with before the intervention period. Thus, a period of high-intensity training with reduced training volume increases expression and phosphorylation levels of FXYD1, which may affect Na(+)/K(+) pump activity and muscle K(+) homeostasis during intense exercise. Furthermore, higher expression of CaMKII and PLN, as well as increased phosphorylation of CaMKII Thr-287 may have improved intracellular Ca(2+) handling.
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Affiliation(s)
- Martin Thomassen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Thomas P Gunnarsson
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Peter M Christensen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Davor Pavlovic
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Michael J Shattock
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
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Wyckelsma VL, McKenna MJ, Serpiello FR, Lamboley CR, Aughey RJ, Stepto NK, Bishop DJ, Murphy RM. Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase α- and β-isoforms in human skeletal muscle. J Appl Physiol (1985) 2015; 118:699-706. [PMID: 25614596 DOI: 10.1152/japplphysiol.00419.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Na(+)-K(+)-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further investigated muscle fiber-type-specific NKA adaptability in eight of these adults following 4-wk repeated-sprint exercise (RSE) training, comprising three sets of 5 × 4-s sprints, 3 days/wk. Single fibers were separated, and myosin heavy chain (I and IIa) and NKA (α1-3 and β1-3) isoform abundance were determined via Western blotting. All six NKA isoforms were expressed in both type I and IIa fibers. No differences between fiber types were found for α1-, α2-, α3-, β1-, or β3-isoform abundances. The NKA β2-isoform was 27% more abundant in type IIa than type I fibers (P < 0.05), with no other fiber-type-specific trends evident. RSE training increased β1 in type IIa fibers (pretraining 0.70 ± 0.25, posttraining 0.84 ± 0.24 arbitrary units, 42%, P < 0.05). No training effects were found for other NKA isoforms. Thus human skeletal muscle expresses all six NKA isoforms and not in a fiber-type-specific manner; this points to their different functional roles in skeletal muscle cells. Detection of elevated NKA β1 after RSE training demonstrates the sensitivity of the single-fiber Western blotting technique for fiber-type-specific intervention effects.
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Affiliation(s)
- V L Wyckelsma
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - M J McKenna
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - F R Serpiello
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - C R Lamboley
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - R J Aughey
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - N K Stepto
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - D J Bishop
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, Victoria, Australia; and
| | - R M Murphy
- Department of Biochemistry, La Trobe University, Melbourne, Victoria, Australia
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25
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Fontes MT, Silva TLBT, Mota MM, Barreto AS, Rossoni LV, Santos MRV. Resistance exercise acutely enhances mesenteric artery insulin-induced relaxation in healthy rats. Life Sci 2013; 94:24-9. [PMID: 24316143 DOI: 10.1016/j.lfs.2013.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 11/11/2013] [Accepted: 11/21/2013] [Indexed: 12/20/2022]
Abstract
AIMS We evaluated the mechanisms involved in insulin-induced vasodilatation after acute resistance exercise in healthy rats. MAIN METHODS Wistar rats were divided into 3 groups: control (CT), electrically stimulated (ES) and resistance exercise (RE). Immediately after acute RE (15 sets with 10 repetitions at 70% of maximal intensity), the animals were sacrificed and rings of mesenteric artery were mounted in an isometric system. After this, concentration-response curves to insulin were performed in control condition and in the presence of LY294002 (PI3K inhibitor), L-NAME (NOS inhibitor), L-NAME+TEA (K(+) channels inhibitor), LY294002+BQ123 (ET-A antagonist) or ouabain (Na(+)/K(+) ATPase inhibitor). KEY FINDINGS Acute RE increased insulin-induced vasorelaxation as compared to control (CT: Rmax=7.3 ± 0.4% and RE: Rmax=15.8 ± 0.8%; p<0.001). NOS inhibition reduced (p<0.001) this vasorelaxation from both groups (CT: Rmax=2.0 ± 0.3%, and RE: Rmax=-1.2 ± 0.1%), while PI3K inhibition abolished the vasorelaxation in CT (Rmax=-0.1±0.3%, p<0.001), and caused vasoconstriction in RE (Rmax=-6.5 ± 0.6%). That insulin-induced vasoconstriction on PI3K inhibition was abolished (p<0.001) by the ET-A antagonist (Rmax=2.9 ± 0.4%). Additionally, acute RE enhanced (p<0.001) the functional activity of the ouabain-sensitive Na(+)/K(+) ATPase activity (Rmax=10.7 ± 0.4%) and of the K(+) channels (Rmax=-6.1±0.5%; p<0.001) in the insulin-induced vasorelaxation as compared to CT. SIGNIFICANCE Such results suggest that acute RE promotes enhanced insulin-induced vasodilatation, which could act as a fine tuning to vascular tone.
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Affiliation(s)
- M T Fontes
- Department of Physiology, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil
| | - T L B T Silva
- Department of Physiology, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil
| | - M M Mota
- Department of Physiology, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil
| | - A S Barreto
- Department of Physiology, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil
| | - L V Rossoni
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, 05508-900, São Paulo, SP, Brazil
| | - M R V Santos
- Department of Physiology, Federal University of Sergipe, 49100-000, São Cristóvão, SE, Brazil.
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26
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Juel C, Nordsborg NB, Bangsbo J. Exercise-induced increase in maximal in vitro Na-K-ATPase activity in human skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2013; 304:R1161-5. [DOI: 10.1152/ajpregu.00591.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study investigated whether maximal in vitro Na-K-ATPase activity in human skeletal muscle is changed with exercise and whether it was altered by acute hypoxia. Needle biopsies from 14 subjects were obtained from vastus lateralis before and after 4 min of intense muscle activity. In addition, six subjects exercised also in hypoxia (12.5% oxygen). The Na-K-ATPase assay revealed a 19% increase ( P < 0.05) in maximal velocity ( Vmax) for Na+-dependent Na-K-ATPase activity after exercise and a tendency ( P < 0.1) toward a decrease in Km for Na+ (increased Na+ affinity) in both normoxia and hypoxia. In contrast, the in vitro Na-K-ATPase activity determined with the 3- O-MFPase technique was 11–32% lower after exercise in normoxia ( P < 0.05) and hypoxia ( P < 0.1). Based on the different results obtained with the Na-K-ATPase assay and the 3- O-MFPase technique, it was suggested that the 3- O-MFPase method is insensitive to changes in Na-K-ATPase activity. To test this possibility, changes in Na-K-ATPase activity was induced by protein kinase C activation. The changes quantified with the Na-K-ATPase assay could not be detected with the 3- O-MFPase method. In addition, purines stimulated Na-K-ATPase activity in rat muscle membranes; these changes could not be detected with the 3- O-MFPase method. Therefore, the 3- O-MFPase technique is not sensitive to changes in Na+ sensitivity, and the method is not suited to detecting changes in Na-K-ATPase activity with exercise. In conclusion, muscle activity in humans induces an increased in vitro Na+-dependent Na-K-ATPase activity, which contributes to the upregulation of the Na-K-ATPase in association with exercise both in normoxia and hypoxia.
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Affiliation(s)
- Carsten Juel
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; and
| | - Nikolai B. Nordsborg
- Department of Nutrition, Exercise and Sport, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sport, University of Copenhagen, Copenhagen, Denmark
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27
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McKenna MJ, Perry BD, Serpiello FR, Caldow MK, Levinger P, Cameron-Smith D, Levinger I. Unchanged [3H]ouabain binding site content but reduced Na+-K+ pump α2-protein abundance in skeletal muscle in older adults. J Appl Physiol (1985) 2012; 113:1505-11. [DOI: 10.1152/japplphysiol.01032.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aging is associated with reduced muscle mass, weakness, and increased fatigability. In skeletal muscle, the Na+-K+ pump (NKA) is important in regulating Na+-K+ gradients, membrane excitability, and thus contractility, but the effects of aging on muscle NKA are unclear. We investigated whether aging is linked with reduced muscle NKA by contrasting muscle NKA isoform gene expression and protein abundance, and NKA total content in 17 Elderly (66.8 ± 6.4 yr, mean ± SD) and 16 Young adults (23.9 ± 2.2 yr). Participants underwent peak oxygen consumption assessment and a vastus lateralis muscle biopsy, which was analyzed for NKA α1-, α2-, α3-, β1-, β2-, and β3-isoform gene expression (real-time RT-PCR), protein abundance (immunoblotting), and NKA total content ([3H]ouabain binding sites). The Elderly had lower peak oxygen consumption (−36.7%, P = 0.000), strength (−36.3%, P = 0.001), NKA α2- (−24.4%, 11.9 ± 4.4 vs. 9.0 ± 2.7 arbitrary units, P = 0.049), and NKA β3-protein abundance (−23.0%, P = 0.041) than Young. The β3-mRNA was higher in Elderly compared with Young ( P = 0.011). No differences were observed between groups for other NKA isoform mRNA or protein abundance, or for [3H]ouabain binding site content. Thus skeletal muscle in elderly individuals was characterized by decreased NKA α2- and β3-protein abundance, but unchanged α1 abundance and [3H]ouabain binding. The latter was likely caused by reduced α2 abundance with aging, preventing an otherwise higher [3H]ouabain binding that might occur with a greater membrane density in smaller muscle fibers. Further study is required to verify reduced muscle NKA α2 with aging and possible contributions to impaired exercise capability and daily living activities.
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Affiliation(s)
- Michael J. McKenna
- Institute of Sport, Exercise and Active Living (ISEAL), Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
| | - Ben D. Perry
- Institute of Sport, Exercise and Active Living (ISEAL), Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
- School of Sport and Exercise Science, Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
| | - Fabio R. Serpiello
- Institute of Sport, Exercise and Active Living (ISEAL), Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
- School of Sport and Exercise Science, Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
- Facolta' di Scienze Motorie, Universita' degli Studi di Verona, Verona, Italy
| | - Marissa K. Caldow
- School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Victoria, Australia; and
| | - Pazit Levinger
- Institute of Sport, Exercise and Active Living (ISEAL), Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
| | | | - Itamar Levinger
- Institute of Sport, Exercise and Active Living (ISEAL), Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
- School of Sport and Exercise Science, Muscle, Ions and Exercise Group, Victoria University, Melbourne, Victoria, Australia
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28
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Gunnarsson TP, Bangsbo J. The 10-20-30 training concept improves performance and health profile in moderately trained runners. J Appl Physiol (1985) 2012; 113:16-24. [DOI: 10.1152/japplphysiol.00334.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of an alteration from regular endurance to interval (10-20-30) training on the health profile, muscular adaptations, maximum oxygen uptake (V̇o2max), and performance of runners was examined. Eighteen moderately trained individuals (6 females and 12 males; V̇o2max: 52.2 ± 1.5 ml·kg−1·min−1) (means ± SE) were divided into a high-intensity training (10-20-30; 3 women and 7 men) and a control (CON; 3 women and 5 men) group. For a 7-wk intervention period the 10-20-30 replaced all training sessions with 10-20-30 training consisting of low-, moderate-, and high-speed running (<30%, <60%, and >90% of maximal intensity) for 30, 20, and 10 s, respectively, in three or four 5-min intervals interspersed by 2 min of recovery, reducing training volume by 54% (14.0 ± 0.9 vs. 30.4 ± 2.3 km/wk) while CON continued the normal training. After the intervention period V̇o2max in 10-20-30 was 4% higher, and performance in a 1,500-m and a 5-km run improved ( P < 0.05) by 21 and 48 s, respectively. In 10-20-30, systolic blood pressure was reduced ( P < 0.05) by 5 ± 2 mmHg, and total and low-density lipoprotein (LDL) cholesterol was lowered ( P < 0.05) by 0.5 ± 0.2 and 0.4 ± 0.1 mmol/l, respectively. No alterations were observed in CON. Muscle membrane proteins and enzyme activity did not change in either of the groups. The present study shows that interval training with short 10-s near-maximal bouts can improve performance and V̇o2max despite a ∼50% reduction in training volume. In addition, the 10-20-30 training regime lowers resting systolic blood pressure and blood cholesterol, suggesting a beneficial effect on the health profile of already trained individuals.
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Affiliation(s)
- T. P. Gunnarsson
- Department of Exercise and Sport Sciences, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark
| | - J. Bangsbo
- Department of Exercise and Sport Sciences, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark
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29
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Boon H, Kostovski E, Pirkmajer S, Song M, Lubarski I, Iversen PO, Hjeltnes N, Widegren U, Chibalin AV. Influence of chronic and acute spinal cord injury on skeletal muscle Na+-K+-ATPase and phospholemman expression in humans. Am J Physiol Endocrinol Metab 2012; 302:E864-71. [PMID: 22275761 DOI: 10.1152/ajpendo.00625.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Na(+)-K(+)-ATPase is an integral membrane protein crucial for the maintenance of ion homeostasis and skeletal muscle contractibility. Skeletal muscle Na(+)-K(+)-ATPase content displays remarkable plasticity in response to long-term increase in physiological demand, such as exercise training. However, the adaptations in Na(+)-K(+)-ATPase function in response to a suddenly decreased and/or habitually low level of physical activity, especially after a spinal cord injury (SCI), are incompletely known. We tested the hypothesis that skeletal muscle content of Na(+)-K(+)-ATPase and the associated regulatory proteins from the FXYD family is altered in SCI patients in a manner dependent on the severity of the spinal cord lesion and postinjury level of physical activity. Three different groups were studied: 1) six subjects with chronic complete cervical SCI, 2) seven subjects with acute, complete cervical SCI, and 3) six subjects with acute, incomplete cervical SCI. The individuals in groups 2 and 3 were studied at months 1, 3, and 12 postinjury, whereas individuals with chronic SCI were compared with an able-bodied control group. Chronic complete SCI was associated with a marked decrease in [(3)H]ouabain binding site concentration in skeletal muscle as well as reduced protein content of the α(1)-, α(2)-, and β(1)-subunit of the Na(+)-K(+)-ATPase. In line with this finding, expression of the Na(+)-K(+)-ATPase α(1)- and α(2)-subunits progressively decreased during the first year after complete but not after incomplete SCI. The expression of the regulatory protein phospholemman (PLM or FXYD1) was attenuated after complete, but not incomplete, cervical SCI. In contrast, FXYD5 was substantially upregulated in patients with complete SCI. In conclusion, the severity of the spinal cord lesion and the level of postinjury physical activity in patients with SCI are important factors controlling the expression of Na(+)-K(+)-ATPase and its regulatory proteins PLM and FXYD5.
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Affiliation(s)
- Hanneke Boon
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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30
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Juel C. Maximal Na⁺-K⁺-ATPase activity is upregulated in association with muscle activity. J Appl Physiol (1985) 2012; 112:2121-3. [PMID: 22383510 DOI: 10.1152/japplphysiol.01421.2011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Carsten Juel
- Department of Biology, University of Copenhagen, Denmark.
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31
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Morris MG, Dawes H, Howells K, Scott OM, Cramp M, Izadi H. Alterations in peripheral muscle contractile characteristics following high and low intensity bouts of exercise. Eur J Appl Physiol 2011; 112:337-43. [PMID: 21556817 DOI: 10.1007/s00421-011-1970-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 04/15/2011] [Indexed: 11/29/2022]
Abstract
The aim of this study was to monitor muscle contractile performance in vivo, using an electrical stimulation protocol, immediately following an acute high and low intensity exercise session conducted at the same average intensity performed on a cycle ergometer. Eighteen healthy males (25.1 ± 4.5 years, 81.6 ± 9.8 kg, 1.83 ± 0.06 m; mean ± SD) participated in the study. On two occasions, separated by 1 week, subjects completed a high and low intensity exercise session in a random order on a cycle ergometer, performing equal total work in each. At the end of each test, a muscle performance test using electrical stimulation was performed within 120 s. Post-exercise muscle data were compared to the subjects' rested muscle. We found a reduction in muscle contractile performance following both high and low intensity exercise protocols but a greater reduction in maximal voluntary contraction (MVC) (P < 0.01), rate of torque development (RTD) (P < 0.001), rate of relaxation (RR(½)), (P < 0.001) the 60 s slope of the fatigue protocol (P < 0.01) and torque frequency response (P < 0.05) following the high intensity bout. Importantly muscle performance remained reduced 1 h following high intensity exercise but was recovered following low intensity exercise. Muscle function was significantly reduced following higher intensity intermittent exercise in comparison to lower intensity exercise even when the average overall intensity was the same. This study is the first to demonstrate the sensitivity of muscle contractile characteristics to different exercise intensities and the impact of higher intensity bursts on muscle performance.
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Affiliation(s)
- Martyn G Morris
- Movement Science Group, Oxford Brookes University, Headington, Oxford, UK.
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32
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Nimmerichter A, Eston R, Bachl N, Williams C. Effects of low and high cadence interval training on power output in flat and uphill cycling time-trials. Eur J Appl Physiol 2011; 112:69-78. [DOI: 10.1007/s00421-011-1957-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/31/2011] [Indexed: 10/18/2022]
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33
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Rasmussen MK, Juel C, Nordsborg NB. Exercise-induced regulation of muscular Na+-K+ pump, FXYD1, and NHE1 mRNA and protein expression: importance of training status, intensity, and muscle type. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1209-20. [PMID: 21325644 DOI: 10.1152/ajpregu.00635.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is investigated if exercise-induced mRNA changes cause similar protein expression changes of Na(+)-K(+) pump isoforms (α(1), α(2), β(1), β(2)), FXYD1, and Na(+)/K(+) exchanger (NHE1) in rat skeletal muscle. Expression was evaluated (n = 8 per group) in soleus and extensor digutorum longus after 1 day, 3 days, and 3 wk (5 sessions/wk) of either sprint (4 × 3-min sprint + 1-min rest) or endurance (20 min) running. Two hours after exercise on day 1, no change in protein expression was apparent in either training group or muscle, whereas sprint exercise increased the mRNA of soleus α(2) (4.9 ± 0.8-fold; P < 0.05), β(2) (13.2 ± 4.4-fold; P < 0.001), and NHE1 (12.0 ± 3.1-fold; P < 0.01). Two hours after sprint exercise, protein expression normalized to control samples was higher on day 3 than day 1 for soleus α(1) (41 ± 18% increase vs. 15 ± 8% reduction; P < 0.05), α(2) (64 ± 35% increase vs. 37 ± 12% reduction; P < 0.05), β(1) (17 ± 21% increase vs. 14 ± 29% reduction; P < 0.05), and FXYD1 (35 ± 16% increase vs. 13 ± 10% reduction; P < 0.05). In contrast, on day 3, soleus α(1) (0.1 ± 0.1-fold; P < 0.001), α(2) (0.2 ± 0.1-fold; P < 0.001), β(1) (0.4 ± 0.1-fold; P < 0.05), and β(2)-mRNA (2.9 ± 1.7-fold; P < 0.001) expression was lower than after exercise on day 1. After 3 wk of training, no change in protein expression relative to control existed. In conclusion, increased expression of Na(+)-K(+) pump subunits, FXYD1 and NHE1 after 3 days exercise training does not appear to be an effect of increased constitutive mRNA levels. Importantly, sprint exercise can reduce mRNA expression concomitant with increased protein expression.
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Affiliation(s)
- Martin Krøyer Rasmussen
- Dept. of Exercise and Sport Sciences, University of Copenhagen, Universitetsparken 13, Copenhagen, Denmark
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Foster EB, Fisher G, Sartin JL, Elsasser TH, Wu G, Cowan W, Pascoe DD. Acute regulation of IGF-I by alterations in post-exercise macronutrients. Amino Acids 2011; 42:1405-16. [PMID: 21293890 DOI: 10.1007/s00726-011-0837-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 01/14/2011] [Indexed: 01/16/2023]
Abstract
This investigation sought to examine the contributions of exercise and nutrient replenishment on in vivo regulation of the insulin-like growth factor-I (IGF-I) axis components. Eight college-aged males completed three high-intensity interval training (HIIT) protocols followed by three post-exercise nutritional protocols: (1) placebo (EX); (2) carbohydrate only (CHO); and (3) essential amino acid/carbohydrate (EAA/CHO). Samples were analyzed for growth hormone (GH), free IGF-I, IGFBP-1, IGFBP-2, insulin, hematocrit, hemoglobin, serum leucine, matrix metalloproteinase-9 (MMP-9) proteolytic activity, and presence of IGFBP-3 protease activity. No evidence for IGFBP-3 proteolysis was observed. Significant increases in [free IGF-I] and [leucine] were observed in the EAA/CHO group only. Significant differences were noted in [IGFBP-1] and [IGFBP-2] across conditions. Significant increases in [GH] and MMP-9 activity were observed in all groups. These results indicate that post-exercise macronutrient ratio is a determinant of [free IGF-I], [IGFBP-1 and -2] and may play a role in modulating the IGF-I axis in vivo.
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Affiliation(s)
- E B Foster
- Department of Kinesiology, Auburn University, Auburn, AL, USA.
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Nordsborg NB, Kusuhara K, Hellsten Y, Lyngby S, Lundby C, Madsen K, Pilegaard H. Contraction-induced changes in skeletal muscle Na(+), K(+) pump mRNA expression - importance of exercise intensity and Ca(2+)-mediated signalling. Acta Physiol (Oxf) 2010; 198:487-98. [PMID: 19895607 DOI: 10.1111/j.1748-1716.2009.02057.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To investigate if exercise intensity and Ca(2+) signalling regulate Na(+),K(+) pump mRNA expression in skeletal muscle. METHODS The importance of exercise intensity was evaluated by having trained and untrained humans perform intense intermittent and prolonged exercise. The importance of Ca(2+) signalling was investigated by electrical stimulation of rat soleus and extensor digitorum longus (EDL) muscles in combination with studies of cell cultures. RESULTS Intermittent cycling exercise at approximately 85% of VO(2peak) increased (P < 0.05) alpha1 and beta1 mRNA expression approximately 2-fold in untrained and trained subjects. In trained subjects, intermittent exercise at approximately 70% of VO(2peak) resulted in a less (P < 0.05) pronounced increase ( approximately 1.4-fold; P < 0.05) for alpha1 and no change in beta1 mRNA. Prolonged low intensity exercise increased (P < 0.05) mRNA expression of alpha1 approximately 3.0-fold and alpha2 approximately 1.8-fold in untrained but not in trained subjects. Electrical stimulation of rat soleus, but not EDL, muscle increased (P < 0.05) alpha1 mRNA expression, but not when combined with KN62 and cyclosporin A incubation. Ionomycin incubation of cultured primary rat skeletal muscle cells increased (P < 0.05) alpha1 and reduced (P < 0.001) alpha2 mRNA expression and these responses were abolished (P < 0.05) by co-incubation with cyclosporin A or KN62. CONCLUSION (1) Exercise-induced increases in Na(+),K(+) pump alpha1 and beta1 mRNA expression in trained subjects are more pronounced after high- than after moderate- and low-intensity exercise. (2) Both prolonged low and short-duration high-intensity exercise increase alpha1 mRNA expression in untrained subjects. (3) Ca(2+)(i) regulates alpha1 mRNA expression in oxidative muscles via Ca(2+)/calmodulin-dependent protein kinase (CaMK) and calcineurin signalling pathways.
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Thomassen M, Christensen PM, Gunnarsson TP, Nybo L, Bangsbo J. Effect of 2-wk intensified training and inactivity on muscle Na+-K+ pump expression, phospholemman (FXYD1) phosphorylation, and performance in soccer players. J Appl Physiol (1985) 2010; 108:898-905. [DOI: 10.1152/japplphysiol.01015.2009] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study examined muscle adaptations and alterations in performance of highly trained soccer players with intensified training or training cessation. Eighteen elite soccer players were, for a 2-wk period, assigned to either a group that performed high-intensity training with a reduction in the amount of training (HI, n = 7), or an inactivity group without training (IN, n = 11). HI improved ( P < 0.05) performance of the 4th, 6th, and 10th sprint in a repeated 20-m sprint test, and IN reduced ( P < 0.05) performance in the 5th to the 10th sprints after the 2-wk intervention period. In addition, the Yo-Yo intermittent recovery level 2 test performance of IN was lowered from 845 ± 48 to 654 ± 30 m. In HI, the protein expression of the Na+-K+ pump α2-isoform was 15% higher ( P < 0.05) after the intervention period, whereas no changes were observed in α1- and β1-isoform expression. In IN, Na+-K+ pump expression was not changed. In HI, the FXYD1ser68-to-FXYD1 ratio was 27% higher ( P < 0.01) after the intervention period, and, in IN, the AB_FXYD1ser68 signal was 18% lower ( P < 0.05) after inactivity. The change in FXYD1ser68-to-FXYD1 ratio was correlated ( r2 = 0.35; P < 0.05) with change in performance in repeated sprint test. The present data suggest that short-term intensified training, even for trained soccer players, can increase muscle Na+-K+ pump α2-isoform expression, and that cessation of training for 2 wk does not affect the expression of Na+-K+ pump isoforms. Resting phosphorylation status of the Na+-K+ pump is changed by training and inactivity and may play a role in performance during repeated, intense exercise.
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Affiliation(s)
- Martin Thomassen
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Peter M. Christensen
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Thomas P. Gunnarsson
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Lars Nybo
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bangsbo
- Copenhagen Muscle Research Centre, Department of Exercise and Sport Sciences, Section of Human Physiology, University of Copenhagen, Copenhagen, Denmark
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Bangsbo J, Gunnarsson TP, Wendell J, Nybo L, Thomassen M. Reduced volume and increased training intensity elevate muscle Na+-K+ pump alpha2-subunit expression as well as short- and long-term work capacity in humans. J Appl Physiol (1985) 2009; 107:1771-80. [PMID: 19797693 DOI: 10.1152/japplphysiol.00358.2009] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study examined muscle adaptations and alterations in work capacity in endurance-trained runners as a result of a reduced amount of training combined with speed endurance training. For a 6- to 9-wk period, 17 runners were assigned to either a speed endurance group with a 25% reduction in the amount of training but including speed endurance training consisting of six to twelve 30-s sprint runs 3-4 times/wk (SET group n = 12) or a control group (n = 5), which continued the endurance training ( approximately 55 km/wk). For the SET group, the expression of the muscle Na(+)-K(+) pump alpha(2)-subunit was 68% higher (P < 0.05) and the plasma K(+) level was reduced (P < 0.05) during repeated intense running after 9 wk. Performance in a 30-s sprint test and the first of the supramaximal exhaustive runs was improved (P < 0.05) by 7% and 36%, respectively, after the speed endurance training period. In the SET group, maximal O(2) uptake was unaltered, but the 3-km (3,000-m) time was reduced (P < 0.05) from 10.4 +/- 0.1 to 10.1 +/- 0.1 min and the 10-km (10,000-m) time was improved from 37.3 +/- 0.4 to 36.3 +/- 0.4 min (means +/- SE). Muscle protein expression and performance remained unaltered in the control group. The present data suggest that both short- and long-term exercise performances can be improved with a reduction in training volume if speed endurance training is performed and that the Na(+)-K(+) pump plays a role in the control of K(+) homeostasis and in the development of fatigue during repeated high-intensity exercise.
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Affiliation(s)
- Jens Bangsbo
- Department of Exercise and Sport Sciences, Section of Human Physiology, Copenhagen Muscle Research Centre, University of Copenhagen, Copenhagen, Denmark.
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van den Burg MMM, Eizema K, de Graaf-Roelfsema E, van Breda E, Wijnberg ID, van der Kolk JH, Everts ME. Effects of acute exercise and long-term exercise on total Na+,K+-ATPase content and Na+,K+-ATPase isoform expression profile in equine muscle. Am J Vet Res 2009; 70:895-901. [DOI: 10.2460/ajvr.70.7.895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Dissociation between force and maximal Na+, K+-ATPase activity in rat fast-twitch skeletal muscle with fatiguing in vitro stimulation. Eur J Appl Physiol 2008; 105:575-83. [DOI: 10.1007/s00421-008-0937-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2008] [Indexed: 02/01/2023]
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Murphy KT, Medved I, Brown MJ, Cameron-Smith D, McKenna MJ. Antioxidant treatment withN-acetylcysteine regulates mammalian skeletal muscle Na+-K+-ATPase α gene expression during repeated contractions. Exp Physiol 2008; 93:1239-48. [DOI: 10.1113/expphysiol.2008.042796] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bibliography. Current world literature. Systemic lupus erythematosus and Sjögren's syndrome. Curr Opin Rheumatol 2008; 20:631-2. [PMID: 18698190 DOI: 10.1097/bor.0b013e3283110091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Iaia FM, Thomassen M, Kolding H, Gunnarsson T, Wendell J, Rostgaard T, Nordsborg N, Krustrup P, Nybo L, Hellsten Y, Bangsbo J. Reduced volume but increased training intensity elevates muscle Na+-K+ pump α1-subunit and NHE1 expression as well as short-term work capacity in humans. Am J Physiol Regul Integr Comp Physiol 2008; 294:R966-74. [DOI: 10.1152/ajpregu.00666.2007] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The present study examined muscle adaptations and alterations in work capacity in endurance-trained runners after a change from endurance to sprint training. Fifteen runners were assigned to either a sprint training (ST, n = 8) or a control (CON, n = 7) group. ST replaced their normal training by 30-s sprint runs three to four times a week, whereas CON continued the endurance training (∼45 km/wk). After the 4-wk sprint period, the expression of the muscle Na+-K+ pump α1-subunit and Na+/H+-exchanger isoform 1 was 29 and 30% higher ( P < 0.05), respectively. Furthermore, plasma K+ concentration was reduced ( P < 0.05) during repeated intense running. In ST, performance in a 30-s sprint test, Yo-Yo intermittent recovery test, and two supramaximal exhaustive runs was improved ( P < 0.05) by 7, 19, 27, and 19%, respectively, after the sprint training period, whereas pulmonary maximum oxygen uptake and 10-k time were unchanged. No changes in CON were observed. The present data suggest a role of the Na+-K+ pump in the control of K+ homeostasis and in the development of fatigue during repeated high-intensity exercise. Furthermore, performance during intense exercise can be improved and endurance performance maintained even with a reduction in training volume if the intensity of training is very high.
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McKenna MJ, Bangsbo J, Renaud JM. Muscle K+, Na+, and Cl− disturbances and Na+-K+ pump inactivation: implications for fatigue. J Appl Physiol (1985) 2008; 104:288-95. [DOI: 10.1152/japplphysiol.01037.2007] [Citation(s) in RCA: 184] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Membrane excitability is a critical regulatory step in skeletal muscle contraction and is modulated by local ionic concentrations, conductances, ion transporter activities, temperature, and humoral factors. Intense fatiguing contractions induce cellular K+ efflux and Na+ and Cl− influx, causing pronounced perturbations in extracellular (interstitial) and intracellular K+ and Na+ concentrations. Muscle interstitial K+ concentration may increase 1- to 2-fold to 11–13 mM and intracellular K+ concentration fall by 1.3- to 1.7-fold; interstitial Na+ concentration may decline by 10 mM and intracellular Na+ concentration rise by 1.5- to 2.0-fold. Muscle Cl− concentration changes reported with muscle contractions are less consistent, with reports of both unchanged and increased intracellular Cl− concentrations, depending on contraction type and the muscles studied. When considered together, these ionic changes depolarize sarcolemmal and t-tubular membranes to depress tetanic force and are thus likely to contribute to fatigue. Interestingly, less severe local ionic changes can also augment subtetanic force, suggesting that they may potentiate muscle contractility early in exercise. Increased Na+-K+-ATPase activity during exercise stabilizes Na+ and K+ concentration gradients and membrane excitability and thus protects against fatigue. However, during intense contraction some Na+-K+ pumps are inactivated and together with further ionic disturbances, likely precipitate muscle fatigue.
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