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Hessel AL, Engels NM, Kuehn MN, Nissen D, Sadler RL, Ma W, Irving TC, Linke WA, Harris SP. Myosin-binding protein C regulates the sarcomere lattice and stabilizes the OFF states of myosin heads. Nat Commun 2024; 15:2628. [PMID: 38521794 PMCID: PMC10960836 DOI: 10.1038/s41467-024-46957-7] [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: 09/06/2023] [Accepted: 03/15/2024] [Indexed: 03/25/2024] Open
Abstract
Muscle contraction is produced via the interaction of myofilaments and is regulated so that muscle performance matches demand. Myosin-binding protein C (MyBP-C) is a long and flexible protein that is tightly bound to the thick filament at its C-terminal end (MyBP-CC8C10), but may be loosely bound at its middle- and N-terminal end (MyBP-CC1C7) to myosin heads and/or the thin filament. MyBP-C is thought to control muscle contraction via the regulation of myosin motors, as mutations lead to debilitating disease. We use a combination of mechanics and small-angle X-ray diffraction to study the immediate and selective removal of the MyBP-CC1C7 domains of fast MyBP-C in permeabilized skeletal muscle. We show that cleavage leads to alterations in crossbridge kinetics and passive structural signatures of myofilaments that are indicative of a shift of myosin heads towards the ON state, highlighting the importance of MyBP-CC1C7 to myofilament force production and regulation.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany.
- Accelerated Muscle Biotechnologies Consultants, Boston, MA, USA.
| | - Nichlas M Engels
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Michel N Kuehn
- Institute of Physiology II, University of Muenster, Muenster, Germany
- Accelerated Muscle Biotechnologies Consultants, Boston, MA, USA
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Rachel L Sadler
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Thomas C Irving
- BioCAT, Department of Biology, Illinois Institute of Technology, Chicago, IL, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany
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2
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Tinnion DJ, Marticorena FM, Dobson B, Hilton NP, Mc Naughton LR, Sparks SA. The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation. Res Sports Med 2023:1-14. [PMID: 38018081 DOI: 10.1080/15438627.2023.2286357] [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: 07/29/2022] [Accepted: 11/03/2023] [Indexed: 11/30/2023]
Abstract
Enterically coated (ENT) or delayed-release (DEL) capsules may lessen gastrointestinal symptoms (GIS) following acute sodium citrate (SC) ingestion, although the effects on blood acid-base balance are undetermined. Fourteen active males ingested 0.4 g.kg-1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07 g.kg-1 BM sodium chloride control (CON). Blood acid-base balance and GIS were measured for 4 h. Ingestion form had no significant effect on total GIS experienced (GEL: 2 ± 7; DEL: 1 ± 8; ENT: 1 ± 4 AU). Most (7/14) participants experienced zero symptoms throughout. Peak GIS typically emerged ≤100 min post-ingestion, with a similar time to reach peak GIS between ingestion form (GEL: 36 ± 70; DEL: 13 ± 28; ENT: 15 ± 33 AU). Blood [HCO3-] was significantly higher with ENT versus GEL (ENT: 29.0 ± 0.8; GEL: 28.5 ± 1.1 mmol.L-1, P = 0.037). Acute ingestion of a reduced SC dose elicited minimal GIS, producing significant changes in blood [HCO3-] from rest, irrespective of ingestion form (GEL: 6.0 ± 0.9; DEL: 5.1 ± 1.0; ENT: 6.2 ± 0.8 mmol.L-1). The necessity of individualized ingestion strategies is also challenged, with sustained increases in blood [HCO3-] of ≥4 mmol.L-1 for up to 153 min highlighted. If commencing exercise at peak alkalosis augments subsequent performance above starting at a standardized time point where HCO3- is still elevated remains unclear.
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Affiliation(s)
- D J Tinnion
- Department of Sport and Physical Activity, Edge Hill, Ormskirk, UK
| | - F M Marticorena
- Applied Physiology and Nutrition Research Group, University of Sao Paulo, Sao Paulo, Brazil
| | - B Dobson
- Department of Sport and Physical Activity, Edge Hill, Ormskirk, UK
| | - N P Hilton
- Department of Sport and Physical Activity, Edge Hill, Ormskirk, UK
| | - L R Mc Naughton
- Department of Sport and Physical Activity, Edge Hill, Ormskirk, UK
| | - S A Sparks
- Department of Sport and Physical Activity, Edge Hill, Ormskirk, UK
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3
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Hessel AL, Engels NM, Kuehn M, Nissen D, Sadler RL, Ma W, Irving TC, Linke WA, Harris SP. Myosin-binding protein C forms C-links and stabilizes OFF states of myosin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.10.556972. [PMID: 37745361 PMCID: PMC10515747 DOI: 10.1101/2023.09.10.556972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Contraction force in muscle is produced by the interaction of myosin motors in the thick filaments and actin in the thin filaments and is fine-tuned by other proteins such as myosin-binding protein C (MyBP-C). One form of control is through the regulation of myosin heads between an ON and OFF state in passive sarcomeres, which leads to their ability or inability to interact with the thin filaments during contraction, respectively. MyBP-C is a flexible and long protein that is tightly bound to the thick filament at its C-terminal end but may be loosely bound at its middle- and N-terminal end (MyBP-CC1C7). Under considerable debate is whether the MyBP-CC1C7 domains directly regulate myosin head ON/OFF states, and/or link thin filaments ("C-links"). Here, we used a combination of mechanics and small-angle X-ray diffraction to study the immediate and selective removal of the MyBP-CC1C7 domains of fast MyBP-C in permeabilized skeletal muscle. After cleavage, the thin filaments were significantly shorter, a result consistent with direct interactions of MyBP-C with thin filaments thus confirming C-links. Ca2+ sensitivity was reduced at shorter sarcomere lengths, and crossbridge kinetics were increased across sarcomere lengths at submaximal activation levels, demonstrating a role in crossbridge kinetics. Structural signatures of the thick filaments suggest that cleavage also shifted myosin heads towards the ON state - a marker that typically indicates increased Ca2+ sensitivity but that may account for increased crossbridge kinetics at submaximal Ca2+ and/or a change in the force transmission pathway. Taken together, we conclude that MyBP-CC1C7 domains play an important role in contractile performance which helps explain why mutations in these domains often lead to debilitating diseases.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Nichlas M Engels
- Department of Cellular and Molecular Medicine, University of Arizona; Tucson, AZ, USA
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Rachel L Sadler
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Thomas C Irving
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster; Muenster, Germany
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Månsson A, Ušaj M, Moretto L, Matusovsky O, Velayuthan LP, Friedman R, Rassier DE. New paradigms in actomyosin energy transduction: Critical evaluation of non-traditional models for orthophosphate release. Bioessays 2023; 45:e2300040. [PMID: 37366639 DOI: 10.1002/bies.202300040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023]
Abstract
Release of the ATP hydrolysis product ortophosphate (Pi) from the active site of myosin is central in chemo-mechanical energy transduction and closely associated with the main force-generating structural change, the power-stroke. Despite intense investigations, the relative timing between Pi-release and the power-stroke remains poorly understood. This hampers in depth understanding of force production by myosin in health and disease and our understanding of myosin-active drugs. Since the 1990s and up to today, models that incorporate the Pi-release either distinctly before or after the power-stroke, in unbranched kinetic schemes, have dominated the literature. However, in recent years, alternative models have emerged to explain apparently contradictory findings. Here, we first compare and critically analyze three influential alternative models proposed previously. These are either characterized by a branched kinetic scheme or by partial uncoupling of Pi-release and the power-stroke. Finally, we suggest critical tests of the models aiming for a unified picture.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Luisa Moretto
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Oleg Matusovsky
- Department of Kinesiology and Physical Education, McGill University, Montreal, Québec, Canada
| | - Lok Priya Velayuthan
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Ran Friedman
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Québec, Canada
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Jalali F, Nazari MA, Bahrami A, Perrier P, Payan Y. FIM: A fatigued-injured muscle model based on the sliding filament theory. Comput Biol Med 2023; 164:107367. [PMID: 37595519 DOI: 10.1016/j.compbiomed.2023.107367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 07/24/2023] [Accepted: 08/12/2023] [Indexed: 08/20/2023]
Abstract
Skeletal muscle modeling has a vital role in movement studies and the development of therapeutic approaches. In the current study, a Huxley-based model for skeletal muscle is proposed, which demonstrates the impact of impairments in muscle characteristics. This model focuses on three identified ions: H+, inorganic phosphate Pi, and Ca2+. Modifications are made to actin-myosin attachment and detachment rates to study the effects of H+ and Pi. Additionally, an activation coefficient is included to represent the role of calcium ions interacting with troponin, highlighting the importance of Ca2+. It is found that maximum isometric muscle force decreases by 9.5% due to a reduction in pH from 7.4 to 6.5 and by 47.5% in case of the combination of a reduction in pH and an increase of Pi concentration up to 30 mM, respectively. Then the force decline caused by a fall in the active calcium ions is studied. When only 15% of the total calcium in the myofibrillar space is able to interact with troponin, up to 80% force drop is anticipated by the model. The proposed fatigued-injured muscle model is useful to study the effect of various shortening velocities and initial muscle-tendon lengths on muscle force; in addition, the benefits of the model go beyond predicting the force in different conditions as it can also predict muscle stiffness and power. The power and stiffness decrease by 40% and 6.5%, respectively, due to the pH reduction, and the simultaneous accumulation of H+ and Pi leads to a 50% and 18% drop in power and stiffness.
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Affiliation(s)
- Fatemeh Jalali
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Mohammad Ali Nazari
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran; Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, 38000, Grenoble, France.
| | - Arash Bahrami
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Pascal Perrier
- Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab, 38000, Grenoble, France
| | - Yohan Payan
- Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, 38000, Grenoble, France
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6
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Ho JQ, Abramowitz MK. Clinical Consequences of Metabolic Acidosis-Muscle. Adv Chronic Kidney Dis 2022; 29:395-405. [PMID: 36175077 DOI: 10.1053/j.ackd.2022.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/10/2022] [Accepted: 04/25/2022] [Indexed: 01/25/2023]
Abstract
Metabolic acidosis is common in people with chronic kidney disease and can contribute to functional decline, morbidity, and mortality. One avenue through which metabolic acidosis can result in these adverse clinical outcomes is by negatively impacting skeletal muscle; this can occur through several pathways. First, metabolic acidosis promotes protein degradation and impairs protein synthesis, which lead to muscle breakdown. Second, metabolic acidosis hinders mitochondrial function, which decreases oxidative phosphorylation and reduces energy production. Third, metabolic acidosis directly limits muscle contraction. The purpose of this review is to examine the specific mechanisms of each pathway through which metabolic acidosis affects muscle, the impact of metabolic acidosis on physical function, and the effect of treating metabolic acidosis on functional outcomes.
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Affiliation(s)
- Jim Q Ho
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY
| | - Matthew K Abramowitz
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY; Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY; Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY.
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7
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Lopes-Silva JP, Correia-Oliveira CR. Acute effects of sodium bicarbonate ingestion on cycling time-trial performance: A systematic review and meta-analysis of randomized controlled trials. Eur J Sport Sci 2022; 23:943-954. [PMID: 35633035 DOI: 10.1080/17461391.2022.2071171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study aimed to investigate the isolated effects of NaHCO3 on cycling time-trial performance. Furthermore, we investigated whether the ingestion time of NaHCO3, standardized or individualized based on time to peak, could be effective in improving cycling time-trial performance. A systematic review was carried out on randomized placebo-controlled studies. A random-effects meta-analysis assessed the standardized mean difference (SMD) between NaHCO3 and placebo conditions. Eighteen studies were qualitatively (systematic review) and quantitatively (meta-analysis) analysed concerning mean power output (Wmean) (n = 182) and time performance (n = 201). The reviewed studies showed a low risk of bias and homogenous results for Wmean (I2 = 0%) and performance time (I2 = 0%). Overall, when compared to placebo, the NaHCO3 ingestion improved the Wmean (SMD: 0.42; 95% CI: 0.21-0.63; P = 0.001) and performance time (SMD: 0.22; 95% CI: 0.02-0.43; P = 0.03). Similarly, the NaHCO3 ingestion using a time-to-peak strategy improved the Wmean (SMD: 0.39; 95% CI: 0.03-0.75; P = 0.04; I2 = 15%) and performance time (SMD: 0.34; 95% CI: 0.07-0.61, P = 0.01, I2 = 0%). The present findings reveal that NaHCO3 ingestion has the potential to increase the overall performance time and Wmean in cycling time trials. HighlightsNaHCO3 is an effective strategy to increase cycling time-trial performance.The standardized protocol did not improve the cycling time-trial performance parameters.The individualized time-to-peak NaHCO3 ingestion has a positive effect on time and Wmean during cycling time-trial performance.
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Affiliation(s)
- João Paulo Lopes-Silva
- Applied Research Group to Performance and Health, CESMAC University Center, Maceió, Brazil
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de Oliveira LF, Dolan E, Swinton PA, Durkalec-Michalski K, Artioli GG, McNaughton LR, Saunders B. Extracellular Buffering Supplements to Improve Exercise Capacity and Performance: A Comprehensive Systematic Review and Meta-analysis. Sports Med 2022; 52:505-526. [PMID: 34687438 DOI: 10.1007/s40279-021-01575-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 02/05/2023]
Abstract
BACKGROUND Extracellular buffering supplements [sodium bicarbonate (SB), sodium citrate (SC), sodium/calcium lactate (SL/CL)] are ergogenic supplements, although questions remain about factors which may modify their effect. OBJECTIVE To quantify the main effect of extracellular buffering agents on exercise outcomes, and to investigate the influence of potential moderators on this effect using a systematic review and meta-analytic approach. METHODS This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three databases were searched for articles that were screened according to inclusion/exclusion criteria. Bayesian hierarchical meta-analysis and meta-regression models were used to investigate pooled effects of supplementation and moderating effects of a range of factors on exercise and biomarker responses. RESULTS 189 articles with 2019 participants were included, 158 involving SB supplementation, 30 with SC, and seven with CL/SL; four studies provided a combination of buffering supplements together. Supplementation led to a mean estimated increase in blood bicarbonate of + 5.2 mmol L-1 (95% credible interval (CrI) 4.7-5.7). The meta-analysis models identified a positive overall effect of supplementation on exercise capacity and performance compared to placebo [ES0.5 = 0.17 (95% CrI 0.12-0.21)] with potential moderating effects of exercise type and duration, training status and when the exercise test was performed following prior exercise. The greatest ergogenic effects were shown for exercise durations of 0.5-10 min [ES0.5 = 0.18 (0.13-0.24)] and > 10 min [ES0.5 = 0.22 (0.10-0.33)]. Evidence of greater effects on exercise were obtained when blood bicarbonate increases were medium (4-6 mmol L-1) and large (> 6 mmol L-1) compared with small (≤ 4 mmol L-1) [βSmall:Medium = 0.16 (95% CrI 0.02-0.32), βSmall:Large = 0.13 (95% CrI - 0.03 to 0.29)]. SB (192 outcomes) was more effective for performance compared to SC (39 outcomes) [βSC:SB = 0.10 (95% CrI - 0.02 to 0.22)]. CONCLUSIONS Extracellular buffering supplements generate large increases in blood bicarbonate concentration leading to positive overall effects on exercise, with sodium bicarbonate being most effective. Evidence for several group-level moderating factors were identified. These data can guide an athlete's decision as to whether supplementation with buffering agents might be beneficial for their specific aims.
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Affiliation(s)
- Luana Farias de Oliveira
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
| | - Eimear Dolan
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
| | - Paul A Swinton
- School of Health Sciences, Robert Gordon University, Aberdeen, UK
| | - Krzysztof Durkalec-Michalski
- Department of Sports Dietetics, Poznań University of Physical Education, Poznań, Poland
- Department of Human Nutrition and Dietetics, Poznań University of Life Sciences, Poznań, Poland
| | - Guilherme G Artioli
- Department of Life Sciences, Manchester Metropolitan University, John Dalton Building, Manchester, M1 5GD, UK
| | - Lars R McNaughton
- Sports Nutrition and Performance Group, Department of Sport and Physical Activity, Edge Hill University, Ormskirk, UK
| | - Bryan Saunders
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil.
- Department of Sports Dietetics, Poznań University of Physical Education, Poznań, Poland.
- Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil.
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Bonilla DA, Kreider RB, Petro JL, Romance R, García-Sillero M, Benítez-Porres J, Vargas-Molina S. Creatine Enhances the Effects of Cluster-Set Resistance Training on Lower-Limb Body Composition and Strength in Resistance-Trained Men: A Pilot Study. Nutrients 2021; 13:2303. [PMID: 34371813 PMCID: PMC8308441 DOI: 10.3390/nu13072303] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 12/26/2022] Open
Abstract
Creatine monohydrate (CrM) supplementation has been shown to improve body composition and muscle strength when combined with resistance training (RT); however, no study has evaluated the combination of this nutritional strategy with cluster-set resistance training (CS-RT). The purpose of this pilot study was to evaluate the effects of CrM supplementation during a high-protein diet and a CS-RT program on lower-limb fat-free mass (LL-FFM) and muscular strength. Twenty-three resistance-trained men (>2 years of training experience, 26.6 ± 8.1 years, 176.3 ± 6.8 cm, 75.6 ± 8.9 kg) participated in this study. Subjects were randomly allocated to a CS-RT+CrM (n = 8), a CS-RT (n = 8), or a control group (n = 7). The CS-RT+CrM group followed a CrM supplementation protocol with 0.1 g·kg-1·day-1 over eight weeks. Two sessions per week of lower-limb CS-RT were performed. LL-FFM corrected for fat-free adipose tissue (dual-energy X-ray absorptiometry) and muscle strength (back squat 1 repetition maximum (SQ-1RM) and countermovement jump (CMJ)) were measured pre- and post-intervention. Significant improvements were found in whole-body fat mass, fat percentage, LL-fat mass, LL-FFM, and SQ-1RM in the CS-RT+CrM and CS-RT groups; however, larger effect sizes were obtained in the CS-RT+CrM group regarding whole body FFM (0.64 versus 0.16), lower-limb FFM (0.62 versus 0.18), and SQ-1RM (1.23 versus 0.75) when compared to the CS-RT group. CMJ showed a significant improvement in the CS-RT+CrM group with no significant changes in CS-RT or control groups. No significant differences were found between groups. Eight weeks of CrM supplementation plus a high-protein diet during a CS-RT program has a higher clinical meaningfulness on lower-limb body composition and strength-related variables in trained males than CS-RT alone. Further research might study the potential health and therapeutic effects of this nutrition and exercise strategy.
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Affiliation(s)
- Diego A. Bonilla
- Research Division, Dynamical Business & Science Society–DBSS International SAS, Bogotá 110861, Colombia;
- Research Group in Biochemistry and Molecular Biology, Universidad Distrital Francisco José de Caldas, Bogotá 110311, Colombia
- Research Group in Physical Activity, Sports and Health Sciences (GICAFS), Universidad de Córdoba, Montería 230002, Colombia
- kDNA Genomics®, Joxe Mari Korta Research Center, University of the Basque Country UPV/EHU, 20018 Donostia-San Sebastián, Spain
| | - Richard B. Kreider
- Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Texas A&M University, College Station, TX 77843, USA;
| | - Jorge L. Petro
- Research Division, Dynamical Business & Science Society–DBSS International SAS, Bogotá 110861, Colombia;
- Research Group in Physical Activity, Sports and Health Sciences (GICAFS), Universidad de Córdoba, Montería 230002, Colombia
| | - Ramón Romance
- Body Composition and Biodynamic Laboratory, Faculty of Education Sciences, University of Málaga, 29071 Málaga, Spain;
| | - Manuel García-Sillero
- Faculty of Sport Sciences, EADE-University of Wales Trinity Saint David, 29018 Málaga, Spain; (M.G.-S.); (S.V.-M.)
| | - Javier Benítez-Porres
- Physical Education and Sports, Faculty of Medicine, University of Málaga, 29071 Málaga, Spain;
| | - Salvador Vargas-Molina
- Faculty of Sport Sciences, EADE-University of Wales Trinity Saint David, 29018 Málaga, Spain; (M.G.-S.); (S.V.-M.)
- Physical Education and Sports, Faculty of Medicine, University of Málaga, 29071 Málaga, Spain;
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10
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Perim P, Gobbi N, Duarte B, Farias de Oliveira L, Costa LAR, Sale C, Gualano B, Dolan E, Saunders B. Beta-alanine did not improve high-intensity performance throughout simulated road cycling. Eur J Sport Sci 2021; 22:1240-1249. [PMID: 34092191 DOI: 10.1080/17461391.2021.1940304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
This study investigated the effect of beta-alanine supplementation on short-duration sprints and final 4-km simulated uphill cycling time-trial performance during a comprehensive and novel exercise protocol representative of the demands of road-race cycling, and determined if changes were related to increases in muscle carnosine content. Seventeen cyclists (age 38 ± 9 y, height 1.76 ± 0.07 m, body mass 71.4 ± 8.8 kg, V̇O2max 52.4 ± 8.3 ml·kg-1·min-1) participated in this placebo-controlled, double-blind study. Cyclists undertook a prolonged intermittent cycling protocol lasting 125 min, with a 10-s sprint every 20 min, finishing with a 4-km time-trial at 5% simulated incline. Participants completed two familiarization sessions, and two main sessions, one pre-supplementation and one post-supplementation following 28 days of 6.4 g·day-1 of beta-alanine (N=11) or placebo (N=6; maltodextrin). Muscle biopsies obtained pre- and post-supplementation were analysed for muscle carnosine content. There were no main effects on sprint performance throughout the intermittent cycling test (all P>0.05). There was no group (P=0.69), time (P=0.50) or group x time interaction (P=0.26) on time-to-complete the 4-km time-trial. Time-to-completion did not change from pre- to post-supplementation for BA (-19.2 ± 45.6 s, P=0.43) or PL (+2.8 ± 31.6 s, P=0.99). Beta-alanine supplementation increased muscle carnosine content from pre- to post-supplementation (+9.4 ± 4.0 mmol·kg-1dm; P<0.0001) but was not related to performance changes (r=0.320, P=0.37). Chronic beta-alanine supplementation increased muscle carnosine content but did not improve short-duration sprint performance throughout simulated road race cycling, nor 4-km uphill time-trial performance conducted at the end of this cycling test.Highlights Performance during prolonged cycling events often depends on the ability to maintain an increased power output during higher intensity periods. Thus, cyclists are likely heavily dependent on their ability to resist fatigue during these periods of high-intensity activity.Meta-analytical data show beta-alanine to be an effective supplement to improve exercise outcomes, but little work exists on its efficacy during dynamic actions that are common during prolonged cycling.Beta-alanine supplementation increased muscle carnosine content but did not generate improvements in the performance of high-intensity cycling (10-s sprints or 4-km uphill time-trial) during a simulated road race cycling protocol.These data suggest that short duration sprints (≤10 s) and longer duration (>10 min) high-intensity activity throughout endurance cycling may not be improved with beta-alanine supplementation despite increases in muscle carnosine content.
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Affiliation(s)
- Pedro Perim
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Nathan Gobbi
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Breno Duarte
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Luana Farias de Oliveira
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Luiz Augusto Riani Costa
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Craig Sale
- Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, United Kingdom
| | - Bruno Gualano
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil.,Food Research Center, University of São Paulo, São Paulo, Brazil
| | - Eimear Dolan
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil
| | - Bryan Saunders
- Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil.,Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, Brazil
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11
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Durkalec-Michalski K, Kusy K, Główka N, Zieliński J. The effect of multi-ingredient intra- versus extra-cellular buffering supplementation combined with branched-chain amino acids and creatine on exercise-induced ammonia blood concentration and aerobic capacity in taekwondo athletes. J Int Soc Sports Nutr 2021; 18:48. [PMID: 34127014 PMCID: PMC8204562 DOI: 10.1186/s12970-021-00451-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 06/04/2021] [Indexed: 12/19/2022] Open
Abstract
Background This study aimed to investigate the effect of multi-ingredient intra- (BA) versus extra- (ALK) cellular buffering factor supplementation, combined with the customary intake of branched-chain amino acids (BCAA) and creatine malate (TCM), on body composition, exercise variables, and biochemical and hematological parameters in 9 elite taekwondo athletes. Methods Eight-week randomized double-blind crossover BA (5.0 g·day−1 of β-alanine) versus ALK (0.07 g·kgFFM−1·day−1 of sodium bicarbonate) supplementation combined with BCAA (0.2 g·kgFFM−1·day−1) and TCM (0.05 g·kgFFM−1·day−1) during a standard 8-week taekwondo training period was implemented. In the course of the experiment, body composition (dual X-ray absorptiometry), aerobic capacity (ergospirometric measurements during an incremental treadmill test until exhaustion), and exercise blood biomarkers concentrations were measured. Data were analyzed using repeated measures within-between interaction analysis of variance with the inclusion of experimental supplementation order. Results The maximum post-exercise blood ammonia concentration decreased in both groups after supplementation (from 80.3 ± 10.6 to 72.4 ± 10.2 µmol∙L−1, p = 0.013 in BA; from 81.4 ± 8.7 to 74.2 ± 8.9 µmol∙L−1, p = 0.027 in ALK), indicating reduced exercise-related adenosine triphosphate degradation. However, no differences were found in body composition, aerobic capacity, blood lactate concentration, and hematological parameters after neither BA (combined with BCAA and TCM) nor ALK (combined with BCAA and TCM) supplementation. Conclusions In highly trained taekwondo athletes, neither extra- nor intracellular buffering enhancement resulting from BA and ALK supplementation, combined with BCAA and TCM treatment, affects body mass and composition, maximum oxygen uptake, and hematological indices, even though certain advantageous metabolic adaptations can be observed. Supplementary Information The online version contains supplementary material available at 10.1186/s12970-021-00451-3.
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Affiliation(s)
- Krzysztof Durkalec-Michalski
- Department of Sports Dietetics, Poznan University of Physical Education, Królowej Jadwigi 27/39, 61-871, Poznań, Poland. .,Department of Human Nutrition and Dietetics, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624, Poznań, Poland.
| | - Krzysztof Kusy
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Królowej Jadwigi 27/39, 61-871, Poznań, Poland
| | - Natalia Główka
- Department of Human Nutrition and Dietetics, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624, Poznań, Poland
| | - Jacek Zieliński
- Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, Królowej Jadwigi 27/39, 61-871, Poznań, Poland
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12
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New insights into muscle function in chronic kidney disease and metabolic acidosis. Curr Opin Nephrol Hypertens 2021; 30:369-376. [PMID: 33767065 DOI: 10.1097/mnh.0000000000000700] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE OF REVIEW : Sarcopenia, defined as decreased muscle mass or function, is prevalent in chronic kidney disease (CKD) increasing the risk of mobility impairment and frailty. CKD leads to metabolic acidosis (MA) and retention of uremic toxins contributing to insulin resistance and impaired muscle mitochondrial energetics. Here we focus on the central role of muscle mitochondrial metabolism in muscle function. RECENT FINDINGS : Mitochondrial dysfunction underlies muscle wasting and poor physical endurance in CKD. Uremic toxins accumulate in muscle disrupting mitochondrial respiration and enzymes. Changes in mitochondrial quantity, quality, and oxidative capacity contribute to mobility impairment in CKD. Major determinants of muscle mitochondrial function are kidney function, inflammation, and oxidative stress. In CKD, MA is the major determinant of muscle mitochondrial function. Metabolomics reveals defects in pathways linked to mitochondrial energy metabolism and acid-base homeostasis underlying insulin resistance in CKD. SUMMARY : Decreased mitochondrial capacity and quality control can impair muscle function contributing to decreased physical endurance. MA augments insulin resistance perpetuating the catabolic state underlying muscle wasting in CKD. Further studies are needed to investigate if targeting of MA improves muscle mitochondrial function and insulin resistance translating into meaningful improvements in physical endurance.
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13
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Saunders B, Oliveira LFD, Dolan E, Durkalec-Michalski K, McNaughton L, Artioli GG, Swinton PA. Sodium bicarbonate supplementation and the female athlete: A brief commentary with small scale systematic review and meta-analysis. Eur J Sport Sci 2021; 22:745-754. [PMID: 33487131 DOI: 10.1080/17461391.2021.1880649] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Sodium bicarbonate (SB) is considered an effective ergogenic supplement for improving high-intensity exercise capacity and performance, although recent data suggests that women may be less amenable to its ergogenic effects than men. Currently, an apparent paucity of data on women means no consensus exists on whether women benefit from SB supplementation. The aim of the current study was to quantify the proportion of the published literature on SB supplementation that includes women, and to synthesise the evidence regarding its effects on blood bicarbonate and exercise performance in women by performing a systematic review and meta-analysis. Electronic searches of the literature were undertaken using three databases (MEDLINE, Embase, SPORTDiscus) to identify relevant articles. All meta-analyses were performed within a Bayesian framework. A total of 149 SB articles were identified, 11 of which contained individual group data for women. Results indicated a pooled blood bicarbonate increase of 7.4 [95%CrI: 4.2-10.4 mmol·L-1] following supplementation and a pooled standardised exercise effect size of 0.37 [95%CrI: -0.06-0.92]. The SB literature is skewed, with only 20% (30 studies) of studies employing female participants, of which only 11 studies (7.4%) provided group analyses exclusively in women. Despite the small amount of available data, results are consistent in showing that SB supplementation in women leads to large changes in blood bicarbonate and that there is strong evidence for a positive ergogenic effect on exercise performance that is likely to be small to medium in magnitude.Highlights This study aimed to quantify the proportion of the published literature on sodium bicarbonate supplementation that includes women and to synthesise the evidence regarding its ergogenic effect on women, using a systematic review and meta-analytic approach.The sodium bicarbonate literature is skewed, with only 30 studies (20%) employing female participants, of which only 11 studies (7.4%) provided group analyses exclusively in women.Despite the small amount of available data, results are consistent in showing that sodium bicarbonate supplementation in women leads to large changes in blood bicarbonate and that there is strong evidence for a positive ergogenic effect on exercise performance that is likely small to medium in magnitude.Based on these findings, we do not believe there is any evidence to support sex-specific sodium bicarbonate dosing recommendations and that current recommendations of 0.2-0.3 g·kg-1BM of SB taken 60-180 min prior to high-intensity exercise appear appropriate for the female athlete.
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Affiliation(s)
- Bryan Saunders
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil.,Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil.,Department of Dietetics, Poznań University of Physical Education, Poznań, Poland
| | - Luana Farias de Oliveira
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
| | - Eimear Dolan
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
| | - Krzysztof Durkalec-Michalski
- Department of Dietetics, Poznań University of Physical Education, Poznań, Poland.,Department of Human Nutrition and Dietetics, Poznań University of Life Sciences, Poznań, Poland
| | - Lars McNaughton
- Sports Nutrition and Performance Group, Department of Sport and Physical Activity, Edge Hill University, Ormskirk, UK
| | - Guilherme Giannini Artioli
- Applied Physiology & Nutrition Research Group, Rheumatology Division, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
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14
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Sudarshi Premawardhana DM, Zhang F, Xu J, Gage MJ. The Poly-E motif in Titin's PEVK region undergoes pH dependent conformational changes. Biochem Biophys Rep 2020; 24:100859. [PMID: 33294637 PMCID: PMC7691732 DOI: 10.1016/j.bbrep.2020.100859] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 10/21/2020] [Accepted: 11/03/2020] [Indexed: 12/03/2022] Open
Abstract
The muscle protein titin plays a crucial role in passive elasticity and the disordered PEVK region within titin is central to that function. The PEVK region is so named due to its high proline, glutamate, valine and lysine content and the high charge density in this region results in a lack of organized structure within this domain. The PEVK region is highly extensible but the molecular interactions that contribute to the elastic nature of the PEVK still remain poorly described. The PEVK region is formed by two unique sequence motifs. The PPAK motif is a 26 to 28 amino acid sequence that contains a mixture of charged and hydrophobic residues and is the primary building block for the PEVK region. Poly-E sequence motifs vary in length and contain clusters of 3–4 glutamic acids distributed throughout the motif. In this study, we derived two 28-residue peptides from the human titin protein sequence and measured their structural characteristics over a range of pHs. Our results demonstrate that the poly-E peptide undergoes a shift from a more rigid and elongated state to a more collapsed state as pH decreases with the midpoint of this transition being at pH ~5.5. Interestingly, a similar conformational shift is not observed in the PPAK peptide. These results suggest that the poly-E motif might provide a nucleating site for the PEVK when the muscle is not in an extended state. Poly-E peptides have a more extended conformation at pH 7.0 than PPAK peptides. Poly-E peptides assume a more relaxed conformation below pH 6. PPAK peptides do not show any conformational sensitivity to changes in pH.
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Affiliation(s)
- Dassanayake Mudiyanselage Sudarshi Premawardhana
- Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA
- UMass Movement Center, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Fang Zhang
- Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Jin Xu
- Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Matthew J. Gage
- Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA
- UMass Movement Center, University of Massachusetts Lowell, Lowell, MA, 01854, USA
- Corresponding author. Department of Chemistry University of Massachusetts Lowell Lowell, Chemistry Department, University of Massachusetts Lowell, Lowell, MA, 01854, USA.
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15
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Tresguerres M, Clifford AM, Harter TS, Roa JN, Thies AB, Yee DP, Brauner CJ. Evolutionary links between intra- and extracellular acid-base regulation in fish and other aquatic animals. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:449-465. [PMID: 32458594 DOI: 10.1002/jez.2367] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/10/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022]
Abstract
The acid-base relevant molecules carbon dioxide (CO2 ), protons (H+ ), and bicarbonate (HCO3 - ) are substrates and end products of some of the most essential physiological functions including aerobic and anaerobic respiration, ATP hydrolysis, photosynthesis, and calcification. The structure and function of many enzymes and other macromolecules are highly sensitive to changes in pH, and thus maintaining acid-base homeostasis in the face of metabolic and environmental disturbances is essential for proper cellular function. On the other hand, CO2 , H+ , and HCO3 - have regulatory effects on various proteins and processes, both directly through allosteric modulation and indirectly through signal transduction pathways. Life in aquatic environments presents organisms with distinct acid-base challenges that are not found in terrestrial environments. These include a relatively high CO2 relative to O2 solubility that prevents internal CO2 /HCO3 - accumulation to buffer pH, a lower O2 content that may favor anaerobic metabolism, and variable environmental CO2 , pH and O2 levels that require dynamic adjustments in acid-base homeostatic mechanisms. Additionally, some aquatic animals purposely create acidic or alkaline microenvironments that drive specialized physiological functions. For example, acidifying mechanisms can enhance O2 delivery by red blood cells, lead to ammonia trapping for excretion or buoyancy purposes, or lead to CO2 accumulation to promote photosynthesis by endosymbiotic algae. On the other hand, alkalinizing mechanisms can serve to promote calcium carbonate skeletal formation. This nonexhaustive review summarizes some of the distinct acid-base homeostatic mechanisms that have evolved in aquatic organisms to meet the particular challenges of this environment.
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Affiliation(s)
- Martin Tresguerres
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Alexander M Clifford
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Till S Harter
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Jinae N Roa
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Angus B Thies
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Daniel P Yee
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, California
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, Canada
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16
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Sundberg CW, Prost RW, Fitts RH, Hunter SK. Bioenergetic basis for the increased fatigability with ageing. J Physiol 2019; 597:4943-4957. [PMID: 31018011 DOI: 10.1113/jp277803] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/18/2019] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The mechanisms for the age-related increase in fatigability during dynamic exercise remain elusive. We tested whether age-related impairments in muscle oxidative capacity would result in a greater accumulation of fatigue causing metabolites, inorganic phosphate (Pi ), hydrogen (H+ ) and diprotonated phosphate (H2 PO4 - ), in the muscle of old compared to young adults during a dynamic knee extension exercise. The age-related increase in fatigability (reduction in mechanical power) of the knee extensors was closely associated with a greater accumulation of metabolites within the working muscle but could not be explained by age-related differences in muscle oxidative capacity. These data suggest that the increased fatigability in old adults during dynamic exercise is primarily determined by age-related impairments in skeletal muscle bioenergetics that result in a greater accumulation of metabolites. ABSTRACT The present study aimed to determine whether the increased fatigability in old adults during dynamic exercise is associated with age-related differences in skeletal muscle bioenergetics. Phosphorus nuclear magnetic resonance spectroscopy was used to quantify concentrations of high-energy phosphates and pH in the knee extensors of seven young (22.7 ± 1.2 years; six women) and eight old adults (76.4 ± 6.0 years; seven women). Muscle oxidative capacity was measured from the phosphocreatine (PCr) recovery kinetics following a 24 s maximal voluntary isometric contraction. The fatiguing exercise consisted of 120 maximal velocity contractions (one contraction per 2 s) against a load equivalent to 20% of the maximal voluntary isometric contraction. The PCr recovery kinetics did not differ between young and old adults (0.023 ± 0.007 s-1 vs. 0.019 ± 0.004 s-1 , respectively). Fatigability (reductions in mechanical power) of the knee extensors was ∼1.8-fold greater with age and was accompanied by a greater decrease in pH (young = 6.73 ± 0.09, old = 6.61 ± 0.04) and increases in concentrations of inorganic phosphate, [Pi ], (young = 22.7 ± 4.8 mm, old = 32.3 ± 3.6 mm) and diprotonated phosphate, [H2 PO4 - ], (young = 11.7 ± 3.6 mm, old = 18.6 ± 2.1 mm) at the end of the exercise in old compared to young adults. The age-related increase in power loss during the fatiguing exercise was strongly associated with intracellular pH (r = -0.837), [Pi ] (r = 0.917) and [H2 PO4 - ] (r = 0.930) at the end of the exercise. These data suggest that the age-related increase in fatigability during dynamic exercise has a bioenergetic basis and is explained by an increased accumulation of metabolites within the muscle.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA.,Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Robert W Prost
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
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17
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Sundberg CW, Fitts RH. Bioenergetic basis of skeletal muscle fatigue. CURRENT OPINION IN PHYSIOLOGY 2019; 10:118-127. [PMID: 31342000 DOI: 10.1016/j.cophys.2019.05.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Energetic demand from high-intensity exercise can easily exceed ATP synthesis rates of mitochondria leading to a reliance on anaerobic metabolism. The reliance on anaerobic metabolism results in the accumulation of intracellular metabolites, namely inorganic phosphate (Pi) and hydrogen (H+), that are closely associated with exercise-induced reductions in power. Cellular and molecular studies have revealed several steps where these metabolites impair contractile function demonstrating a causal role in fatigue. Elevated Pi or H+ directly inhibits force and power of the cross-bridge and decreases myofibrillar Ca2+ sensitivity, whereas Pi also inhibits Ca2+ release from the sarcoplasmic reticulum (SR). When both metabolites are elevated, they act synergistically to cause marked reductions in power, indicating that fatigue during high-intensity exercise has a bioenergetic basis.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI.,Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI
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