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Hajj‐Boutros G, Sonjak V, Faust A, Balram S, Lagacé J, St‐Martin P, Divsalar DN, Sadeghian F, Liu‐Ambrose T, Blaber AP, Dionne IJ, Duchesne S, Kontulainen S, Theou O, Morais JA. Myths and Methodologies: Understanding the health impact of head down bedrest for the benefit of older adults and astronauts. Study protocol of the Canadian Bedrest Study. Exp Physiol 2024; 109:812-827. [PMID: 38372420 PMCID: PMC11061626 DOI: 10.1113/ep091473] [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: 08/18/2023] [Accepted: 01/23/2024] [Indexed: 02/20/2024]
Abstract
Weightlessness during spaceflight can harm various bodily systems, including bone density, muscle mass, strength and cognitive functions. Exercise appears to somewhat counteract these effects. A terrestrial model for this is head-down bedrest (HDBR), simulating gravity loss. This mirrors challenges faced by older adults in extended bedrest and space environments. The first Canadian study, backed by the Canadian Space Agency, Canadian Institutes of Health Research, and Canadian Frailty Network, aims to explore these issues. The study seeks to: (1) scrutinize the impact of 14-day HDBR on physiological, psychological and neurocognitive systems, and (2) assess the benefits of exercise during HDBR. Eight teams developed distinct protocols, harmonized in three videoconferences, at the McGill University Health Center. Over 26 days, 23 participants aged 55-65 underwent baseline measurements, 14 days of -6° HDBR, and 7 days of recovery. Half did prescribed exercise thrice daily combining resistance and endurance exercise for a total duration of 1 h. Assessments included demographics, cardiorespiratory fitness, bone health, body composition, quality of life, mental health, cognition, muscle health and biomarkers. This study has yielded some published outcomes, with more forthcoming. Findings will enrich our comprehension of HDBR effects, guiding future strategies for astronaut well-being and aiding bedrest-bound older adults. By outlining evidence-based interventions, this research supports both space travellers and those enduring prolonged bedrest.
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Affiliation(s)
- Guy Hajj‐Boutros
- Research Institute of McGill University Health CentreMcGill UniversityMontréalQuebecCanada
| | - Vita Sonjak
- Research Institute of McGill University Health CentreMcGill UniversityMontréalQuebecCanada
| | - Andréa Faust
- Research Institute of McGill University Health CentreMcGill UniversityMontréalQuebecCanada
| | - Sharmila Balram
- Research Institute of McGill University Health CentreMcGill UniversityMontréalQuebecCanada
| | - Jean‐Christophe Lagacé
- Faculté des Sciences de l'activité physique, Centre de recherche sur le VieillissementUniversité de SherbrookeSherbrookeQuebecCanada
| | - Philippe St‐Martin
- Faculté des Sciences de l'activité physique, Centre de recherche sur le VieillissementUniversité de SherbrookeSherbrookeQuebecCanada
| | - Donya Naz Divsalar
- Department of Biomedical Physiology and KinesiologySimon Fraser UniversityGreater VancouverBritish ColumbiaCanada
| | - Farshid Sadeghian
- Department of Biomedical Physiology and KinesiologySimon Fraser UniversityGreater VancouverBritish ColumbiaCanada
| | - Teresa Liu‐Ambrose
- Aging, Mobility and Cognitive Neuroscience Laboratory, Department of Physical Therapy, Faculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Health Research InstituteVancouverBritish ColumbiaCanada
- Centre for Hip Health and MobilityVancouver Coastal Health Research InstituteVancouverBritish ColumbiaCanada
| | - Andrew P. Blaber
- Department of Biomedical Physiology and KinesiologySimon Fraser UniversityGreater VancouverBritish ColumbiaCanada
| | - Isabelle J. Dionne
- Faculté des Sciences de l'activité physique, Centre de recherche sur le VieillissementUniversité de SherbrookeSherbrookeQuebecCanada
| | - Simon Duchesne
- Department of Radiology and Nuclear MedicineUniversité LavalQuebec CityQuebecCanada
- CERVO Brain Research CenterQuebec CityQuebecCanada
| | - Saija Kontulainen
- College of KinesiologyUniversity of SaskatchewanSaskatoonSaskatchewanCanada
| | - Olga Theou
- Physiotherapy and Geriatric MedicineDalhousie UniversityHalifaxNova ScotiaCanada
| | - José A. Morais
- Division of Geriatric Medicine, McGill University Health CentreMcGill UniversityMontréalQuebecCanada
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Hannaian SJ, Lov J, Hawley SE, Dargegen M, Malenda D, Gritsas A, Gouspillou G, Morais JA, Churchward-Venne TA. Acute ingestion of a ketone monoester, whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of myofibrillar protein synthesis rates in young males: a double-blind randomized trial. Am J Clin Nutr 2024; 119:716-729. [PMID: 38215886 PMCID: PMC10972741 DOI: 10.1016/j.ajcnut.2024.01.004] [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: 09/14/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 01/14/2024] Open
Abstract
BACKGROUND Ketone bodies may have anabolic effects in skeletal muscle via their capacity to stimulate protein synthesis. Whether orally ingested exogenous ketones can stimulate postprandial myofibrillar protein synthesis (MyoPS) rates with and without dietary protein co-ingestion is unknown. OBJECTIVES This study aimed to evaluate the effects of ketone monoester intake and elevated blood β-hydroxybutyrate (β-OHB) concentration, with and without dietary protein co-ingestion, on postprandial MyoPS rates and mechanistic target of rapamycin complex 1 (mTORC1) pathway signaling. METHODS In a randomized, double-blind, parallel group design, 36 recreationally active healthy young males (age: 24.2 ± 4.1 y; body fat: 20.9% ± 5.8%; body mass index: 23.4 ± 2 kg/m2) received a primed continuous infusion of L-[ring-2H5]-phenylalanine and ingested one of the following: 1) the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KET), 2) 10 g whey protein (PRO), or 3) the combination of both (KET+PRO). Blood and muscle biopsy samples were collected during basal and postprandial (300 min) conditions to assess β-OHB, glucose, insulin, and amino acid concentrations, MyoPS rates, and mTORC1 pathway signaling. RESULTS Capillary blood β-OHB concentration increased similarly during postprandial conditions in KET and KET+PRO, with both being greater than PRO from 30 to 180 min (treatment × time interaction: P < 0.001). Postprandial plasma leucine and essential amino acid (EAA) incremental area under the curve (iAUC) over 300 min was greater (treatment: both P < 0.001) in KET+PRO compared with PRO and KET. KET, PRO, and KET+PRO stimulated postprandial MyoPS rates (0-300 min) higher than basal conditions [absolute change: 0.020%/h; (95% CI: 0.013, 0.027%/h), 0.014%/h (95% CI: 0.009, 0.019%/h), 0.019%/h (95% CI: 0.014, 0.024%/h), respectively (time: P < 0.001)], with no difference between treatments (treatment: P = 0.383) or treatment × time interaction (interaction: P = 0.245). mTORC1 pathway signaling responses did not differ between treatments (all P > 0.05). CONCLUSIONS Acute oral intake of a ketone monoester, 10 g whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of postprandial MyoPS rates in healthy young males. This trial was registered at clinicaltrials.gov as NCT04565444 (https://clinicaltrials.gov/study/NCT04565444).
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Affiliation(s)
- Sarkis J Hannaian
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada; Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Jamie Lov
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada
| | - Stephanie E Hawley
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada
| | - Manon Dargegen
- Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Divine Malenda
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada
| | - Ari Gritsas
- Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Gilles Gouspillou
- Département des Sciences de l'activité Physique, Faculté des Sciences, UQAM, Montréal, Quebec, Canada
| | - José A Morais
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada; Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada; Division of Geriatric Medicine, McGill University, Montréal, Quebec, Canada
| | - Tyler A Churchward-Venne
- Department of Kinesiology and Physical Education, McGill University, Montréal, Quebec, Canada; Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada; Division of Geriatric Medicine, McGill University, Montréal, Quebec, Canada.
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Ely IA, Phillips BE, Smith K, Wilkinson DJ, Piasecki M, Breen L, Larsen MS, Atherton PJ. A focus on leucine in the nutritional regulation of human skeletal muscle metabolism in ageing, exercise and unloading states. Clin Nutr 2023; 42:1849-1865. [PMID: 37625315 DOI: 10.1016/j.clnu.2023.08.010] [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: 01/13/2023] [Revised: 04/23/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023]
Abstract
Muscle protein synthesis (MPS) and muscle protein breakdown (MPB) are influenced through dietary protein intake and physical (in)activity, which it follows, regulate skeletal muscle (SKM) mass across the lifespan. Following consumption of dietary protein, the bio-availability of essential amino acids (EAA), and primarily leucine (LEU), drive a transient increase in MPS with an ensuing refractory period before the next MPS stimulation is possible (due to the "muscle full" state). At the same time, MPB is periodically constrained via reflex insulin actions. Layering exercise on top of protein intake increases the sensitivity of SKM to EAA, therefore extending the muscle full set-point (∼48 h), to permit long-term remodelling (e.g., hypertrophy). In contrast, ageing and physical inactivity are associated with a premature muscle full set-point in response to dietary protein/EAA and contractile activity. Of all the EAA, LEU is the most potent stimulator of the mechanistic target of rapamycin complex 1 (mTORC1)-signalling pathway, with the phosphorylation of mTORC1 substrates increasing ∼3-fold more than with all other EAA. Furthermore, maximal MPS stimulation is also achieved following low doses of LEU-enriched protein/EAA, negating the need for larger protein doses. As a result, LEU supplementation has been of long term interest to maximise muscle anabolism and subsequent net protein accretion, especially when in tandem with resistance exercise. This review highlights current knowledge vis-à-vis the anabolic effects of LEU supplementation in isolation, and in enriched protein/EAA sources (i.e., EAA and/or protein sources with added LEU), in the context of ageing, exercise and unloading states.
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Affiliation(s)
- Isabel A Ely
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK
| | - Bethan E Phillips
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK
| | - Kenneth Smith
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK
| | - Daniel J Wilkinson
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK
| | - Mathew Piasecki
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | | | - Philip J Atherton
- Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham NIHR Biomedical Research Centre, Derby, DE22 3DT, UK.
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Aragon AA, Tipton KD, Schoenfeld BJ. Age-related muscle anabolic resistance: inevitable or preventable? Nutr Rev 2023; 81:441-454. [PMID: 36018750 DOI: 10.1093/nutrit/nuac062] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Age-related loss of muscle mass, strength, and performance, commonly referred to as sarcopenia, has wide-ranging detrimental effects on human health, the ramifications of which can have serious implications for both morbidity and mortality. Various interventional strategies have been proposed to counteract sarcopenia, with a particular emphasis on those employing a combination of exercise and nutrition. However, the efficacy of these interventions can be confounded by an age-related blunting of the muscle protein synthesis response to a given dose of protein/amino acids, which has been termed "anabolic resistance." While the pathophysiology of sarcopenia is undoubtedly complex, anabolic resistance is implicated in the progression of age-related muscle loss and its underlying complications. Several mechanisms have been proposed as underlying age-related impairments in the anabolic response to protein consumption. These include decreased anabolic molecular signaling activity, reduced insulin-mediated capillary recruitment (thus, reduced amino acid delivery), and increased splanchnic retention of amino acids (thus, reduced availability for muscular uptake). Obesity and sedentarism can exacerbate, or at least facilitate, anabolic resistance, mediated in part by insulin resistance and systemic inflammation. This narrative review addresses the key factors and contextual elements involved in reduction of the acute muscle protein synthesis response associated with aging and its varied consequences. Practical interventions focused on dietary protein manipulation are proposed to prevent the onset of anabolic resistance and mitigate its progression.
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Affiliation(s)
- Alan A Aragon
- is with the Department of Family and Consumer Sciences, California State University, Northridge, California, USA
| | - Kevin D Tipton
- is with the Institute of Performance Nutrition, Edinburgh, Scotland
| | - Brad J Schoenfeld
- is with the Department of Health Sciences, CUNY Lehman College, Bronx, New York, USA
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Abdulla H, Phillips B, Wilkinson D, Gates A, Limb M, Jandova T, Bass J, Lewis J, Williams J, Smith K, Idris I, Atherton P. Effects of GLP-1 Infusion Upon Whole-body Glucose Uptake and Skeletal Muscle Perfusion During Fed-state in Older Men. J Clin Endocrinol Metab 2023; 108:971-978. [PMID: 36260533 PMCID: PMC9999358 DOI: 10.1210/clinem/dgac613] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/05/2022] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Ageing skeletal muscles become both insulin resistant and atrophic. The hormone glucagon-like peptide 1 (GLP-1) facilitates postprandial glucose uptake as well as augmenting muscle perfusion, independent of insulin action. We thus hypothesized exogenous GLP-1 infusions would enhance muscle perfusion and positively affect glucose metabolism during fed-state clamps in older people. METHODS Eight men (71 ± 1 years) were studied in a randomized crossover trial. Basal blood samples were taken before postprandial (fed-state) insulin and glucose clamps, accompanied by amino acid infusions, for 3 hours. Reflecting this, following insertions of peripheral and femoral vessels cannulae and baseline measurements, peripheral IV infusions of octreotide, insulin (Actrapid), 20% glucose, and mixed amino acids; Vamin 14-EF with or without a femoral arterial GLP-1 infusion were started. GLP-1, insulin, and C-peptide were measured by ELISA. Muscle microvascular blood flow was assessed via contrast enhanced ultrasound. Whole-body glucose handling was assayed by assessing glucose infusion rate parameters. RESULTS Skeletal muscle microvascular blood flow significantly increased in response to GLP-1 vs feeding alone (5.0 ± 2.1 vs 1.9 ± 0.7 fold-change from basal, respectively; P = 0.008), while also increasing whole-body glucose uptake (area under the curve 16.9 ± 1.7 vs 11.4 ± 1.8 mg/kg-1/180 minutes-1, P = 0.02 ± GLP, respectively). CONCLUSIONS The beneficial effects of GLP-1 on whole-body glycemic control are evident with insulin clamped at fed-state levels. GLP-1 further enhances the effects of insulin on whole-body glucose uptake in older men, underlining its role as a therapeutic target. The effects of GLP-1 in enhancing microvascular flow likely also affects other glucose-regulatory organs, reflected by greater whole-body glucose uptake.
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Affiliation(s)
- Haitham Abdulla
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
- Diabetes and Endocrinology Centre, University Hospitals Birmingham NHS Foundation Trust, Heartlands Hospitals, Birmingham B9 5SS, UK
| | - Bethan Phillips
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
- NIHR, Nottingham BRC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Daniel Wilkinson
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
- NIHR, Nottingham BRC, University of Nottingham, Nottingham NG7 2UH, UK
| | - Amanda Gates
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
| | - Marie Limb
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
| | - Tereza Jandova
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
- Department of Physiology and Biochemistry, Faculty of Physical Education and Sport, Charles University, Prague 6, Czech Republic
| | - Joseph Bass
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
| | - Johnathan Lewis
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
| | - John Williams
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, Centre of Metabolism, Ageing and Physiology (COMAP), Academic Unit of Injury, Recovery and Inflammation Sciences (IRIS), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby DE22 3DT, UK
- NIHR, Nottingham BRC, University of Nottingham, Nottingham NG7 2UH, UK
- Department of Anaesthesia, University Hospitals Derby and Burton NHS Foundation Trust, Derby DE22 3NE, UK
| | | | | | - Philip Atherton
- Correspondence: Philip J. Atherton, PhD, University of Nottingham School of Medicine, Royal Derby Hospital, Uttoxeter Road, Derby, DE22 3DT, UK.
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Dietary protein, exercise, ageing and physical inactivity: interactive influences on skeletal muscle proteostasis. Proc Nutr Soc 2020; 80:106-117. [PMID: 33023679 DOI: 10.1017/s0029665120007879] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Dietary protein is a pre-requisite for the maintenance of skeletal muscle mass; stimulating increases in muscle protein synthesis (MPS), via essential amino acids (EAA), and attenuating muscle protein breakdown, via insulin. Muscles are receptive to the anabolic effects of dietary protein, and in particular the EAA leucine, for only a short period (i.e. about 2-3 h) in the rested state. Thereafter, MPS exhibits tachyphylaxis despite continued EAA availability and sustained mechanistic target of rapamycin complex 1 signalling. Other notable characteristics of this 'muscle full' phenomenon include: (i) it cannot be overcome by proximal intake of additional nutrient signals/substrates regulating MPS; meaning a refractory period exists before a next stimulation is possible, (ii) it is refractory to pharmacological/nutraceutical enhancement of muscle blood flow and thus is not induced by muscle hypo-perfusion, (iii) it manifests independently of whether protein intake occurs in a bolus or intermittent feeding pattern, and (iv) it does not appear to be dependent on protein dose per se. Instead, the main factor associated with altering muscle full is physical activity. For instance, when coupled to protein intake, resistance exercise delays the muscle full set-point to permit additional use of available EAA for MPS to promote muscle remodelling/growth. In contrast, ageing is associated with blunted MPS responses to protein/exercise (anabolic resistance), while physical inactivity (e.g. immobilisation) induces a premature muscle full, promoting muscle atrophy. It is crucial that in catabolic scenarios, anabolic strategies are sought to mitigate muscle decline. This review highlights regulatory protein turnover interactions by dietary protein, exercise, ageing and physical inactivity.
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7
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Novel Essential Amino Acid Supplements Following Resistance Exercise Induce Aminoacidemia and Enhance Anabolic Signaling Irrespective of Age: A Proof-of-Concept Trial. Nutrients 2020; 12:nu12072067. [PMID: 32664648 PMCID: PMC7400893 DOI: 10.3390/nu12072067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/09/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred ~60–120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (~8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.
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Aubertin-Leheudre M, Pion CH, Vallée J, Marchand S, Morais JA, Bélanger M, Robitaille R. Improved Human Muscle Biopsy Method To Study Neuromuscular Junction Structure and Functions with Aging. J Gerontol A Biol Sci Med Sci 2019; 75:2098-2102. [DOI: 10.1093/gerona/glz292] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Indexed: 11/12/2022] Open
Abstract
Abstract
Reduced mobility and physical independence of elders has emerged as a major clinical and public health priority with extended life expectancy. The impact of the neuromuscular function on muscle activity and properties has emerged as a critical factor influencing the progress and outcome of muscle changes with aging. However, very little is known about the neuromuscular junctions (NMJs) in humans, in part due to technical constraints limiting the access to healthy, fresh neuromuscular tissue. Here, we describe a method, called Biopsy using Electrostimulation for Enhanced NMJ Sampling (BeeNMJs) that improves the outcome of muscle biopsies. We used local cutaneous stimulation to identify the area enriched with NMJs for each participant at the right Vastus lateralis (VL). The needle biopsy was then performed in proximity of that point. The BeeNMJs procedure was safe for the participants. We observed NMJs in 53.3% of biopsies in comparison with only 16.7% using the traditional method. Furthermore, we observed an average of 30.13 NMJs per sample compared to only 2.33 for the traditional method. Importantly, high-quality neuromuscular material was obtained whereby pre-, postsynaptic, and glial elements were routinely labeled, simultaneously with myosin heavy chain type I. The BeeNMJs approach will facilitate studies of NMJs, particularly in human disease or aging process.
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Affiliation(s)
- Mylene Aubertin-Leheudre
- Département des sciences de l’activité physique, Montreal, QC, Canada
- Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
- Centre de Recherche, Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada
| | - Charlotte H Pion
- Département des sciences de l’activité physique, Montreal, QC, Canada
- Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
- Centre de Recherche, Institut Universitaire de Gériatrie de Montréal, Montreal, QC, Canada
| | - Joanne Vallée
- Département de neurosciences, Montreal, QC, Canada
- Groupe de recherche sur le système nerveux central, Université de Montréal, Montreal, QC, Canada
| | - Sandrine Marchand
- Département de neurosciences, Montreal, QC, Canada
- Groupe de recherche sur le système nerveux central, Université de Montréal, Montreal, QC, Canada
| | - José A Morais
- McGill University Health Centre, Research Institute and Geriatric Medicine, Faculty of Medicine, McGill University, Montreal, Canada
| | - Marc Bélanger
- Département des sciences de l’activité physique, Montreal, QC, Canada
- Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
| | - Richard Robitaille
- Groupe de Recherche en Activité Physique Adaptée, Université du Québec à Montréal, Montreal, QC, Canada
- Département de neurosciences, Montreal, QC, Canada
- Groupe de recherche sur le système nerveux central, Université de Montréal, Montreal, QC, Canada
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Collins BC, Laakkonen EK, Lowe DA. Aging of the musculoskeletal system: How the loss of estrogen impacts muscle strength. Bone 2019; 123:137-144. [PMID: 30930293 PMCID: PMC6491229 DOI: 10.1016/j.bone.2019.03.033] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 02/06/2023]
Abstract
Skeletal muscle weakness occurs with aging and in females this is compounded by the loss of estrogen with ovarian failure. Estrogen deficiency mediates decrements in muscle strength from both inadequate preservation of skeletal muscle mass and decrements in the quality of the remaining skeletal muscle. Processes and components of skeletal muscle that are affected by estrogens are beginning to be identified. This review focuses on mechanisms that contribute to the loss of muscle force generation when estrogen is low in females, and conversely the maintenance of strength by estrogen. Evidence is accumulating that estrogen deficiency induces apoptosis in skeletal muscle contributing to loss of mass and thus strength. Estrogen sensitive processes that affect quality, i.e., force generating capacity of muscle, include myosin phosphorylation and satellite cell function. Further detailing these mechanisms and identifying additional mechanisms that underlie estrogenic effects on skeletal muscle is important foundation for the design of therapeutic strategies to minimize skeletal muscle pathologies, such as sarcopenia and dynapenia.
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Affiliation(s)
- Brittany C Collins
- Department of Human Genetics, Medical School, University of Utah, United States of America
| | - Eija K Laakkonen
- Gerontology Research Center and Faculty of Sport and Health Sciences, University of Jyväskylä, Finland
| | - Dawn A Lowe
- Divisions of Rehabilitation Science and Physical Therapy, Department of Rehabilitation Medicine, Medical School, University of Minnesota, United States of America.
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Graber TG, Fandrey KR, Thompson LV. Novel individualized power training protocol preserves physical function in adult and older mice. GeroScience 2019; 41:165-183. [PMID: 31076998 PMCID: PMC6544743 DOI: 10.1007/s11357-019-00069-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/16/2019] [Indexed: 11/27/2022] Open
Abstract
Sarcopenia, the age-related loss of muscle mass and strength, contributes to frailty, functional decline, and reduced quality of life in older adults. Exercise is a recognized therapy for sarcopenia and muscle dysfunction, though not a cure. Muscle power declines at an increased rate compared to force, and force output declines earlier than mass. Thus, there is a need for research of exercise focusing on improving power output and functionality in older adults. Our primary purpose was proof-of-concept that a novel individualized power exercise modality would induce positive adaptations in adult mice, before the exercise program was applied to an aged cohort. We hypothesized that after following our protocol, both adult and older mice would show improved function, though there would be evidence of anabolic resistance in the older mice. Male C57BL/6 mice (12 months of age at study conclusion) were randomized into control (n = 9) and exercise (n = 6) groups. The trained group used progressive resistance (with a weighted harness) and intensity (~ 4-10 rpm) on a custom motorized running wheel. The mice trained similarly to a human workout regimen (4-5 sets/session, 3 sessions/week, for 12 weeks). We determined significant (p < 0.05) positive adaptations post-intervention, including: neuromuscular function (rotarod), strength/endurance (inverted cling grip test), training physiology (force/power output per session), muscle size (soleus mass), and power/velocity of contraction (in vitro physiology). Secondly, we trained a cohort of older male mice (28 months old at conclusion): control (n = 12) and exercised (n = 8). While the older exercised mice did preserve function and gain benefits, they also demonstrated evidence of anabolic resistance.
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Affiliation(s)
- Ted G. Graber
- Department of Nutrition and Metabolism, Division of Rehabilitation Science, University of Texas Medical Branch, Galveston, TX USA
| | - Katie R. Fandrey
- Program in Physical Therapy, University of Minnesota-Twin Cities, Minneapolis, MN USA
| | - LaDora V. Thompson
- Department of Physical Therapy & Athletic Training, Boston University, Boston, MA USA
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11
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Tessier AJ, Chevalier S. An Update on Protein, Leucine, Omega-3 Fatty Acids, and Vitamin D in the Prevention and Treatment of Sarcopenia and Functional Decline. Nutrients 2018; 10:E1099. [PMID: 30115829 PMCID: PMC6116139 DOI: 10.3390/nu10081099] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 08/09/2018] [Accepted: 08/14/2018] [Indexed: 12/16/2022] Open
Abstract
Aging is associated with sarcopenia and functional decline, leading to frailty and disability. As a modifiable risk factor, nutrition may represent a target for preventing or postponing the onset of these geriatric conditions. Among nutrients, high-quality protein, leucine, vitamin D, and omega-3 polyunsaturated fatty acids (n-3 PUFA) are of particular interest for their demonstrated effects on skeletal muscle health. This narrative review aims to examine the recent observational and interventional evidence on the associations and the role of these nutrients in the muscle mass, strength, mobility, and physical function of free-living older adults, who are either healthy or at risk of frailty. Recent evidence supports a higher protein intake recommendation of 1.0⁻1.2 g/kg/day in healthy older adults; an evenly distributed mealtime protein intake or minimal protein per meal may be beneficial. In addition, vitamin D supplementation of 800⁻1000 IU, particularly when vitamin D status is low, and doses of ~3 g/day of n-3 PUFA may be favorable for physical function, muscle mass, and strength. Reviewed studies are highly heterogenous, yet the quantity, quality, and timing of intakes should be considered when designing intervention studies. Combined protein, leucine, vitamin D, and n-3 PUFA supplements may convey added benefits and may represent an intervention strategy in the prevention of sarcopenia and functional decline.
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Affiliation(s)
- Anne-Julie Tessier
- School of Human Nutrition, McGill University, 21111 Lakeshore Rd, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada.
- Research Institute of the McGill University Health Centre, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada.
| | - Stéphanie Chevalier
- School of Human Nutrition, McGill University, 21111 Lakeshore Rd, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada.
- Research Institute of the McGill University Health Centre, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada.
- Department of Medicine, McGill University, 845 Sherbrooke St. W, Montreal, QC H3A 0G4, Canada.
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12
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Morais JA, Jacob KW, Chevalier S. Effects of aging and insulin resistant states on protein anabolic responses in older adults. Exp Gerontol 2018; 108:262-268. [DOI: 10.1016/j.exger.2018.04.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 03/20/2018] [Accepted: 04/29/2018] [Indexed: 12/25/2022]
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13
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Kim Y, Men SS, Liang C, Receno CN, Brutsaert TD, Korol DL, Heffernan KS, DeRuisseau KC. Effects of long-term exposures to low iron and branched-chain amino acid containing diets on aging skeletal muscle of Fisher 344 × Brown Norway rats. Appl Physiol Nutr Metab 2017; 43:165-173. [PMID: 29024598 DOI: 10.1139/apnm-2017-0272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Aging skeletal muscle displays an altered iron status that may promote oxidative stress and sarcopenia. A diet containing low iron (LI) could reduce muscle iron status and attenuate age-related muscle atrophy. Supplemental branched-chain amino acids (BCAA) may also alleviate sarcopenia by promoting muscle protein synthesis and iron status improvement. This study examined individual and combined effects of LI and BCAA diets on anabolic signaling and iron status in skeletal muscle of aging rats. Twenty-nine-month-old male Fisher 344 × Brown Norway rats consumed the following control-base diets: control + regular iron (35 mg iron/kg) (CR; n = 11); control + LI (∼6 mg iron/kg) (CL; n = 11); 2×BCAA + regular iron (BR; n = 10); and 2×BCAA + LI (BL; n = 12) for 12 weeks. Although LI and/or 2×BCAA did not affect plantaris muscle mass, 2×BCAA groups showed lower muscle iron content than did CR and CL groups (P < 0.05). p70 ribosomal protein S6 kinase phosphorylation was greater in 2×BCAA and LI animals compared with CR animals (P < 0.05). Interactions between IRON and BCAA were observed for proteins indicative of mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator 1 alpha) and oxidative capacity (cytochrome c oxidase subunit 2 and citrate synthase) (P < 0.05) wherein the combined diet (BL) negated potential benefits of individual diets. Antioxidant capacity, superoxide dismutase activity, and oxidative injury (3-nitrotyrosine, protein carbonyls, and 4-hydroxynonenal) were similar between groups. In conclusion, 12 weeks of LI and 2×BCAA diets showed significant impacts on increasing anabolic signaling as well as ameliorating iron status; however, these interventions did not affect muscle mass.
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Affiliation(s)
- Yuho Kim
- a Department of Exercise Science, Syracuse University, 820 Comstock Ave, Room 201 WB, Syracuse, NY 13244, USA.,b Muscle Energetics Laboratory, National Heart, Lung, and Blood Institute, 10 Center Drive Room B1D400, Bethesda, MD 20892, USA
| | - Sok Sambo Men
- c Department of Nutrition Science, Syracuse University, 426 Ostrom Avenue, Syracuse, NY 13244, USA
| | - Chen Liang
- d Department of Exercise Science, Syracuse University, 820 Comstock Ave., Room 201 WB, Syracuse, NY 13244, USA
| | - Candace N Receno
- d Department of Exercise Science, Syracuse University, 820 Comstock Ave., Room 201 WB, Syracuse, NY 13244, USA
| | - Tom D Brutsaert
- d Department of Exercise Science, Syracuse University, 820 Comstock Ave., Room 201 WB, Syracuse, NY 13244, USA
| | - Donna L Korol
- e Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA
| | - Kevin S Heffernan
- d Department of Exercise Science, Syracuse University, 820 Comstock Ave., Room 201 WB, Syracuse, NY 13244, USA
| | - Keith C DeRuisseau
- d Department of Exercise Science, Syracuse University, 820 Comstock Ave., Room 201 WB, Syracuse, NY 13244, USA
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14
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Gheller BJF, Riddle ES, Lem MR, Thalacker-Mercer AE. Understanding Age-Related Changes in Skeletal Muscle Metabolism: Differences Between Females and Males. Annu Rev Nutr 2017; 36:129-56. [PMID: 27431365 DOI: 10.1146/annurev-nutr-071715-050901] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Skeletal muscle is the largest metabolic organ system in the human body. As such, metabolic dysfunction occurring in skeletal muscle impacts whole-body nutrient homeostasis. Macronutrient metabolism changes within the skeletal muscle with aging, and these changes are associated in part with age-related skeletal muscle remodeling. Moreover, age-related changes in skeletal muscle metabolism are affected differentially between males and females and are likely driven by changes in sex hormones. Intrinsic and extrinsic factors impact observed age-related changes and sex-related differences in skeletal muscle metabolism. Despite some support for sex-specific differences in skeletal muscle metabolism with aging, more research is necessary to identify underlying differences in mechanisms. Understanding sex-specific aging skeletal muscle will assist with the development of therapies to attenuate adverse metabolic and functional outcomes.
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Affiliation(s)
- Brandon J F Gheller
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853;
| | - Emily S Riddle
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853;
| | - Melinda R Lem
- Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853;
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15
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Xia Z, Cholewa J, Zhao Y, Shang HY, Yang YQ, Araújo Pessôa K, Su QS, Lima-Soares F, Zanchi NE. Targeting Inflammation and Downstream Protein Metabolism in Sarcopenia: A Brief Up-Dated Description of Concurrent Exercise and Leucine-Based Multimodal Intervention. Front Physiol 2017; 8:434. [PMID: 28690550 PMCID: PMC5479895 DOI: 10.3389/fphys.2017.00434] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 06/06/2017] [Indexed: 01/31/2023] Open
Abstract
Sarcopenia is defined as the progressive loss of muscle mass with age, and poses a serious threat to the physiological and psychological health of the elderly population with consequential economic and social burdens. Chronic low-grade inflammation plays a central role in the development of sarcopenia such that it alters cellular protein metabolism to favor proteolysis over synthesis, and thereby accelerates muscular atrophy. The purpose of this review is to highlight how exercise and nutrition intervention strategies can attenuate or treat sarcopenia. Resistance exercise increases not only muscle mass but also muscle strength, while aerobic exercise is able to ameliorate the age-related metabolic disorders. Concurrent exercise training integrates the advantages of both aerobic and resistance exercise, and may exert a significant synergistic effect in the aging organism. Higher protein intakes rich in the amino acid leucine appear to restore skeletal muscle protein metabolism balance by rescuing protein synthesis in older adults. There is good reason to believe that a multimodal treatment, a combination of exercise and increased leucine consumption in the diet, can combat some of the muscle loss associated with aging. Future research is needed to consolidate these findings to humans, and to further clarify to what extent and by which mechanisms protein metabolism might be directly involved in sarcopenia pathogenesis and the multimodal treatment responses.
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Affiliation(s)
- Zhi Xia
- Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan UniversityJi'an, China.,Department of Sports Medicine, Chengdu Sport UniversityChengdu, China
| | - Jason Cholewa
- Department of Kinesiology, Coastal Carolina UniversityConway, SC, United States
| | - Yan Zhao
- Exercise Physiology and Biochemistry Laboratory, College of Physical Education, Jinggangshan UniversityJi'an, China
| | - Hua-Yu Shang
- Department of Sports Medicine, Chengdu Sport UniversityChengdu, China
| | - Yue-Qin Yang
- Exercise Intervention and Health Promotion Hubei Province Synergy Innovation Center, Wuhan Sports UniversityWuhan, China
| | - Kassiana Araújo Pessôa
- Department of Physical Education, Federal University of MaranhãoSão Luís, Brazil.,Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME)São Luís, Brazil
| | - Quan-Sheng Su
- Department of Sports Medicine, Chengdu Sport UniversityChengdu, China
| | - Fernanda Lima-Soares
- Department of Physical Education, Federal University of MaranhãoSão Luís, Brazil.,Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME)São Luís, Brazil
| | - Nelo Eidy Zanchi
- Department of Physical Education, Federal University of MaranhãoSão Luís, Brazil.,Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME)São Luís, Brazil
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16
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Paddon-Jones D, Coss-Bu JA, Morris CR, Phillips SM, Wernerman J. Variation in Protein Origin and Utilization: Research and Clinical Application. Nutr Clin Pract 2017; 32:48S-57S. [PMID: 28388379 DOI: 10.1177/0884533617691244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Muscle health can be rapidly compromised in clinical environments. Modifiable strategies to preserve metabolic homeostasis in adult patient populations include physical activity and pharmacologic support; however, optimizing dietary practices, or more specifically protein intake, is a necessary prerequisite for any other treatment strategy to be fully effective. Simply increasing protein intake is a well-intentioned but often unfocused strategy to protect muscle health in an intensive care setting. Protein quality is a frequently overlooked factor with the potential to differentially influence health outcomes. Quality can be assessed by a variety of techniques, with digestible indispensable amino acid score being the current and most comprehensive technique endorsed by the Food and Agriculture Organization. In practical terms, animal-based proteins are consistently scored higher in quality compared with incomplete proteins, regardless of the assessment method. Consequently, choosing parenteral and/or enteral feeding options that contain high-quality proteins, rich in the branched-chain amino acid leucine, may help establish a dietary framework with the potential to support clinical practice and improve health outcomes in critically ill patients.
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Affiliation(s)
- Douglas Paddon-Jones
- 1 Department of Nutrition and Metabolism, The University of Texas Medical Branch, Galveston, Texas, USA
| | - Jorge A Coss-Bu
- 2 Pediatrics Critical Care, Baylor College of Medicine, Houston, Texas, USA
| | - Claudia R Morris
- 3 Division of Pediatric Emergency Medicine, Emory School of Medicine, Atlanta, Georgia, USA
| | - Stuart M Phillips
- 4 Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jan Wernerman
- 5 Department of Clinical Science, Karolinska University, Solna, Sweden
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17
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De Bandt JP. Leucine and Mammalian Target of Rapamycin-Dependent Activation of Muscle Protein Synthesis in Aging. J Nutr 2016; 146:2616S-2624S. [PMID: 27934653 DOI: 10.3945/jn.116.234518] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/11/2016] [Accepted: 06/15/2016] [Indexed: 12/17/2022] Open
Abstract
The preservation or restoration of muscle mass is of prime importance for healthy aging. However, aging has been repeatedly shown to be associated with resistance of muscle to the anabolic effects of feeding. Leucine supplementation has been proposed as a possible strategy because of its regulatory role on protein homeostasis. Indeed, it acts independently of growth factors and leads to enhanced cap-dependent mRNA translation initiation and increased protein synthesis. Leucine acts as a signaling molecule directly at the muscle level via the activation of mammalian/mechanistic target of rapamycin complex 1 (mTORC1). However, in aged muscle, mTORC1 activation seems to be impaired, with decreased sensitivity and responsiveness of muscle protein synthesis to amino acids, whereas the phosphorylation state of several components of this signaling pathway appears to be higher in the basal state. This may stem from specific age-related impairment of muscle signaling and from decreased nutrient and growth factor delivery to the muscle. Whether aging per se affects mTORC1 signaling remains to be established, because aging is frequently associated with inadequate protein intake, decreased insulin sensitivity, inactivity, inflammatory processes, etc. Whatever its origin, this anabolic resistance to feeding can be mitigated by quantitative and qualitative manipulation of protein supply, such as leucine supplementation; however, there remains the question of possible adverse effects of long-term, high-dose leucine supplementation in terms of insulin resistance and tumorigenesis.
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Affiliation(s)
- Jean-Pascal De Bandt
- EA4466 PRETRAM, Nutrition Biology Laboratory, Faculty of Pharmacy, Paris Descartes University, Sorbonne Paris Cité, Paris, France
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18
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Shad BJ, Thompson JL, Breen L. Does the muscle protein synthetic response to exercise and amino acid-based nutrition diminish with advancing age? A systematic review. Am J Physiol Endocrinol Metab 2016; 311:E803-E817. [PMID: 27555299 DOI: 10.1152/ajpendo.00213.2016] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/16/2016] [Indexed: 01/06/2023]
Abstract
The precise role of age-related muscle anabolic resistance in the progression of sarcopenia and functional decline in older individuals is unclear. The present aim was to assess whether the muscle protein synthesis (MPS) response to acute exercise (endurance or resistance) and/or amino acid-based nutrition is attenuated in older compared with young individuals. A systematic review was conducted on studies that directly examined the influence of age on the MPS response to exercise and/or amino acid-based nutrition. Each study arm was synthesized and reported as providing sufficient or insufficient "evidence of age-related muscle anabolic resistance". Subsequently, three models were established to compare age-related differences in the MPS response to 1) exercise alone, 2) amino acid-based nutrition alone, or 3) the combination of exercise and amino acid-based nutrition. Following exercise alone, 8 of the 17 study arms provided sufficient evidence of age-related muscle anabolic resistance, while in response to amino acid-based nutrition alone, 8 of the 21 study arms provided sufficient evidence of age-related muscle anabolic resistance. When exercise and amino acid-based nutrition were combined, only 2 of the 10 study arms provided sufficient evidence of age-related muscle anabolic resistance. Our results highlight that optimization of exercise and amino acid-based nutrition is sufficient to induce a comparable MPS response between young and older individuals. However, the exercise volume completed and/or the amino acid/protein dose and leucine content must exceed a certain threshold to stimulate equivalent MPS rates in young and older adults, below which age-related muscle anabolic resistance may become apparent.
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Affiliation(s)
- Brandon J Shad
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, United Kingdom; and
| | - Janice L Thompson
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, United Kingdom; and
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, United Kingdom
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, United Kingdom; and
- MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, United Kingdom
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19
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Phillips SM, Chevalier S, Leidy HJ. Protein "requirements" beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab 2016; 41:565-572. [PMID: 26960445 DOI: 10.1139/apnm-2015-0550] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2023]
Abstract
Substantial evidence supports the increased consumption of high-quality protein to achieve optimal health outcomes. A growing body of research indicates that protein intakes well above the current Recommended Dietary Allowance help to promote healthy aging, appetite regulation, weight management, and goals aligned with athletic performance. Higher protein intakes may help prevent age-related sarcopenia, the loss of muscle mass, and strength that predisposes older adults to frailty, disability, and loss of autonomy. Higher protein diets also improve satiety and lead to greater reductions in body weight and fat mass compared with standard protein diets, and may therefore serve as a successful strategy to help prevent and/or treat obesity. Athletes can also benefit from higher protein intakes to maximize athletic performance given the critical role protein plays in stimulating muscle protein remodelling after exercise. Protein quality, per meal dose, and timing of ingestion are also important considerations. Despite persistent beliefs to the contrary, we can find no evidence-based link between higher protein diets and renal disease or adverse bone health. This brief synopsis highlights recent learnings based on presentations at the 2015 Canadian Nutrition Society conference, Advances in Protein Nutrition across the Lifespan. Current evidence indicates intakes in the range of at least 1.2 to 1.6 g/(kg·day) of high-quality protein is a more ideal target for achieving optimal health outcomes in adults.
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Affiliation(s)
- Stuart M Phillips
- a Department of Kinesiology, Exercise Metabolism Research Group - Protein Metabolism Research Lab, McMaster University, 1280 Main Street W., Hamilton, ON L8S 4K1, Canada
| | - Stéphanie Chevalier
- b Department of Medicine, McGill University, Hamilton, ON L8S 4K1, Canada
- c School of Dietetics and Human Nutrition, McGill University, McGill University Health Centre-Research Institute, Crabtree Nutrition Laboratories, 1001, boul. Décarie, E02.7226 Montréal, QC H4A 3J1, Canada
| | - Heather J Leidy
- d Department of Nutrition and Exercise Physiology, School of Medicine, University of Missouri, Columbia, MO 65203, USA
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20
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Francaux M, Demeulder B, Naslain D, Fortin R, Lutz O, Caty G, Deldicque L. Aging Reduces the Activation of the mTORC1 Pathway after Resistance Exercise and Protein Intake in Human Skeletal Muscle: Potential Role of REDD1 and Impaired Anabolic Sensitivity. Nutrients 2016; 8:nu8010047. [PMID: 26784225 PMCID: PMC4728660 DOI: 10.3390/nu8010047] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/06/2016] [Accepted: 01/11/2016] [Indexed: 01/07/2023] Open
Abstract
This study was designed to better understand the molecular mechanisms involved in the anabolic resistance observed in elderly people. Nine young (22 ± 0.1 years) and 10 older (69 ± 1.7 years) volunteers performed a one-leg extension exercise consisting of 10 × 10 repetitions at 70% of their 3-RM, immediately after which they ingested 30 g of whey protein. Muscle biopsies were taken from the vastus lateralis at rest in the fasted state and 30 min after protein ingestion in the non-exercised (Pro) and exercised (Pro+ex) legs. Plasma insulin levels were determined at the same time points. No age difference was measured in fasting insulin levels but the older subjects had a 50% higher concentration than the young subjects in the fed state (p < 0.05). While no difference was observed in the fasted state, in response to exercise and protein ingestion, the phosphorylation state of PKB (p < 0.05 in Pro and Pro+ex) and S6K1 (p = 0.059 in Pro; p = 0.066 in Pro+ex) was lower in the older subjects compared with the young subjects. After Pro+ex, REDD1 expression tended to be higher (p = 0.087) in the older group while AMPK phosphorylation was not modified by any condition. In conclusion, we show that the activation of the mTORC1 pathway is reduced in skeletal muscle of older subjects after resistance exercise and protein ingestion compared with young subjects, which could be partially due to an increased expression of REDD1 and an impaired anabolic sensitivity.
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Affiliation(s)
- Marc Francaux
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Bénédicte Demeulder
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Damien Naslain
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Raphael Fortin
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Olivier Lutz
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Gilles Caty
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Louise Deldicque
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
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21
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Smith GI, Mittendorfer B. Sexual dimorphism in skeletal muscle protein turnover. J Appl Physiol (1985) 2015; 120:674-82. [PMID: 26702024 DOI: 10.1152/japplphysiol.00625.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/21/2015] [Indexed: 02/08/2023] Open
Abstract
Skeletal muscle is the major constituent of lean body mass and essential for the body's locomotor function. Women have less muscle mass (and more body fat) than men and are therefore not able to exert the same absolute maximal force as men. The difference in body composition between the sexes is evident from infancy but becomes most marked after puberty (when boys experience an accelerated growth spurt) and persists into old age. During early adulthood until approximately the fourth decade of life, muscle mass is relatively stable, both in men and women, but then begins to decline, and the rate of loss is slower in women than in men. In this review we discuss the underlying mechanisms responsible for the age-associated sexual dimorphism in muscle mass (as far as they have been elucidated to date) and highlight areas that require more research to advance our understanding of the control of muscle mass throughout life.
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Affiliation(s)
- Gordon I Smith
- Washington University, School of Medicine, St. Louis, Missouri
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22
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Wall BT, Gorissen SH, Pennings B, Koopman R, Groen BBL, Verdijk LB, van Loon LJC. Aging Is Accompanied by a Blunted Muscle Protein Synthetic Response to Protein Ingestion. PLoS One 2015; 10:e0140903. [PMID: 26536130 PMCID: PMC4633096 DOI: 10.1371/journal.pone.0140903] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 10/01/2015] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Progressive loss of skeletal muscle mass with aging (sarcopenia) forms a global health concern. It has been suggested that an impaired capacity to increase muscle protein synthesis rates in response to protein intake is a key contributor to sarcopenia. We assessed whether differences in post-absorptive and/or post-prandial muscle protein synthesis rates exist between large cohorts of healthy young and older men. PROCEDURES We performed a cross-sectional, retrospective study comparing in vivo post-absorptive muscle protein synthesis rates determined with stable isotope methodologies between 34 healthy young (22±1 y) and 72 older (75±1 y) men, and post-prandial muscle protein synthesis rates between 35 healthy young (22±1 y) and 40 older (74±1 y) men. FINDINGS Post-absorptive muscle protein synthesis rates did not differ significantly between the young and older group. Post-prandial muscle protein synthesis rates were 16% lower in the older subjects when compared with the young. Muscle protein synthesis rates were >3 fold more responsive to dietary protein ingestion in the young. Irrespective of age, there was a strong negative correlation between post-absorptive muscle protein synthesis rates and the increase in muscle protein synthesis rate following protein ingestion. CONCLUSIONS Aging is associated with the development of muscle anabolic inflexibility which represents a key physiological mechanism underpinning sarcopenia.
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Affiliation(s)
- Benjamin Toby Wall
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - Stefan H. Gorissen
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - Bart Pennings
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - René Koopman
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - Bart B. L. Groen
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - Lex B. Verdijk
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
| | - Luc J. C. van Loon
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, 6200 MD, The Netherlands
- * E-mail:
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Liebau F, Sundström M, van Loon LJC, Wernerman J, Rooyackers O. Short-term amino acid infusion improves protein balance in critically ill patients. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:106. [PMID: 25882298 PMCID: PMC4403712 DOI: 10.1186/s13054-015-0844-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/26/2015] [Indexed: 12/12/2022]
Abstract
Introduction Evidence behind the recommendations for protein feeding during critical illness is weak. Mechanistic studies are needed to elucidate the effects of amino acid and/or protein supplementation on protein metabolism before larger clinical trials with higher levels of protein feeding are initiated. Methods We studied the effects of parenteral amino acid supplementation (equivalent to 1 g/kg/day) over the course of 3 hours on whole-body protein turnover in critically ill patients in the intensive care unit (ICU) during the first week after admission. Patients were studied at baseline during ongoing nutrition and during extra amino acid supplementation. If the patient was still in the ICU 2 to 4 days later, these measurements were repeated. Protein kinetics were measured using continuous stable isotope-labeled phenylalanine and tyrosine infusions. Results Thirteen patients were studied on the first study occasion only, and seven were studied twice. Parenteral amino acid supplementation significantly improved protein balance on both occasions, from a median of −4 to +7 μmol phenylalanine/kg/hr (P =0.001) on the first study day and from a median of 0 to +12 μmol phenylalanine/kg/hr (P =0.018) on the second study day. The more positive protein balance was attributed to an increased protein synthesis rate, which reached statistical significance during the first measurement (from 58 to 65 μmol phenylalanine/kg/hr; n =13; P =0.007), but not during the second measurement (from 58 to 69 μmol phenylalanine/kg/hr; n =7; P =0.09). Amino acid oxidation rates, estimated by phenylalanine hydroxylation, did not increase during the 3-hour amino acid infusion. A positive correlation (r =0.80; P <0.0001) was observed between total amino acids and/or protein given to the patient and whole-body protein balance. Conclusion Extra parenteral amino acids infused over a 3-hour period improved whole-body protein balance and did not increase amino acid oxidation rates in critically ill patients during the early phase (first week) of critical illness. Electronic supplementary material The online version of this article (doi:10.1186/s13054-015-0844-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Felix Liebau
- Division of Anesthesia and Intensive Care, Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet and Karolinska University Hospital, Hälsovägen 13, Huddinge, 14186, Sweden.
| | - Martin Sundström
- Division of Anesthesia and Intensive Care, Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet and Karolinska University Hospital, Hälsovägen 13, Huddinge, 14186, Sweden.
| | - Luc J C van Loon
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, Universiteitssingel 40, Maastricht, 6229ER, The Netherlands.
| | - Jan Wernerman
- Division of Anesthesia and Intensive Care, Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet and Karolinska University Hospital, Hälsovägen 13, Huddinge, 14186, Sweden.
| | - Olav Rooyackers
- Division of Anesthesia and Intensive Care, Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet and Karolinska University Hospital, Hälsovägen 13, Huddinge, 14186, Sweden.
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Markofski MM, Dickinson JM, Drummond MJ, Fry CS, Fujita S, Gundermann DM, Glynn EL, Jennings K, Paddon-Jones D, Reidy PT, Sheffield-Moore M, Timmerman KL, Rasmussen BB, Volpi E. Effect of age on basal muscle protein synthesis and mTORC1 signaling in a large cohort of young and older men and women. Exp Gerontol 2015; 65:1-7. [PMID: 25735236 DOI: 10.1016/j.exger.2015.02.015] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 02/25/2015] [Accepted: 02/27/2015] [Indexed: 12/21/2022]
Abstract
The rate of muscle loss with aging is higher in men than women. However, women have smaller muscles throughout the adult life. Protein content is a major determinant of skeletal muscle size. This study was designed to determine if age and sex differentially impact basal muscle protein synthesis and mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling. We performed a secondary data analysis on a cohort of 215 healthy, non-obese (BMI<30kg·m(-2)) young (18-40y; 74 men, 52 women) and older (60-87y; 57 men, 32 women) adults. The database contained information on physical characteristics, basal muscle protein fractional synthetic rate (FSR; n=215; stable isotope methodology) and mTORC1 signaling (n=125, Western blotting). FSR and mTORC1 signaling were measured at rest and after an overnight fast. mTORC1 and S6K1 phosphorylation were higher (p<0.05) in older subjects with no sex differences. However, there were no age or sex differences or interaction for muscle FSR (p>0.05). Body mass index, fat free mass, or body fat was not a significant covariate and did not influence the results. We conclude that age and sex do not influence basal muscle protein synthesis. However, basal mTORC1 hyperphosphorylation in the elderly may contribute to insulin resistance and the age-related anabolic resistance of skeletal muscle protein metabolism to nutrition and exercise.
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Affiliation(s)
- Melissa M Markofski
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Jared M Dickinson
- Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Micah J Drummond
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Christopher S Fry
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Satoshi Fujita
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - David M Gundermann
- Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Erin L Glynn
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Kristofer Jennings
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Preventive Medicine and Community Health, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Douglas Paddon-Jones
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Paul T Reidy
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Melinda Sheffield-Moore
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Internal Medicine, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Kyle L Timmerman
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Blake B Rasmussen
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA
| | - Elena Volpi
- Sealy Center on Aging, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA; Department of Internal Medicine, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA.
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25
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Chevalier S, Burgos SA, Morais JA, Gougeon R, Bassil M, Lamarche M, Marliss EB. Protein and glucose metabolic responses to hyperinsulinemia, hyperglycemia, and hyperaminoacidemia in obese men. Obesity (Silver Spring) 2015; 23:351-8. [PMID: 25452199 DOI: 10.1002/oby.20943] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 09/29/2014] [Indexed: 12/28/2022]
Abstract
OBJECTIVE In insulin-resistant states, resistance of protein anabolism occurs concurrently with that of glucose, but can be compensated for by abundant amino acid (AA) provision. This effect and its mechanism were sought in obesity. METHODS Pancreatic clamps were performed in 8 lean and 11 obese men, following 5-h postabsorptive, 3-h infusions of octreotide, basal glucagon, and growth hormone, with clamped postprandial-level insulin, glucose, and AA. Whole-body [1-(13) C]-leucine and [3-(3) H]-glucose kinetics, skeletal muscle protein ((2) H5 -phenylalanine) fractional synthesis rates, and insulin signaling were determined. RESULTS Clamp Δ insulin and Δ branched-chain AA did not differ; fasting glucagon and growth hormone were maintained. Glucose uptake was 20% less in obese concurrent with less Akt(Ser473) , but also less IRS-1(Ser636/639) phosphorylation. Stimulation of whole-body, myofibrillar, and sarcoplasmic protein synthesis was similar. Whole-body protein catabolism suppression tended to be less (P=0.06), resulting in lesser net balance (1.09 ± 0.07 vs. 1.31 ± 0.08 μmol [kg FFM(-1) ] min(-1) , P=0.048). Increments in muscle S6K1(Thr389) phosphorylation were less in the obese, but 4E-BP1(Ser65) did not differ. CONCLUSIONS Hyperaminoacidemia with hyperinsulinemia stimulated protein synthesis (possibly via nutrient signaling) normally in obesity, but suppression of proteolysis may be compromised. Whether long-term high protein intakes could compensate for the insulin resistance of protein anabolism remains to be determined.
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Affiliation(s)
- Stéphanie Chevalier
- Crabtree Nutrition Laboratories, Department of Medicine, McGill University, and Research Institute of the McGill University Health Centre, Montreal, Quebec City, Canada
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Keske MA, Premilovac D, Bradley EA, Dwyer RM, Richards SM, Rattigan S. Muscle microvascular blood flow responses in insulin resistance and ageing. J Physiol 2015; 594:2223-31. [PMID: 25581640 DOI: 10.1113/jphysiol.2014.283549] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 12/08/2014] [Indexed: 12/18/2022] Open
Abstract
Insulin resistance plays a key role in the development of type 2 diabetes. Skeletal muscle is the major storage site for glucose following a meal and as such has a key role in maintenance of blood glucose concentrations. Insulin resistance is characterised by impaired insulin-mediated glucose disposal in skeletal muscle. Multiple mechanisms can contribute to development of muscle insulin resistance and our research has demonstrated an important role for loss of microvascular function within skeletal muscle. We have shown that insulin can enhance blood flow to the microvasculature in muscle thus improving the access of glucose and insulin to the myocytes to augment glucose disposal. Obesity, insulin resistance and ageing are all associated with impaired microvascular responses to insulin in skeletal muscle. Impairments in insulin-mediated microvascular perfusion in muscle can directly cause insulin resistance, and this event can occur early in the aetiology of this condition. Understanding the mechanisms involved in the loss of microvascular function in muscle has the potential to identify novel treatment strategies to prevent or delay progression of insulin resistance and type 2 diabetes.
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Affiliation(s)
- Michelle A Keske
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Dino Premilovac
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,School of Medicine, University of Tasmania, Hobart, Australia
| | - Eloise A Bradley
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Renee M Dwyer
- School of Medicine, University of Tasmania, Hobart, Australia
| | | | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
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27
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Moore DR. Keeping older muscle “young” through dietary protein and physical activity. Adv Nutr 2014; 5:599S-607S. [PMID: 25469405 PMCID: PMC4188243 DOI: 10.3945/an.113.005405] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Sarcopenia is characterized by decreases in both muscle mass and muscle function. The loss of muscle mass, which can precede decrements in muscle function, is ultimately rooted in an imbalance between the rates of muscle protein synthesis and breakdown that favors a net negative balance (i.e., synthesis < breakdown). A preponderance of evidence highlights a blunted muscle protein synthetic response to dietary protein, commonly referred to as “anabolic resistance,” as a major underlying cause of the insipid loss of muscle with age. Dietary strategies to overcome this decreased dietary amino acid sensitivity include the ingestion of leucine-enriched, rapidly digested proteins and/or greater protein ingestion in each main meal to maximally stimulate muscle anabolism. Anabolic resistance is also a hallmark of a sedentary lifestyle at any age. Given that older adults may be more likely to experience periods of reduced activity (either voluntarily or through acute illness), it is proposed that inactivity is the precipitating factor in the development of anabolic resistance and the subsequent progression from healthy aging to frailty. However, even acute bouts of activity can restore the sensitivity of older muscle to dietary protein. Provided physical activity is incorporated into the daily routine, muscle in older adults should retain its capacity for a robust anabolic response to dietary protein comparable to that in their younger peers. Therefore, through its ability to “make nutrition better,” physical activity should be viewed as a vital component to maintaining muscle mass and function with age.
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Abstract
Reduction of lean mass is a primary body composition change associated with aging. Because many factors contribute to lean mass reduction, the problem has been given various names depending on the proposed cause, such as "age-related sarcopenia," "dynapenia," "myopenia," "sarcopenic obesity," or simply "sarcopenia." There is currently no consensus on how to best diagnose the reduction of lean mass and its consequences on health. We propose that simple body composition methods can be used to indirectly evaluate sarcopenia, provided that those techniques are validated against the "quality of lean" criterion that associates muscle mass and metabolic function with the components of fat-free mass. Promising field methods include the use of stable isotopes for the evaluation of water compartments and new approaches to bioelectrical impedance analysis, which is also associated with the monitoring of water homeostasis.
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Affiliation(s)
- Sandra M. L. Ribeiro
- School of Arts, Sciences, and Humanities, University of São Paulo, São Paulo, Brazil; and,Body Composition Laboratory, USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA
| | - Joseph J. Kehayias
- Body Composition Laboratory, USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA,To whom correspondence should be addressed. E-mail:
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Churchward-Venne TA, Breen L, Phillips SM. Alterations in human muscle protein metabolism with aging: Protein and exercise as countermeasures to offset sarcopenia. Biofactors 2014; 40:199-205. [PMID: 24105883 DOI: 10.1002/biof.1138] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 07/24/2013] [Accepted: 08/08/2013] [Indexed: 01/07/2023]
Abstract
Aging is associated with a reduction in skeletal muscle mass-sarcopenia-the etiology of which is multifactorial. One mechanism is that aging has, as one of its hallmarks, a reduced sensitivity of skeletal muscle to the normally potent anabolic effects of protein feeding and resistance exercise, and to the anticatabolic effects of insulin, the combination of which has been termed "anabolic resistance." However, this reduced sensitivity of skeletal muscle to anabolic stimuli may, in some cases, be overcome by providing a greater quantity of the nutrition and/or exercise stimulus. Daily habitual physical activity appears to be a primary determinant of anabolic resistance as we have recently shown that as little as 14 days of reduced ambulatory activity was sufficient to induce anabolic resistance in the elderly by attenuating the postprandial increase in muscle protein synthesis (MPS). The etiology of anabolic resistance is complex and may include alterations in amino acid uptake/utilization, cell signaling status, muscle blood flow, and microvascular perfusion (impacting amino acid delivery and availability). Further, there appears to be sexual dimorphism with advancing age in the response of MPS to amino acid/insulin provision. Maintenance of physical activity during aging is of fundamental importance for skeletal muscle to allow it to appropriately respond to the anabolic effects of nutrition.
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Affiliation(s)
- Tyler A Churchward-Venne
- Exercise Metabolism Research Group, Department of Kinesiology (TAC-V, SMP), McMaster University, Hamilton, Ontario, Canada
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30
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Smith GI, Yoshino J, Reeds DN, Bradley D, Burrows RE, Heisey HD, Moseley AC, Mittendorfer B. Testosterone and progesterone, but not estradiol, stimulate muscle protein synthesis in postmenopausal women. J Clin Endocrinol Metab 2014; 99:256-65. [PMID: 24203065 PMCID: PMC3879672 DOI: 10.1210/jc.2013-2835] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CONTEXT The effect of the female sex steroids, estradiol and progesterone, on muscle protein turnover is unclear. Therefore, it is unknown whether the changes in the hormonal milieu throughout the life span in women contribute to the changes in muscle protein turnover and muscle mass (eg, age associated muscle loss). OBJECTIVE The objective of this study was to provide a comprehensive evaluation of the effect of sex hormones on muscle protein synthesis and gene expression of growth-regulatory factors [ie, myogenic differentiation 1 (MYOD1), myostatin (MSTN), follistatin (FST), and forkhead box O3 (FOXO3)]. SUBJECTS AND DESIGN We measured the basal rate of muscle protein synthesis and the expression of muscle growth-regulatory genes in 12 premenopausal women and four groups of postmenopausal women (n=24 total) who were studied before and after treatment with T, estradiol, or progesterone or no intervention (control group). All women were healthy, and pre- and postmenopausal women were carefully matched on body mass, body composition, and insulin sensitivity. RESULTS The muscle protein fractional synthesis rate was approximately 20% faster, and MYOD1, FST, and FOXO3 mRNA expressions were approximately 40%-90% greater (all P<.05) in postmenopausal than premenopausal women. In postmenopausal women, both T and progesterone treatment increased the muscle protein fractional synthesis rate by approximately 50% (both P<.01), whereas it was not affected by estradiol treatment and was unchanged in the control group. Progesterone treatment increased MYOD1 mRNA expression (P<.05) but had no effect on MSTN, FST, and FOXO3 mRNA expression. T and estradiol treatment had no effect on skeletal muscle MYOD1, MSTN, FST, and FOXO3 mRNA expression. CONCLUSION Muscle protein turnover is faster in older, postmenopausal women compared with younger, premenopausal women, but these age-related differences do not appear to be explained by the age- and menopause-related changes in the plasma sex hormone milieu.
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Affiliation(s)
- Gordon I Smith
- Center for Human Nutrition, Division of Geriatrics and Nutritional Science, Department of Internal Medicine, Washington University School of Medicine, St Louis, Missouri 63110
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Kiskini A, Hamer HM, Wall BT, Groen BBL, de Lange A, Bakker JA, Senden JMG, Verdijk LB, van Loon LJC. The muscle protein synthetic response to the combined ingestion of protein and carbohydrate is not impaired in healthy older men. AGE (DORDRECHT, NETHERLANDS) 2013; 35:2389-2398. [PMID: 23529503 PMCID: PMC3824983 DOI: 10.1007/s11357-013-9522-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 03/08/2013] [Indexed: 06/02/2023]
Abstract
Aging is associated with a progressive decline in skeletal muscle mass. It has been hypothesized that an attenuated muscle protein synthetic response to the main anabolic stimuli may contribute to the age-related loss of muscle tissue. The aim of the present study was to compare the muscle protein synthetic response following ingestion of a meal-like amount of dietary protein plus carbohydrate between healthy young and older men. Twelve young (21 ± 1 years) and 12 older (75 ± 1 years) men consumed 20 g of intrinsically L-[1-(13)C]phenylalanine-labeled protein with 40 g of carbohydrate. Ingestion of specifically produced intrinsically L-[1-(13)C]phenylalanine-labeled protein allowed us to assess the subsequent incorporation of casein-derived amino acids into muscle protein. Blood samples were collected at regular intervals, with muscle biopsies obtained prior to and 2 and 6 h after protein plus carbohydrate ingestion. The acute post-prandial rise in plasma glucose and insulin concentrations was significantly greater in the older compared with the younger males. Plasma amino acid concentrations increased rapidly following drink ingestion in both groups. However, plasma leucine concentrations were significantly lower at t = 90 min in the older when compared with the young group (P < 0.05). Muscle protein-bound L-[1-(13)C]phenylalanine enrichments increased to 0.0071 ± 0.0016 and 0.0072 ± 0.0013 mole percent excess (MPE) at 2 h and 0.0229 ± 0.0016 and 0.0213 ± 0.0024 MPE at 6 h following ingestion of the intrinsically labeled protein in the young and older males, respectively, with no differences between groups (P > 0.05). We conclude that the use of dietary protein-derived amino acids for muscle protein synthesis is not impaired in healthy older men following intake of protein plus carbohydrate.
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Affiliation(s)
- Alexandra Kiskini
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Henrike M. Hamer
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Benjamin T. Wall
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Bart B. L. Groen
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Anneke de Lange
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Jaap A. Bakker
- />Department of Clinical Genetics, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Joan M. G. Senden
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Lex B. Verdijk
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
| | - Luc J. C. van Loon
- />Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, PO Box 616, Maastricht, 6200 MD the Netherlands
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Chevalier S, Farsijani S. Cancer cachexia and diabetes: similarities in metabolic alterations and possible treatment. Appl Physiol Nutr Metab 2013; 39:643-53. [PMID: 24869969 DOI: 10.1139/apnm-2013-0369] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cancer cachexia is a metabolic syndrome featuring many alterations typical of type 2 diabetes (T2D). While muscle wasting is a hallmark of cachexia, epidemiological evidence also supports an accelerated age-related muscle loss in T2D. Insulin resistance manifests in both conditions and impairs glucose disposal and protein anabolism by tissues. A greater contribution of gluconeogenesis to glucose production may limit amino acid availability for muscle protein synthesis, further aggravating muscle loss. In the context of inter-dependence between glucose and protein metabolism, the present review summarizes the current state of knowledge on alterations that may lead to muscle wasting in human cancer. By highlighting the similarities with T2D, a disease that has been more extensively studied, the objective of this review is to provide a better understanding of the pathophysiology of cancer cachexia and to consider potential treatments usually targeted for T2D. Nutritional approaches aimed at stimulating protein anabolism might include specially formulated food with optimal protein and amino acid composition. Because the gradual muscle loss in T2D may be attenuated by diabetes treatment, anti-diabetic drugs might be considered in cachexia treatment. Metformin emerges as a choice candidate as it acts both on reducing gluconeogenesis and improving insulin sensitivity, and has demonstrated tumour suppressor properties in multiple cancer types. Such a multimodal approach to slow or reverse muscle wasting in cachexia warrants further investigation.
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Affiliation(s)
- Stéphanie Chevalier
- a Department of Medicine and School of Dietetics and Human Nutrition, Crabtree Nutrition Laboratories, McGill University Health Centre-Royal Victoria Hospital, 687 ave des Pins Ouest, room H6.61, Montreal, QC H3A 1A1, Canada
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Breen L, Phillips SM. Interactions between exercise and nutrition to prevent muscle waste during ageing. Br J Clin Pharmacol 2013; 75:708-15. [PMID: 22957963 PMCID: PMC3575937 DOI: 10.1111/j.1365-2125.2012.04456.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Accepted: 08/27/2012] [Indexed: 12/19/2022] Open
Abstract
The underlying cause of sarcopenia and dynapenia (age-related strength loss) are not fully elucidated, but may be the result, or combination, of alterations in lifestyle or inflammatory and endocrine profiles. What is clear is that functional ability is limited and mortality risk is elevated. Mechanistically, muscle atrophy is the result of the prolonged periods of net negative muscle protein balance, brought about by the imbalance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Contractile loading of skeletal muscle, through resistive-type exercise and amino acid ingestion both act as a strong stimulus for MPS and, when combined, can induce a net positive protein balance and muscle hypertrophy. Given that MPS in older muscles displays a blunted response to anabolic stimuli compared with the young, the combined effect and manipulation of contractile and nutrient interventions to optimize muscle anabolism could be extremely important for counteracting sarcopenia. Specifically, the dose, absorption kinetics, leucine content, but less-so the timing of ingestion, are important determinants of the mRNA translational signalling response regulating MPS. In addition, resistance exercise-induced rates of MPS and hypertrophy appear to be dependent on exercise volume (to achieve maximal muscle fibre recruitment), as opposed to the absolute load that is lifted. A number of recent studies in young adults lend weight to this notion by showing that contraction can be manipulated; allowing low load weight lifting to effectively stimulate rates of MPS to a level comparable with traditional high loads, a finding with important implications for older adults interested in undertaking resistance exercise.
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Affiliation(s)
- Leigh Breen
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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Dillon EL. Nutritionally essential amino acids and metabolic signaling in aging. Amino Acids 2012; 45:431-41. [PMID: 23239011 DOI: 10.1007/s00726-012-1438-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 11/28/2012] [Indexed: 02/07/2023]
Abstract
Aging is associated with a gradual decline in skeletal muscle mass and strength leading to increased risk for functional impairments. Although basal rates of protein synthesis and degradation are largely unaffected with age, the sensitivity of older muscle cells to the anabolic actions of essential amino acids appears to decline. The major pathway through which essential amino acids induce anabolic responses involves the mammalian target of rapamycin (mTOR) Complex 1, a signaling pathway that is especially sensitive to regulation by the branched chain amino acid leucine. Recent evidence suggests that muscle of older individuals require increasing concentrations of leucine to maintain robust anabolic responses through the mTOR pathway. While the exact mechanisms for the age-related alterations in nutritional signaling through the mTOR pathway remain elusive, there is increasing evidence that decreased sensitivity to insulin action, reductions in endothelial function, and increased oxidative stress may be underlying factors in this decrease in anabolic sensitivity. Ensuring adequate nutrition, including sources of high quality protein, and promoting regular physical activity will remain among the frontline defenses against the onset of sarcopenia in older individuals.
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Affiliation(s)
- E Lichar Dillon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, USA.
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Normal protein anabolic response to hyperaminoacidemia in insulin-resistant patients with lung cancer cachexia. Clin Nutr 2012; 31:765-73. [DOI: 10.1016/j.clnu.2012.05.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 04/19/2012] [Accepted: 05/05/2012] [Indexed: 11/30/2022]
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Sexually dimorphic effect of aging on skeletal muscle protein synthesis. Biol Sex Differ 2012; 3:11. [PMID: 22620287 PMCID: PMC3467175 DOI: 10.1186/2042-6410-3-11] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 05/06/2012] [Indexed: 12/25/2022] Open
Abstract
Background Although there appear to be no differences in muscle protein turnover in young and middle aged men and women, we have reported significant differences in the rate of muscle protein synthesis between older adult men and women. This suggests that aging may affect muscle protein turnover differently in men and women. Methods We measured the skeletal muscle protein fractional synthesis rate (FSR) by using stable isotope-labeled tracer methods during basal postabsorptive conditions and during a hyperaminoacidemic-hyperinsulinemic-euglycemic clamp in eight young men (25–45 y), ten young women (25–45 y), ten old men (65–85 y) and ten old women (65–85 y). Results The basal muscle protein FSR was not different in young and old men (0.040 ± 0.004 and 0.043 ± 0.005%·h-1, respectively) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR both in young (to 0.063 ± 0.006%·h-1) and old (to 0.051 ± 0.008%·h-1) men but the increase (0.023 ± 0.004 vs. 0.009 ± 0.004%·h-1, respectively) was ~60% less in the old men (P = 0.03). In contrast, the basal muscle protein FSR was ~30% greater in old than young women (0.060 ± 0.003 vs. 0.046 ± 0.004%·h-1, respectively; P < 0.05) and combined insulin, glucose and amino acid infusion significantly increased the muscle protein FSR in young (P < 0.01) but not in old women (P = 0.10) so that the FSR was not different between young and old women during the clamp (0.074 ± 0.006%·h-1 vs. 0.072 ± 0.006%·h-1, respectively). Conclusions There is sexual dimorphism in the age-related changes in muscle protein synthesis and thus the metabolic processes responsible for the age-related decline in muscle mass.
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Abstract
PURPOSE OF REVIEW Investigations into the regulation of muscle protein synthesis (MPS) are a cornerstone of understanding the control of muscle mass. Rates of MPS are finely tuned according to levels of activity, nutrient availability and health status. For instance, rates of MPS are positively regulated by exercise and nutrition, and negatively regulated by inactivity (e.g. disuse), ageing (i.e. sarcopenia) and in muscle-wasting related diseases (e.g. cancer). RECENT FINDINGS Skeletal muscles display a high degree of intrinsic regulation. Increases in MPS after exercise occur independently of the systemic milieu for example growth hormone/testosterone concentrations. In the absence of exercise, increases in MPS after feeding are of finite duration despite enduring precursor availability; that is muscles can sense they are 'full'. Intriguingly, exercise delays this 'muscle-full' response to allow for building and repair. In contrast, muscle-wasting conditions exhibit a premature 'muscle-full' response to nutrition and exercise (i.e. anabolic resistance), which may cause atrophy. Observations of 'dissociations' between MPS and anabolic signalling pathways have cast doubt on how much we understand of the molecular regulation of human MPS. SUMMARY Anabolic and anticatabolic interventions in health and disease should be aimed at manipulating the 'muscle-full' set point to maximize muscle maintenance/hypertrophy.
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Affiliation(s)
- Bethan E Phillips
- Division of Clinical Physiology, School of Graduate Entry Medicine and Health, University of Nottingham, Derby, UK
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Burd NA, Wall BT, van Loon LJC. The curious case of anabolic resistance: old wives' tales or new fables? J Appl Physiol (1985) 2011; 112:1233-5. [PMID: 22134695 DOI: 10.1152/japplphysiol.01343.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Nicholas A Burd
- Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+ (MUMC+ Maastricht, The Netherlands
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