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Mattingly ML, Ruple BA, Sexton CL, Godwin JS, McIntosh MC, Smith MA, Plotkin DL, Michel JM, Anglin DA, Kontos NJ, Fei S, Phillips SM, Mobley CB, Vechetti I, Vann CG, Roberts MD. Resistance training in humans and mechanical overload in rodents do not elevate muscle protein lactylation. Front Physiol 2023; 14:1281702. [PMID: 37841321 PMCID: PMC10569119 DOI: 10.3389/fphys.2023.1281702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 09/20/2023] [Indexed: 10/17/2023] Open
Abstract
Although several reports have hypothesized that exercise may increase skeletal muscle protein lactylation, empirical evidence in humans is lacking. Thus, we adopted a multi-faceted approach to examine if acute and subchronic resistance training (RT) altered skeletal muscle protein lactylation levels. In mice, we also sought to examine if surgical ablation-induced plantaris hypertrophy coincided with increases in muscle protein lactylation. To examine acute responses, participants' blood lactate concentrations were assessed before, during, and after eight sets of an exhaustive lower body RT bout (n = 10 trained college-aged men). Vastus lateralis biopsies were also taken before, 3-h post, and 6-h post-exercise to assess muscle protein lactylation. To identify training responses, another cohort of trained college-aged men (n = 14) partook in 6 weeks of lower-body RT (3x/week) and biopsies were obtained before and following the intervention. Five-month-old C57BL/6 mice were subjected to 10 days of plantaris overload (OV, n = 8) or served as age-matched sham surgery controls (Sham, n = 8). Although acute resistance training significantly increased blood lactate responses ∼7.2-fold (p < 0.001), cytoplasmic and nuclear protein lactylation levels were not significantly altered at the post-exercise time points, and no putative lactylation-dependent mRNA was altered following exercise. Six weeks of RT did not alter cytoplasmic protein lactylation (p = 0.800) despite significantly increasing VL muscle size (+3.5%, p = 0.037), and again, no putative lactylation-dependent mRNA was significantly affected by training. Plantaris muscles were larger in OV versus Sham mice (+43.7%, p < 0.001). However, cytoplasmic protein lactylation was similar between groups (p = 0.369), and nuclear protein lactylation was significantly lower in OV versus Sham mice (p < 0.001). The current null findings, along with other recent null findings in the literature, challenge the thesis that lactate has an appreciable role in promoting skeletal muscle hypertrophy.
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Affiliation(s)
| | - Bradley A. Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Casey L. Sexton
- Department of Physiology and Aging, University of Florida, Gainesville, FL, United States
| | - Joshua S. Godwin
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Morgan A. Smith
- Department of Genetics, Standford University, Stanford, CA, United States
| | | | - J. Max Michel
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Derick A. Anglin
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Shengyi Fei
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, United States
| | | | - C. Brooks Mobley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Ivan Vechetti
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Christopher G. Vann
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States
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McIntosh MC, Sexton CL, Godwin JS, Ruple BA, Michel JM, Plotkin DL, Ziegenfuss TN, Lopez HL, Smith R, Dwaraka VB, Sharples AP, Dalbo VJ, Mobley CB, Vann CG, Roberts MD. Different Resistance Exercise Loading Paradigms Similarly Affect Skeletal Muscle Gene Expression Patterns of Myostatin-Related Targets and mTORC1 Signaling Markers. Cells 2023; 12:898. [PMID: 36980239 PMCID: PMC10047349 DOI: 10.3390/cells12060898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 03/17/2023] Open
Abstract
Although transcriptome profiling has been used in several resistance training studies, the associated analytical approaches seldom provide in-depth information on individual genes linked to skeletal muscle hypertrophy. Therefore, a secondary analysis was performed herein on a muscle transcriptomic dataset we previously published involving trained college-aged men (n = 11) performing two resistance exercise bouts in a randomized and crossover fashion. The lower-load bout (30 Fail) consisted of 8 sets of lower body exercises to volitional fatigue using 30% one-repetition maximum (1 RM) loads, whereas the higher-load bout (80 Fail) consisted of the same exercises using 80% 1 RM loads. Vastus lateralis muscle biopsies were collected prior to (PRE), 3 h, and 6 h after each exercise bout, and 58 genes associated with skeletal muscle hypertrophy were manually interrogated from our prior microarray data. Select targets were further interrogated for associated protein expression and phosphorylation induced-signaling events. Although none of the 58 gene targets demonstrated significant bout x time interactions, ~57% (32 genes) showed a significant main effect of time from PRE to 3 h (15↑ and 17↓, p < 0.01), and ~26% (17 genes) showed a significant main effect of time from PRE to 6 h (8↑ and 9↓, p < 0.01). Notably, genes associated with the myostatin (9 genes) and mammalian target of rapamycin complex 1 (mTORC1) (9 genes) signaling pathways were most represented. Compared to mTORC1 signaling mRNAs, more MSTN signaling-related mRNAs (7 of 9) were altered post-exercise, regardless of the bout, and RHEB was the only mTORC1-associated mRNA that was upregulated following exercise. Phosphorylated (phospho-) p70S6K (Thr389) (p = 0.001; PRE to 3 h) and follistatin protein levels (p = 0.021; PRE to 6 h) increased post-exercise, regardless of the bout, whereas phospho-AKT (Thr389), phospho-mTOR (Ser2448), and myostatin protein levels remained unaltered. These data continue to suggest that performing resistance exercise to volitional fatigue, regardless of load selection, elicits similar transient mRNA and signaling responses in skeletal muscle. Moreover, these data provide further evidence that the transcriptional regulation of myostatin signaling is an involved mechanism in response to resistance exercise.
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Affiliation(s)
| | - Casey L. Sexton
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | | | - J. Max Michel
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | | | | | | | | | - Adam P. Sharples
- Institute for Physical Performance, Norwegian School of Sport Sciences, 0164 Oslo, Norway
| | - Vincent J. Dalbo
- School of Health, Medical and Applied Sciences, Central Queensland University, Rockhampton 4700, Australia
| | | | - Christopher G. Vann
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, NC 03824, USA
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3
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Vann CG, Orenduff MC, Hubal MJ, Kraus WE, Kraus VB. Effects Of Six Months Of Aerobic Exercise On Mir Expression In Skeletal Muscle. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000882968.30180.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Vann CG, Zhang X, Khodabukus A, Orenduff MC, Chen YH, Corcoran DL, Truskey GA, Bursac N, Kraus VB. Differential microRNA profiles of intramuscular and secreted extracellular vesicles in human tissue-engineered muscle. Front Physiol 2022; 13:937899. [PMID: 36091396 PMCID: PMC9452896 DOI: 10.3389/fphys.2022.937899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Exercise affects the expression of microRNAs (miR/s) and muscle-derived extracellular vesicles (EVs). To evaluate sarcoplasmic and secreted miR expression in human skeletal muscle in response to exercise-mimetic contractile activity, we utilized a three-dimensional tissue-engineered model of human skeletal muscle ("myobundles"). Myobundles were subjected to three culture conditions: no electrical stimulation (CTL), chronic low frequency stimulation (CLFS), or intermittent high frequency stimulation (IHFS) for 7 days. RNA was isolated from myobundles and from extracellular vesicles (EVs) secreted by myobundles into culture media; miR abundance was analyzed by miRNA-sequencing. We used edgeR and a within-sample design to evaluate differential miR expression and Pearson correlation to evaluate correlations between myobundle and EV populations within treatments with statistical significance set at p < 0.05. Numerous miRs were differentially expressed between myobundles and EVs; 116 miRs were differentially expressed within CTL, 3 within CLFS, and 2 within IHFS. Additionally, 25 miRs were significantly correlated (18 in CTL, 5 in CLFS, 2 in IHFS) between myobundles and EVs. Electrical stimulation resulted in differential expression of 8 miRs in myobundles and only 1 miR in EVs. Several KEGG pathways, known to play a role in regulation of skeletal muscle, were enriched, with differentially overrepresented miRs between myobundle and EV populations identified using miEAA. Together, these results demonstrate that in vitro exercise-mimetic contractile activity of human engineered muscle affects both their expression of miRs and number of secreted EVs. These results also identify novel miRs of interest for future studies of the role of exercise in organ-organ interactions in vivo.
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Affiliation(s)
- Christopher G Vann
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States
| | - Xin Zhang
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States.,Department of Orthopaedic Surgery, Duke University School of Medicine, Duke University, Durham, NC, United States
| | - Alastair Khodabukus
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Melissa C Orenduff
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States
| | - Yu-Hsiu Chen
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States
| | - David L Corcoran
- Department of Genetics, University of North Carolina School of Medicine, University of North Carolina, Chapel Hill, NC, United States
| | - George A Truskey
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Nenad Bursac
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, United States
| | - Virginia B Kraus
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States.,Department of Orthopaedic Surgery, Duke University School of Medicine, Duke University, Durham, NC, United States.,Department of Medicine, Duke University School of Medicine, Duke University, Durham, NC, United States
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Vann CG, Sexton CL, Osburn SC, Smith MA, Haun CT, Rumbley MN, Mumford PW, Montgomery NT, Ruple BA, McKendry J, Mcleod J, Bashir A, Beyers RJ, Brook MS, Smith K, Atherton PJ, Beck DT, McDonald JR, Young KC, Phillips SM, Roberts MD. Effects of High-Volume Versus High-Load Resistance Training on Skeletal Muscle Growth and Molecular Adaptations. Front Physiol 2022; 13:857555. [PMID: 35360253 PMCID: PMC8962955 DOI: 10.3389/fphys.2022.857555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
We evaluated the effects of higher-load (HL) versus (lower-load) higher-volume (HV) resistance training on skeletal muscle hypertrophy, strength, and muscle-level molecular adaptations. Trained men (n = 15, age: 23 ± 3 years; training experience: 7 ± 3 years) performed unilateral lower-body training for 6 weeks (3× weekly), where single legs were randomly assigned to HV and HL paradigms. Vastus lateralis (VL) biopsies were obtained prior to study initiation (PRE) as well as 3 days (POST) and 10 days following the last training bout (POSTPR). Body composition and strength tests were performed at each testing session, and biochemical assays were performed on muscle tissue after study completion. Two-way within-subject repeated measures ANOVAs were performed on most dependent variables, and tracer data were compared using dependent samples t-tests. A significant interaction existed for VL muscle cross-sectional area (assessed via magnetic resonance imaging; interaction p = 0.046), where HV increased this metric from PRE to POST (+3.2%, p = 0.018) whereas HL training did not (-0.1%, p = 0.475). Additionally, HL increased leg extensor strength more so than HV training (interaction p = 0.032; HV < HL at POST and POSTPR, p < 0.025 for each). Six-week integrated non-myofibrillar protein synthesis (iNon-MyoPS) rates were also higher in the HV versus HL condition, while no difference between conditions existed for iMyoPS rates. No interactions existed for other strength, VL morphology variables, or the relative abundances of major muscle proteins. Compared to HL training, 6 weeks of HV training in previously trained men optimizes VL hypertrophy in lieu of enhanced iNon-MyoPS rates, and this warrants future research.
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Affiliation(s)
- Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL, United States
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, United States
| | - Casey L. Sexton
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C. Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Morgan A. Smith
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | | | - Petey W. Mumford
- Department of Kinesiology, Lindenwood University, St. Charles, MO, United States
| | | | - Bradley A. Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - James McKendry
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Jonathan Mcleod
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Adil Bashir
- MRI Research Center, Auburn University, Auburn, AL, United States
| | - Ronald J. Beyers
- MRI Research Center, Auburn University, Auburn, AL, United States
| | - Matthew S. Brook
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Nottingham, United Kingdom
| | - Kenneth Smith
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Nottingham, United Kingdom
| | - Philip J. Atherton
- MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, Clinical, Metabolic, and Molecular Physiology, University of Nottingham, Nottingham, United Kingdom
| | - Darren T. Beck
- School of Kinesiology, Auburn University, Auburn, AL, United States
- Edward Via College of Osteopathic Medicine – Auburn Campus, Auburn, AL, United States
| | | | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL, United States
- Edward Via College of Osteopathic Medicine – Auburn Campus, Auburn, AL, United States
| | | | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States
- Edward Via College of Osteopathic Medicine – Auburn Campus, Auburn, AL, United States
- *Correspondence: Michael D. Roberts,
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Osburn SC, Vann CG, Church DD, Ferrando AA, Roberts MD. Proteasome- and Calpain-Mediated Proteolysis, but Not Autophagy, Is Required for Leucine-Induced Protein Synthesis in C2C12 Myotubes. Physiologia 2021; 1:22-33. [PMID: 34927140 PMCID: PMC8681867 DOI: 10.3390/physiologia1010005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Muscle protein synthesis and proteolysis are tightly coupled processes. Given that muscle growth is promoted by increases in net protein balance, it stands to reason that bolstering protein synthesis through amino acids while reducing or inhibiting proteolysis could be a synergistic strategy in enhancing anabolism. However, there is contradictory evidence suggesting that the proper functioning of proteolytic systems in muscle is required for homeostasis. To add clarity to this issue, we sought to determine if inhibiting different proteolytic systems in C2C12 myotubes in conjunction with acute and chronic leucine treatments affected markers of anabolism. In Experiment 1, myotubes underwent 1-h, 6-h, and 24-h treatments with serum and leucine-free DMEM containing the following compounds (n = 6 wells per treatment): (i) DMSO vehicle (CTL), (ii) 2 mM leucine + vehicle (Leu-only), (iii) 2 mM leucine + 40 μM MG132 (20S proteasome inhibitor) (Leu + MG132), (iv) 2 mM leucine + 50 μM calpeptin (calpain inhibitor) (Leu + CALP), and (v) 2 mM leucine + 1 μM 3-methyladenine (autophagy inhibitor) (Leu + 3MA). Protein synthesis levels significantly increased (p < 0.05) in the Leu-only and Leu + 3MA 6-h treatments compared to CTL, and levels were significantly lower in Leu + MG132 and Leu + CALP versus Leu-only and CTL. With 24-h treatments, total protein yield was significantly lower in Leu + MG132 cells versus other treatments. Additionally, the intracellular essential amino acid (EAA) pool was significantly greater in 24-h Leu + MG132 treatments versus other treatments. In a follow-up experiment, myotubes were treated for 48 h with CTL, Leu-only, and Leu + MG132 for morphological assessments. Results indicated Leu + MG132 yielded significantly smaller myotubes compared to CTL and Leu-only. Our data are limited in scope due to the utilization of select proteolysis inhibitors. However, this is the first evidence to suggest proteasome and calpain inhibition with MG132 and CALP, respectively, abrogate leucine-induced protein synthesis in myotubes. Additionally, longer-term Leu + MG132 treatments translated to an atrophy phenotype. Whether or not proteasome inhibition in vivo reduces leucine- or EAA-induced anabolism remains to be determined.
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Affiliation(s)
| | - Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
- Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC 27708, USA
| | - David D. Church
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Arny A. Ferrando
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Mesquita PHC, Vann CG, Phillips SM, McKendry J, Young KC, Kavazis AN, Roberts MD. Skeletal Muscle Ribosome and Mitochondrial Biogenesis in Response to Different Exercise Training Modalities. Front Physiol 2021; 12:725866. [PMID: 34646153 PMCID: PMC8504538 DOI: 10.3389/fphys.2021.725866] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/13/2021] [Indexed: 11/20/2022] Open
Abstract
Skeletal muscle adaptations to resistance and endurance training include increased ribosome and mitochondrial biogenesis, respectively. Such adaptations are believed to contribute to the notable increases in hypertrophy and aerobic capacity observed with each exercise mode. Data from multiple studies suggest the existence of a competition between ribosome and mitochondrial biogenesis, in which the first adaptation is prioritized with resistance training while the latter is prioritized with endurance training. In addition, reports have shown an interference effect when both exercise modes are performed concurrently. This prioritization/interference may be due to the interplay between the 5’ AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin complex 1 (mTORC1) signaling cascades and/or the high skeletal muscle energy requirements for the synthesis and maintenance of cellular organelles. Negative associations between ribosomal DNA and mitochondrial DNA copy number in human blood cells also provide evidence of potential competition in skeletal muscle. However, several lines of evidence suggest that ribosome and mitochondrial biogenesis can occur simultaneously in response to different types of exercise and that the AMPK-mTORC1 interaction is more complex than initially thought. The purpose of this review is to provide in-depth discussions of these topics. We discuss whether a curious competition between mitochondrial and ribosome biogenesis exists and show the available evidence both in favor and against it. Finally, we provide future research avenues in this area of exercise physiology.
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Affiliation(s)
| | | | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - James McKendry
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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Ruple BA, Godwin JS, Mesquita PHC, Osburn SC, Vann CG, Lamb DA, Sexton CL, Candow DG, Forbes SC, Frugé AD, Kavazis AN, Young KC, Seaborne RA, Sharples AP, Roberts MD. Resistance training rejuvenates the mitochondrial methylome in aged human skeletal muscle. FASEB J 2021; 35:e21864. [PMID: 34423880 DOI: 10.1096/fj.202100873rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 11/11/2022]
Abstract
Resistance training (RT) dynamically alters the skeletal muscle nuclear DNA methylome. However, no study has examined if RT affects the mitochondrial DNA (mtDNA) methylome. Herein, ten older, Caucasian untrained males (65 ± 7 y.o.) performed six weeks of full-body RT (twice weekly). Body composition and knee extensor torque were assessed prior to and 72 h following the last RT session. Vastus lateralis (VL) biopsies were also obtained. VL DNA was subjected to reduced representation bisulfite sequencing providing excellent coverage across the ~16-kilobase mtDNA methylome (254 CpG sites). Biochemical assays were also performed, and older male data were compared to younger trained males (22 ± 2 y.o., n = 7, n = 6 Caucasian & n = 1 African American). RT increased whole-body lean tissue mass (p = .017), VL thickness (p = .012), and knee extensor torque (p = .029) in older males. RT also affected the mtDNA methylome, as 63% (159/254) of the CpG sites demonstrated reduced methylation (p < .05). Several mtDNA sites presented a more "youthful" signature in older males after RT in comparison to younger males. The 1.12 kilobase mtDNA D-loop/control region, which regulates replication and transcription, possessed enriched hypomethylation in older males following RT. Enhanced expression of mitochondrial H- and L-strand genes and complex III/IV protein levels were also observed (p < .05). While limited to a shorter-term intervention, this is the first evidence showing that RT alters the mtDNA methylome in skeletal muscle. Observed methylome alterations may enhance mitochondrial transcription, and RT evokes mitochondrial methylome profiles to mimic younger men. The significance of these findings relative to broader RT-induced epigenetic changes needs to be elucidated.
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Affiliation(s)
- Bradley A Ruple
- School of Kinesiology, Auburn University, Auburn, Alabama, USA
| | - Joshua S Godwin
- School of Kinesiology, Auburn University, Auburn, Alabama, USA
| | | | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, Alabama, USA
| | | | - Donald A Lamb
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, Alabama, USA
| | - Casey L Sexton
- School of Kinesiology, Auburn University, Auburn, Alabama, USA
| | - Darren G Candow
- Faculty of Kinesiology and Health Studies, University of Regina, Regina, Saskatchewan, Canada
| | - Scott C Forbes
- Faculty of Education, Department of Physical Education Studies, Brandon University, Brandon, Manitoba, Canada
| | - Andrew D Frugé
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, Alabama, USA
| | | | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama, USA.,Edward Via College of Osteopathic Medicine, Auburn, Alabama, USA
| | - Robert A Seaborne
- Centre for Genomics and Child Health, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Adam P Sharples
- Institute for Physical Performance, Norwegian School of Sport Sciences, Olso, Norway
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, USA.,Edward Via College of Osteopathic Medicine, Auburn, Alabama, USA
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Vann CG, Haun CT, Osburn SC, Romero MA, Roberson PA, Mumford PW, Mobley CB, Holmes HM, Fox CD, Young KC, Roberts MD. Molecular Differences in Skeletal Muscle After 1 Week of Active vs. Passive Recovery From High-Volume Resistance Training. J Strength Cond Res 2021; 35:2102-2113. [PMID: 34138821 DOI: 10.1519/jsc.0000000000004071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
ABSTRACT Vann, CG, Haun, CT, Osburn, SC, Romero, MA, Roberson, PA, Mumford, PW, Mobley, CB, Holmes, HM, Fox, CD, Young, KC, and Roberts, MD. Molecular differences in skeletal muscle after 1 week of active vs. passive recovery from high-volume resistance training. J Strength Cond Res 35(8): 2102-2113, 2021-Numerous studies have evaluated how deloading after resistance training (RT) affects strength and power outcomes. However, the molecular adaptations that occur after deload periods remain understudied. Trained, college-aged men (n = 30) performed 6 weeks of whole-body RT starting at 10 sets of 10 repetitions per exercise per week and finishing at 32 sets of 10 repetitions per exercise per week. After this period, subjects performed either active (AR; n = 16) or passive recovery (PR; n = 14) for 1 week where AR completed ∼15% of the week 6 training volume and PR ceased training. Variables related to body composition and recovery examined before RT (PRE), after 6 weeks of RT (POST), and after the 1-week recovery period (DL). Vastus lateralis (VL) muscle biopsies and blood samples were collected at each timepoint, and various biochemical and histological assays were performed. Group × time interactions (p < 0.05) existed for skeletal muscle myosin heavy chain (MHC)-IIa mRNA (AR > PR at POST and DL) and 20S proteasome activity (post-hoc tests revealed no significance in groups over time). Time effects (P < 0.05) existed for total mood disturbance and serum creatine kinase and mechano growth factor mRNA (POST > PRE &D L), VL pressure to pain threshold and MHC-IIx mRNA (PRE&DL > POST), Atrogin-1 and MuRF-1 mRNA (PRE < POST < DL), MHC-I mRNA (PRE < POST & DL), myostatin mRNA (PRE & POST < DL), and mechanistic target of rapamycin (PRE > POST & DL). No interactions or time effects were observed for barbell squat velocity, various hormones, histological metrics, polyubiquitinated proteins, or phosphorylated/pan protein levels of 4E-BP1, p70S6k, and AMPK. One week of AR after a high-volume training block instigates marginal molecular differences in skeletal muscle relative to PR. From a practical standpoint, however, both paradigms elicited largely similar responses.
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Affiliation(s)
| | - Cody T Haun
- Department of Exercise Science, LaGrange College, Lagrange, Georgia
| | | | - Matthew A Romero
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California
| | - Paul A Roberson
- Department of Cellular and Molecular Physiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania
| | - Petey W Mumford
- Department of Exercise Science, Lindenwood University, St. Charles, Missouri
| | - C Brooks Mobley
- Department of Physiology, University of Kentucky, Lexington, Kentucky; and
| | | | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama
- Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama
- Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
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Vann CG, Morton RW, Mobley CB, Vechetti IJ, Ferguson BK, Haun CT, Osburn SC, Sexton CL, Fox CD, Romero MA, Roberson PA, Oikawa SY, McGlory C, Young KC, McCarthy JJ, Phillips SM, Roberts MD. An intron variant of the GLI family zinc finger 3 (GLI3) gene differentiates resistance training-induced muscle fiber hypertrophy in younger men. FASEB J 2021; 35:e21587. [PMID: 33891350 PMCID: PMC8234740 DOI: 10.1096/fj.202100113rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/17/2021] [Accepted: 03/25/2021] [Indexed: 12/25/2022]
Abstract
We examined the association between genotype and resistance training-induced changes (12 wk) in dual x-ray energy absorptiometry (DXA)-derived lean soft tissue mass (LSTM) as well as muscle fiber cross-sectional area (fCSA; vastus lateralis; n = 109; age = 22 ± 2 y, BMI = 24.7 ± 3.1 kg/m2 ). Over 315 000 genetic polymorphisms were interrogated from muscle using DNA microarrays. First, a targeted investigation was performed where single nucleotide polymorphisms (SNP) identified from a systematic literature review were related to changes in LSTM and fCSA. Next, genome-wide association (GWA) studies were performed to reveal associations between novel SNP targets with pre- to post-training change scores in mean fCSA and LSTM. Our targeted investigation revealed no genotype-by-time interactions for 12 common polymorphisms regarding the change in mean fCSA or change in LSTM. Our first GWA study indicated no SNP were associated with the change in LSTM. However, the second GWA study indicated two SNP exceeded the significance level with the change in mean fCSA (P = 6.9 × 10-7 for rs4675569, 1.7 × 10-6 for rs10263647). While the former target is not annotated (chr2:205936846 (GRCh38.p12)), the latter target (chr7:41971865 (GRCh38.p12)) is an intron variant of the GLI Family Zinc Finger 3 (GLI3) gene. Follow-up analyses indicated fCSA increases were greater in the T/C and C/C GLI3 genotypes than the T/T GLI3 genotype (P < .05). Data from the Auburn cohort also revealed participants with the T/C and C/C genotypes exhibited increases in satellite cell number with training (P < .05), whereas T/T participants did not. Additionally, those with the T/C and C/C genotypes achieved myonuclear addition in response to training (P < .05), whereas the T/T participants did not. In summary, this is the first GWA study to examine how polymorphisms associate with the change in hypertrophy measures following resistance training. Future studies are needed to determine if the GLI3 variant differentiates hypertrophic responses to resistance training given the potential link between this gene and satellite cell physiology.
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Affiliation(s)
- Christopher G Vann
- School of Kinesiology, Auburn University, Auburn, AL, USA.,Duke Molecular Physiology Institute, Duke University School of Medicine, Duke University, Durham, NC, USA
| | - Robert W Morton
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Christopher B Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, USA.,The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Ivan J Vechetti
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | | | | | | | - Casey L Sexton
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | | | - Sara Y Oikawa
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Chris McGlory
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, USA
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, USA.,The Center for Muscle Biology, University of Kentucky, Lexington, KY, USA
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, USA
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Roberson PA, Mobley CB, Romero MA, Haun CT, Osburn SC, Mumford PW, Vann CG, Greer RA, Ferrando AA, Roberts MD. LAT1 Protein Content Increases Following 12 Weeks of Resistance Exercise Training in Human Skeletal Muscle. Front Nutr 2021; 7:628405. [PMID: 33521042 PMCID: PMC7840583 DOI: 10.3389/fnut.2020.628405] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 12/11/2020] [Indexed: 12/24/2022] Open
Abstract
Introduction: Amino acid transporters are essential for cellular amino acid transport and promoting protein synthesis. While previous literature has demonstrated the association of amino acid transporters and protein synthesis following acute resistance exercise and amino acid supplementation, the chronic effect of resistance exercise and supplementation on amino acid transporters is unknown. The purpose herein was to determine if amino acid transporters and amino acid metabolic enzymes were related to skeletal muscle hypertrophy following resistance exercise training with different nutritional supplementation strategies. Methods: 43 college-aged males were separated into a maltodextrin placebo (PLA, n = 12), leucine (LEU, n = 14), or whey protein concentrate (WPC, n = 17) group and underwent 12 weeks of total-body resistance exercise training. Each group's supplement was standardized for total energy and fat, and LEU and WPC supplements were standardized for total leucine (6 g/d). Skeletal muscle biopsies were obtained prior to training and ~72 h following each subject's last training session. Results: All groups increased type I and II fiber cross-sectional area (fCSA) following training (p < 0.050). LAT1 protein increased following training (p < 0.001) and increased more in PLA than LEU and WPC (p < 0.050). BCKDHα protein increased and ATF4 protein decreased following training (p < 0.001). Immunohistochemistry indicated total LAT1/fiber, but not membrane LAT1/fiber, increased with training (p = 0.003). Utilizing all groups, the change in ATF4 protein, but no other marker, trended to correlate with the change in fCSA (r = 0.314; p = 0.055); however, when regression analysis was used to delineate groups, the change in ATF4 protein best predicted the change in fCSA only in LEU (r 2 = 0.322; p = 0.043). In C2C12 myoblasts, LAT1 protein overexpression caused a paradoxical decrease in protein synthesis levels (p = 0.002) and decrease in BCKDHα protein (p = 0.001). Conclusions: Amino acid transporters and metabolic enzymes are affected by resistance exercise training, but do not appear to dictate muscle fiber hypertrophy. In fact, overexpression of LAT1 in vitro decreased protein synthesis.
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Affiliation(s)
- Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - C Brooks Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, KY, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Rory A Greer
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Arny A Ferrando
- Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AK, United States
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13
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Lamb DA, Moore JH, Smith MA, Vann CG, Osburn SC, Ruple BA, Fox CD, Smith KS, Altonji OM, Power ZM, Cerovsky AE, Ross CO, Cao AT, Goodlett MD, Huggins KW, Fruge AD, Young KC, Roberts MD. The effects of resistance training with or without peanut protein supplementation on skeletal muscle and strength adaptations in older individuals. J Int Soc Sports Nutr 2020; 17:66. [PMID: 33317565 PMCID: PMC7734909 DOI: 10.1186/s12970-020-00397-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 12/07/2020] [Indexed: 12/21/2022] Open
Abstract
Several studies suggest resistance training (RT) while supplementing with various protein supplements can enhance strength and muscle mass in older individuals. However, to date, no study has examined the effects of RT with a peanut protein powder (PP) supplement on these outcomes. Herein, 39 older, untrained individuals (n = 17 female, n = 22 male; age = 58.6 ± 8.0 years; body mass index =28.7 ± 5.8) completed a 6-week (n = 22) or 10-week (n = 17) RT program, where full-body training was implemented twice weekly (ClinicalTrials.gov trial registration NCT04015479; registered July 11, 2019). Participants in each program were randomly assigned to consume either a PP supplement once per day (75 total g powder providing 30 g protein, > 9.2 g essential amino acids, ~ 315 kcal; n = 20) or no supplement (CTL; n = 19). Right leg vastus lateralis (VL) muscle biopsies were obtained prior to and 24 h following the first training bout in all participants to assess the change in myofibrillar protein synthetic rates (MyoPS) as measured via the deuterium-oxide (D2O) tracer method. Pre- and Post-intervention testing in all participants was conducted using dual energy x-ray absorptiometry (DXA), VL ultrasound imaging, a peripheral quantitative computed tomography (pQCT) scan at the mid-thigh, and right leg isokinetic dynamometer assessments. Integrated MyoPS rates over a 24-h period were not significantly different (p < 0.05) between supplement groups following the first training bout. Regarding chronic changes, there were no significant supplement-by-time interactions in DXA-derived fat mass, lean soft tissue mass or percent body fat between supplementation groups. There was, however, a significant increase in VL thickness in PP versus CTL participants when the 6- and 10-week cohorts were pooled (interaction p = 0.041). There was also a significant increase in knee flexion torque in the 10-week PP group versus the CTL group (interaction p = 0.032). In conclusion, a higher-protein, defatted peanut powder supplement in combination with RT positively affects select markers of muscle hypertrophy and strength in an untrained, older adult population. Moreover, subanalyses indicated that gender did not play a role in these adaptations.
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Affiliation(s)
- Donald A Lamb
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, 36849, USA
| | - Johnathon H Moore
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Morgan A Smith
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Christopher G Vann
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Shelby C Osburn
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Bradley A Ruple
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Carlton D Fox
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Kristen S Smith
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, 36849, USA
| | - Olivia M Altonji
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, 36849, USA
| | - Zade M Power
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Annsley E Cerovsky
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - C Owen Ross
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Andy T Cao
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA
| | - Michael D Goodlett
- Athletics Department, Auburn University, Auburn, AL, 36849, USA.,Edward Via College of Osteopathic Medicine Auburn, Auburn, AL, 36832, USA
| | - Kevin W Huggins
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, 36849, USA
| | - Andrew D Fruge
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, 36849, USA
| | - Kaelin C Young
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA.,Edward Via College of Osteopathic Medicine Auburn, Auburn, AL, 36832, USA
| | - Michael D Roberts
- Molecular and Applied Sciences Laboratory, Applied Physiology Laboratory, School of Kinesiology, Auburn University, 301 Wire Road, Office 260, Auburn, AL, 36849, USA. .,Edward Via College of Osteopathic Medicine Auburn, Auburn, AL, 36832, USA.
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14
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Mesquita PH, Lamb DA, Parry HA, Moore JH, Smith MA, Vann CG, Osburn SC, Fox CD, Ruple BA, Huggins KW, Fruge AD, Young KC, Kavazis AN, Roberts MD. Acute and chronic effects of resistance training on skeletal muscle markers of mitochondrial remodeling in older adults. Physiol Rep 2020; 8:e14526. [PMID: 32748504 PMCID: PMC7399374 DOI: 10.14814/phy2.14526] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 02/06/2023] Open
Abstract
We investigated the acute and chronic effects of resistance training (RT) on skeletal muscle markers of mitochondrial content and remodeling in older, untrained adults. Sixteen participants (n = 6 males, n = 10 females; age = 59 ± 4 years) completed 10 weeks of full-body RT (2 day/week). Muscle biopsies from the vastus lateralis were obtained prior to RT (Pre), 24 hr following the first training session (Acute), and 72 hr following the last training session (Chronic). Protein levels of mitochondrial electron transport chain complexes I-V (+39 to +180%, p ≤ .020) and markers of mitochondrial fusion Mfn1 (+90%, p = .003), Mfn2 (+110%, p < .001), and Opa1 (+261%, p = .004) increased following chronic RT. Drp1 protein levels also increased (+134%, p = .038), while Fis1 protein levels did not significantly change (-5%, p = .584) following chronic RT. Interestingly, protein markers of mitochondrial biogenesis (i.e., PGC-1α, TFAM, and NRF1) or mitophagy (i.e., Pink1 and Parkin) were not significantly altered (p > .050) after 10 weeks of RT. In summary, chronic RT promoted increases in content of electron transport chain proteins (i.e., increased protein levels of all five OXPHOS complexes) and increase in the levels of proteins related to mitochondrial dynamics (i.e., increase in fusion protein markers) in skeletal muscle of older adults. These results suggest that chronic RT could be a useful strategy to increase mitochondrial protein content in older individuals.
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Affiliation(s)
| | - Donald A. Lamb
- Department of Nutrition, Dietetics and Hospitality ManagementAuburn UniversityAuburnALUSA
| | | | | | | | | | | | | | | | - Kevin W. Huggins
- Department of Nutrition, Dietetics and Hospitality ManagementAuburn UniversityAuburnALUSA
| | - Andrew D. Fruge
- Department of Nutrition, Dietetics and Hospitality ManagementAuburn UniversityAuburnALUSA
| | - Kaelin C. Young
- School of KinesiologyAuburn UniversityAuburnALUSA
- Department of Cell Biology and PhysiologyEdward Via College of Osteopathic MedicineAuburnALUSA
| | | | - Michael D. Roberts
- School of KinesiologyAuburn UniversityAuburnALUSA
- Department of Cell Biology and PhysiologyEdward Via College of Osteopathic MedicineAuburnALUSA
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15
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Roberts MD, Haun CT, Vann CG, Osburn SC, Young KC. Sarcoplasmic Hypertrophy in Skeletal Muscle: A Scientific "Unicorn" or Resistance Training Adaptation? Front Physiol 2020; 11:816. [PMID: 32760293 PMCID: PMC7372125 DOI: 10.3389/fphys.2020.00816] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/18/2020] [Indexed: 12/19/2022] Open
Abstract
Skeletal muscle fibers are multinucleated cells that contain mostly myofibrils suspended in an aqueous media termed the sarcoplasm. Select evidence suggests sarcoplasmic hypertrophy, or a disproportionate expansion of the sarcoplasm relative to myofibril protein accretion, coincides with muscle fiber or tissue growth during resistance training. There is also evidence to support other modes of hypertrophy occur during periods of resistance training including a proportional accretion of myofibril protein with fiber or tissue growth (i.e., conventional hypertrophy), or myofibril protein accretion preceding fiber or tissue growth (i.e., myofibril packing). In this review, we discuss methods that have been used to investigate these modes of hypertrophy. Particular attention is given to sarcoplasmic hypertrophy throughout. Thus, descriptions depicting this process as well as the broader implications of this phenomenon will be posited. Finally, we propose future human and rodent research that can further our understanding in this area of muscle physiology.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
| | - Cody T Haun
- Fitomics, LLC, Birmingham, AL, United States
| | | | | | - Kaelin C Young
- School of Kinesiology, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
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16
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Sexton CL, Vann CG, Osburn SC, Smith MA, Rumbley MN, Beck DT, Young KC, Roberts MD. Effects Of High-Load And High-Volume Resistance Training On Maximal Strength, Peak Torque, And Mean Torque. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675876.81084.98] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Smith MA, Vann CG, Sexton CL, Osburn SC, Beck DT, McDonald JR, Roberts MD, Young KC. High-Volume And High-Intensity Resistance Training Effects On Upper-Leg Lean Tissue Mass And Muscle Cross-Sectional Area. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000670180.43544.81] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Vann CG, Sexton CL, Osburn SC, Smith MA, Fox CD, Ferguson BK, Ruple BA, Haun CT, Young KC, Beck DT, McDonald JR, Phillips SM, Roberts MD. Effects Of High-Load Versus High-Volume Resistance Training On Muscle Sarcoplasmic, Actin, And Myosin Protein Concentrations. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000684436.20159.cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Fox CD, Vann CG, Osburn SC, Sexton CL, Smith MA, Moore JH, Phillips SM, Young KC, Roberts MD. Effects Of Six Weeks Of Unilateral High-volume Versus High-intensity Resistance Training On Vastus Lateralis Muscle Morphology In Previously Trained, College-aged Males. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000684432.21015.0d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Lamb DA, Moore JH, Mesquita PHC, Smith MA, Vann CG, Osburn SC, Fox CD, Lopez HL, Ziegenfuss TN, Huggins KW, Goodlett MD, Fruge AD, Kavazis AN, Young KC, Roberts MD. Resistance training increases muscle NAD + and NADH concentrations as well as NAMPT protein levels and global sirtuin activity in middle-aged, overweight, untrained individuals. Aging (Albany NY) 2020; 12:9447-9460. [PMID: 32369778 PMCID: PMC7288928 DOI: 10.18632/aging.103218] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022]
Abstract
We examined if resistance training affected muscle NAD+ and NADH concentrations as well as nicotinamide phosphoribosyltransferase (NAMPT) protein levels and sirtuin (SIRT) activity markers in middle-aged, untrained (MA) individuals. MA participants (59±4 years old; n=16) completed 10 weeks of full-body resistance training (2 d/wk). Body composition, knee extensor strength, and vastus lateralis muscle biopsies were obtained prior to training (Pre) and 72 hours following the last training bout (Post). Data from trained college-aged men (22±3 years old, training age: 6±2 years old; n=15) were also obtained for comparative purposes. Muscle NAD+ (+127%, p<0.001), NADH (+99%, p=0.002), global SIRT activity (+13%, p=0.036), and NAMPT protein (+15%, p=0.014) increased from Pre to Post in MA participants. Additionally, Pre muscle NAD+ and NADH in MA participants were lower than college-aged participants (p<0.05), whereas Post values were similar between cohorts (p>0.10). Interestingly, muscle citrate synthase activity levels (i.e., mitochondrial density) increased in MA participants from Pre to Post (+183%, p<0.001), and this increase was significantly associated with increases in muscle NAD+ (r2=0.592, p=0.001). In summary, muscle NAD+, NADH, and global SIRT activity are positively affected by resistance training in middle-aged, untrained individuals. Whether these adaptations facilitated mitochondrial biogenesis remains to be determined.
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Affiliation(s)
- Donald A Lamb
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL 36849, USA
| | | | | | - Morgan A Smith
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Hector L Lopez
- Center for Applied Health Sciences, Canfield, OH 44406, USA
| | | | - Kevin W Huggins
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL 36849, USA
| | - Michael D Goodlett
- Athletics Department, Auburn University, Auburn, AL 36849, USA.,Edward Via College of Osteopathic Medicine, Auburn, AL 36832, USA
| | - Andrew D Fruge
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL 36849, USA
| | | | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Edward Via College of Osteopathic Medicine, Auburn, AL 36832, USA
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Edward Via College of Osteopathic Medicine, Auburn, AL 36832, USA
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21
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Vann CG, Morton RW, Ferguson BK, Osburn SC, Sexton CL, Oikawa SY, McGlory C, Young KC, Phillips SM, Roberts MD. Targeted SNP Interrogation to Determine if Select Polymorphisms are Associated with Skeletal Muscle Hypertrophy Following 12 Weeks of Resistance Training. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Vann CG, Osburn SC, Mumford PW, Roberson PA, Fox CD, Sexton CL, Johnson MR, Johnson JS, Shake J, Moore JH, Millevoi K, Beck DT, Badisa VLD, Mwashote BM, Ibeanusi V, Singh RK, Roberts MD. Skeletal Muscle Protein Composition Adaptations to 10 Weeks of High-Load Resistance Training in Previously-Trained Males. Front Physiol 2020; 11:259. [PMID: 32292355 PMCID: PMC7135893 DOI: 10.3389/fphys.2020.00259] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/06/2020] [Indexed: 01/14/2023] Open
Abstract
While high-load resistance training increases muscle hypertrophy, the intramuscular protein responses to this form of training remains largely unknown. In the current study, recreationally resistance-trained college-aged males (N = 15; mean ± SD: 23 ± 3 years old, 6 ± 5 years training) performed full-body, low-volume, high-load [68–90% of one repetition maximum (1RM)] resistance training over 10 weeks. Back squat strength testing, body composition testing, and a vastus lateralis biopsy were performed before (PRE) and 72 h after the 10-week training program (POST). Fiber type-specific cross-sectional area (fCSA), myofibrillar protein concentrations, sarcoplasmic protein concentrations, myosin heavy chain and actin protein abundances, and muscle tissue percent fluid were analyzed. The abundances of individual sarcoplasmic proteins in 10 of the 15 participants were also assessed using proteomics. Significant increases (p < 0.05) in type II fCSA and back squat strength occurred with training, although whole-body fat-free mass paradoxically decreased (p = 0.026). No changes in sarcoplasmic protein concentrations or muscle tissue percent fluid were observed. Myosin heavy chain protein abundance trended downward (−2.9 ± 5.8%, p = 0.069) and actin protein abundance decreased (−3.2 ± 5.3%, p = 0.034) with training. Proteomics indicated only 13 sarcoplasmic proteins were altered with training (12 up-regulated, 1 down-regulated, p < 0.05). Bioinformatics indicated no signaling pathways were affected, and proteins involved with metabolism (e.g., ATP-PCr, glycolysis, TCA cycle, or beta-oxidation) were not affected. These data comprehensively describe intramuscular protein adaptations that occur following 10 weeks of high-load resistance training. Although previous data from our laboratory suggests high-volume resistance training enhances the ATP-PCr and glycolytic pathways, we observed different changes in metabolism-related proteins in the current study with high-load training.
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Affiliation(s)
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Casey L Sexton
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Joel S Johnson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Jacob Shake
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Kevin Millevoi
- Department of Exercise Science, LaGrange College, LaGrange, GA, United States
| | - Darren T Beck
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine Auburn, Auburn, AL, United States
| | - Veera L D Badisa
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Benjamin M Mwashote
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Victor Ibeanusi
- School of the Environment, Florida A&M University, Tallahassee, FL, United States
| | - Rakesh K Singh
- Translational Science Laboratory, College of Medicine, Florida State University, Tallahassee, FL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine Auburn, Auburn, AL, United States
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Roberts MD, Young KC, Fox CD, Vann CG, Roberson PA, Osburn SC, Moore JH, Mumford PW, Romero MA, Beck DT, Haun CT, Badisa VLD, Mwashote BM, Ibeanusi V, Kavazis AN. An optimized procedure for isolation of rodent and human skeletal muscle sarcoplasmic and myofibrillar proteins. J Biol Methods 2020; 7:e127. [PMID: 32201709 PMCID: PMC7081056 DOI: 10.14440/jbm.2020.307] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 11/25/2019] [Accepted: 11/25/2019] [Indexed: 11/23/2022] Open
Abstract
Several published protocols exist for isolating contractile or myofibrillar (MF) proteins from skeletal muscle, however, achieving complete resuspension of the myofibril pellet can be technically challenging. We performed several previously published MF isolation methods with the intent of determining which method was most suitable for MF protein isolation and solubilization. Here, we provide an optimized protocol to isolate sarcoplasmic and solubilized MF protein fractions from mammalian skeletal muscle suitable for several downstream assays.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, AL 36849, USA
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, AL 36849, USA
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | - Darren T Beck
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, AL 36849, USA
| | | | - Veera L D Badisa
- School of the Environment, Florida A&M University, Tallahassee, FL 32307, USA
| | - Benjamin M Mwashote
- School of the Environment, Florida A&M University, Tallahassee, FL 32307, USA
| | - Victor Ibeanusi
- School of the Environment, Florida A&M University, Tallahassee, FL 32307, USA
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, AL 36849, USA
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24
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Vann CG, Roberson PA, Osburn SC, Mumford PW, Romero MA, Fox CD, Moore JH, Haun CT, Beck DT, Moon JR, Kavazis AN, Young KC, Badisa VLD, Mwashote BM, Ibeanusi V, Singh RK, Roberts MD. Skeletal Muscle Myofibrillar Protein Abundance Is Higher in Resistance-Trained Men, and Aging in the Absence of Training May Have an Opposite Effect. Sports (Basel) 2020; 8:sports8010007. [PMID: 31936810 PMCID: PMC7022975 DOI: 10.3390/sports8010007] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/03/2020] [Accepted: 01/08/2020] [Indexed: 12/16/2022] Open
Abstract
Resistance training generally increases skeletal muscle hypertrophy, whereas aging is associated with a loss in muscle mass. Interestingly, select studies suggest that aging, as well as resistance training, may lead to a reduction in the abundance of skeletal muscle myofibrillar (or contractile) protein (per mg tissue). Proteomic interrogations have also demonstrated that aging, as well as weeks to months of resistance training, lead to appreciable alterations in the muscle proteome. Given this evidence, the purpose of this small pilot study was to examine total myofibrillar as well as total sarcoplasmic protein concentrations (per mg wet muscle) from the vastus lateralis muscle of males who were younger and resistance-trained (denoted as YT, n = 6, 25 ± 4 years old, 10 ± 3 self-reported years of training), younger and untrained (denoted as YU, n = 6, 21 ± 1 years old), and older and untrained (denoted as OU, n = 6, 62 ± 8 years old). The relative abundances of actin and myosin heavy chain (per mg tissue) were also examined using SDS-PAGE and Coomassie staining, and shotgun proteomics was used to interrogate the abundances of individual sarcoplasmic and myofibrillar proteins between cohorts. Whole-body fat-free mass (YT > YU = OU), VL thickness (YT > YU = OU), and leg extensor peak torque (YT > YU = OU) differed between groups (p < 0.05). Total myofibrillar protein concentrations were greater in YT versus OU (p = 0.005), but were not different between YT versus YU (p = 0.325). The abundances of actin and myosin heavy chain were greater in YT versus YU (p < 0.05) and OU (p < 0.001). Total sarcoplasmic protein concentrations were not different between groups. While proteomics indicated that marginal differences existed for individual myofibrillar and sarcoplasmic proteins between YT versus other groups, age-related differences were more prominent for myofibrillar proteins (YT = YU > OU, p < 0.05: 7 proteins; OU > YT = YU, p < 0.05: 11 proteins) and sarcoplasmic proteins (YT = YU > OU, p < 0.05: 8 proteins; OU > YT&YU, p < 0.05: 29 proteins). In summary, our data suggest that modest (~9%) myofibrillar protein packing (on a per mg muscle basis) was evident in the YT group. This study also provides further evidence to suggest that notable skeletal muscle proteome differences exist between younger and older humans. However, given that our n-sizes are low, these results only provide a preliminary phenotyping of the reported protein and proteomic variables.
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Affiliation(s)
- Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Paul. A. Roberson
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Shelby C. Osburn
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Petey W. Mumford
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Matthew A. Romero
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Carlton D. Fox
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Johnathon H. Moore
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Cody T. Haun
- Department of Exercise Science, LaGrange College, LaGrange, GA 30240, USA;
| | - Darren T. Beck
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36832, USA
| | | | - Andreas N. Kavazis
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
| | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36832, USA
| | - Veera L. D. Badisa
- School of the Environment, Florida A&M University, Tallahassee, FL 32306, USA; (V.L.D.B.); (B.M.M.); (V.I.)
| | - Benjamin M. Mwashote
- School of the Environment, Florida A&M University, Tallahassee, FL 32306, USA; (V.L.D.B.); (B.M.M.); (V.I.)
| | - Victor Ibeanusi
- School of the Environment, Florida A&M University, Tallahassee, FL 32306, USA; (V.L.D.B.); (B.M.M.); (V.I.)
| | - Rakesh K. Singh
- Translational Science Lab, College of Medicine, Florida State University, Tallahassee, FL32306, USA;
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA; (C.G.V.); (P.A.R.); (S.C.O.); (P.W.M.); (M.A.R.); (C.D.F.); (J.H.M.); (D.T.B.); (A.N.K.); (K.C.Y.)
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL 36832, USA
- Correspondence:
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Roberts MD, Mobley CB, Vann CG, Haun CT, Schoenfeld BJ, Young KC, Kavazis AN. Synergist ablation-induced hypertrophy occurs more rapidly in the plantaris than soleus muscle in rats due to different molecular mechanisms. Am J Physiol Regul Integr Comp Physiol 2019; 318:R360-R368. [PMID: 31850817 DOI: 10.1152/ajpregu.00304.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined molecular mechanisms that were altered during rapid soleus (type I fiber-dominant) and plantaris (type II fiber-dominant) hypertrophy in rats. Twelve Wistar rats (3.5 mo old; 6 female, 6 male) were subjected to surgical right-leg soleus and plantaris dual overload [synergist ablation (SA)], and sham surgeries were performed on left legs (CTL). At 14 days after surgery, the muscles were dissected. Plantaris mass was 27% greater in the SA than CTL leg (P < 0.001), soleus mass was 13% greater in the SA than CTL leg (P < 0.001), and plantaris mass was higher than soleus mass in the SA leg (P = 0.001). Plantaris total RNA concentrations and estimated total RNA levels (suggestive of ribosome density) were 19% and 47% greater in the SA than CTL leg (P < 0.05), protein synthesis levels were 64% greater in the SA than CTL leg (P = 0.038), and satellite cell number per fiber was 60% greater in the SA than CTL leg (P = 0.003); no differences in these metrics were observed between soleus SA and CTL legs. Plantaris, as well as soleus, 20S proteasome activity was lower in the SA than CTL leg (P < 0.05), although the degree of downregulation was greater in the plantaris than soleus muscle (-63% vs. -20%, P = 0.001). These data suggest that early-phase plantaris hypertrophy occurs more rapidly than soleus hypertrophy, which coincided with greater increases in ribosome biogenesis, protein synthesis, and satellite cell density, as well as greater decrements in 20S proteasome activity, in the plantaris muscle.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Veterinary Medicine, Auburn, Alabama
| | - Christopher B Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky.,Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
| | | | - Cody T Haun
- Department of Exercise Science, LaGrange College, LaGrange, Georgia
| | - Brad J Schoenfeld
- Department of Health Sciences, City University of New York Lehman College, Bronx, New York
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Veterinary Medicine, Auburn, Alabama
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Roberson PA, Romero MA, Osburn SC, Mumford PW, Vann CG, Fox CD, McCullough DJ, Brown MD, Roberts MD. Skeletal muscle LINE-1 ORF1 mRNA is higher in older humans but decreases with endurance exercise and is negatively associated with higher physical activity. J Appl Physiol (1985) 2019; 127:895-904. [PMID: 31369326 DOI: 10.1152/japplphysiol.00352.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The long interspersed nuclear element-1 (L1) is a retrotransposon that constitutes 17% of the human genome and is associated with various diseases and aging. Estimates suggest that ~100 L1 copies are capable of copying and pasting into other regions of the genome. Herein, we examined if skeletal muscle L1 markers are affected by aging or an acute bout of cycling exercise in humans. Apparently healthy younger (23 ± 3 y, n = 15) and older participants (58 ± 8 y, n = 15) donated a vastus lateralis biopsy before 1 h of cycling exercise (PRE) at ~70% of heart rate reserve. Second (2 h) and third (8 h) postexercise muscle biopsies were also obtained. L1 DNA and mRNA expression were quantified using three primer sets [5' untranslated region (UTR), L1.3, and ORF1]. 5'UTR and L1.3 DNA methylation as well as ORF1 protein expression were also quantified. PRE 5'UTR, ORF1, or L1.3 DNA were not different between age groups (P > 0.05). ORF1 mRNA was greater in older versus younger participants (P = 0.014), and cycling lowered this marker at 2 h versus PRE (P = 0.027). 5'UTR and L1.3 DNA methylation were higher in younger versus older participants (P < 0.05). Accelerometry data collected during a 2-wk period before the exercise bout indicated higher moderate-to-vigorous physical activity (MVPA) levels per day was associated with lower PRE ORF1 mRNA in all participants (r = -0.398, P = 0.032). In summary, skeletal muscle ORF1 mRNA is higher in older apparently healthy humans, which may be related to lower DNA methylation patterns. ORF1 mRNA is also reduced with endurance exercise and is negatively associated with higher daily MVPA levels.NEW & NOTEWORTHY The long interspersed nuclear element-1 (L1) gene is highly abundant in the genome and encodes for an autonomous retrotransposon, which is capable of copying and pasting itself into other portions of the genome. This is the first study in humans to demonstrate that certain aspects of skeletal muscle L1 activity are altered with aging. Additionally, this is the first study in humans to demonstrate that L1 ORF1 mRNA levels decrease after a bout of endurance exercise, regardless of age.
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Affiliation(s)
| | | | | | | | | | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Danielle J McCullough
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, Alabama
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine Auburn Campus, Auburn, Alabama
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Mumford PW, Romero MA, Osburn SC, Roberson PA, Vann CG, Mobley CB, Brown MD, Kavazis AN, Young KC, Roberts MD. Skeletal muscle LINE-1 retrotransposon activity is upregulated in older versus younger rats. Am J Physiol Regul Integr Comp Physiol 2019; 317:R397-R406. [PMID: 31188650 DOI: 10.1152/ajpregu.00110.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long interspersed element-1 (LINE-1) is a retrotransposon capable of replicating and inserting LINE-1 copies into the genome. Others have reported skeletal muscle LINE-1 markers are higher in older versus younger mice, but data are lacking in other species. Herein, gastrocnemius muscle from male Fischer 344 rats that were 3, 12, and 24 mo old (n = 9 per group) were analyzed for LINE-1 mRNA, DNA, promoter methylation and DNA accessibility. qPCR primers were designed for active (L1.3) and inactive (L1.Tot) LINE-1 elements as well as part of the ORF1 sequence. L1.3, L1.Tot, and ORF1 mRNAs were higher (P < 0.05) in 12/24 versus 3-mo-old rats. L1.3 DNA was higher in the 24-mo-old rats versus other groups, and ORF1 DNA was greater in 12/24 versus 3-mo-old rats. ORF1 protein was higher in 12/24 versus 3-mo-old rats. RNA-sequencing indicated mRNAs related to DNA methylation (Tet1) and histone acetylation (Hdac2) were lower in 24 versus 3-mo-old rats. L1.3 DNA accessibility was higher in 24-mo-old versus 3-mo-old rats. No age-related differences in nuclear histone deacetylase (HDAC) activity existed, although nuclear DNA methyltransferase (DNMT) activity was lower in 12/24 versus 3-mo-old rats (P < 0.05). In summary, markers of skeletal muscle LINE-1 activity increase across the age spectrum of rats, and this may be related to deficits in DNMT activity and/or increased LINE-1 DNA accessibility.
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Affiliation(s)
| | | | | | | | | | - Christopher B Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | | | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
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Haun CT, Vann CG, Osburn SC, Mumford PW, Roberson PA, Romero MA, Fox CD, Johnson CA, Parry HA, Kavazis AN, Moon JR, Badisa VLD, Mwashote BM, Ibeanusi V, Young KC, Roberts MD. Muscle fiber hypertrophy in response to 6 weeks of high-volume resistance training in trained young men is largely attributed to sarcoplasmic hypertrophy. PLoS One 2019; 14:e0215267. [PMID: 31166954 PMCID: PMC6550381 DOI: 10.1371/journal.pone.0215267] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/22/2019] [Indexed: 01/10/2023] Open
Abstract
Cellular adaptations that occur during skeletal muscle hypertrophy in response to high-volume resistance training are not well-characterized. Therefore, we sought to explore how actin, myosin, sarcoplasmic protein, mitochondrial, and glycogen concentrations were altered in individuals that exhibited mean skeletal muscle fiber cross-sectional area (fCSA) hypertrophy following 6 weeks of high-volume resistance training. Thirty previously resistance-trained, college-aged males (mean ± standard deviation: 21±2 years, 5±3 training years) had vastus lateralis (VL) muscle biopsies obtained prior to training (PRE), at week 3 (W3), and at week 6 (W6). Muscle tissue from 15 subjects exhibiting PRE to W6 VL mean fCSA increases ranging from 320–1600 μm2 was further interrogated using various biochemical and histological assays as well as proteomic analysis. Seven of these individuals donated a VL biopsy after refraining from training 8 days following the last training session (W7) to determine how deloading affected biomarkers. The 15 fCSA hypertrophic responders experienced a +23% increase in mean fCSA from PRE to W6 (p<0.001) and, while muscle glycogen concentrations remained unaltered, citrate synthase activity levels decreased by 24% (p<0.001) suggesting mitochondrial volume decreased. Interestingly, repeated measures ANOVAs indicated that p-values approached statistical significance for both myosin and actin (p = 0.052 and p = 0.055, respectively), and forced post hoc tests indicated concentrations for both proteins decreased ~30% from PRE to W6 (p<0.05 for each target). Phalloidin-actin staining similarly revealed actin concentrations per fiber decreased from PRE to W6. Proteomic analysis of the sarcoplasmic fraction from PRE to W6 indicated 40 proteins were up-regulated (p<0.05), KEGG analysis indicated that the glycolysis/gluconeogenesis pathway was upregulated (FDR sig. <0.001), and DAVID indicated that the following functionally-annotated pathways were upregulated (FDR value <0.05): a) glycolysis (8 proteins), b) acetylation (23 proteins), c) gluconeogenesis (5 proteins) and d) cytoplasm (20 proteins). At W7, sarcoplasmic protein concentrations remained higher than PRE (+66%, p<0.05), and both actin and myosin concentrations remained lower than PRE (~-50%, p<0.05). These data suggest that short-term high-volume resistance training may: a) reduce muscle fiber actin and myosin protein concentrations in spite of increasing fCSA, and b) promote sarcoplasmic expansion coincident with a coordinated up-regulation of sarcoplasmic proteins involved in glycolysis and other metabolic processes related to ATP generation. Interestingly, these effects seem to persist up to 8 days following training.
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Affiliation(s)
- Cody T. Haun
- Department of Exercise Science, LaGrange College, LaGrange, GA, United States of America
| | - Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Shelby C. Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Petey W. Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Paul A. Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Matthew A. Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Carlton D. Fox
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Christopher A. Johnson
- School of Medicine, University of Alabama Birmingham, Birmingham, AL, United States of America
| | - Hailey A. Parry
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Andreas N. Kavazis
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | | | - Veera L. D. Badisa
- School of the Environment, Florida A&M University, Tallahassee, FL, United States of America
| | - Benjamin M. Mwashote
- School of the Environment, Florida A&M University, Tallahassee, FL, United States of America
| | - Victor Ibeanusi
- School of the Environment, Florida A&M University, Tallahassee, FL, United States of America
| | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine—Auburn Campus, Auburn, AL, United States of America
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine—Auburn Campus, Auburn, AL, United States of America
- * E-mail:
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Fox CD, Vann CG, Haun CT, Osburn SC, Romero MA, Roberson PA, Mumford PW, Moon JR, Young KC, Roberts MD. Active and Passive Recovery Following High Volume Resistance Training: Markers of Molecular Gene Expression. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000562448.20086.4d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Moore JH, Haun CT, Grandprey EL, Joubert KP, Vann CG, Roberson PA, Mumford PW, Romero MA, Osburn SC, Mobely CB, Moon JR, Roberts MD, Young KC. A Comparison of Techniques for Estimating and Detecting Changes in Skeletal Muscle Cross-Sectional Area. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000563330.19472.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Grandprey EL, Joubert KP, Haun CT, Vann CG, Roberson PA, Mumford PW, Romero MA, Osburn SC, Mobley CB, Moon JR, Roberts MD, Young KC. Agreement Between Dual-Energy X-Ray Absorptiometry and a New Standing Bioimpedance Spectroscopy Device for Detecting Changes in Fat-Free Tissue. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000562016.77533.e1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Haun CT, Vann CG, Mobley CB, Osburn SC, Mumford PW, Roberson PA, Romero MA, Fox CD, Parry HA, Kavazis AN, Moon JR, Young KC, Roberts MD. Pre-training Skeletal Muscle Fiber Size and Predominant Fiber Type Best Predict Hypertrophic Responses to 6 Weeks of Resistance Training in Previously Trained Young Men. Front Physiol 2019; 10:297. [PMID: 30971942 PMCID: PMC6445136 DOI: 10.3389/fphys.2019.00297] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/06/2019] [Indexed: 12/24/2022] Open
Abstract
Limited evidence exists regarding differentially expressed biomarkers between previously-trained low versus high hypertrophic responders in response to resistance training. Herein, 30 college-aged males (training age 5 ± 3 years; mean ± SD) partook in 6 weeks of high-volume resistance training. Body composition, right leg vastus lateralis (VL) biopsies, and blood were obtained prior to training (PRE) and at the 3-week (W3) and 6-week time points (W6). The 10 lowest (LOW) and 10 highest (HIGH) hypertrophic responders were clustered based upon a composite hypertrophy score of PRE-to-W6 changes in right leg VL mean muscle fiber cross-sectional area (fCSA), VL thickness assessed via ultrasound, upper right leg lean soft tissue mass assessed via dual x-ray absorptiometry (DXA), and mid-thigh circumference. Two-way ANOVAs were used to compare biomarker differences between the LOW and HIGH clusters over time, and stepwise linear regression was performed to elucidate biomarkers that explained significant variation in the composite hypertrophy score from PRE to W3, W3 to W6, and PRE to W6 in all 30 participants. PRE-to-W6 HIGH and LOW responders exhibited a composite hypertrophy change of +10.7 ± 3.2 and -2.1 ± 1.6%, respectively (p < 0.001). Compared to HIGH responders, LOW responders exhibited greater PRE type II fCSA (+18%, p = 0.022). Time effects (p < 0.05) existed for total RNA/mg muscle (W6 > W3 > PRE), phospho (p)-4EBP1 (PRE > W3&W6), pan-mTOR (PRE > W3 < W6), p-mTOR (PRE > W3 < W6), pan-AMPKα (PRE > W3 < W6), pan-p70s6k (PRE > W3), muscle ubiquitin-labeled proteins (PRE > W6), mechano growth factor mRNA (W6 > W3&PRE), 45S rRNA (PRE > W6), and muscle citrate synthase activity (PRE > W3&W6). No interactions existed for the aforementioned biomarkers and/or other assayed targets (muscle 20S proteasome activity, serum total testosterone, muscle androgen receptor protein levels, muscle glycogen, or serum creatine kinase). Regression analysis indicated PRE type II fiber percentage (R2 = 0.152, β = 0.390, p = 0.033) and PRE type II fCSA (R2 = 0.207, β = -0.455, p = 0.019) best predicted the PRE-to-W6 change in the composite hypertrophy score. While our sample size is limited, these data suggest: (a) HIGH responders may exhibit more growth potential given that they possessed lower PRE type II fCSA values and (b) possessing a greater type II fiber percentage as a trained individual may be advantageous for hypertrophy in response to resistance training.
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Affiliation(s)
- Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Exercise Science, LaGrange College, LaGrange, GA, United States
| | | | - C Brooks Mobley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Carlton D Fox
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | | | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, United States
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Haun CT, Vann CG, Roberts BM, Vigotsky AD, Schoenfeld BJ, Roberts MD. A Critical Evaluation of the Biological Construct Skeletal Muscle Hypertrophy: Size Matters but So Does the Measurement. Front Physiol 2019; 10:247. [PMID: 30930796 PMCID: PMC6423469 DOI: 10.3389/fphys.2019.00247] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 02/25/2019] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle is highly adaptable and has consistently been shown to morphologically respond to exercise training. Skeletal muscle growth during periods of resistance training has traditionally been referred to as skeletal muscle hypertrophy, and this manifests as increases in muscle mass, muscle thickness, muscle area, muscle volume, and muscle fiber cross-sectional area (fCSA). Delicate electron microscopy and biochemical techniques have also been used to demonstrate that resistance exercise promotes ultrastructural adaptations within muscle fibers. Decades of research in this area of exercise physiology have promulgated a widespread hypothetical model of training-induced skeletal muscle hypertrophy; specifically, fCSA increases are accompanied by proportional increases in myofibrillar protein, leading to an expansion in the number of sarcomeres in parallel and/or an increase in myofibril number. However, there is ample evidence to suggest that myofibrillar protein concentration may be diluted through sarcoplasmic expansion as fCSA increases occur. Furthermore, and perhaps more problematic, are numerous investigations reporting that pre-to-post training change scores in macroscopic, microscopic, and molecular variables supporting this model are often poorly associated with one another. The current review first provides a brief description of skeletal muscle composition and structure. We then provide a historical overview of muscle hypertrophy assessment. Next, current-day methods commonly used to assess skeletal muscle hypertrophy at the biochemical, ultramicroscopic, microscopic, macroscopic, and whole-body levels in response to training are examined. Data from our laboratory, and others, demonstrating correlations (or the lack thereof) between these variables are also presented, and reasons for comparative discrepancies are discussed with particular attention directed to studies reporting ultrastructural and muscle protein concentration alterations. Finally, we critically evaluate the biological construct of skeletal muscle hypertrophy, propose potential operational definitions, and provide suggestions for consideration in hopes of guiding future research in this area.
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Affiliation(s)
- Cody T Haun
- Department of Exercise Science, LaGrange College, LaGrange, GA, United States
| | | | - Brandon M Roberts
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andrew D Vigotsky
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States
| | - Brad J Schoenfeld
- Department of Health Sciences, CUNY Lehman College, Bronx, NY, United States
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Roberson PA, Romero MA, Mumford PW, Osburn SC, Haun CT, Vann CG, Kluess HA, Roberts MD. Protein Supplementation Throughout 10 Weeks of Progressive Run Training Is Not Beneficial for Time Trial Improvement. Front Nutr 2018; 5:97. [PMID: 30456213 PMCID: PMC6230989 DOI: 10.3389/fnut.2018.00097] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/02/2018] [Indexed: 12/24/2022] Open
Abstract
Introduction: Protein supplementation is proposed to promote recovery and adaptation following endurance exercise. While prior literature demonstrates improved performance when supplementing protein during or following endurance exercise, chronic supplementation research is limited. Methods: Runners (VO2peak = 53.6 ± 8.9 ml/kg/min) were counter-balanced into a placebo group (PLA; n = 8) or protein group (PRO; n = 9) based on sex and VO2peak, and underwent 10 weeks of progressive endurance training. Prior to training, body composition, blood cell differentials, non-invasive mitochondrial capacity using near-infrared spectroscopy, and a 5 km treadmill time trial (TT) were evaluated. Progressive training then commenced (5–10% increase in weekly volume with a recovery week following 3 weeks of training) whereby PRO supplemented with 25 g of whey protein following workouts and prior to sleep (additional 50 g daily). PLA supplemented similarly with a < 1 g sugar pill per day. Following training, participants were reanalyzed for the aforementioned tests. Results: VO2peak and initial 5 km TT were not significantly different between groups. PRO consumed significantly more dietary protein throughout the training period (PRO = 132 g/d or 2.1 g/kg/day; PLA = 84 g/d or 1.2 g/kg/day). Running volume increased significantly over time, but was not significantly different between groups throughout training. Blood measures were unaltered with training or supplementation. Mitochondrial capacity trended toward improving over time (time p = 0.063) with no difference between groups. PLA increased lean mass 0.7 kg (p < 0.05) while PRO experienced infinitesimal change (−0.1 kg, interaction p = 0.049). PLA improved 5 km TT performance 6.4% (1 min 31 s), while PRO improved only 2.7% (40 s) (interaction p = 0.080). Conclusion: This is the first evidence to suggest long-term protein supplementation during progressive run training is not beneficial for runners.
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Affiliation(s)
- Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Heidi A Kluess
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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Haun CT, Vann CG, Mobley CB, Roberson PA, Osburn SC, Holmes HM, Mumford PM, Romero MA, Young KC, Moon JR, Gladden LB, Arnold RD, Israetel MA, Kirby AN, Roberts MD. Effects of Graded Whey Supplementation During Extreme-Volume Resistance Training. Front Nutr 2018; 5:84. [PMID: 30255024 PMCID: PMC6141782 DOI: 10.3389/fnut.2018.00084] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/24/2018] [Indexed: 12/31/2022] Open
Abstract
We examined hypertrophic outcomes of weekly graded whey protein dosing (GWP) vs. whey protein (WP) or maltodextrin (MALTO) dosed once daily during 6 weeks of high-volume resistance training (RT). College-aged resistance-trained males (training age = 5 ± 3 years; mean ± SD) performed 6 weeks of RT wherein frequency was 3 d/week and each session involved 2 upper- and 2 lower-body exercises (10 repetitions/set). Volume increased from 10 sets/exercise (week 1) to 32 sets/exercise (week 6), which is the highest volume investigated in this timeframe. Participants were assigned to WP (25 g/d; n = 10), MALTO (30 g/d; n = 10), or GWP (25–150 g/d from weeks 1–6; n = 11), and supplementation occurred throughout training. Dual-energy x-ray absorptiometry (DXA), vastus lateralis (VL), and biceps brachii ultrasounds for muscle thicknesses, and bioelectrical impedance spectroscopy (BIS) were performed prior to training (PRE) and after weeks 3 (MID) and 6 (POST). VL biopsies were also collected for immunohistochemical staining. The GWP group experienced the greatest PRE to POST reduction in DXA fat mass (FM) (−1.00 kg, p < 0.05), and a robust increase in DXA fat- and bone-free mass [termed lean body mass (LBM) throughout] (+2.93 kg, p < 0.05). However, the MALTO group also experienced a PRE to POST increase in DXA LBM (+2.35 kg, p < 0.05), and the GWP and MALTO groups experienced similar PRE to POST increases in type II muscle fiber cross-sectional area (~+300 μm2). When examining the effects of training on LBM increases (ΔLBM) in all participants combined, PRE to MID (+1.34 kg, p < 0.001) and MID to POST (+0.85 kg, p < 0.001) increases were observed. However, when adjusting ΔLBM for extracellular water (ECW) changes, intending to remove the confounder of edema, a significant increase was observed from PRE to MID (+1.18 kg, p < 0.001) but not MID to POST (+0.25 kg; p = 0.131). Based upon DXA data, GWP supplementation may be a viable strategy to improve body composition during high-volume RT. However, large LBM increases observed in the MALTO group preclude us from suggesting that GWP supplementation is clearly superior in facilitating skeletal muscle hypertrophy. With regard to the implemented RT program, ECW-corrected ΔLBM gains were largely dampened, but still positive, in resistance-trained participants when RT exceeded ~20 sets/exercise/wk.
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Affiliation(s)
- Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | | | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Hudson M Holmes
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Petey M Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL, United States
| | | | - L Bruce Gladden
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Robert D Arnold
- Harrison School of Pharmacy, Auburn University, Auburn, AL, United States
| | | | - Annie N Kirby
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, AL, United States
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Roberts MD, Romero MA, Mobley CB, Mumford PW, Roberson PA, Haun CT, Vann CG, Osburn SC, Holmes HH, Greer RA, Lockwood CM, Parry HA, Kavazis AN. Skeletal muscle mitochondrial volume and myozenin-1 protein differences exist between high versus low anabolic responders to resistance training. PeerJ 2018; 6:e5338. [PMID: 30065891 PMCID: PMC6065464 DOI: 10.7717/peerj.5338] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/09/2018] [Indexed: 12/22/2022] Open
Abstract
Background We sought to examine how 12 weeks of resistance exercise training (RET) affected skeletal muscle myofibrillar and sarcoplasmic protein levels along with markers of mitochondrial physiology in high versus low anabolic responders. Methods Untrained college-aged males were classified as anabolic responders in the top 25th percentile (high-response cluster (HI); n = 13, dual x-ray absorptiometry total body muscle mass change (Δ) = +3.1 ± 0.3 kg, Δ vastus lateralis (VL) thickness = +0.59 ± 0.05 cm, Δ muscle fiber cross sectional area = +1,426 ± 253 μm2) and bottom 25th percentile (low-response cluster (LO); n = 12, +1.1 ± 0.2 kg, +0.24 ± 0.07 cm, +5 ± 209 μm2; p < 0.001 for all Δ scores compared to HI). VL muscle prior to (PRE) and following RET (POST) was assayed for myofibrillar and sarcoplasmic protein concentrations, myosin and actin protein content, and markers of mitochondrial volume. Proteins related to myofibril formation, as well as whole lysate PGC1-α protein levels were assessed. Results Main effects of cluster (HI > LO, p = 0.018, Cohen’s d = 0.737) and time (PRE > POST, p = 0.037, Cohen’s d = −0.589) were observed for citrate synthase activity, although no significant interaction existed (LO PRE = 1.35 ± 0.07 mM/min/mg protein, LO POST = 1.12 ± 0.06, HI PRE = 1.53 ± 0.11, HI POST = 1.39 ± 0.10). POST myofibrillar myozenin-1 protein levels were up-regulated in the LO cluster (LO PRE = 0.96 ± 0.13 relative expression units, LO POST = 1.25 ± 0.16, HI PRE = 1.00 ± 0.11, HI POST = 0.85 ± 0.12; within-group LO increase p = 0.025, Cohen’s d = 0.691). No interactions or main effects existed for other assayed markers. Discussion Our data suggest myofibrillar or sarcoplasmic protein concentrations do not differ between HI versus LO anabolic responders prior to or following a 12-week RET program. Greater mitochondrial volume in HI responders may have facilitated greater anabolism, and myofibril myozenin-1 protein levels may represent a biomarker that differentiates anabolic responses to RET. However, mechanistic research validating these hypotheses is needed.
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Affiliation(s)
| | | | | | | | | | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | | | | | - Rory A Greer
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, AL, USA
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Haun CT, Mobley CB, Vann CG, Romero MA, Roberson PA, Mumford PW, Kephart WC, Healy JC, Patel RK, Osburn SC, Beck DT, Arnold RD, Nie B, Lockwood CM, Roberts MD. Soy protein supplementation is not androgenic or estrogenic in college-aged men when combined with resistance exercise training. Sci Rep 2018; 8:11151. [PMID: 30042516 PMCID: PMC6057888 DOI: 10.1038/s41598-018-29591-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 07/02/2018] [Indexed: 12/14/2022] Open
Abstract
It is currently unclear as to whether sex hormones are significantly affected by soy or whey protein consumption. Additionally, estrogenic signaling may be potentiated via soy protein supplementation due to the presence of phytoestrogenic isoflavones. Limited also evidence suggests that whey protein supplementation may increase androgenic signaling. Therefore, the purpose of this study was to examine the effects of soy protein concentrate (SPC), whey protein concentrate (WPC), or placebo (PLA) supplementation on serum sex hormones, androgen signaling markers in muscle tissue, and estrogen signaling markers in subcutaneous (SQ) adipose tissue of previously untrained, college-aged men (n = 47, 20 ± 1 yrs) that resistance trained for 12 weeks. Fasting serum total testosterone increased pre- to post-training, but more so in subjects consuming WPC (p < 0.05), whereas serum 17β-estradiol remained unaltered. SQ estrogen receptor alpha (ERα) protein expression and hormone-sensitive lipase mRNA increased with training regardless of supplementation. Muscle androgen receptor (AR) mRNA increased while ornithine decarboxylase mRNA (a gene target indicative of androgen signaling) decreased with training regardless of supplementation (p < 0.05). No significant interactions of supplement and time were observed for adipose tissue ERα/β protein levels, muscle tissue AR protein levels, or mRNAs in either tissue indicative of altered estrogenic or androgenic activity. Interestingly, WPC had the largest effect on increasing type II muscle fiber cross sectional area values (Cohen's d = 1.30), whereas SPC had the largest effect on increasing this metric in type I fibers (Cohen's d = 0.84). These data suggest that, while isoflavones were detected in SPC, chronic WPC or SPC supplementation did not appreciably affect biomarkers related to muscle androgenic signaling or SQ estrogenic signaling. The noted fiber type-specific responses to WPC and SPC supplementation warrant future research.
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Affiliation(s)
- Cody T Haun
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - C Brooks Mobley
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Christopher G Vann
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Matthew A Romero
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Paul A Roberson
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Petey W Mumford
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Wesley C Kephart
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - James C Healy
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, USA
| | - Romil K Patel
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Shelby C Osburn
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Darren T Beck
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, USA
| | - Robert D Arnold
- Department of Drug Discovery & Development, Harrison School of Pharmacy, Auburn University Pharmaceutical Research Building, Auburn, AL, USA
| | - Ben Nie
- Department of Drug Discovery & Development, Harrison School of Pharmacy, Auburn University Pharmaceutical Research Building, Auburn, AL, USA
| | | | - Michael D Roberts
- Molecular and Applied Sciences Laboratory, School of Kinesiology, Auburn University, Auburn, AL, USA. .,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, AL, USA.
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Roberts MD, Haun CT, Mobley CB, Mumford PW, Romero MA, Roberson PA, Vann CG, McCarthy JJ. Physiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders to Resistance Exercise Training: Current Perspectives and Future Research Directions. Front Physiol 2018; 9:834. [PMID: 30022953 PMCID: PMC6039846 DOI: 10.3389/fphys.2018.00834] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/13/2018] [Indexed: 12/22/2022] Open
Abstract
Numerous reports suggest there are low and high skeletal muscle hypertrophic responders following weeks to months of structured resistance exercise training (referred to as low and high responders herein). Specifically, divergent alterations in muscle fiber cross sectional area (fCSA), vastus lateralis thickness, and whole body lean tissue mass have been shown to occur in high versus low responders. Differential responses in ribosome biogenesis and subsequent protein synthetic rates during training seemingly explain some of this individual variation in humans, and mechanistic in vitro and rodent studies provide further evidence that ribosome biogenesis is critical for muscle hypertrophy. High responders may experience a greater increase in satellite cell proliferation during training versus low responders. This phenomenon could serve to maintain an adequate myonuclear domain size or assist in extracellular remodeling to support myofiber growth. High responders may also express a muscle microRNA profile during training that enhances insulin-like growth factor-1 (IGF-1) mRNA expression, although more studies are needed to better validate this mechanism. Higher intramuscular androgen receptor protein content has been reported in high versus low responders following training, and this mechanism may enhance the hypertrophic effects of testosterone during training. While high responders likely possess “good genetics,” such evidence has been confined to single gene candidates which typically share marginal variance with hypertrophic outcomes following training (e.g., different myostatin and IGF-1 alleles). Limited evidence also suggests pre-training muscle fiber type composition and self-reported dietary habits (e.g., calorie and protein intake) do not differ between high versus low responders. Only a handful of studies have examined muscle biomarkers that are differentially expressed between low versus high responders. Thus, other molecular and physiological variables which could potentially affect the skeletal muscle hypertrophic response to resistance exercise training are also discussed including rDNA copy number, extracellular matrix and connective tissue properties, the inflammatory response to training, and mitochondrial as well as vascular characteristics.
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Affiliation(s)
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew A Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - John J McCarthy
- Department of Physiology, University of Kentucky College of Medicine, Lexington, KY, United States
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Roberson PA, Brooks Mobley C, Haun CT, Mumford PW, Romero MA, Kephart WC, Osburn SC, Vann CG, Lockwood CM, Roberts MD. Amino Acid Transport and Metabolism Alterations Following 12 Weeks of Resistance Training with Supplementation. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538668.98803.36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Colquhoun RJ, Magrini MA, Haun CT, Muddle TW, Tomko PM, Luera MJ, Mackey CS, Vann CG, Martin JS, Young KC, DeFreitas JM, Roberts MD, Jenkins ND. Relationships between Motor Unit Behavior during Maximal Effort Contractions and Skeletal Muscle Phenotype. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000535746.29814.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Vann CG, Haun CT, Mobley CB, Romero MA, Roberson PA, Mumford PW, Kephart WC, Osburn SO, Roberts MD. Hypertrophic Responses Do Not Completely Explain Increases in Strength After 12 Weeks of Resistance Training in Previously Untrained Young Men. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536466.81979.b2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mobley CB, Haun CT, Roberson PA, Mumford PW, Kephart WC, Romero MA, Osburn SC, Vann CG, Young KC, Beck DT, Martin JS, Lockwood CM, Roberts MD. Biomarkers associated with low, moderate, and high vastus lateralis muscle hypertrophy following 12 weeks of resistance training. PLoS One 2018; 13:e0195203. [PMID: 29621305 PMCID: PMC5886420 DOI: 10.1371/journal.pone.0195203] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/19/2018] [Indexed: 12/20/2022] Open
Abstract
We sought to identify biomarkers which delineated individual hypertrophic responses to resistance training. Untrained, college-aged males engaged in full-body resistance training (3 d/wk) for 12 weeks. Body composition via dual x-ray absorptiometry (DXA), vastus lateralis (VL) thickness via ultrasound, blood, VL muscle biopsies, and three-repetition maximum (3-RM) squat strength were obtained prior to (PRE) and following (POST) 12 weeks of training. K-means cluster analysis based on VL thickness changes identified LOW [n = 17; change (mean±SD) = +0.11±0.14 cm], modest (MOD; n = 29, +0.40±0.06 cm), and high (HI; n = 21, +0.69±0.14 cm) responders. Biomarkers related to histology, ribosome biogenesis, proteolysis, inflammation, and androgen signaling were analyzed between clusters. There were main effects of time (POST>PRE, p<0.05) but no cluster×time interactions for increases in DXA lean body mass, type I and II muscle fiber cross sectional area and myonuclear number, satellite cell number, and macronutrients consumed. Interestingly, PRE VL thickness was ~12% greater in LOW versus HI (p = 0.021), despite POST values being ~12% greater in HI versus LOW (p = 0.006). However there was only a weak correlation between PRE VL thickness scores and change in VL thickness (r2 = 0.114, p = 0.005). Forced post hoc analysis indicated that muscle total RNA levels (i.e., ribosome density) did not significantly increase in the LOW cluster (351±70 ng/mg to 380±62, p = 0.253), but increased in the MOD (369±115 to 429±92, p = 0.009) and HI clusters (356±77 to 470±134, p<0.001; POST HI>POST LOW, p = 0.013). Nonetheless, there was only a weak association between change in muscle total RNA and VL thickness (r2 = 0.079, p = 0.026). IL-1β mRNA levels decreased in the MOD and HI clusters following training (p<0.05), although associations between this marker and VL thickness changes were not significant (r2 = 0.0002, p = 0.919). In conclusion, individuals with lower pre-training VL thickness values and greater increases muscle total RNA levels following 12 weeks of resistance training experienced greater VL muscle growth, although these biomarkers individually explained only ~8–11% of the variance in hypertrophy.
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Affiliation(s)
| | - Cody T. Haun
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Paul A. Roberson
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Petey W. Mumford
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Wesley C. Kephart
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Matthew A. Romero
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Shelby C. Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Christopher G. Vann
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
| | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | - Darren T. Beck
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | - Jeffrey S. Martin
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
| | | | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States of America
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine–Auburn Campus, Auburn, AL, United States of America
- * E-mail:
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Colquhoun RJ, Magrini MA, Haun CT, Muddle TWD, Tomko PM, Luera MJ, Mackey CS, Vann CG, Martin JS, Young KC, DeFreitas JM, Roberts MD, Jenkins NDM. Muscle phenotype is related to motor unit behavior of the vastus lateralis during maximal isometric contractions. Physiol Rep 2018. [PMID: 29527830 PMCID: PMC5845862 DOI: 10.14814/phy2.13636] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous investigations have reported a relationship between skeletal muscle phenotype and motor unit (MU) firing parameters during submaximal contractions. The purpose of the current investigation, however, was to examine the relationships between motor unit firing behavior during a maximal voluntary contraction, Myosin Heavy Chain (MHC) isoform content, and various molecular neuromuscular targets of the vastus lateralis (VL) muscle in resistance-trained men. Ten resistance-trained males completed a trapezoidal ramp contraction up to 100% of their maximal voluntary isometric strength (MVIC). Surface electromyography was recorded from the VL using a multichannel electrode array and decomposed to examine the firing characteristics of individual MUs. A skeletal muscle biopsy of the VL was also collected from each subject. Regression analyses were performed to identify relationships between type II fiber area and the slopes and/or intercepts of the mean firing rate (FRMEAN ) versus recruitment threshold (RT), max firing rate (FRMAX ) versus RT, and RT versus MU action potential amplitude (MUAPPP ) relationships. There were significant inverse relationships between type II fiber area and the y-intercept of the FR versus RT relationship (P < 0.05). Additionally, strong relationships (r > 0.5) were found between type II fiber area and FRMEAN versus RT slope and RT versus MUAPPP slope and intercept. These data further support the hypothesis that skeletal muscle phenotype is related to MU behavior during isometric contraction. However, our data, in concert with previous investigations, may suggest that these relationships are influenced by the intensity of the contraction.
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Affiliation(s)
- Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cody T Haun
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Tyler W D Muddle
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Patrick M Tomko
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Micheal J Luera
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Christopher G Vann
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Jeffrey S Martin
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Kaelin C Young
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Michael D Roberts
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Nathaniel D M Jenkins
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
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