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Libardi CA, Godwin JS, Reece TM, Ugrinowitsch C, Herda TJ, Roberts MD. Effects of low-load resistance training with blood flow restriction on muscle fiber myofibrillar and extracellular area. Front Physiol 2024; 15:1368646. [PMID: 38444764 PMCID: PMC10912282 DOI: 10.3389/fphys.2024.1368646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/05/2024] [Indexed: 03/07/2024] Open
Abstract
Blood flow restriction applied during low-load resistance training (LL-BFR) induces a similar increase in the cross-sectional area of muscle fibers (fCSA) compared to traditional high-load resistance training (HL-RT). However, it is unclear whether LL-BFR leads to differential changes in myofibrillar spacing in muscle fibers and/or extracellular area compared to HL-RT. Therefore, this study aimed to investigate whether the hypertrophy of type I and II fibers induced by LL-BFR or HL-RT is accompanied by differential changes in myofibrillar and non-myofibrillar areas. In addition, we examined if extracellular spacing was differentially affected between these two training protocols. Twenty recreationally active participants were assigned to LL-BFR or HL-RT groups and underwent a 6-week training program. Muscle biopsies were taken before and after the training period. The fCSA of type I and II fibers, the area occupied by myofibrillar and non-myofibrillar components, and extracellular spacing were analyzed using immunohistochemistry techniques. Despite the significant increase in type II and mean (type I + II) fCSA (p < 0.05), there were no significant changes in the proportionality of the myofibrillar and non-myofibrillar areas [∼86% and ∼14%, respectively (p > 0.05)], indicating that initial adaptations to LL-BFR are primarily characterized by conventional hypertrophy rather than disproportionate non-myofibrillar expansion. Additionally, extracellular spacing was not significantly altered between protocols. In summary, our study reveals that LL-BFR, like HL-RT, induces skeletal muscle hypertrophy with proportional changes in the areas occupied by myofibrillar, non-myofibrillar, and extracellular components.
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Affiliation(s)
- Cleiton A. Libardi
- MUSCULAB–Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of Sao Carlos, Sao Carlos, Brazil
| | - Joshua S. Godwin
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Tanner M. Reece
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, United States
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of Sao Paulo, Sao Paulo, Brazil
- Department of Health Sciences and Human Performance, The University of Tampa, Tampa, FL, United States
| | - Trent J. Herda
- Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, KS, United States
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Plotkin DL, Rodas MA, Vigotsky AD, McIntosh MC, Breeze E, Ubrik R, Robitzsch C, Agyin-Birikorang A, Mattingly ML, Michel JM, Kontos NJ, Lennon S, Frugé AD, Wilburn CM, Weimar WH, Bashir A, Beyers RJ, Henselmans M, Contreras BM, Roberts MD. Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift. Front Physiol 2023; 14:1279170. [PMID: 37877099 PMCID: PMC10593473 DOI: 10.3389/fphys.2023.1279170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 09/27/2023] [Indexed: 10/26/2023] Open
Abstract
We examined how set-volume equated resistance training using either the back squat (SQ) or hip thrust (HT) affected hypertrophy and various strength outcomes. Untrained college-aged participants were randomized into HT (n = 18) or SQ (n = 16) groups. Surface electromyograms (sEMG) from the right gluteus maximus and medius muscles were obtained during the first training session. Participants completed 9 weeks of supervised training (15-17 sessions), before and after which gluteus and leg muscle cross-sectional area (mCSA) was assessed via magnetic resonance imaging. Strength was also assessed prior to and after the training intervention via three-repetition maximum (3RM) testing and an isometric wall push test. Gluteus mCSA increases were similar across both groups. Specifically, estimates [(-) favors HT (+) favors SQ] modestly favored the HT versus SQ for lower [effect ±SE, -1.6 ± 2.1 cm2; CI95% (-6.1, 2.0)], mid [-0.5 ± 1.7 cm2; CI95% (-4.0, 2.6)], and upper [-0.5 ± 2.6 cm2; CI95% (-5.8, 4.1)] gluteal mCSAs but with appreciable variance. Gluteus medius + minimus [-1.8 ± 1.5 cm2; CI95% (-4.6, 1.4)] and hamstrings [0.1 ± 0.6 cm2; CI95% (-0.9, 1.4)] mCSA demonstrated little to no growth with small differences between groups. mCSA changes were greater in SQ for the quadriceps [3.6 ± 1.5 cm2; CI95% (0.7, 6.4)] and adductors [2.5 ± 0.7 cm2; CI95% (1.2, 3.9)]. Squat 3RM increases favored SQ [14 ± 2 kg; CI95% (9, 18),] and hip thrust 3RM favored HT [-26 ± 5 kg; CI95% (-34, -16)]. 3RM deadlift [0 ± 2 kg; CI95% (-4, 3)] and wall push strength [-7 ± 12N; CI95% (-32, 17)] similarly improved. All measured gluteal sites showed greater mean sEMG amplitudes during the first bout hip thrust versus squat set, but this did not consistently predict gluteal hypertrophy outcomes. Squat and hip thrust training elicited similar gluteal hypertrophy, greater thigh hypertrophy in SQ, strength increases that favored exercise allocation, and similar deadlift and wall push strength increases.
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Affiliation(s)
| | | | - Andrew D. Vigotsky
- Departments of Biomedical Engineering and Statistics, Evanston, IL, United States
- Department of Neuroscience, Northwestern University, Chicago, IL, United States
| | | | - Emma Breeze
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Rachel Ubrik
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Cole Robitzsch
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | | | - J. Max Michel
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Sarah Lennon
- College of Nursing, Auburn University, Auburn, AL, United States
| | - Andrew D. Frugé
- College of Nursing, Auburn University, Auburn, AL, United States
| | | | - Wendi H. Weimar
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Adil Bashir
- MRI Research Center, Auburn University, Auburn, AL, United States
| | - Ronald J. Beyers
- MRI Research Center, Auburn University, Auburn, AL, United States
| | - Menno Henselmans
- International Scientific Research Foundation for Fitness and Nutrition, Amsterdam, Netherlands
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Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev 2023; 103:2679-2757. [PMID: 37382939 PMCID: PMC10625844 DOI: 10.1152/physrev.00039.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/12/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital-Bispebjerg and Frederiksberg, and Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo A Nader
- Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Paul T Reidy
- Department of Kinesiology, Nutrition and Health, Miami University, Oxford, Ohio, United States
| | - Riki Ogasawara
- Healthy Food Science Research Group, Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Cleiton A Libardi
- MUSCULAB-Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, United States
| | - Karyn A Esser
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, Florida, United States
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Plotkin DL, Rodas MA, Vigotsky AD, McIntosh MC, Breeze E, Ubrik R, Robitzsch C, Agyin-Birikorang A, Mattingly ML, Michel JM, Kontos NJ, Frugé AD, Wilburn CM, Weimar WH, Bashir A, Beyers RJ, Henselmans M, Contreras BM, Roberts MD. Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.21.545949. [PMID: 37461495 PMCID: PMC10349977 DOI: 10.1101/2023.06.21.545949] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Purpose We examined how set-volume equated resistance training using either the back squat (SQ) or hip thrust (HT) affected hypertrophy and various strength outcomes. Methods Untrained college-aged participants were randomized into HT or SQ groups. Surface electromyograms (sEMG) from the right gluteus maximus and medius muscles were obtained during the first training session. Participants completed nine weeks of supervised training (15-17 sessions), before and after which we assessed muscle cross-sectional area (mCSA) via magnetic resonance imaging and strength via three-repetition maximum (3RM) testing and an isometric wall push test. Results Glutei mCSA growth was similar across both groups. Estimates [(-) favors HT; (+) favors SQ] modestly favored the HT compared to SQ for lower [effect ± SE, -1.6 ± 2.1 cm2], mid [-0.5± 1.7 cm2], and upper [-0.5 ± 2.6 cm2], but with appreciable variance. Gluteus medius+minimus [-1.8 ± 1.5 cm2] and hamstrings [0.1 ± 0.6 cm2] mCSA demonstrated little to no growth with small differences between groups. Thigh mCSA changes were greater in SQ for the quadriceps [3.6 ± 1.5 cm2] and adductors [2.5 ± 0.7 cm2]. Squat 3RM increases favored SQ [14 ± 2.5 kg] and hip thrust 3RM favored HT [-26 ± 5 kg]. 3RM deadlift [0 ± 2 kg] and wall push strength [-7 ± 13 N] similarly improved. All measured gluteal sites showed greater mean sEMG amplitudes during the first bout hip thrust versus squat set, but this did not consistently predict gluteal hypertrophy outcomes. Conclusion Nine weeks of squat versus hip thrust training elicited similar gluteal hypertrophy, greater thigh hypertrophy in SQ, strength increases that favored exercise allocation, and similar strength transfers to the deadlift and wall push.
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Affiliation(s)
| | | | - Andrew D. Vigotsky
- Departments of Biomedical Engineering and Statistics, Evanston, IL, USA
- Department of Neuroscience, Northwestern University, Chicago, IL, USA
| | | | - Emma Breeze
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Rachel Ubrik
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Cole Robitzsch
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | | | - J. Max Michel
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | | | | | | | | | - Adil Bashir
- MRI Research Center, Auburn University, Auburn AL, USA
| | | | - Menno Henselmans
- International Scientific Research Foundation for Fitness and Nutrition, Amsterdam, Netherlands
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Reece TM, Godwin JS, Strube MJ, Ciccone AB, Stout KW, Pearson JR, Vopat BG, Gallagher PM, Roberts MD, Herda TJ. Myofiber hypertrophy adaptations following 6 weeks of low-load resistance training with blood flow restriction in untrained males and females. J Appl Physiol (1985) 2023; 134:1240-1255. [PMID: 37022967 PMCID: PMC10190928 DOI: 10.1152/japplphysiol.00704.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/07/2023] Open
Abstract
The effects of low-load resistance training with blood flow restriction (BFR) on hypertrophy of type I/II myofibers remains unclear, especially in females. The purpose of the present study is to examine changes in type I/II myofiber cross-sectional area (fCSA) and muscle CSA (mCSA) of the vastus lateralis (VL) from before (Pre) to after (Post) 6 wk of high-load resistance training (HL; n = 15, 8 females) and low-load resistance training with BFR (n = 16, 8 females). Mixed-effects models were used to analyze fCSA with group (HL, BFR), sex (M, F), fiber type (I, II), and time (Pre, Post) included as factors. mCSA increased from pre- to posttraining (P < 0.001, d = 0.91) and was greater in males compared with females (P < 0.001, d = 2.26). Type II fCSA increased pre- to post-HL (P < 0.05, d = 0.46) and was greater in males compared with females (P < 0.05, d = 0.78). There were no significant increases in fCSA pre- to post-BFR for either fiber type or sex. Cohen's d, however, revealed moderate effect sizes in type I and II fCSA for males (d = 0.59 and 0.67), although this did not hold true for females (d = 0.29 and 0.34). Conversely, the increase in type II fCSA was greater for females than for males after HL. In conclusion, low-load resistance training with BFR may not promote myofiber hypertrophy to the level of HL resistance training, and similar responses were generally observed for males and females. In contrast, comparable effect sizes for mCSA and 1-repetition maximum (1RM) between groups suggest that BFR could play a role in a resistance training program.NEW & NOTEWORTHY This is the first study, to our knowledge, to examine myofiber hypertrophy from low-load resistance training with blood flow restriction (BFR) in females. Although this type of training did not result in myofiber hypertrophy, there were comparable increases in muscle cross-sectional area compared with high-load resistance training. These findings possibly highlight that males and females respond in a similar manner to high-load resistance training and low-load resistance training with BFR.
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Affiliation(s)
- Tanner M Reece
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, Missouri, United States
| | - Joshua S Godwin
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Michael J Strube
- Department of Psychological and Brain Sciences, Washington University, St. Louis, Missouri, United States
| | - Anthony B Ciccone
- Department of Exercise Science and Outdoor Recreation, Utah Valley University, Orem, Utah, United States
| | - Kevan W Stout
- Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, United States
| | - Jeremy R Pearson
- Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, United States
| | - Bryan G Vopat
- University of Kansas School of Medicine-Wichita, Wichita, Kansas, United States
| | - Philip M Gallagher
- Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Trent J Herda
- Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, 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] [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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Sexton CL, Godwin JS, McIntosh MC, Ruple BA, Osburn SC, Hollingsworth BR, Kontos NJ, Agostinelli PJ, Kavazis AN, Ziegenfuss TN, Lopez HL, Smith R, Young KC, Dwaraka VB, Frugé AD, Mobley CB, Sharples AP, Roberts MD. Skeletal Muscle DNA Methylation and mRNA Responses to a Bout of Higher versus Lower Load Resistance Exercise in Previously Trained Men. Cells 2023; 12:263. [PMID: 36672198 PMCID: PMC9856538 DOI: 10.3390/cells12020263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/24/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
We sought to determine the skeletal muscle genome-wide DNA methylation and mRNA responses to one bout of lower load (LL) versus higher load (HL) resistance exercise. Trained college-aged males (n = 11, 23 ± 4 years old, 4 ± 3 years self-reported training) performed LL or HL bouts to failure separated by one week. The HL bout (i.e., 80 Fail) consisted of four sets of back squats and four sets of leg extensions to failure using 80% of participants estimated one-repetition maximum (i.e., est. 1-RM). The LL bout (i.e., 30 Fail) implemented the same paradigm with 30% of est. 1-RM. Vastus lateralis muscle biopsies were collected before, 3 h, and 6 h after each bout. Muscle DNA and RNA were batch-isolated and analyzed using the 850k Illumina MethylationEPIC array and Clariom S mRNA microarray, respectively. Performed repetitions were significantly greater during the 30 Fail versus 80 Fail (p < 0.001), although total training volume (sets × reps × load) was not significantly different between bouts (p = 0.571). Regardless of bout, more CpG site methylation changes were observed at 3 h versus 6 h post exercise (239,951 versus 12,419, respectively; p < 0.01), and nuclear global ten-eleven translocation (TET) activity, but not global DNA methyltransferase activity, increased 3 h and 6 h following exercise regardless of bout. The percentage of genes significantly altered at the mRNA level that demonstrated opposite DNA methylation patterns was greater 3 h versus 6 h following exercise (~75% versus ~15%, respectively). Moreover, high percentages of genes that were up- or downregulated 6 h following exercise also demonstrated significantly inversed DNA methylation patterns across one or more CpG sites 3 h following exercise (65% and 82%, respectively). While 30 Fail decreased DNA methylation across various promoter regions versus 80 Fail, transcriptome-wide mRNA and bioinformatics indicated that gene expression signatures were largely similar between bouts. Bioinformatics overlay of DNA methylation and mRNA expression data indicated that genes related to "Focal adhesion," "MAPK signaling," and "PI3K-Akt signaling" were significantly affected at the 3 h and 6 h time points, and again this was regardless of bout. In conclusion, extensive molecular profiling suggests that post-exercise alterations in the skeletal muscle DNA methylome and mRNA transcriptome elicited by LL and HL training bouts to failure are largely similar, and this could be related to equal volumes performed between bouts.
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Affiliation(s)
- Casey L. Sexton
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | | | | | | | | | | | | | | | | | | | - Hector L. Lopez
- The Center for Applied Health Sciences, Canfield, OH 44406, USA
| | | | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
- Edward Via College of Osteopathic Medicine, Auburn, AL 24060, USA
| | | | - Andrew D. Frugé
- College of Nursing, Auburn University, Auburn, AL 36849, USA
| | | | - Adam P. Sharples
- Institute for Physical Performance, Norwegian School of Sport Sciences, 0863 Oslo, Norway
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
- Edward Via College of Osteopathic Medicine, Auburn, AL 24060, USA
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8
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Kojić F, Arsenijević R, Ilić V, Đurić S. Relationship between hypertrophy, strength gains and tensiomyography adaptations: a moderator role of contraction duration. Eur J Appl Physiol 2022; 122:2223-2231. [PMID: 35831629 DOI: 10.1007/s00421-022-04998-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/21/2022] [Indexed: 11/03/2022]
Abstract
The aim of the study was to investigate how the relationship between resistance training-induced hypertrophy, strength, and passive contractile adaptations is affected by contraction duration. Twenty university students (11 males) were randomly assigned to either the fast eccentric/fast concentric phase group (F/F; 1 s both phases) or the slow eccentric/fast concentric phase group (S/F; 4 s and 1 s, respectively). Both experimental groups completed a 7-week biceps curl training programme with a total of 14 sessions (2 days/week). Elbow flexor muscle thickness (MT), one-repetition maximum (1RM), and tensiomyographic (TMG) parameters (radial displacement-Dm and contraction time-Tc) were assessed. The percentage change (∆) in MT correlated significantly with the ∆1RM only in the S/F group (r = 0.712, p < 0.05). Both groups demonstrated significant negative associations between ∆MT and ∆Dm (r = 0.717-0.760, p < 0.01). Conversely, no significance was found between ∆MT and ∆Tc (F/F: r = -0.398, p = 0.255; S/F: r = 0.410, p = 0.239), ∆1RM and ∆Tc (F/F: r = -0.278, p = 0.436; S/F: r = 0.223, p = 0.536), nor ∆1RM and ∆Dm (F/F: r = - 0.131, p = 0.719; S/F: r = - 0.351, p = 0.320). The main findings indicate that the relationship between hypertrophy and strength gains is significantly stronger when resistance training was paced with slower eccentric contractions comparing to fast ones. On the other hand, reduced Dm values indicate increase in MT regardless of contraction duration, while strength gains are not correlated with corresponding TMG changes.
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Affiliation(s)
- Filip Kojić
- Teachers Education Faculty, University of Belgrade, Belgrade, Serbia
| | - Radenko Arsenijević
- Faculty of Sport and Physical Education, University of Prishtina, Leposavic, Serbia
| | - Vladimir Ilić
- Faculty of Sport and Physical Education, University of Belgrade, Belgrade, Serbia
| | - Saša Đurić
- Liberal Arts Department, General Education, American University of the Middle East, Al-Egaila, Block 3, Street No. 106, Kuwait City, Kuwait.
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Khudyakov JI, Holser RR, Vierra CA, Ly ST, Niel TK, Hasan BM, Crocker DE, Costa DP. Changes in apolipoprotein abundance dominate proteome responses to prolonged fasting in elephant seals. J Exp Biol 2022; 225:274459. [DOI: 10.1242/jeb.243572] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 01/27/2022] [Indexed: 01/10/2023]
Abstract
ABSTRACT
Unlike many animals that reduce activity during fasting, northern elephant seals (NES) undergo prolonged fasting during energy-intensive life-history stages such as reproduction and molting, fueling fasting energy needs by mobilizing fat stores accrued during foraging. NES display several unique metabolic features such as high fasting metabolic rates, elevated blood lipid and high-density lipoprotein (HDL) cholesterol levels, efficient protein sparing and resistance to oxidative stress during fasting. However, the cellular mechanisms that regulate these adaptations are still not fully understood. To examine how metabolic coordination is achieved during prolonged fasting, we profiled changes in blubber, skeletal muscle and plasma proteomes of adult female NES over a 5 week fast associated with molting. We found that while blubber and muscle proteomes were remarkably stable over fasting, over 50 proteins changed in abundance in plasma, including those associated with lipid storage, mobilization, oxidation and transport. Apolipoproteins dominated the blubber, plasma and muscle proteome responses to fasting. APOA4, APOE and APOC3, which are associated with lipogenesis and triglyceride accumulation, decreased, while APOA1, APOA2 and APOM, which are associated with lipid mobilization and HDL function, increased over fasting. Our findings suggest that changes in apolipoprotein composition may underlie the maintenance of high HDL levels and, together with adipokines and hepatokines that facilitate lipid catabolism, may mediate the metabolic transitions between feeding and fasting in NES. Many of these proteins have not been previously studied in this species and provide intriguing hypotheses about metabolic regulation during prolonged fasting in mammals.
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Affiliation(s)
- Jane I. Khudyakov
- Biological Sciences Department, University of the Pacific, Stockton, CA 95211, USA
| | - Rachel R. Holser
- Institute of Marine Sciences, University of California, Santa Cruz, CA 95064, USA
| | - Craig A. Vierra
- Biological Sciences Department, University of the Pacific, Stockton, CA 95211, USA
| | - Serena T. Ly
- Biological Sciences Department, University of the Pacific, Stockton, CA 95211, USA
| | - Theron K. Niel
- Biological Sciences Department, University of the Pacific, Stockton, CA 95211, USA
| | - Basma M. Hasan
- Biological Sciences Department, University of the Pacific, Stockton, CA 95211, USA
| | - Daniel E. Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA 94928, USA
| | - Daniel P. Costa
- Institute of Marine Sciences, University of California, Santa Cruz, CA 95064, USA
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10
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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] [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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11
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Fox CD, Mesquita PHC, Godwin JS, Angleri V, Damas F, Ruple BA, Sexton CL, Brown MD, Kavazis AN, Young KC, Ugrinowitsch C, Libardi CA, Roberts MD. Frequent Manipulation of Resistance Training Variables Promotes Myofibrillar Spacing Changes in Resistance-Trained Individuals. Front Physiol 2021; 12:773995. [PMID: 34975527 PMCID: PMC8715010 DOI: 10.3389/fphys.2021.773995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/17/2021] [Indexed: 11/21/2022] Open
Abstract
We sought to determine if manipulating resistance training (RT) variables differentially altered the expression of select sarcoplasmic and myofibril proteins as well as myofibrillar spacing in myofibers. Resistance-trained men (n = 20; 26 ± 3 years old) trained for 8 weeks where a randomized leg performed either a standard (CON) or variable RT protocol (VAR: manipulation of load, volume, muscle action, and rest intervals at each RT session). A pre-training (PRE) vastus lateralis biopsy was obtained from a randomized single leg, and biopsies were obtained from both legs 96 h following the last training bout. The sarcoplasmic protein pool was assayed for proteins involved in energy metabolism, and the myofibril protein pool was assayed for relative myosin heavy chain (MHC) and actin protein abundances. Sections were also histologically analyzed to obtain myofibril spacing characteristics. VAR resulted in ~12% greater volume load (VL) compared to CON (p < 0.001). The mean fiber cross-sectional area increased following both RT protocols [CON: 14.6% (775.5 μm2), p = 0.006; VAR: 13.9% (743.2 μm2), p = 0.01 vs. PRE for both], but without significant differences between protocols (p = 0.79). Neither RT protocol affected a majority of assayed proteins related to energy metabolism, but both training protocols increased hexokinase 2 protein levels and decreased a mitochondrial beta-oxidation marker (VLCAD protein; p < 0.05). Citrate synthase activity levels increased with CON RT (p < 0.05), but not VAR RT. The relative abundance of MHC (summed isoforms) decreased with both training protocols (p < 0.05). However, the relative abundance of actin protein (summed isoforms) decreased with VAR only (13.5 and 9.0%, respectively; p < 0.05). A decrease in percent area occupied by myofibrils was observed from PRE to VAR (−4.87%; p = 0.048), but not for the CON (4.53%; p = 0.979). In contrast, there was an increase in percent area occupied by non-contractile space from PRE to VAR (10.14%; p = 0.048), but not PRE to CON (0.72%; p = 0.979). In conclusion, while both RT protocols increased muscle fiber hypertrophy, a higher volume-load where RT variables were frequently manipulated increased non-contractile spacing in resistance-trained individuals.
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Affiliation(s)
- Carlton D. Fox
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Joshua S. Godwin
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Vitor Angleri
- MUSCULAB, Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Felipe Damas
- MUSCULAB, Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Bradley A. Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Casey L. Sexton
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Michael D. Brown
- 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
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Cleiton A. Libardi
- MUSCULAB, Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
- *Correspondence: Cleiton A. Libardi, ; Michael D. Roberts,
| | - 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
- *Correspondence: Cleiton A. Libardi, ; Michael D. Roberts,
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12
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Ruple BA, Godwin JS, Mesquita PHC, Osburn SC, Sexton CL, Smith MA, Ogletree JC, Goodlett MD, Edison JL, Ferrando AA, Fruge AD, Kavazis AN, Young KC, Roberts MD. Myofibril and Mitochondrial Area Changes in Type I and II Fibers Following 10 Weeks of Resistance Training in Previously Untrained Men. Front Physiol 2021; 12:728683. [PMID: 34630147 PMCID: PMC8497692 DOI: 10.3389/fphys.2021.728683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/25/2021] [Indexed: 12/19/2022] Open
Abstract
Resistance training increases muscle fiber hypertrophy, but the morphological adaptations that occur within muscle fibers remain largely unresolved. Fifteen males with minimal training experience (24±4years, 23.9±3.1kg/m2 body mass index) performed 10weeks of conventional, full-body resistance training (2× weekly). Body composition, the radiological density of the vastus lateralis muscle using peripheral quantitative computed tomography (pQCT), and vastus lateralis muscle biopsies were obtained 1week prior to and 72h following the last training bout. Quantification of myofibril and mitochondrial areas in type I (positive for MyHC I) and II (positive for MyHC IIa/IIx) fibers was performed using immunohistochemistry (IHC) techniques. Relative myosin heavy chain and actin protein abundances per wet muscle weight as well as citrate synthase (CS) activity assays were also obtained on tissue lysates. Training increased whole-body lean mass, mid-thigh muscle cross-sectional area, mean and type II fiber cross-sectional areas (fCSA), and maximal strength values for leg press, bench press, and deadlift (p<0.05). The intracellular area occupied by myofibrils in type I or II fibers was not altered with training, suggesting a proportional expansion of myofibrils with fCSA increases. However, our histological analysis was unable to differentiate whether increases in myofibril number or girth occurred. Relative myosin heavy chain and actin protein abundances also did not change with training. IHC indicated training increased mitochondrial areas in both fiber types (p=0.018), albeit CS activity levels remained unaltered with training suggesting a discordance between these assays. Interestingly, although pQCT-derived muscle density increased with training (p=0.036), suggestive of myofibril packing, a positive association existed between training-induced changes in this metric and changes in mean fiber myofibril area (r=0.600, p=0.018). To summarize, our data imply that shorter-term resistance training promotes a proportional expansion of the area occupied by myofibrils and a disproportional expansion of the area occupied by mitochondria in type I and II fibers. Additionally, IHC and biochemical techniques should be viewed independently from one another given the lack of agreement between the variables assessed herein. Finally, the pQCT may be a viable tool to non-invasively track morphological changes (specifically myofibril density) in muscle tissue.
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Affiliation(s)
- Bradley A Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Joshua S Godwin
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Casey L Sexton
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Morgan A Smith
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | | | - Michael D Goodlett
- Athletics Department, Auburn University, Auburn, AL, United States.,Department of Geriatrics, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | - Joseph L Edison
- Athletics Department, Auburn University, Auburn, AL, United States.,Department of Geriatrics, Edward Via College of Osteopathic Medicine, 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
| | - Andrew D Fruge
- Department of Nutrition, Dietetics and Hospitality Management, Auburn University, Auburn, AL, United States
| | | | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Geriatrics, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Department of Geriatrics, Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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13
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Naimo MA, Varanoske AN, Hughes JM, Pasiakos SM. Skeletal Muscle Quality: A Biomarker for Assessing Physical Performance Capabilities in Young Populations. Front Physiol 2021; 12:706699. [PMID: 34421645 PMCID: PMC8376973 DOI: 10.3389/fphys.2021.706699] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/09/2021] [Indexed: 12/28/2022] Open
Abstract
Muscle quality (MQ), defined as the amount of strength and/or power per unit of muscle mass, is a novel index of functional capacity that is increasingly relied upon as a critical biomarker of muscle health in low functioning aging and pathophysiological adult populations. Understanding the phenotypical attributes of MQ and how to use it as an assessment tool to explore the efficacy of resistance exercise training interventions that prioritize functional enhancement over increases in muscle size may have implications for populations beyond compromised adults, including healthy young adults who routinely perform physically demanding tasks for competitive or occupational purposes. However, MQ has received far less attention in healthy young populations than it has in compromised adults. Researchers and practitioners continue to rely upon static measures of lean mass or isolated measures of strength and power, rather than using MQ, to assess integrated functional responses to resistance exercise training and physical stress. Therefore, this review will critically examine MQ and the evidence base to establish this metric as a practical and important biomarker for functional capacity and performance in healthy, young populations. Interventions that enhance MQ, such as high-intensity stretch shortening contraction resistance exercise training, will be highlighted. Finally, we will explore the potential to leverage MQ as a practical assessment tool to evaluate function and enhance performance in young populations in non-traditional research settings.
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Affiliation(s)
- Marshall A Naimo
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Alyssa N Varanoske
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States.,Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States
| | - Julie M Hughes
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Stefan M Pasiakos
- Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
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14
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Monti E, Toniolo L, Marcucci L, Bondì M, Martellato I, Šimunič B, Toninello P, Franchi MV, Narici MV, Reggiani C. Are muscle fibres of body builders intrinsically weaker? A comparison with single fibres of aged-matched controls. Acta Physiol (Oxf) 2021; 231:e13557. [PMID: 32921001 DOI: 10.1111/apha.13557] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/21/2020] [Accepted: 09/03/2020] [Indexed: 12/17/2022]
Abstract
AIM Skeletal muscles of Body Builders (BB) represent an interesting model to study muscle mass gains in response to high volume resistance training. It is debated whether muscle contractile performance improves in proportion to mass. Here, we aim to assess whether muscle hypertrophy does not occur at the expense of performance. METHODS Six BB and Six untrained controls (CTRL) were recruited. Cross-sectional area (CSA) and maximum voluntary contraction (MVC) of quadriceps femoris muscle (QF) and CSA and architecture of vastus lateralis (VL) were determined. Moreover, a biopsy was taken from VL mid-portion and single fibres were analysed. RESULTS QF CSA and MVC were 32% (n.s., P = .052) and 58% (P = .009) higher in BB than in CTRL, respectively. VL CSA was 37% higher in BB (P = .030). Fast 2A fibres CSA was 24% (P = .048) greater in BB than in CTRL, when determined in immunostained sections of biopsy samples. Single permeabilized fast fibres CSA was 37% (n.s., P = .052) higher in BB than in CTRL, and their force was slightly higher in BB (n.s.), while specific tension (P0 ) was 19% (P = .024) lower. The lower P0 was not explained either by lower myosin content or by impaired calcium diffusion. Conversely, the swelling caused by skinning-induced permeabilization was different and, when used to correct P0 , differences between populations disappeared. CONCLUSIONS The results show that high degree of muscle hypertrophy is not detrimental for force generation capacity, as increases in fibre size and force are strictly proportional once the differential swelling response is accounted for.
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Affiliation(s)
- Elena Monti
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Luana Toniolo
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Lorenzo Marcucci
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Michela Bondì
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Ivan Martellato
- Department of Biomedical Sciences University of Padova Padova Italy
| | - Bostjan Šimunič
- Science and Research Centre Koper Institute for Kinesiology Research Koper Slovenia
| | - Paolo Toninello
- Clinic of Plastic Surgery Padova University Hospital Padova Italy
| | | | - Marco V. Narici
- Department of Biomedical Sciences University of Padova Padova Italy
- Science and Research Centre Koper Institute for Kinesiology Research Koper Slovenia
- CIR‐MYO Myology Centre Department of Biomedical Sciences University of Padua Padova Italy
| | - Carlo Reggiani
- Department of Biomedical Sciences University of Padova Padova Italy
- Science and Research Centre Koper Institute for Kinesiology Research Koper Slovenia
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15
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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] [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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16
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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] [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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