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Rodrigues Junior CF, Murata GM, Gerlinger-Romero F, Nachbar RT, Marzuca-Nassr GN, Gorjão R, Vitzel KF, Hirabara SM, Pithon-Curi TC, Curi R. Changes in Skeletal Muscle Protein Metabolism Signaling Induced by Glutamine Supplementation and Exercise. Nutrients 2023; 15:4711. [PMID: 38004105 PMCID: PMC10674901 DOI: 10.3390/nu15224711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
AIM To evaluate the effects of resistance exercise training (RET) and/or glutamine supplementation (GS) on signaling protein synthesis in adult rat skeletal muscles. METHODS The following groups were studied: (1) control, no exercise (C); (2) exercise, hypertrophy resistance exercise training protocol (T); (3) no exercise, supplemented with glutamine (G); and (4) exercise and supplemented with glutamine (GT). The rats performed hypertrophic training, climbing a vertical ladder with a height of 1.1 m at an 80° incline relative to the horizontal with extra weights tied to their tails. The RET was performed three days a week for five weeks. Each training session consisted of six ladder climbs. The extra weight load was progressively increased for each animal during each training session. The G groups received daily L-glutamine by gavage (one g per kilogram of body weight per day) for five weeks. The C group received the same volume of water during the same period. The rats were euthanized, and the extensor digitorum longus (EDL) muscles from both hind limbs were removed and immediately weighed. Glutamine and glutamate concentrations were measured, and histological, signaling protein contents, and mRNA expression analyses were performed. RESULTS Supplementation with free L-glutamine increased the glutamine concentration in the EDL muscle in the C group. The glutamate concentration was augmented in the EDL muscles from T rats. The EDL muscle mass did not change, but a significant rise was reported in the cross-sectional area (CSA) of the fibers in the three experimental groups. The levels of the phosphorylated proteins (pAkt/Akt, pp70S6K/p70S6K, p4E-BP1/4E-BP1, and pS6/S6 ratios) were significantly increased in EDL muscles of G rats, and the activation of p4E-BP1 was present in T rats. The fiber CSAs of the EDL muscles in T, G, and GT rats were increased compared to the C group. These changes were accompanied by a reduction in the 26 proteasome activity of EDL muscles from T rats. CONCLUSION Five weeks of GS and/or RET induced muscle hypertrophy, as indicated by the increased CSAs of the EDL muscle fibers. The increase in CSA was mediated via the upregulated phosphorylation of Akt, 4E-BP1, p70S6k, and S6 in G animals and 4E-BP1 in T animals. In the EDL muscles from T animals, a decrease in proteasome activity, favoring a further increase in the CSA of the muscle fibers, was reported.
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Affiliation(s)
- Carlos Flores Rodrigues Junior
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
| | - Gilson Masahiro Murata
- Divisions of Nephrology and Molecular Medicine, LIM-29, Department of Medicine, University of São Paulo, São Paulo 05508-220, Brazil;
| | | | - Renato Tadeu Nachbar
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
| | - Gabriel Nasri Marzuca-Nassr
- Departamento de Ciencias de la Rehabilitación, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile;
- Interuniversity Center for Healthy Aging (Code RED21993), Talca 3460000, Chile
| | - Renata Gorjão
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Kaio Fernando Vitzel
- School of Health Sciences, Massey University (University of New Zealand), Auckland 0745, New Zealand;
| | - Sandro Massao Hirabara
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Tania Cristina Pithon-Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
- Butantan Institute, São Paulo 05585-000, Brazil
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Reggiani C, Schiaffino S. Muscle hypertrophy and muscle strength: dependent or independent variables? A provocative review. Eur J Transl Myol 2020; 30:9311. [PMID: 33117512 PMCID: PMC7582410 DOI: 10.4081/ejtm.2020.9311] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 08/23/2020] [Indexed: 01/02/2023] Open
Abstract
The question whether the muscle hypertrophy induced by resistance training, hormone administration or genetic manipulation is accompanied by a proportional increase in muscle strength is still open. This review summarizes and analyses data obtained in human and rodent muscles in studies that have monitored in parallel changes in muscle size and changes in muscle force, measured in isometric contractions in vivo, in isolated muscles ex vivo (in rodents) and in single muscle fibers. Although a general positive relation exists among the two variables, a number of studies show a clear dissociation with increase of muscle size with no change or even decrease in strength and, vice versa, increase in strength without increase in size. The possible mechanisms of such dissociation, which involves neural motor control and/or cellular and molecular adaptations of muscle fibers, are briefly discussed.
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Affiliation(s)
- Carlo Reggiani
- Department of Biomedical Sciences of the University of Padova, Padova, Italy.,Science and Research Centre Koper, Institute for Kinesiology Research, Koper, Slovenia
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Loenneke JP, Dankel SJ, Bell ZW, Buckner SL, Mattocks KT, Jessee MB, Abe T. Is muscle growth a mechanism for increasing strength? Med Hypotheses 2019; 125:51-56. [DOI: 10.1016/j.mehy.2019.02.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 11/24/2022]
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Krutki P, Mrówczyński W, Bączyk M, Łochyński D, Celichowski J. Adaptations of motoneuron properties after weight-lifting training in rats. J Appl Physiol (1985) 2017; 123:664-673. [DOI: 10.1152/japplphysiol.00121.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 06/01/2017] [Accepted: 06/06/2017] [Indexed: 11/22/2022] Open
Abstract
Resistance training, with repeated short-term and high-intensity exercises, is responsible for an increase in muscle mass and force. The aim of this study was to determine whether such training induces adaptations in the electrophysiological properties of motoneurons innervating the trained muscles and to relate these adaptive changes to previous observations made on motor unit contractile properties. The study was performed on adult male Wistar rats. Animals from the training group were subjected to a 5-wk voluntary progressive weight-lifting program, whereas control rats were restricted to standard cage activity. Intracellular recordings from lumbar spinal motoneurons were made under pentobarbital anesthesia. Membrane properties were measured, and rhythmic firing of motoneurons was analyzed. Strength training evoked adaptive changes in both slow- and fast-type motoneurons, indicating their increased excitability. A shorter spike duration, a higher input resistance, a lower rheobase, a decrease in the minimum current required to evoke rhythmic firing, an increase in the maximum frequencies of the early-state firing (ESF) and the steady-state firing (SSF), and an increase in the respective slopes of the frequency-current ( f/ I) relationship were observed in fast motoneurons of the trained group. The increase in the maximum ESF and SSF frequencies and an increase in the SSF f/ I slope were also present in slow motoneurons. Higher maximum firing rates of motoneurons as well as higher discharge frequencies evoked at the same level of intracellular depolarization current imply higher levels of tetanic forces developed by motor units over the operating range of force production after strength training. NEW & NOTEWORTHY Neuronal responses to weight-lifting training can be observed in altered properties of both slow and fast motoneurons. Motoneurons of trained animals are more excitable, require lower intracellular currents to evoke rhythmic firing, and have the ability to evoke higher maximum discharge frequencies during repetitive firing.
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Affiliation(s)
- Piotr Krutki
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland; and
| | | | - Marcin Bączyk
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland; and
| | - Dawid Łochyński
- Department of Musculoskeletal Rehabilitation, Poznań University of Physical Education, Poznań, Poland
| | - Jan Celichowski
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland; and
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Dankel SJ, Buckner SL, Jessee MB, Grant Mouser J, Mattocks KT, Abe T, Loenneke JP. Correlations Do Not Show Cause and Effect: Not Even for Changes in Muscle Size and Strength. Sports Med 2017; 48:1-6. [DOI: 10.1007/s40279-017-0774-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Łochyński D, Kaczmarek D, Mrówczyński W, Warchoł W, Majerczak J, Karasiński J, Korostyński M, Zoladz JA, Celichowski J. Contractile properties of motor units and expression of myosin heavy chain isoforms in rat fast-type muscle after volitional weight-lifting training. J Appl Physiol (1985) 2016; 121:858-869. [PMID: 27539495 DOI: 10.1152/japplphysiol.00330.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/17/2016] [Indexed: 11/22/2022] Open
Abstract
Dynamic resistance training increases the force and speed of muscle contraction, but little is known about modifications to the contractile properties of the main physiological types of motor units (MUs) that contribute to these muscle adaptations. Although the contractile profile of MU muscle fibers is tightly coupled to myosin heavy chain (MyHC) protein expression, it is not well understood if MyHC transition is a prerequisite for modifications to the contractile characteristics of MUs. In this study, we examined MU contractile properties, the mRNA expression of MyHC, parvalbumin, and sarcoendoplasmic reticulum Ca2+ pump isoforms, as well as the MyHC protein content after 5 wk of volitional progressive weight-lifting training in the medial gastrocnemius muscle in rats. The training had no effect on MyHC profiling or Ca2+-handling protein gene expression. Maximum force increased in slow (by 49%) and fast (by 21%) MUs. Within fast MUs, the maximum force increased in most fatigue-resistant and intermediate but not most fatigable MUs. Twitch contraction time was shortened in slow and fast fatigue-resistant MUs. Twitch half-relaxation was shortened in fast most fatigue-resistant and intermediate MUs. The force-frequency curve shifted rightward in fast fatigue-resistant MUs. Fast fatigable MUs fatigued less within the initial 15 s while fast fatigue-resistant units increased the ability to potentiate the force within the first minute of the standard fatigue test. In conclusion, at the early stage of resistance training, modifications to the contractile characteristics of MUs appear in the absence of MyHC transition and the upregulation of Ca2+-handling genes.
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Affiliation(s)
- Dawid Łochyński
- Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Motor Rehabilitation, Poznan University of Physical Education, Poznań, Poland;
| | - Dominik Kaczmarek
- Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Physiology, Biochemistry, and Hygiene, Poznan University of Physical Education, Poznań, Poland
| | | | - Wojciech Warchoł
- Chair of Biophysics, Poznan University of Medical Sciences, Poznań, Poland
| | - Joanna Majerczak
- Department of Muscle Physiology, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland
| | - Janusz Karasiński
- Department of Cell Biology and Imaging, Institute of Zoology, Jagiellonian University, Krakow, Poland; and
| | - Michał Korostyński
- Department of Molecular Neuropharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - Jerzy A Zoladz
- Department of Muscle Physiology, Faculty of Rehabilitation, University School of Physical Education, Krakow, Poland
| | - Jan Celichowski
- Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland
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Lee S, Hong KS, Kim K. Effect of previous strength training episode and retraining on facilitation of skeletal muscle hypertrophy and contractile properties after long-term detraining in rats. J Exerc Rehabil 2016; 12:79-82. [PMID: 27162768 PMCID: PMC4849495 DOI: 10.12965/jer.1632608.304] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/07/2016] [Indexed: 12/04/2022] Open
Abstract
In the present study, we investigated the effects of previous strength training and retraining following long-term cessation of exercise on muscle mass and contractile properties. Female Sprague-Dawley rats (n=24) aged eight weeks were randomly assigned one of the four groups: control (CON), detraining (DT), training (TR), and retraining (RT). The training regimen consisted of climbing ladder 5×3 sets, once every third day for eight weeks with weight attached to the tail. The weight carried during each training session was initially 50% of body weight and progressively increased by 10% per session. The rats in DT were detained for 20 weeks followed by eight weeks strength training. The rats in the both TR and RT groups underwent eight weeks training. DT was age matched new training group while RT was retraining group after 20 weeks of detraining. Soleus, gastrocnemius, tibialis anterior, and flexor hallucis longus (FHL) muscles were harvested in order to measure the weight, and in situ contractile properties of FHL were measured including specific twitch tension (Spt) and specific tetanic tension (Spo). TR showed significant increase in muscle mass compared to CON (P<0.05). DT and RT showed significant increase in muscle mass when compared to all other groups (P<0.05). There was no statistical difference in Spt and Spo among the groups. The present study showed that previous strength training facilitates retraining-induced muscle hypertrophy following long-term cessation of exercise.
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Affiliation(s)
- Sukho Lee
- Department of Counseling, Health, and Kinesiology, College of Education and Human Development, Texas A&M University-San Antonio, San Antonio, TX, USA
| | - Kwang-Seok Hong
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Kijeong Kim
- School of Exercise & Sport Science, College of Natural Sciences, University of Ulsan, Ulsan, Korea
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8
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Rader EP, Miller GR, Chetlin RD, Wirth O, Baker BA. Volitional Weight-Lifting in Rats Promotes Adaptation via Performance and Muscle Morphology prior to Gains in Muscle Mass. ENVIRONMENTAL HEALTH INSIGHTS 2014; 8:1-9. [PMID: 25392697 PMCID: PMC4216651 DOI: 10.4137/ehi.s15257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/15/2014] [Accepted: 04/16/2014] [Indexed: 06/04/2023]
Abstract
Investigation of volitional animal models of resistance training has been instrumental in our understanding of adaptive training. However, these studies have lacked reactive force measurements, a precise performance measure, and morphological analysis at a distinct phase of training - when initial strength gains precede muscle hypertrophy. Our aim was to expose rats to one month of training (70 or 700 g load) on a custom-designed weight-lifting apparatus for analysis of reactive forces and muscle morphology prior to muscle hypertrophy. Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered. For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%. Additionally, number of muscle fibers per section increased by 18% for SOL muscles. These results establish that distinct morphological alterations accompany early strength gains in a volitional animal model of load-dependent adaptive resistance training.
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Affiliation(s)
- Erik P Rader
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - G Roger Miller
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Robert D Chetlin
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
- West Virginia University School of Medicine, Department of Neurology, WV, USA
| | - Oliver Wirth
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Brent A Baker
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA
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9
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Adams GR, Bamman MM. Characterization and regulation of mechanical loading-induced compensatory muscle hypertrophy. Compr Physiol 2013; 2:2829-70. [PMID: 23720267 DOI: 10.1002/cphy.c110066] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In mammalian systems, skeletal muscle exists in a dynamic state that monitors and regulates the physiological investment in muscle size to meet the current level of functional demand. This review attempts to consolidate current knowledge concerning development of the compensatory hypertrophy that occurs in response to a sustained increase in the mechanical loading of skeletal muscle. Topics covered include: defining and measuring compensatory hypertrophy, experimental models, loading stimulus parameters, acute responses to increased loading, hyperplasia, myofiber-type adaptations, the involvement of satellite cells, mRNA translational control, mechanotransduction, and endocrinology. The authors conclude with their impressions of current knowledge gaps in the field that are ripe for future study.
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Affiliation(s)
- Gregory R Adams
- Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA.
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Tamaki T. Multipotency and physiological role of skeletal muscle interstitium-derived stem cells. JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2012. [DOI: 10.7600/jpfsm.1.423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Johnson WL, Jindrich DL, Zhong H, Roy RR, Edgerton VR. Application of a rat hindlimb model: a prediction of force spaces reachable through stimulation of nerve fascicles. IEEE Trans Biomed Eng 2011; 58:3328-38. [PMID: 21244999 DOI: 10.1109/tbme.2011.2106784] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A device to generate standing or locomotion through chronically placed electrodes has not been fully developed due in part to limitations of clinical experimentation and the high number of muscle activation inputs of the leg. We investigated the feasibility of functional electrical stimulation paradigms that minimize the input dimensions for controlling the limbs by stimulating at nerve fascicles, utilizing a model of the rat hindlimb, which combined previously collected morphological data with muscle physiological parameters presented herein. As validation of the model, we investigated the suitability of a lumped-parameter model for the prediction of muscle activation during dynamic tasks. Using the validated model, we found that the space of forces producible through activation of muscle groups sharing common nerve fascicles was nonlinearly dependent on the number of discrete muscle groups that could be individually activated (equivalently, the neuroanatomical level of activation). Seven commonly innervated muscle groups were sufficient to produce 78% of the force space producible through individual activation of the 42 modeled hindlimb muscles. This novel, neuroanatomically derived reduction in input dimension emphasizes the potential to simplify controllers for functional electrical stimulation to improve functional recovery after a neuromuscular injury.
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Affiliation(s)
- Will L Johnson
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90024, USA.
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12
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O'Connor PJ, Herring MP, Caravalho A. Mental Health Benefits of Strength Training in Adults. Am J Lifestyle Med 2010. [DOI: 10.1177/1559827610368771] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This review summarizes evidence from randomized controlled trials to examine whether strength training influences anxiety, chronic pain, cognition, depression, fatigue symptoms, self-esteem, and sleep. The weight of the available evidence supported the conclusion that strength training is associated with reductions in anxiety symptoms among healthy adults (5 trials); reductions in pain intensity among patients with low back pain (5 trials), osteoarthritis (8 trials), and fibromyalgia (4 trials); improvements in cognition among older adults (7 trials); improvements in sleep quality among depressed older adults (2 trials); reductions in symptoms of depression among patients with diagnosed depression (4 trials) and fibromyalgia (2 trials); reductions in fatigue symptoms (10 trials); and improvements in self-esteem (6 trials). The evidence indicates that larger trials with a greater range of patient samples are needed to better estimate the magnitude and the consistency of the relationship between strength training and these mental health outcomes. Plausible social, psychological, and neural mechanisms by which strength training could influence these outcomes rarely have been explored. This review revealed the high-priority research need for animal and human research aimed at better understanding the brain mechanisms underlying mental health changes with strength training.
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Barone R, Bellafiore M, Leonardi V, Zummo G. Structural analysis of rat patellar tendon in response to resistance and endurance training. Scand J Med Sci Sports 2009; 19:782-9. [DOI: 10.1111/j.1600-0838.2008.00863.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Alway SE, Siu PM, Murlasits Z, Butler DC. Muscle hypertrophy models: applications for research on aging. ACTA ACUST UNITED AC 2005; 30:591-624. [PMID: 16293906 DOI: 10.1139/h05-143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Muscle hypertrophy is an adaptive response to overload that requires increasing gene transcription and synthesis of muscle-specific proteins resulting in increased protein accumulation. Progressive resistance training (P(RT)) is thought to be among the best means for achieving hypertrophy in humans. However, hypertrophy and functional adaptations to P(RT) in the muscles of humans are often difficult to evaluate because adaptations can take weeks, months, or even years before they become evident, and there is a large variability in response to P(RT) among humans. In contrast, various animal models have been developed which quickly result in extensive muscle hypertrophy. Several such models allow precise control of the loading parameters and records of muscle activation and performance throughout overload. Scientists using animal models of muscle hypertrophy should be familiar with the advantages and disadvantages of each and thereby choose the model that best addresses their research question. The purposes of this paper are to review animal models currently being used in basic research laboratories, discuss the hypertrophic and functional outcomes as well as applications of these models to aging, and highlight a few mechanisms involved in regulating hypertrophy as a result of applying these animal models to questions in research on aging.
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Affiliation(s)
- Stephen E Alway
- Laboratory of Muscle Biology and Sarcopenia, Division of Exercise Physiology, West Virginia University School of Medicine, Robert C Byrd Health Sciences Center, Morgantown, WV 26506, USA
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Galbán CJ, Maderwald S, Uffmann K, de Greiff A, Ladd ME. Diffusive sensitivity to muscle architecture: a magnetic resonance diffusion tensor imaging study of the human calf. Eur J Appl Physiol 2005; 93:253-62. [PMID: 15322853 DOI: 10.1007/s00421-004-1186-2] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of this study was to examine the diffusive properties of adjacent muscles at rest, and to determine the relationship between diffusive and architectural properties, which are task-specific to muscles. The principle, second, and third eigenvalues, trace of the diffusion tensor, and two anisotropic parameters, ellipsoid eccentricity (e) and fractional anisotropy (FA), of various muscles in the human calf were calculated by diffusion tensor imaging (DTI). Linear correlations of the calculated parameters to the muscle physiological cross-sectional area (PCSA), which is proportional to maximum muscle force, were performed to ascertain any linear relation between muscle architecture and diffusivity. Images of the left calf were acquired from six healthy male volunteers. Seven muscles were investigated in this study. These comprised the soleus, lateral gastrocnemius, medial gastrocnemius, posterior tibialis, anterior tibialis, extensor digitorum longus, and peroneus longus. All data were presented as the mean and standard error of the mean (SEM). In general, differences in diffusive parameter values occurred primarily between functionally different muscles. A strong correlation was also found between PCSA and the third eigenvalue, e, and FA. A mathematical derivation revealed a linear relationship between PCSA and the third eigenvalue as a result of their dependence on the average radius of all fibers within a single muscle. These findings demonstrated the ability of DTI to differentiate between functionally different muscles in the same region of the body on the basis of their diffusive properties.
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Affiliation(s)
- Craig J Galbán
- Department of Diagnostic and Interventional Radiology OZII, University Hospital of Essen, Hufelandstrasse 55, 45122 Essen, Germany.
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Lee S, Barton ER, Sweeney HL, Farrar RP. Viral expression of insulin-like growth factor-I enhances muscle hypertrophy in resistance-trained rats. J Appl Physiol (1985) 2004; 96:1097-104. [PMID: 14766764 DOI: 10.1152/japplphysiol.00479.2003] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Muscle hypertrophy is the product of increased drive through protein synthetic pathways and the incorporation of newly divided satellite cells. Gains in muscle mass and strength can be achieved through exercise regimens that include resistance training. Increased insulin-like growth factor-I (IGF-I) can also promote hypertrophy through increased protein synthesis and satellite cell proliferation. However, it is not known whether the combined effect of IGF-I and resistance training results in an additive hypertrophic response. Therefore, rats in which viral administration of IGF-I was directed to one limb were subjected to ladder climbing to test the interaction of each intervention on muscle mass and strength. After 8 wk of resistance training, a 23.3% increase in muscle mass and a 14.4% increase in peak tetanic tension (P(o)) were observed in the flexor hallucis longus (FHL). Viral expression of IGF-I without resistance training produced a 14.8% increase in mass and a 16.6% increase in P(o) in the FHL. The combined interventions produced a 31.8% increase in muscle mass and a 28.3% increase in P(o) in the FHL. Therefore, the combination of resistance training and overexpression of IGF-I induced greater hypertrophy than either treatment alone. The effect of increased IGF-I expression on the loss of muscle mass associated with detraining was also addressed. FHL muscles treated with IGF-I lost only 4.8% after detraining, whereas the untreated FHL lost 8.3% muscle mass. These results suggest that a combination of resistance training and overexpression of IGF-I could be an effective measure for attenuating the loss of training-induced adaptations.
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Affiliation(s)
- Sukho Lee
- Department of Kinesiology, University of Texas, Austin 78712, USA
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Norenberg KM, Fitts RH. Contractile responses of the rat gastrocnemius and soleus muscles to isotonic resistance exercise. J Appl Physiol (1985) 2004; 97:2322-32. [PMID: 15322071 DOI: 10.1152/japplphysiol.00955.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Male rats were divided into control and weight-trained (WT) groups. WT rats performed squat-type exercises twice daily, 5 days/wk, for 14 wk. They averaged 36 lifts/day, with an average weight of 555 g. Muscle-to-body weight ratio (mg/g) of the soleus (Sol) was not different from control, but it increased 11 and 6% in the gastrocnemius (Gast) and plantaris, respectively (P < 0.05). The normalized twitch tension of the in situ Sol was elevated by 21%, whereas single-skinned type I fibers from the Sol showed an increased rate constant of tension redevelopment (K(tr)) but no other contractile adaptations to WT. In contrast, the Gast type I fibers showed an increase (P < 0.05) in maximal velocity of shortening (25%), peak power (15%), K(tr) (18%), and normalized tension (7%). The K(tr) and normalized tension of the Gast type IIa fibers increased by 24% (P < 0.05) and 12% (P < 0.05), respectively, whereas velocity and power showed a tendency to increase. Fiber size, determined by myosin ATPase histochemistry, was not different for any fiber type from the Gast or Sol. These results indicate that isotonic resistance exercise of the calf targets the Gast (type I and type IIa fibers) and has little effect on the Sol.
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Affiliation(s)
- K M Norenberg
- Dept. of Biological Sciences, Marquette University, P. O. Box 1881, Milwaukee, WI 53201-1881, USA
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Sakakima H, Yoshida Y, Sakae K, Morimoto N. Different frequency treadmill running in immobilization-induced muscle atrophy and ankle joint contracture of rats. Scand J Med Sci Sports 2004; 14:186-92. [PMID: 15144359 DOI: 10.1111/j.1600-0838.2004.382.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated the effects of different frequencies of treadmill running on immobilization-induced soleus and gastrocnemius muscle atrophy and ankle joint contracture in rats using morphology and histochemistry. The right ankle joint of rat was immobilized for 2 weeks. Thereafter, the rats were randomly assigned to four groups for 6 weeks of exercise under different conditions: free cage activity and free remobilization (FR), once-a-week treadmill running (low-frequency running program (LFR)), three-time-a-week running (middle-frequency running program (MFR)), and six-time-a-week running (high-frequency running program (HFR)) groups. Two weeks of immobilization significantly reduced the cross-sectional area of soleus type I (62%, P<0.05) and type II muscle fibers (66%, P<0.05), gastrocnemius type I (78%, P<0.05) and type II muscle fibers (68%, P<0.05), and the range of ankle joint movement (46%, P<0.05). Immobilization also increased the ratio of type II to total fiber numbers in the soleus (P<0.05), and gastrocnemius (P<0.05), and induced pathological changes in muscle fibers. Some of these changes could not be corrected by free remobilization; however, the LFR, MFR, and HFR groups clearly recovered toward normal levels with exercise frequency, the effect on muscle recovery being more beneficial in the MFR and HFR groups. In addition, the range of ankle joint contracture was improved in LFR, MFR, and HFR groups in comparison with that in the FR group. These findings indicate that treadmill running exercise improved the immobilization-induced muscle fiber histochemical alterations and the range of the ankle motion in rats. Running three times and six times a week was more beneficial for recovery of immobilization-induced muscle atrophy and joint contracture compared with no running or once-a-week running.
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Affiliation(s)
- Harutoshi Sakakima
- School of Health Sciences, Faculty of Medicine, Kagoshima University, 8-35-1, Sakuragaoka, Kagoshima 890-8520, Japan.
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Hornberger TA, Farrar RP. Physiological Hypertrophy of the FHL Muscle Following 8 Weeks of Progressive Resistance Exercise in the Rat. ACTA ACUST UNITED AC 2004; 29:16-31. [PMID: 15001801 DOI: 10.1139/h04-002] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In humans, progressive resistance exercise is recognized for its ability to induce skeletal muscle hypertrophy. In an attempt to develop an animal model which mimics human progressive resistance exercise, Sprague-Dawley rats were trained to climb a 1.1-m vertical (80° incline) ladder with weights secured to their tail. The rats were trained once every 3 days for 8 weeks. Each training session consisted of 4-9 (6.02 ± 0.23) climbs requiring 8-12 dynamic movements per climb. Based on performance, the weight carried during each session was progressively increased. Over the course of 8 weeks, the maximal amount of weight the rats could carry increased 287%, p ≤ 0.001. The improved training performance was associated with a 23% absolute increase in the weight of the flexor hallucis longus (FHL), with a concomitant 24% increase in both total and myofibrillar protein, p ≤ 0.001. Peak tetanic tension (Po) of the FHL increased 20%, p ≤ 0.001, while specific tetanic tension (SPo) was not altered. No change in twitch tension (Pt) was observed, which resulted in a 22% decrease in specific twitch tension (SPt) p ≤ 0.01. Despite a decrease in resistance to fatigue, p ≤ 0.05, myosin heavy chain composition, ATP, ADP, creatine, and creatine phosphate concentrations of the FHL were not altered. The results of this study describe an animal model that mimics many of the training parameters and physiological adaptations observed with human progressive resistance exercise. Key words: contractile properties, high-energy phosphates, myosin heavy chain, fatigue resistance
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Willems MET, Stauber WT. Fatigue and recovery at long and short muscle lengths after eccentric training. Med Sci Sports Exerc 2002; 34:1738-43. [PMID: 12439077 DOI: 10.1097/00005768-200211000-00008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To determine the effects of high-speed eccentric training of rat plantar flexor muscles on: 1) maximum (120 Hz) force at 90 degrees ankle position; 2) fatigue (40 concentric muscle actions, ROM 50 degrees) and recovery (6 concentric muscle actions) tested at short or long muscle lengths; and 3) low-frequency fatigue. METHODS Training consisted of eccentric muscle actions from ankle positions of 140 degrees to 40 degrees (velocity approximately 400 degrees x s(-1)) followed by unresisted concentric muscle actions (5 x 10 repetitions, 5 d x wk(-1) for 6 wk). Fatigue was induced by concentric muscle actions with a rest of 12.5 s between muscle actions, and recovery consisted of equivalent concentric muscle actions performed every 5 min for 30 min. Low-frequency fatigue was measured 35 min after testing at 90 degrees ankle position by using the ratio of isometric force produced by 20- and 100-Hz stimulation frequencies. RESULTS Eccentric training increased maximal isometric force per muscle weight by 22% whereas muscle weights were unchanged. In control muscles (C), isometric force immediately preceding each concentric muscle action decreased more at long lengths than at short lengths during the fatigue protocol; this length-dependent difference disappeared after 30 min of recovery. At short lengths, isometric force decreased less in trained muscles (T) (C: 78.4 +/- 3.6%; T: 59.6 +/- 4.4%) and recovered more during the following 30-min period (C: 84.7 +/- 2.5%; T: 95.4 +/- 2.8% of initial values). Changes in F20/F100 were smaller for trained muscles (C: 35.4 +/- 2.0%; T: 22.0 +/- 1.4%). CONCLUSIONS High-speed eccentric training (5 d x wk(-1) for 6 wk) reduced fatigability and enhanced recovery mainly at long muscle lengths. It also reduced low-frequency fatigue, which may be attributed to alterations in intracellular calcium handling.
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Affiliation(s)
- Mark E T Willems
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, 26506-9229, USA.
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Diaz-Herrera P, García-Castellano JM, Torres A, Morcuende JA, Calbet JA, Sarrat R. Effect of high-intensity running in rectus femoris muscle fiber in rats. J Orthop Res 2001; 19:229-32. [PMID: 11347695 DOI: 10.1016/s0736-0266(00)00031-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effect of a 12-week high-intensity intermittent exercise program on fiber type composition and the oxidative capacity of rectus femoris skeletal muscle from 20 male Wistar rats (Trained, n = 10; Sedentary, n = 10) was histochemically determined. The training exercise program was developed in a motorized treadmill. It consisted of four running bouts of 2 min duration at 48 m/min, alternated with recovery intervals of 4 min. Training increased relative cross-sectional area of oxidative fibers (I, IIA, IIX) and decreased the same parameter in type IIB non-oxidative fibers (P < 0.001). Our results suggest that this type of strength exercise program is enough to induce changes in muscle fiber composition. This opens a possibility to use this kind of exercise in preventing and treating muscle atrophy.
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Affiliation(s)
- P Diaz-Herrera
- Departamento de Morfología, Facultad de Medicina, Universidad de Las Palmas de Gran Canaria, Spain.
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Willems ME, Stauber WT. Effect of resistance training on muscle fatigue and recovery in intact rats. Med Sci Sports Exerc 2000; 32:1887-93. [PMID: 11079518 DOI: 10.1097/00005768-200011000-00011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To examine the effect of resistance training on muscle fatigue from intermittent contractions and subsequent recovery in intact rats. METHODS By using electrical stimulation, plantar flexor muscles were trained with eccentric and concentric contractions (5 x 10 repetitions, 5 d x wk(-1) for 6 wk) during ankle rotations. By using nerve stimulation, concentric contractions (40) imposed on isometric contractions (stimulation time, 1.9 s; rest period, 13.6 s; intermittent contractions) induced fatigue. During recovery, equivalent contractions were used every 5 min for 30 min. RESULTS Training increased isometric forces (19% and 23% at ankle positions of 1.57 and 0.70 rad), but muscle weights were not changed. After training, smaller declines in isometric (control, 68.9+/-1.4%; trained, 58.8+/-2.9%) and average concentric force (control, 71.6+/-0.7%; trained, 65.5+/-2.8%) occurred from fatigue. Recovery for 5 min returned isometric and average concentric force to 61.7+/-2.2% and 65.1+/-2.5% of initial values for controls and 76.9+/-2.2% and 77.1+/-2.2% after training. After recovery for 30 min, these forces were 87.6+/-0.7% and 89.2+/-1.1% of initial values for controls and recovered almost completely (94.2+/-1.3% and 94.6+/-1.6%) in trained muscles. During fatigue, the decline in force during successive concentric contractions was larger after training (from 19.7+/-1.1% to 50.1+/-2.0%; controls, from 19.9+/-2.0% to 41.7+/-1.4%). Recovery of this decline in force was training-independent and complete within 5 min. CONCLUSIONS Rat plantar flexor muscles adapt to 6 wk of 5 d x wk(-1) resistance training with: 1) increased isometric force, 2) smaller losses in isometric and average concentric force during fatigue, 3) larger force decline during concentric contractions during fatigue, and 4) improved recovery following fatigue. Different mechanisms might account for the recovery of the average concentric force and the decline in force during concentric contractions.
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Affiliation(s)
- M E Willems
- Department of Physiology, West Virginia University, Morgantown 26506-9229, USA
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Young M, Paul A, Rodda J, Duxson M, Sheard P. Examination of intrafascicular muscle fiber terminations: implications for tension delivery in series-fibered muscles. J Morphol 2000; 245:130-45. [PMID: 10906747 DOI: 10.1002/1097-4687(200008)245:2<130::aid-jmor4>3.0.co;2-r] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mammalian skeletal muscles with long fascicle lengths are predominantly composed of short muscle fibers that terminate midbelly with no direct connection to the muscle origin or insertion. The manner in which these short fibers terminate and transmit tension through the muscle to their tendons is poorly understood. We made an extensive morphological study of a series-fibered muscle, the guinea pig sternomastoid, in order to define the full range of structural specializations for tension transmission from short fibers within this muscle. Terminations were examined in single fibers, teased small bundles of fibers, and in sections at both the light and electron microscopic level. In many cases, sites of fiber termination were defined by reactivity for the enzyme acetylcholinesterase, which also marks myotendinous junctions. Additionally, transport of the lipophilic fluorescent dye, DiI, or injection of Lucifer Yellow were used to visualize undisturbed fiber terminations in whole muscles using confocal and fluorescence microscopy. At the light microscopic level, we find that intrafascicularly terminating fibers end about equally often in either a long progressive taper, or in a series of small or larger blunt steps. Combinations of these two morphologies are also seen. However, when analyzed at higher resolution with confocal or electron microscopy, the apparently smooth progressive tapers appear also to be predominantly composed of a series of fine stepped terminations. Stepwise terminations in most cases join face-to-face with complementary endings of neighboring muscle fibers, some via an extended collagenous bridge and others at close interdigitating myomyonal junctions. These muscle-to-muscle junctions show many of the features of myotendinous junctions, including dense subsarcolemmal plaques in regions of myofibrillar termination and we suggest that they serve to pass tension from fiber to fiber along the longitudinal axis of the muscle. In addition, we observe regions of apparent side-to-side adhesion between neighboring fibers at sites where there is no apparent fiber tapering or structural specialization typical of myofibril termination. These sites show acetylcholinesterase reactivity, and large numbers of collagen fibers passing laterally from fiber to fiber. These latter connections seem most likely to be involved in lateral transmission of tension, either from fiber to fiber, or from fiber to endomysium. Overall, our results suggest that tension from intrafascicularly terminating fibers is likely to be passed along the muscle to the tendon using both in-series and in-parallel arrangements. The results are discussed in light of current theories of tension delivery within the series-fibered muscles typical of large, nonprimate mammals.
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Affiliation(s)
- M Young
- Department of Anatomy and Structural Biology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Ishihara A, Roy RR, Ohira Y, Ibata Y, Edgerton VR. Hypertrophy of rat plantaris muscle fibers after voluntary running with increasing loads. J Appl Physiol (1985) 1998; 84:2183-9. [PMID: 9609816 DOI: 10.1152/jappl.1998.84.6.2183] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
There have been no systematic comparisons of skeletal muscle adaptations in response to voluntary wheel running under controlled loading conditions. To accomplish this, a voluntary running wheel for rats and mice was developed in which a known load can be controlled and monitored electronically. Five-week-old male Sprague-Dawley rats (10 rats/group) were assigned randomly to either a 1) sedentary control group (Control); 2) voluntary exercised with no load (Run-No-Load) group; or 3) voluntary exercised with additional load (Run-Load) group for 8 wk. The load for the Run-Load group was progressively increased to reach approximately 60% of body weight during the last week of training. The proportions of fast glycolytic (FG), fast oxidative glycolytic (FOG), or slow oxidative (SO) fibers in the plantaris were similar in all groups. The absolute and relative plantaris weights were greater in the Run-Load group compared with the Control and Run-No-Load groups. The mean fiber cross-sectional areas of FG, FOG, and SO fibers were 20, 25, and 15% greater in the Run-Load than in Control rats. In addition, these fiber types were 16, 21, and 12% larger in Run-Load than in Run-No-Load rats. The muscle weights and mean cross-sectional areas of each fiber type were highly correlated with the average running distances and total work performed in the Run-Load, but not the Run-No-Load, group. The slope of the relationship between fiber size and running distance and total work performed was significant for each fiber type but was higher for FG and FOG fibers compared with SO fibers. These data show that the load on a rat running voluntarily can determine the magnitude of a hypertrophic response and the population of motor units that are recruited to perform at a given loading condition.
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Affiliation(s)
- A Ishihara
- Laboratory of Neurochemistry, Faculty of Integrated Human Studies, Kyoto University, Kyoto 606-01, Japan
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