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Muscle Biology and Healing

49 citationsUpdated Oct 2026
Illustration: Muscle Biology and Healing

Overview

Skeletal muscle possesses a distinct regenerative capacity driven by the coordinated regulation of stem cell populations, particularly satellite cells [12]. Understanding the basic principles of this regeneration and healing process is essential for avoiding complications and accelerating the return to competition [1]. Emerging research delineates the mechanisms underlying normal versus aberrant tissue repair, highlighting that type 2 innate immunity is required for regeneration after injury [16, 7]. While genetic determinants of muscle formation and repair are diverse [30], the prevention of fibrosis remains a critical strategy to enhance regeneration and facilitate efficient healing [2].

Clinical management of muscle tissue loss and injury involves a spectrum of therapeutic modalities, including physical exercises, electrical stimulation, medications, regenerative medicine, and surgical procedures [8]. Current strategies for muscle regeneration face challenges regarding future clinical translation [3], though adipose-derived mesenchymal stem cells have demonstrated efficacy in preclinical and clinical studies for muscle, tendon, bone, and cartilage regeneration [6]. However, the long-term safety and side effects of these cells remain unresolved concerns [6]. Most data on minimizing muscle damage in proximal nerve injuries derives from experimental animal studies, with limited clinical data available [8].

Diagnostic and classification frameworks support clinical decision-making. Ultrasonography offers a fast, relatively inexpensive, and patient-friendly method for dynamic muscle assessment, allowing for the detection, severity assessment, and serial evaluation of healing [13]. A consistent English terminology and comprehensive classification system for athletic muscle injuries are established in the Munich consensus statement [14]. Anatomical context is defined by compartments, which are enclosed spaces formed by fascia or a combination of fascia and bone containing one or more muscles [50]. Muscles may operate within a preferred sarcomere length range [49], and fatty infiltration should be used with caution as an indicator of chronicity or a contraindicating parameter for repair [27].

How It Works

Current clinical strategies and novel methods for muscle regeneration face significant challenges regarding future clinical translation [3]. While therapeutic modalities for skeletal muscle strain injuries present opportunities to further improve treatment [9], the most productive research in wound healing biology focuses on the identification and study of middle-sized proteins, specifically chemoattractants and growth factors [11]. Skeletal muscle stem cell populations possess a regenerative capacity highlighted by studies on their origin, gene expression, and coordinated regulation [12].

Cellular and Molecular Regulation: IL-10 plays a central role in regulating the switch of muscle macrophages from a M1 to M2 phenotype in injured muscle in vivo [17]. This transition is necessary for normal growth and regeneration of muscle [17]. Matrix metalloproteinases (MMPs) are involved in muscle repair [21], with fast and slow twitch muscles exhibiting different patterns of MMP-9 and MMP-2 activity during regeneration [21]. FGF signaling can play a role in the regulation of postnatal skeletal muscle maintenance [33] and could offer potentially novel and efficient therapeutic options for attenuating muscle atrophy during aging, illness, and spaceflight [33]. The myriad roles of microRNAs in muscle biology pose interesting prospects for their therapeutic manipulation in muscle disease [32].

Therapeutic Interventions: Preclinical and clinical studies have demonstrated the efficacy of adipose-derived mesenchymal stem cells in muscle, tendon, bone, and cartilage regeneration [6]; however, several worries about the safety and side effects of these cells at long-term remain unsolved [6]. Customized platelet-rich plasma is a promising method to improve PRP's beneficial effect on skeletal muscle repair [15]. The simultaneous use of platelet-rich plasma and suramin reduced fibrosis in the injured muscle [22] and promoted healing without negatively affecting the muscle's contractile properties [22]. Decorin can efficiently prevent fibrosis and enhance muscle regeneration in the lacerated muscle [24]. Additionally, the inherent pro-regenerative potential of tissue-specific endothelium could be used therapeutically to orchestrate fibrosis-free healing and to restore homeostasis in tissues [31].

Pathophysiology and Predictive Markers: Sarcopenia reflects a progressive withdrawal of anabolism and an increased catabolism [18] and is associated with a reduced muscle regeneration capacity [18]. Understanding sex-dependent responses to different forms of muscle atrophy and inflammation is of pivotal importance to design innovative, tailored, and efficient interventions [23]. Epigenetic mechanism observations have the potential to become useful tools in sports medicine as predictors of approaching pathophysiological alterations and injury biomarkers [20].

What the Evidence Shows

Muscle Biology and Regeneration Mechanisms

Satellite cell function in muscle fiber repair and remodeling is integrated from in vivo human studies within the wider context of satellite cell biology, which is largely based on animal and cell models [4]. IL-10 plays a central role in regulating the switch of muscle macrophages from a M1 to M2 phenotype in injured muscle in vivo, and this transition is necessary for normal growth and regeneration of muscle [17]. Sarcopenia reflects a progressive withdrawal of anabolism and an increased catabolism, along with a reduced muscle regeneration capacity [18]. The most productive research in wound healing biology now seems to be identification and study of middle-sized proteins called chemoattractants and growth factors [11]. MMPs are involved in muscle repair, and fast and slow twitch muscles exhibit different patterns of MMP-9 and MMP-2 activity [21]. Altered expression and secretion of soluble mediators, such as IL-6 and IGF-1, can modulate regulatory networks involved in the altered regeneration and fibrosis during aging and diseases [51].

Fibrosis and Aberrant Repair

Simultaneous PRP and suramin use reduced fibrosis in the injured muscle and promoted healing without negatively affecting the muscle's contractile properties [22]. Fatty infiltration is irreversible and progressive if left untreated, though slight reversal of muscle atrophy has been noted after repair in some studies [37].

Therapeutic Modalities and Interventions

Immobilization resulted in slower muscle regeneration and the development of a large area of scar tissue [5]. Treatment with pulsed ultrasound can promote the satellite cell proliferation phase of myoregeneration, but it does not seem to have significant effects on the overall morphological manifestations of muscle regeneration [36]. Exposure to 1 hour of HBO treatment initiated within 20 minutes after exercise for 3 to 5 days enhances muscle torque recovery [45]. The treatment did not affect the level or duration of pain or the loss of strength or function following exercise [43]. Single intramuscular administration of MPCs improved histological outcome and force recovery of the injured skeletal muscle in a rat injury model [35]. Stem cell therapies and tissue engineering offer promising avenues for enhancing skeletal muscle repair, with muscle-derived stem cells (MDSCs) showing potential for long-term regeneration and multipotency [26]. While preclinical and clinical studies have demonstrated efficacy in muscle, tendon, bone, and cartilage regeneration, several worries about their safety and side effects at long-term remain unsolved [6]. Early surgical intervention with fasciotomy played a substantial role in allowing optimal muscle regeneration, leading to complete functional recovery [34]. Strategies to minimize muscle damage in proximal nerve injuries include physical exercises, electrical stimulation, medications, regenerative medicine, and surgical procedures, noting that most data comes from experimental animal studies while clinical data remains limited [8].

Clinical Outcomes and Imaging

Ultrasonography offers dynamic muscle assessment and is fast, relatively inexpensive, and easier for patients, allowing for detection and severity assessment as well as serial evaluation to follow healing [13]. A consistent English terminology as well as a comprehensive classification system for athletic muscle injuries which is proven in the daily practice are presented [14]. Objective strength testing shows that surgical repair of a clinical tear of the pectoralis major results in greater recovery of peak torque and work performed than conservative management [28]. Outcomes after repair of partial- and full-thickness rotator cuff tears using a bioinductive implant show safety and efficacy at 1-year follow-up [25]. Nonoperative treatment remains a viable option for certain patients with traumatic rotator cuff tears; however, the results of our study demonstrate a considerable early failure rate [42]. Randomised trials are needed to assess and compare conservative with surgical interventions and to evaluate different surgical procedures [44]. Epigenetic mechanism observations have the potential to become useful tools in sports medicine, as predictors of approaching pathophysiological alterations and injury biomarkers that have already taken place [20].

Practical Considerations

General Principles and Pathophysiology

Aberrant repair and fibrosis development in skeletal muscle are driven by mechanisms that differ from those underlying normal muscle-tissue repair [7]. Sarcopenia, defined as a loss of muscle mass and function in the elderly, reduces mobility and diminishes quality of life, potentially leading to fall-related injuries that require costly hospitalization and extended rehabilitation [47]. In the context of rotator cuff pathology, fatty infiltration in the intact supraspinatus tendon is a normal physiological response associated with increasing age and female gender [27].

Cellular Mechanisms and Regenerative Medicine

Satellite cell function in muscle fiber repair and remodeling is integrated from in vivo human studies within the wider context of satellite cell biology, a field whose literature is largely based on animal and cell models [4]. Satellite cells and other cell types address the therapeutic potential for muscle regeneration [10]. Muscle-derived stem cells are well suited for gene therapy and tissue engineering applications for the musculoskeletal system, with the potential to revolutionize the management of certain musculoskeletal diseases [48].

Treatment Modalities

Proximal Hamstring Tears: The presented technique for repair of proximal hamstring tears provides a strong repair that can tolerate rehabilitation and give good long-term results [29].

Proximal Nerve Injuries: Various strategies including physical exercises, electrical stimulation, medications, regenerative medicine, and surgical procedures are used to minimize muscle damage in proximal nerve injuries [8]. Most data on muscle preservation strategies for these injuries comes from experimental animal studies, while clinical data remains limited [8].

Muscle Soreness and Damage Reduction: Commonly used therapeutic modalities affect muscle regeneration and identify opportunities to further improve the treatment of skeletal muscle strain injuries [9]. In clinical practice, the use of CWI and CRYO is recommended for reducing exercise-induced muscle damage [39]. NSAIDs decrease perceived soreness but do not impact muscle weakness [41]. Clinicians should base advisory guidance and management on sound medical principles regarding muscle soreness and delayed-onset muscle soreness [41].

Blood Flow Restriction: Blood flow restriction exercise aims to clarify how to apply BFR effectively for enhancing strength and hypertrophy while understanding associated safety issues [38].

Key Evidence

  • [L5] Recognition of basic principles of skeletal muscle regeneration and healing processes can help avoid dangers and accelerate return to competition. [1] (10.1177/0363546505274714)
  • [Paper] These results support our hypothesis that prevention of fibrosis could enhance muscle regeneration, thereby facilitating more efficient muscle healing. [2] (10.1152/japplphysiol.00915.2002)
  • [L5] This review provides a comprehensive overview of the epidemiology of muscle tissue loss, highlights current strategies in clinical treatment, and discusses novel methods for muscle regeneration and challenges for their future clinical translation. [3] (10.1155/2018/1984879)
  • [L5] This review integrates recent results from in vivo human studies on satellite cell function in muscle fiber repair and remodeling within the wider context of satellite cell biology, whose literature is largely based on animal and cell models. [4] (10.3389/fphys.2015.00283)
  • [L5] Immobilization resulted in slower muscle regeneration and the development of a large area of scar tissue. [5] (10.1177/03635465990270021801)
  • [L4] While preclinical and clinical studies have demonstrated efficacy in muscle, tendon, bone, and cartilage regeneration, several worries about their safety and side effects at long-term remain unsolved. [6] (10.3390/ijms20123105)
  • [L5] This article reviews the emerging findings of the mechanisms that underlie normal versus aberrant muscle-tissue repair. [7] (10.1186/2044-5040-1-21)
  • [L5] It outlines various strategies including physical exercises, electrical stimulation, medications, regenerative medicine, and surgical procedures to minimize muscle damage, noting that most data comes from experimental animal studies while clinical data remains limited. [8] (10.1177/17531934231216646)
  • [L5] It summarizes how commonly used therapeutic modalities affect muscle regeneration and identifies opportunities to further improve the treatment of skeletal muscle strain injuries. [9] (10.1123/jsr.2016-0107)
  • [Paper] The most productive research in wound healing biology now seems to be identification and study of middle-sized proteins called chemoattractants and growth factors. [11] (10.1016/s0894-1130(89)80035-3)
  • [Paper] The present review examines studies focusing on the origin, gene expression, and coordinated regulation of stem cell populations to highlight the regenerative capacity of skeletal muscle and emphasize the challenges for this field. [12] (10.1101/gad.1419406)
  • [L5] Ultrasonography offers dynamic muscle assessment and is fast, relatively inexpensive, and easier for patients, allowing for detection and severity assessment as well as serial evaluation to follow healing. [13] (10.1148/radiol.2017160267)
  • [L5] A consistent English terminology as well as a comprehensive classification system for athletic muscle injuries which is proven in the daily practice are presented. [14] (10.1136/bjsports-2012-091448)
  • [L5] This approach is a promising method to improve PRP's beneficial effect on skeletal muscle repair. [15] (10.1177/2325967116s00143)
  • [L5] Type 2 innate immunity is required for regeneration of skeletal muscle after injury. [16] (10.1016/j.cell.2013.02.053)
  • [L5] Collectively, these data show that IL-10 plays a central role in regulating the switch of muscle macrophages from a M1 to M2 phenotype in injured muscle in vivo, and this transition is necessary for normal growth and regeneration of muscle. [17] (10.4049/jimmunol.1103180)
  • [L4] Sarcopenia reflects a progressive withdrawal of anabolism and an increased catabolism, along with a reduced muscle regeneration capacity. [18] (10.1093/bmb/ldq008)
  • [Paper] The main topic will be muscle, nerve and muscle-nerve transplants: basic science, experimental research, and clinical application. [19] (10.1016/0363-5023(90)90134-d)
  • [L4] Epigenetic mechanism observations have the potential to become useful tools in sports medicine, as predictors of approaching pathophysiological alterations and injury biomarkers that have already taken place. [20] (10.3390/genes13081471)
  • [L5] MMPs are involved in muscle repair, and that fast and slow twitch muscles exhibit different patterns of MMP-9 and MMP-2 activity. [21] (10.1387/ijdb.072331mz)
  • [L5] Simultaneous PRP and suramin use reduced fibrosis in the injured muscle and promoted healing without negatively affecting the muscle's contractile properties. [22] (10.1177/03635465211030295)
  • [L5] Understanding sex-dependent responses to different forms of muscle atrophy and inflammation is of pivotal importance to design innovative, tailored, and efficient interventions. [23] (10.3390/ijms24054651)
  • [L5] These results suggest that decorin can efficiently prevent fibrosis and enhance muscle regeneration in the lacerated muscle. [24] (10.1177/03635465010290040201)
  • [L4] Outcomes after repair of partial- and full-thickness rotator cuff tears using a bioinductive implant show safety and efficacy at 1-year follow-up. [25] (10.1016/j.arthro.2019.02.019)
  • [L5] Stem cell therapies and tissue engineering offer promising avenues for enhancing skeletal muscle repair, with muscle-derived stem cells (MDSCs) showing potential for long-term regeneration and multipotency. [26] (10.1016/j.csm.2008.08.009)
  • [L4] Therefore, fatty infiltration should be used with caution as an indicator of chronicity or a contraindicating parameter for repair. [27] (10.1177/17585732211024504)
  • [L3] Objective strength testing shows that surgical repair of a clinical tear of the pectoralis major results in greater recovery of peak torque and work performed than conservative management. [28] (10.1136/bjsm.35.3.202)
  • [Paper] The presented technique provides a strong repair that can tolerate rehabilitation and give good long-term results. [29] (10.1016/j.eats.2016.10.004)
  • [L5] Genetic determinants of formation or repair of various muscles during different stages of myogenesis are unexpectedly diverse. [30] (10.1097/mco.0b013e328336ea98)
  • [L5] This transformative model has opened a fresh chapter in translational vascular medicine and raised the possibility that the inherent pro-regenerative potential of tissue-specific endothelium could be used therapeutically to orchestrate fibrosis-free healing and to restore homeostasis in tissues. [31] (10.1038/nature17040)
  • [Paper] The myriad roles of microRNAs in muscle biology pose interesting prospects for their therapeutic manipulation in muscle disease. [32] (10.1016/j.tig.2008.01.007)
  • [Paper] These results support the theory that FGF signaling can play a role in regulation of postnatal skeletal muscle maintenance, and could offer potentially novel and efficient therapeutic options for attenuating muscle atrophy during aging, illness and spaceflight. [33] (10.1186/1471-2474-8-32)
  • [L5] Early surgical intervention with fasciotomy played a substantial role in allowing optimal muscle regeneration, leading to complete functional recovery. [34] (10.2106/00004623-200211000-00021)
  • [Paper] Single intramuscular administration of MPCs improved histological outcome and force recovery of the injured skeletal muscle in a rat injury model. [35] (10.1177/0363546521989235)
  • [L5] Treatment with pulsed ultrasound can promote the satellite cell proliferation phase of myoregeneration, but it does not seem to have significant effects on the overall morphological manifestations of muscle regeneration. [36] (10.1177/03635465990270011701)
  • [L5] Fatty infiltration is irreversible and progressive if left untreated, though slight reversal of muscle atrophy has been noted after repair in some studies. [37] (10.5435/jaaos-21-10-613)
  • [L2] It aims to clarify how to apply BFR effectively for enhancing strength and hypertrophy while understanding associated safety issues. [38] (10.3389/fphys.2019.00533)
  • [L1] In clinical practice, the authors recommend the use of CWI and CRYO for reducing exercise-induced muscle damage. [39] (10.1186/s12891-024-07315-2)
  • [L5] Clinicians should base advisory guidance and management on sound medical principles, noting that while NSAIDs decrease perceived soreness, they do not impact muscle weakness. [41] (10.1016/j.csm.2011.09.009)
  • [L4] Nonoperative treatment remains a viable option for certain patients with traumatic rotator cuff tears; however, the results of our study demonstrate a considerable early failure rate. [42] (10.1016/j.jse.2023.11.012)
  • [L1] The treatment did not affect the level or duration of pain or the loss of strength or function following exercise. [43] (10.1177/0363546503262196)
  • [L5] Randomised trials are needed to assess and compare conservative with surgical interventions and to evaluate different surgical procedures. [44] (10.1007/s00167-009-0735-y)
  • [L1] Exposure to 1 hour of HBO treatment initiated within 20 minutes after exercise for 3 to 5 days enhances muscle torque recovery. [45] (10.1177/03635465990270050901)
  • [L5] Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. [47] (10.1152/physrev.00061.2017)
  • [L5] Muscle-derived stem cells are well suited for gene therapy and tissue engineering applications for the musculoskeletal system, with the potential to revolutionize the management of certain musculoskeletal diseases. [48] (10.5435/00124635-200802000-00004)
  • [L5] The paper introduces the concept that muscles may have a preferred sarcomere length operating range. [49] (10.1098/rstb.2010.0316)
  • [Paper] A compartment is defined as an enclosed space formed by fascia or by a combination of fascia and bone that contains one or more muscles. [50] (10.1016/s0749-0712(21)00394-2)
  • [L5] This review discusses the cellular mediators of fibrosis and how the altered expression and secretion of soluble mediators, such as IL-6 and IGF-1, can modulate regulatory networks involved in the altered regeneration and fibrosis during aging and diseases. [51] (10.3390/cells8030232)

References

[1] Muscle Injuries. The American Journal of Sports Medicine. 2005. DOI: 10.1177/0363546505274714

[2] Antifibrotic effects of suramin in injured skeletal muscle after laceration. Journal of Applied Physiology. 2003. DOI: 10.1152/japplphysiol.00915.2002

[3] Current Methods for Skeletal Muscle Tissue Repair and Regeneration. BioMed Research International. 2018. DOI: 10.1155/2018/1984879

[4] Satellite cells in human skeletal muscle plasticity. Frontiers in Physiology. 2015. DOI: 10.3389/fphys.2015.00283

[5] Suturing Versus Immobilization of a Muscle Laceration. The American Journal of Sports Medicine. 1999. DOI: 10.1177/03635465990270021801

[6] Adipose-Derived Mesenchymal Stem Cells: A Promising Tool in the Treatment of Musculoskeletal Diseases. International Journal of Molecular Sciences. 2019. DOI: 10.3390/ijms20123105

[7] Aberrant repair and fibrosis development in skeletal muscle. Skeletal Muscle. 2011. DOI: 10.1186/2044-5040-1-21

[8] Muscle preservation in proximal nerve injuries: a current update. Journal of Hand Surgery (European Volume). 2024. DOI: 10.1177/17531934231216646

[9] Regeneration of Skeletal Muscle After Eccentric Injury. Journal of Sport Rehabilitation. 2017. DOI: 10.1123/jsr.2016-0107

[10] 10_1186_2044_5040_3_2. 2044.

[11] Frontiers in wound healing research that may affect the work of hand therapists. Journal of Hand Therapy. 1989. DOI: 10.1016/s0894-1130(89)80035-3

[12] Muscle stem cells in development, regeneration, and disease. Genes & Development. 2006. DOI: 10.1101/gad.1419406

[13] Imaging of Muscle Injuries in Sports Medicine: Sports Imaging Series. Radiology. 2017. DOI: 10.1148/radiol.2017160267

[14] Terminology and classification of muscle injuries in sport: The Munich consensus statement. British Journal of Sports Medicine. 2012. DOI: 10.1136/bjsports-2012-091448

[15] Customized Platelet-Rich Plasma for Skeletal Muscle Injuries. Orthopaedic Journal of Sports Medicine. 2016. DOI: 10.1177/2325967116s00143

[16] Type 2 Innate Signals Stimulate Fibro/Adipogenic Progenitors to Facilitate Muscle Regeneration. Cell. 2013. DOI: 10.1016/j.cell.2013.02.053

[17] IL-10 Triggers Changes in Macrophage Phenotype That Promote Muscle Growth and Regeneration. The Journal of Immunology. 2012. DOI: 10.4049/jimmunol.1103180

[18] Sarcopenia: characteristics, mechanisms and functional significance. British Medical Bulletin. 2010. DOI: 10.1093/bmb/ldq008

[19] Third Vienna Muscle Symposium. The Journal of Hand Surgery. 1990. DOI: 10.1016/0363-5023(90)90134-d

[20] Epigenetic Alterations in Sports-Related Injuries. Genes. 2022. DOI: 10.3390/genes13081471

[21] Distinct patterns of MMP-9 and MMP-2 activity in slow and fast twitch skeletal muscle regeneration in vivo. The International Journal of Developmental Biology. 2008. DOI: 10.1387/ijdb.072331mz

[22] Use of Platelet-Rich Plasma Plus Suramin, an Antifibrotic Agent, to Improve Muscle Healing After Injuries. The American Journal of Sports Medicine. 2021. DOI: 10.1177/03635465211030295

[23] Sex Differences in Inflammation and Muscle Wasting in Aging and Disease. International Journal of Molecular Sciences. 2023. DOI: 10.3390/ijms24054651

[24] The Use of an Antifibrosis Agent to Improve Muscle Recovery after Laceration. The American Journal of Sports Medicine. 2001. DOI: 10.1177/03635465010290040201

[25] Patient‐Reported Outcomes After Use of a Bioabsorbable Collagen Implant to Treat Partial and Full‐Thickness Rotator Cuff Tears. Arthroscopy. 2019. DOI: 10.1016/j.arthro.2019.02.019

[26] Stem Cells for the Treatment of Skeletal Muscle Injury. Clinics in Sports Medicine. 2009. DOI: 10.1016/j.csm.2008.08.009

[27] Fatty infiltration in the intact supraspinatus tendon; a normal physiological response with increasing age and female gender. Shoulder & Elbow. 2021. DOI: 10.1177/17585732211024504

[28] Pectoralis major tears: comparison of surgical and conservative treatment. British Journal of Sports Medicine. 2001. DOI: 10.1136/bjsm.35.3.202

[29] Repair of Proximal Hamstring Tears: A Surgical Technique. Arthroscopy Techniques. 2017. DOI: 10.1016/j.eats.2016.10.004

[30] Muscle stem cells in developmental and regenerative myogenesis. Current Opinion in Clinical Nutrition and Metabolic Care. 2010. DOI: 10.1097/mco.0b013e328336ea98

[31] Angiocrine functions of organ-specific endothelial cells. Nature. 2016. DOI: 10.1038/nature17040

[32] MicroRNAs flex their muscles. Trends in Genetics. 2008. DOI: 10.1016/j.tig.2008.01.007

[33] FGFR1 inhibits skeletal muscle atrophy associated with hindlimb suspension. BMC Musculoskeletal Disorders. 2007. DOI: 10.1186/1471-2474-8-32

[34] COMPARTMENT SYNDROME IN A PATIENT WITH FAMILIAL RHABDOMYOLYSIS. The Journal of Bone and Joint Surgery-American Volume. 2002. DOI: 10.2106/00004623-200211000-00021

[35] Muscle Precursor Cells Enhance Functional Muscle Recovery and Show Synergistic Effects With Postinjury Treadmill Exercise in a Muscle Injury Model in Rats. The American Journal of Sports Medicine. 2021. DOI: 10.1177/0363546521989235

[36] Effects of Therapeutic Ultrasound on the Regeneration of Skeletal Myofibers After Experimental Muscle Injury. The American Journal of Sports Medicine. 1999. DOI: 10.1177/03635465990270011701

[37] Fatty Infiltration and Rotator Cuff Atrophy. Journal of the American Academy of Orthopaedic Surgeons. 2013. DOI: 10.5435/jaaos-21-10-613

[38] Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety. Frontiers in Physiology. 2019. DOI: 10.3389/fphys.2019.00533

[39] The effects of hydrotherapy and cryotherapy on recovery from acute post-exercise induced muscle damage—a network meta-analysis. BMC Musculoskeletal Disorders. 2024. DOI: 10.1186/s12891-024-07315-2

[41] Muscle Soreness and Delayed-Onset Muscle Soreness. Clinics in Sports Medicine. 2012. DOI: 10.1016/j.csm.2011.09.009

[42] Outcomes of initial nonoperative treatment of traumatic full-thickness rotator cuff tears. Journal of Shoulder and Elbow Surgery. 2024. DOI: 10.1016/j.jse.2023.11.012

[43] Sports Massage after Eccentric Exercise. The American Journal of Sports Medicine. 2004. DOI: 10.1177/0363546503262196

[44] Rotator cuff injury: still a clinical controversy?. Knee Surgery, Sports Traumatology, Arthroscopy. 2009. DOI: 10.1007/s00167-009-0735-y

[45] Effects of Hyperbaric Oxygen on a Human Model of Injury. The American Journal of Sports Medicine. 1999. DOI: 10.1177/03635465990270050901

[47] Sarcopenia: Aging-Related Loss of Muscle Mass and Function. Physiological Reviews. 2019. DOI: 10.1152/physrev.00061.2017

[48] Regenerative Medicine for the Musculoskeletal System Based on Muscle-derived Stem Cells. Journal of the American Academy of Orthopaedic Surgeons. 2008. DOI: 10.5435/00124635-200802000-00004

[49] Skeletal muscle design to meet functional demands. Philosophical Transactions of the Royal Society B: Biological Sciences. 2011. DOI: 10.1098/rstb.2010.0316

[50] ANATOMY OF THE UPPER EXTREMITY MUSCLE COMPARTMENTS. Hand Clinics. 1998. DOI: 10.1016/s0749-0712(21)00394-2

[51] Signals from the Niche: Insights into the Role of IGF-1 and IL-6 in Modulating Skeletal Muscle Fibrosis. Cells. 2019. DOI: 10.3390/cells8030232

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h. Licensor means the individual(s) or entity(ies) granting rights under this Public License.

i. NonCommercial means not primarily intended for or directed towards commercial advantage or monetary compensation. For purposes of this Public License, the exchange of the Licensed Material for other material subject to Copyright and Similar Rights by digital file-sharing or similar means is NonCommercial provided there is no payment of monetary compensation in connection with the exchange.

j. Share means to provide material to the public by any means or process that requires permission under the Licensed Rights, such as reproduction, public display, public performance, distribution, dissemination, communication, or importation, and to make material available to the public including in ways that members of the public may access the material from a place and at a time individually chosen by them.

k. Sui Generis Database Rights means rights other than copyright resulting from Directive 96/9/EC of the European Parliament and of the Council of 11 March 1996 on the legal protection of databases, as amended and/or succeeded, as well as other essentially equivalent rights anywhere in the world.

l. You means the individual or entity exercising the Licensed Rights under this Public License. Your has a corresponding meaning.

Section 2 -- Scope.

a. License grant.

1. Subject to the terms and conditions of this Public License, the Licensor hereby grants You a worldwide, royalty-free, non-sublicensable, non-exclusive, irrevocable license to exercise the Licensed Rights in the Licensed Material to:

a. reproduce and Share the Licensed Material, in whole or in part, for NonCommercial purposes only; and

b. produce, reproduce, and Share Adapted Material for NonCommercial purposes only.

2. Exceptions and Limitations. For the avoidance of doubt, where Exceptions and Limitations apply to Your use, this Public License does not apply, and You do not need to comply with its terms and conditions.

3. Term. The term of this Public License is specified in Section 6(a).

4. Media and formats; technical modifications allowed. The Licensor authorizes You to exercise the Licensed Rights in all media and formats whether now known or hereafter created, and to make technical modifications necessary to do so. The Licensor waives and/or agrees not to assert any right or authority to forbid You from making technical modifications necessary to exercise the Licensed Rights, including technical modifications necessary to circumvent Effective Technological Measures. For purposes of this Public License, simply making modifications authorized by this Section 2(a) (4) never produces Adapted Material.

5. Downstream recipients.

a. Offer from the Licensor -- Licensed Material. Every recipient of the Licensed Material automatically receives an offer from the Licensor to exercise the Licensed Rights under the terms and conditions of this Public License.

b. No downstream restrictions. You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, the Licensed Material if doing so restricts exercise of the Licensed Rights by any recipient of the Licensed Material.

6. No endorsement. Nothing in this Public License constitutes or may be construed as permission to assert or imply that You are, or that Your use of the Licensed Material is, connected with, or sponsored, endorsed, or granted official status by, the Licensor or others designated to receive attribution as provided in Section 3(a)(1)(A)(i).

b. Other rights.

1. Moral rights, such as the right of integrity, are not licensed under this Public License, nor are publicity, privacy, and/or other similar personality rights; however, to the extent possible, the Licensor waives and/or agrees not to assert any such rights held by the Licensor to the limited extent necessary to allow You to exercise the Licensed Rights, but not otherwise.

2. Patent and trademark rights are not licensed under this Public License.

3. To the extent possible, the Licensor waives any right to collect royalties from You for the exercise of the Licensed Rights, whether directly or through a collecting society under any voluntary or waivable statutory or compulsory licensing scheme. In all other cases the Licensor expressly reserves any right to collect such royalties, including when the Licensed Material is used other than for NonCommercial purposes.

Section 3 -- License Conditions.

Your exercise of the Licensed Rights is expressly made subject to the following conditions.

a. Attribution.

1. If You Share the Licensed Material (including in modified form), You must:

a. retain the following if it is supplied by the Licensor with the Licensed Material:

i. identification of the creator(s) of the Licensed Material and any others designated to receive attribution, in any reasonable manner requested by the Licensor (including by pseudonym if designated);

ii. a copyright notice;

iii. a notice that refers to this Public License;

iv. a notice that refers to the disclaimer of warranties;

v. a URI or hyperlink to the Licensed Material to the extent reasonably practicable;

b. indicate if You modified the Licensed Material and retain an indication of any previous modifications; and

c. indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License.

2. You may satisfy the conditions in Section 3(a)(1) in any reasonable manner based on the medium, means, and context in which You Share the Licensed Material. For example, it may be reasonable to satisfy the conditions by providing a URI or hyperlink to a resource that includes the required information.

3. If requested by the Licensor, You must remove any of the information required by Section 3(a)(1)(A) to the extent reasonably practicable.

4. If You Share Adapted Material You produce, the Adapter's License You apply must not prevent recipients of the Adapted Material from complying with this Public License.

Section 4 -- Sui Generis Database Rights.

Where the Licensed Rights include Sui Generis Database Rights that apply to Your use of the Licensed Material:

a. for the avoidance of doubt, Section 2(a)(1) grants You the right to extract, reuse, reproduce, and Share all or a substantial portion of the contents of the database for NonCommercial purposes only;

b. if You include all or a substantial portion of the database contents in a database in which You have Sui Generis Database Rights, then the database in which You have Sui Generis Database Rights (but not its individual contents) is Adapted Material; and

c. You must comply with the conditions in Section 3(a) if You Share all or a substantial portion of the contents of the database.

For the avoidance of doubt, this Section 4 supplements and does not replace Your obligations under this Public License where the Licensed Rights include other Copyright and Similar Rights.

Section 5 -- Disclaimer of Warranties and Limitation of Liability.

a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.

b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION, NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES, COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.

c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

Creative Commons may be contacted at creativecommons.org.