View source for Muscle hypertrophy

← Muscle hypertrophy

The edit appears to have already been undone. You may have attempted to undo a page move, protection action or import action; these cannot be undone this way. Any autoconfirmed user can move the page back to its previous location, and any administrator can modify or remove protection.

You do not have permission to edit this page, for the following reason:

This IP address range has been globally blocked.
This does not affect your ability to read Wikipedia pages.

Most people who see this message have done nothing wrong. Some kinds of blocks restrict editing from specific service providers or telecom companies in response to recent abuse or vandalism, and can sometimes affect other users who are unrelated to that abuse. Review the information below for assistance if you do not believe that you have done anything wrong.

This block affects editing on all Wikimedia wikis.

The IP address or range 62.210.0.0/16 has been globally blocked by ‪Hasley‬ for the following reason(s):

Open proxy/Webhost: See the help page if you are affected:

This block will expire on 16:21, 18 December 2025. Your current IP address is 62.210.136.28.

Even while globally blocked, you will usually still be able to edit pages on Meta-Wiki.

If you believe you were blocked by mistake, you can find additional information and instructions in the No open proxies global policy. Otherwise, to discuss the block please post a request for review on Meta-Wiki. You could also send an email to the stewards VRT queue at stewards@wikimedia.org including all above details.

Other useful links: Global blocks · Help:I have been blocked

You can view and copy the source of this page:

{{short description|Enlargement or overgrowth of a muscle organ}}
{{Use mdy dates|date=February 2023}}
[[File:Hairy chest - Foto Giovanni Dall'Orto, 25 luglio 2010a.jpg|thumb|200px|Athletes use a combination of strength training, diet, and nutritional supplementation to induce muscle hypertrophy.]]

'''Muscle hypertrophy''' or '''muscle building''' involves a [[hypertrophy]] or increase in size of [[skeletal muscle]] through a growth in size of its component [[myocyte|cells]]. Two factors contribute to hypertrophy: [[sarcoplasm]]ic hypertrophy, which focuses more on increased muscle [[glycogen]] storage; and [[myofibril]]lar hypertrophy, which focuses more on increased myofibril size.<ref name="Essentials of Strength and Conditioning">{{cite book |editor1-first=Thomas R. |editor1-last=Baechle |editor2-first=Roger W. |editor2-last=Earle | name-list-style = vanc |title=Essentials of strength training and conditioning |date=2008 |publisher=Human Kinetics |location=Champaign, IL |isbn=978-0-7360-5803-2 |edition=3rd}}{{page needed|date=October 2016}}</ref> It is the primary focus of [[bodybuilding]]-related activities.

==Hypertrophy stimulation==
A range of stimuli can increase the volume of muscle cells. These changes occur as an adaptive response that serves to increase the ability to generate [[force]] or resist [[Muscle fatigue|fatigue]] in anaerobic conditions.

===Strength training===
[[File:Small group fitness sessions bundall.jpg|thumb|300px|Strength training is used to regulate muscle hypertrophy.]]
{{Main|Strength training}}
[[Strength training]] (resistance training) causes neural and muscular adaptations which increase the capacity of an athlete to exert force through voluntary muscular contraction: After an initial period of neuro-muscular adaptation, the muscle tissue expands by creating [[sarcomere]]s (contractile elements) and increasing non-contractile elements like [[Sarcoplasmic reticulum|sarcoplasmic]] fluid.<ref>{{cite book |last1=Schoenfeld |first1=Brad | name-list-style = vanc |title=Science and Development of Muscle Hypertrophy | publisher = Human Kinetics | date = 2016 |pages=1–15 | isbn = 978-1-4925-1960-7 }}</ref>

Muscular hypertrophy can be induced by [[progressive overload]] (a strategy of progressively increasing resistance or repetitions over successive bouts of exercise to maintain a high [[rating of perceived exertion|level of effort]]).<ref>{{cite journal | vauthors = Seynnes OR, de Boer M, Narici MV | title = Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training | journal = Journal of Applied Physiology | volume = 102 | issue = 1 | pages = 368–73 | date = January 2007 | pmid = 17053104 | doi = 10.1152/japplphysiol.00789.2006 | s2cid = 28981041 }}</ref>  However, the precise mechanisms are not clearly understood; the current accepted theory is through the combination of mechanical tension, metabolic stress, and muscle damage. Although, there is insufficient evidence to suggest that metabolic stress has any significant effect on hypertrophy outcomes.<ref>{{Cite journal |last1=Bernárdez-Vázquez |first1=Roberto |last2=Raya-González |first2=Javier |last3=Castillo |first3=Daniel |last4=Beato |first4=Marco |date=2022 |title=Resistance Training Variables for Optimization of Muscle Hypertrophy: An Umbrella Review |journal=Frontiers in Sports and Active Living |volume=4 |pages=949021 |doi=10.3389/fspor.2022.949021 |doi-access=free |issn=2624-9367 |pmc=9302196 |pmid=35873210}}</ref>

Muscular hypertrophy plays an important role in competitive [[bodybuilding]] and strength sports like [[powerlifting]], American football, and [[Olympic weightlifting]].

===Anaerobic training===
{{Main|Anaerobic exercise}}

The best approach to specifically achieve muscle growth remains controversial (as opposed to focusing on gaining strength, power, or endurance); it was generally considered that consistent anaerobic strength training will produce hypertrophy over the long term, in addition to its effects on muscular strength and endurance. Muscular hypertrophy can be increased through [[strength training]] and other short-duration, high-intensity [[anaerobic exercises]]. Lower-intensity, longer-duration [[aerobic exercise]] generally does not result in very effective tissue hypertrophy; instead, endurance athletes enhance storage of fats and [[Glycogen|carbohydrates]] within the muscles,<ref>{{cite journal | vauthors = van Loon LJ, Goodpaster BH | title = Increased intramuscular lipid storage in the insulin-resistant and endurance-trained state | journal = Pflügers Archiv | volume = 451 | issue = 5 | pages = 606–16 | date = February 2006 | pmid = 16155759 | doi = 10.1007/s00424-005-1509-0 | s2cid = 6567497 }}</ref> as well as [[neovascularization]].<ref>{{cite journal | vauthors = Soares JM | title = Effects of training on muscle capillary pattern: intermittent vs continuous exercise | journal = The Journal of Sports Medicine and Physical Fitness | volume = 32 | issue = 2 | pages = 123–7 | date = June 1992 | pmid = 1279273 }}</ref><ref>{{cite journal | vauthors = Prior BM, Yang HT, Terjung RL | title = What makes vessels grow with exercise training? | journal = Journal of Applied Physiology | volume = 97 | issue = 3 | pages = 1119–28 | date = September 2004 | pmid = 15333630 | doi = 10.1152/japplphysiol.00035.2004 | s2cid = 36656568 }}</ref>

==Temporary swelling==
{{more medical citations needed|section|date=May 2017}}
During a workout, increased blood flow to metabolically active areas causes muscles to temporarily increase in size. This phenomenon is referred to as transient hypertrophy, or more commonly known as being "pumped up" or getting "a pump."<ref>{{cite web| url=http://woman.thenest.com/causes-muscles-expand-work-out-6597.html |title=What Causes Your Muscles to Expand When You Work Out? | author=Joseph Eitel |access-date=May 5, 2017}}</ref> About two hours after a workout and typically for seven to eleven days, muscles swell due to an inflammation response as tissue damage is repaired.<ref>{{cite web |url=http://www.livestrong.com/article/75670-swell-after-workout/ |date=January 22, 2010 |title=Why Do You Swell After Workout? |author=Claire Lunardoni}}</ref> Longer-term hypertrophy occurs due to more permanent changes in muscle structure.

Hirono et al. explained the causes of Muscle swelling:<ref>{{Cite journal |last1=Hirono |first1=Tetsuya |last2=Ikezoe |first2=Tome |last3=Taniguchi |first3=Masashi |last4=Tanaka |first4=Hiroki |last5=Saeki |first5=Junya |last6=Yagi |first6=Masahide |last7=Umehara |first7=Jun |last8=Ichihashi |first8=Noriaki |date=2022-02-01 |title=Relationship Between Muscle Swelling and Hypertrophy Induced by Resistance Training |url=https://pubmed.ncbi.nlm.nih.gov/31904714/ |journal=Journal of Strength and Conditioning Research |volume=36 |issue=2 |pages=359–364 |doi=10.1519/JSC.0000000000003478 |issn=1533-4287 |pmid=31904714|hdl=2433/267710 |hdl-access=free }}</ref><blockquote>"Muscle swelling occurs as a result of the following:

(a) resistance exercise can increase [[phosphocreatine]] and [[hydrogen ion]] accumulations due to [[blood lactate]] and [[growth hormone]] production, and

(b) the high lactate and hydrogen ion concentrations may accelerate water uptake in muscle cells according to [[cell permeability]] because the molecular weights of the lactate and hydrogen ions are smaller than that of muscle glycogen."</blockquote>

==Factors affecting hypertrophy==
Biological factors (such as [[DNA]] and sex), nutrition, and training variables can affect muscle hypertrophy.<ref>{{Cite web|url=https://www.unm.edu/~lkravitz/Article%20folder/musclesgrowLK.html|title=How do muscles grow? }}</ref>

Individual differences in genetics account for a substantial portion of the variance in existing muscle mass. A classical twin study design (similar to those of behavioral genetics) estimated that about 53% of the variance in lean body mass is heritable,<ref>Arden, N. K. and Spector, T. D. (1997), Genetic Influences on Muscle Strength, Lean Body Mass, and Bone Mineral Density: A Twin Study. J Bone Miner Res, 12: 2076-2081. doi:10.1359/jbmr.1997.12.12.2076</ref> along with about 45% of the variance in muscle fiber proportion.<ref>{{cite journal | vauthors = Simoneau JA, Bouchard C | title = Genetic determinism of fiber type proportion in human skeletal muscle | journal = FASEB Journal | volume = 9 | issue = 11 | pages = 1091–5 | date = August 1995 | pmid = 7649409 | doi = 10.1096/fasebj.9.11.7649409 | doi-access = free | s2cid = 9613549 }}</ref>
[[File:Testosteron.svg|250px|thumb|right|Testosterone helps to increase muscle hypertrophy.]]
During puberty in males, hypertrophy occurs at an increased rate. Natural hypertrophy normally stops at full growth in the late teens. As [[testosterone]] is one of the body's major growth hormones, on average, males find hypertrophy much easier (on an absolute scale) to achieve than females, and, on average, have about 60% more muscle mass than women.<ref>{{cite journal | vauthors = Miller AE, MacDougall JD, Tarnopolsky MA, Sale DG | title = Gender differences in strength and muscle fiber characteristics | journal = European Journal of Applied Physiology and Occupational Physiology | volume = 66 | issue = 3 | pages = 254–62 | year = 1993 | pmid = 8477683 | doi = 10.1007/BF00235103 | hdl-access = free | hdl = 11375/22586 | s2cid = 206772211 }}</ref> Taking additional testosterone, as in [[anabolic steroid]]s, will increase results. It is also considered a [[Doping (sport)|performance-enhancing drug]], the use of which can cause competitors to be suspended or banned from competitions. Testosterone is also a medically regulated substance in most<ref name="urlSearch National Drug Schedule - NAPRA">{{cite web |url=http://napra.ca/pages/Schedules/Search.aspx |title=Search National Drug Schedule - NAPRA |archive-url=https://web.archive.org/web/20140201220518/http://napra.ca/pages/Schedules/Search.aspx |archive-date=February 1, 2014 |url-status=dead }}</ref><ref name="urlControlled Substances Act">{{cite web |url=https://www.fda.gov/RegulatoryInformation/Legislation/ucm148726.htm |title=Controlled Substances Act |website=[[Food and Drug Administration]] }}</ref> countries, making it illegal to possess without a [[medical prescription]]. Anabolic steroid use can cause [[testicular atrophy]], cardiac arrest,<ref name="pmid16292586">{{cite journal | vauthors = Fineschi V, Riezzo I, Centini F, Silingardi E, Licata M, Beduschi G, Karch SB | title = Sudden cardiac death during anabolic steroid abuse: morphologic and toxicologic findings in two fatal cases of bodybuilders | journal = International Journal of Legal Medicine | volume = 121 | issue = 1 | pages = 48–53 | date = January 2007 | pmid = 16292586 | doi = 10.1007/s00414-005-0055-9 | s2cid = 20004739 }}</ref> and [[gynecomastia]].<ref name="pmid20139230">{{cite journal | vauthors = Basaria S | title = Androgen abuse in athletes: detection and consequences | journal = The Journal of Clinical Endocrinology and Metabolism | volume = 95 | issue = 4 | pages = 1533–43 | date = April 2010 | pmid = 20139230 | doi = 10.1210/jc.2009-1579 | doi-access = free }}</ref>

In the long term, a positive energy balance, when more calories are consumed rather than burned, is helpful for [[anabolism]] and therefore muscle hypertrophy. An increased requirement for protein can help elevate protein synthesis, which is seen in athletes training for muscle hypertrophy. However, there is no scientific consensus on whether strength-training athletes have increased protein requirements.<ref>{{cite journal | vauthors = Phillips SM | title = Protein requirements and supplementation in strength sports | journal = Nutrition | volume = 20 | issue = 7–8 | pages = 689–95 | date = July 2004 | pmid = 15212752 | doi = 10.1016/j.nut.2004.04.009 | url = https://www.researchgate.net/publication/8494999 | access-date = May 15, 2017 }}</ref>

Training variables, in the context of strength training, such as frequency, intensity, and total volume also directly affect the increase of muscle hypertrophy. A gradual increase in all of these training variables will yield muscular hypertrophy.<ref>{{cite journal | vauthors = Wernbom M, Augustsson J, Thomeé R | title = The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humansq | journal = Sports Medicine | volume = 37 | issue = 3 | pages = 225–64 | date = March 1, 2007 | pmid = 17326698 | doi = 10.2165/00007256-200737030-00004 | s2cid = 31127952 }}</ref>

==Changes in protein synthesis and muscle cell biology associated with stimuli==
===Protein synthesis===
{{Main|Protein biosynthesis}}
[[File:Summary of the protein biosynthesis process.png|thumb|300px|alt=A nucleus within a cell showing DNA, RNA and enzymes at the different stages of protein biosynthesis| Protein biosynthesis starting with transcription and post-transcriptional modifications in the nucleus. Then the mature mRNA is exported to the cytoplasm where it is translated. The polypeptide chain then folds and is post-translationally modified.]]
The message filters down to alter the pattern of [[gene expression]]. The additional contractile proteins appear to be incorporated into existing myofibrils (the chains of [[sarcomere]]s within a muscle cell). There appears to be some limit to how large a myofibril can become: at some point, they split. These events appear to occur within each muscle fiber. That is hypertrophy results primarily from the growth of each muscle cell rather than an increase in the number of cells. [[Skeletal muscle]] cells are however unique in the body in that they can contain multiple nuclei, and the number of nuclei can increase.<ref>{{cite journal | vauthors = Bruusgaard JC, Johansen IB, Egner IM, Rana ZA, Gundersen K | title = Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 107 | issue = 34 | pages = 15111–6 | date = August 2010 | pmid = 20713720 | pmc = 2930527 | doi = 10.1073/pnas.0913935107 | bibcode = 2010PNAS..10715111B | doi-access = free }}</ref>

[[Cortisol]] decreases amino acid uptake by muscle tissue, and inhibits protein synthesis.<ref>{{cite book | author = Manchester KL | title = Mammalian Protein Metabolism | page = 229 | year = 1970 | doi = 10.1016/B978-0-12-510604-7.50011-6 | chapter = 33 – Sites of Hormonal Regulation of Protein Metabolism | publisher = Academic Press, New York | isbn = 978-0-12-510604-7 | chapter-url-access = registration | chapter-url = https://archive.org/details/mammalianprotein0000munr }}</ref> The short-term increase in protein synthesis that occurs subsequent to resistance training returns to normal after approximately 28 hours in adequately fed male youths.<ref>{{cite journal | vauthors = Tang JE, Perco JG, Moore DR, Wilkinson SB, Phillips SM | title = Resistance training alters the response of fed state mixed muscle protein synthesis in young men | journal = American Journal of Physiology. Regulatory, Integrative and Comparative Physiology | volume = 294 | issue = 1 | pages = R172-8 | date = January 2008 | pmid = 18032468 | doi = 10.1152/ajpregu.00636.2007 | s2cid = 9743221 }}</ref> Another study determined that muscle protein synthesis was elevated even 72 hours following training.<ref>{{cite journal | vauthors = Miller BF, Olesen JL, Hansen M, Døssing S, Crameri RM, Welling RJ, Langberg H, Flyvbjerg A, Kjaer M, Babraj JA, Smith K, Rennie MJ | display-authors = 6 | title = Coordinated collagen and muscle protein synthesis in human patella tendon and quadriceps muscle after exercise | journal = The Journal of Physiology | volume = 567 | issue = Pt 3 | pages = 1021–33 | date = September 2005 | pmid = 16002437 | pmc = 1474228 | doi = 10.1113/jphysiol.2005.093690 }}</ref>

A small study performed on young and elderly found that ingestion of 340 grams of lean beef (90&nbsp;g protein) did not increase muscle protein synthesis any more than ingestion of 113 grams of lean beef (30&nbsp;g protein). In both groups, muscle protein synthesis increased by 50%. The study concluded that more than 30&nbsp;g protein in a single meal did not further enhance the stimulation of muscle protein synthesis in young and elderly.<ref>{{cite journal | vauthors = Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D | title = A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects | journal = Journal of the American Dietetic Association | volume = 109 | issue = 9 | pages = 1582–6 | date = September 2009 | pmid = 19699838 | pmc = 3197704 | doi = 10.1016/j.jada.2009.06.369 }}</ref> However, this study didn't check protein synthesis in relation to training; therefore conclusions from this research are controversial. A 2018 review of the scientific literature<ref>{{cite journal | vauthors = Schoenfeld BJ, Aragon AA | title = How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution | journal = Journal of the International Society of Sports Nutrition | volume = 15 | issue = 1 | pages = 10 | date = February 27, 2018 | pmid = 29497353 | pmc = 5828430 | doi = 10.1186/s12970-018-0215-1 | doi-access = free }}</ref> concluded that for the purpose of building lean muscle tissue, a minimum of 1.6 g protein per kilogram of body weight is required, which can for example be divided over 4 meals or snacks and spread out over the day.{{citation needed|date=July 2022}}

It is not uncommon for bodybuilders to advise a protein intake as high as 2–4&nbsp;g per kilogram of bodyweight per day.<ref name="urlwww.leehayward.com">{{cite web | url = http://www.leehayward.com/protein_part2.htm |title=Bodybuilders and Protein – Part 2 | work = Leehayward.com | access-date=June 19, 2011}}</ref> However, scientific literature has suggested this is higher than necessary, as protein intakes greater than 1.8&nbsp;g per kilogram of body weight showed to have no greater effect on muscle hypertrophy.<ref name="Httpjapphysiologyorgcgicontentabstract">{{cite journal | vauthors = Tarnopolsky MA, Atkinson SA, MacDougall JD, Chesley A, Phillips S, Schwarcz HP | title = Evaluation of protein requirements for trained strength athletes | journal = Journal of Applied Physiology | volume = 73 | issue = 5 | pages = 1986–95 | date = November 1992 | pmid = 1474076 | doi = 10.1152/jappl.1992.73.5.1986 | s2cid = 46188182 }}</ref> A study carried out by American College of Sports Medicine (2002) put the recommended daily protein intake for athletes at 1.2–1.8&nbsp;g per kilogram of body weight.<ref name="Httpjapphysiologyorgcgicontentabstract" /><ref>{{cite journal | vauthors = Rankin JW | title = Weight loss and gain in athletes | journal = Current Sports Medicine Reports | volume = 1 | issue = 4 | pages = 208–13 | date = August 2002 | pmid = 12831697 | doi = 10.1249/00149619-200208000-00004 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Lemon PW | title = Effect of exercise on protein requirements | journal = Journal of Sports Sciences | volume = 9 Spec No | pages = 53–70 | year = 1991 | pmid = 1895363 | doi = 10.1080/02640419108729866 }}</ref> Conversely, [[Mauro Di Pasquale|Di Pasquale]] (2008), citing recent studies, recommends a minimum protein intake of 2.2 g/kg "for anyone involved in competitive or intense recreational sports who wants to maximize lean body mass but does not wish to gain weight. However athletes involved in strength events (..) may need even more to maximize body composition and athletic performance. In those attempting to minimize body fat and thus maximize body composition, for example in sports with weight classes and in bodybuilding, it's possible that protein may well make up over 50% of their daily caloric intake."<ref>{{cite book|last=Di Pasquale|first=Mauro G. | name-list-style = vanc |title=Sports Nutrition: Energy metabolism and exercise|editor=Ira Wolinsky, Judy A. Driskell|publisher=CRC Press|year=2008|page=79|chapter=Use of Proteins in Energy Metabolism|author-link=Mauro Di Pasquale|isbn=978-0-8493-7950-5}}</ref>

===Microtrauma===
{{Main|Microtrauma}}
[[Image:Skeletal muscle.png|thumb|250px|[[Muscle]] fibres may be "microtorn" during microtrauma]]
Microtrauma is tiny damage to the muscle fibers. The precise relation between microtrauma and muscle growth is not entirely understood yet.{{citation needed|date=July 2022}}

One theory is that microtrauma plays a significant role in muscle growth.<ref name="pmid14715915">{{cite journal | vauthors = Chargé SB, Rudnicki MA | title = Cellular and molecular regulation of muscle regeneration | journal = Physiological Reviews | volume = 84 | issue = 1 | pages = 209–38 | date = January 2004 | pmid = 14715915 | doi = 10.1152/physrev.00019.2003 | s2cid = 9556386 }}</ref><ref name=" New Mexicos Flagship University The University of New Mexico ">{{cite web | title=How Do Muscles Grow? | website=The University of New Mexico | url=http://www.unm.edu/~lkravitz/Article%20folder/musclesgrowLK.html | ref={{sfnref | New Mexico's Flagship University | The University of New Mexico }}}}</ref> When microtrauma occurs (from weight training or other strenuous activities), the body responds by overcompensating, replacing the damaged tissue and adding more, so that the risk of repeat damage is reduced. Damage to these fibers has been theorized as the possible cause for the symptoms of [[delayed onset muscle soreness]] (DOMS), and is why progressive overload is essential to continued improvement, as the body adapts and becomes more resistant to stress.

However, other work examining the time course of changes in muscle protein synthesis and their relationship to hypertrophy showed that damage was unrelated to hypertrophy.<ref name=pmid27219125>{{cite journal | vauthors = Damas F, Phillips SM, Libardi CA, Vechin FC, Lixandrão ME, Jannig PR, Costa LA, Bacurau AV, Snijders T, Parise G, Tricoli V, Roschel H, Ugrinowitsch C | display-authors = 6 | title = Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage | journal = The Journal of Physiology | volume = 594 | issue = 18 | pages = 5209–22 | date = September 2016 | pmid = 27219125 | pmc = 5023708 | doi = 10.1113/JP272472 }}</ref> In fact, in one study<ref name=pmid27219125/> the authors showed that it was not until the damage subsided that protein synthesis was directed to muscle growth.

==Myofibrillar vs. sarcoplasmic hypertrophy==
{{disputed|section|date=May 2017}}
[[File:Hyperplasia vs Hypertrophy.svg|250px|thumb|right|Hypertrophy of cell]]
In the bodybuilding and fitness community and even in some academic books skeletal muscle hypertrophy is described as being in one of two types: Sarcoplasmic or myofibrillar.{{qualify evidence}} According to this hypothesis, during sarcoplasmic hypertrophy, the volume of [[sarcoplasm]]ic fluid in the muscle cell increases with no accompanying increase in muscular strength, whereas during myofibrillar hypertrophy, [[actin]] and [[myosin]] contractile proteins increase in number and add to muscular strength as well as a small increase in the size of the muscle. Sarcoplasmic hypertrophy is greater in the muscles of [[bodybuilder]]s because studies suggest sarcoplasmic hypertrophy shows a greater increase in muscle size while myofibrillar hypertrophy proves to increase overall muscular strength making it more dominant in [[Olympic weightlifting|Olympic weightlifters]].<ref>{{cite book|url=https://books.google.com/books?id=QWSn4iKgNo8C&pg=PA50|title=Science and practice of strength training| last1 = Kraemer | first1 = William J. | last2 = Zatsiorsky | first2 = Vladimir M. | name-list-style = vanc |publisher=Human Kinetics|year=2006|isbn=978-0-7360-5628-1|location=Champaign, IL|page=50}}</ref> These two forms of adaptations rarely occur completely independently of one another; one can experience a large increase in fluid with a slight increase in proteins, a large increase in proteins with a small increase in fluid, or a relatively balanced combination of the two.

==In sports==
Examples of increased muscle hypertrophy are seen in various professional sports, mainly strength related sports such as [[boxing]], [[olympic weightlifting]], [[mixed martial arts]], [[rugby football|rugby]], [[professional wrestling]] and various forms of gymnastics. Athletes in other more skill-based sports such as basketball, baseball, [[ice hockey]], and football may also train for increased muscle hypertrophy to better suit their position of play. For example, a [[center (basketball)]] may want to be bigger and more muscular to better overpower their opponents in the low post.<ref>{{Cite news|url=http://www.slamonline.com/nba/chris-bosh-gaining-weight-to-play-center/#5LUvmeqjg2V5wykA.97|title=Chris Bosh Gaining Weight to Play Center|last=Khorshidi|first=Eldon| name-list-style = vanc |date=September 10, 2012|work=SLAM|access-date=April 7, 2017}}</ref> Athletes training for these sports train extensively not only in [[strength training|strength]] but also in [[cardiovascular]] and [[muscular endurance]] training.{{Citation needed|date=June 2021}}

== Pathology ==
{{Main|Pseudoathletic appearance}}

Some neuromuscular diseases result in true hypertrophy of one or more skeletal muscles, confirmed by MRI or muscle biopsy. As this muscle hypertrophy is not the result of resistance training nor heavy manual labour, this is why the muscle hypertrophy is described as a [[pseudoathletic appearance]].

As muscle hypertrophy is a response to strenuous anaerobic activity, ordinary everyday activity would become strenuous in diseases that result in premature [[muscle fatigue]] (neural or metabolic), or disrupt the [[Muscle cell#Skeletal muscle contraction|excitation-contraction]] coupling in muscle, or cause repetitive or sustained involuntary muscle contractions ([[fasciculation]]s, [[myotonia]], or [[spasticity]]).<ref>{{Cite journal |last=Walters |first=Jon |date=October 2017 |title=Muscle hypertrophy and pseudohypertrophy |journal=Practical Neurology |volume=17 |issue=5 |pages=369–379 |doi=10.1136/practneurol-2017-001695 |issn=1474-7766 |pmid=28778933|doi-access=free }}</ref><ref>{{Cite journal |last=Nadaj-Pakleza |first=Aleksandra |date=2022-07-01 |title=Muscle hypertrophy: indicative of good health or disease? / Hypertrophie musculaire: signe de bonne santé ou de maladie ? |url=https://www.cahiers-myologie.org/articles/myolog/abs/2022/01/myolog202225p10/myolog202225p10.html |journal=Les Cahiers de Myologie |language=fr, en |issue=25 |pages=10–15 |doi=10.1051/myolog/202225004 |issn=2108-2219|doi-access=free }}</ref> In [[lipodystrophy]], an abnormal deficit of subcutaneous fat accentuates the appearance of the muscles, though the muscles are quantifiably hypertrophic (possibly due to a metabolic abnormality).<ref>{{Cite journal |last1=Ji |first1=Hongzhao |last2=Weatherall |first2=Paul |last3=Adams-Huet |first3=Beverley |last4=Garg |first4=Abhimanyu |date=August 2013 |title=Increased skeletal muscle volume in women with familial partial lipodystrophy, Dunnigan variety |journal=The Journal of Clinical Endocrinology and Metabolism |volume=98 |issue=8 |pages=E1410–1413 |doi=10.1210/jc.2013-1297 |issn=1945-7197 |pmc=3733861 |pmid=23783098}}</ref><ref>{{Citation |last1=El-Darouti |first1=Mohammad Ali |title=Loss of Subcutaneous Fat, Muscle Hypertrophy, Diabetes and Hyperlipidemia |date=2019 |url=https://doi.org/10.1007/978-3-030-21855-3_2 |work=Challenging Cases in Dermatology Volume 2: Advanced Diagnoses and Management Tactics |pages=7–11 |editor-last=El-Darouti |editor-first=Mohammad Ali |access-date=2023-10-12 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-21855-3_2 |isbn=978-3-030-21855-3 |last2=Al-Ali |first2=Faiza Mohamed |s2cid=202826748 |editor2-last=Al-Ali |editor2-first=Faiza Mohamed}}</ref>

Diseases that result in true muscle hypertrophy include, but not limited to, select: muscular dystrophies, metabolic myopathies, endocrine myopathies, congenital myopathies, non-dystrophic myotonias and pseudomyotonias, denervation, spasticity, and lipodystrophy. The muscle hypertrophy may persist throughout the course of the disease, or may later atrophy, or become pseudohypertrophic (muscle atrophy with infiltration of fat or other tissue). For instance, Duchenne and Becker muscular dystrophy may start as true muscle hypertrophy, but later develop into pseudohypertrophy.<ref>{{Cite journal |last1=Kornegay |first1=Joe N. |last2=Childers |first2=Martin K. |last3=Bogan |first3=Daniel J. |last4=Bogan |first4=Janet R. |last5=Nghiem |first5=Peter |last6=Wang |first6=Jiahui |last7=Fan |first7=Zheng |last8=Howard |first8=James F. |last9=Schatzberg |first9=Scott J. |last10=Dow |first10=Jennifer L. |last11=Grange |first11=Robert W. |last12=Styner |first12=Martin A. |last13=Hoffman |first13=Eric P. |last14=Wagner |first14=Kathryn R. |date=February 2012 |title=The paradox of muscle hypertrophy in muscular dystrophy |journal=Physical Medicine and Rehabilitation Clinics of North America |volume=23 |issue=1 |pages=149–172, xii |doi=10.1016/j.pmr.2011.11.014 |issn=1558-1381 |pmc=5951392 |pmid=22239881}}</ref>

== See also ==
{{div col|colwidth=30em}}
* [[Anabolism]]
* [[Colorado Experiment]]
* [[Davis' law]]
* [[Follistatin]]
* [[Lean body mass]]
* [[Muscle atrophy]]
* [[Muscle dystrophy]]
* [[Myostatin]]
* [[Pseudoathletic appearance]]
* [[Pseudohypertrophy]]
{{div col end}}

== References ==
{{reflist}}

== Further reading ==
{{refbegin|30em}}
* {{cite journal | vauthors = Bodine SC, Stitt TN, Gonzalez M, Kline WO, Stover GL, Bauerlein R, Zlotchenko E, Scrimgeour A, Lawrence JC, Glass DJ, Yancopoulos GD | display-authors = 6 | title = Akt/mTOR pathway is a crucial regulator of skeletal muscle hypertrophy and can prevent muscle atrophy in vivo | journal = Nature Cell Biology | volume = 3 | issue = 11 | pages = 1014–9 | date = November 2001 | pmid = 11715023 | doi = 10.1038/ncb1101-1014 | s2cid = 16284975 }}
* {{cite journal | vauthors = Charette SL, McEvoy L, Pyka G, Snow-Harter C, Guido D, Wiswell RA, Marcus R | title = Muscle hypertrophy response to resistance training in older women | journal = Journal of Applied Physiology | volume = 70 | issue = 5 | pages = 1912–6 | date = May 1991 | pmid = 1864770 | doi = 10.1152/jappl.1991.70.5.1912 }}
* {{cite journal | vauthors = Cureton KJ, Collins MA, Hill DW, McElhannon FM | title = Muscle hypertrophy in men and women | journal = Medicine and Science in Sports and Exercise | volume = 20 | issue = 4 | pages = 338–44 | date = August 1988 | pmid = 3173042 | doi = 10.1249/00005768-198808000-00003 | doi-access = free }}
* {{cite journal | vauthors = Frontera WR, Meredith CN, O'Reilly KP, Knuttgen HG, Evans WJ | title = Strength conditioning in older men: skeletal muscle hypertrophy and improved function | journal = Journal of Applied Physiology | volume = 64 | issue = 3 | pages = 1038–44 | date = March 1988 | pmid = 3366726 | doi = 10.1152/jappl.1988.64.3.1038 }}
* {{cite journal | vauthors = Glass DJ | title = Signalling pathways that mediate skeletal muscle hypertrophy and atrophy | journal = Nature Cell Biology | volume = 5 | issue = 2 | pages = 87–90 | date = February 2003 | pmid = 12563267 | doi = 10.1038/ncb0203-87 | s2cid = 8938588 }}
* {{cite journal | vauthors = Glass DJ | title = Skeletal muscle hypertrophy and atrophy signaling pathways | journal = The International Journal of Biochemistry & Cell Biology | volume = 37 | issue = 10 | pages = 1974–84 | date = October 2005 | pmid = 16087388 | doi = 10.1016/j.biocel.2005.04.018 | s2cid = 20190898 }}
* {{cite journal | vauthors = Schuelke M, Wagner KR, Stolz LE, Hübner C, Riebel T, Kömen W, Braun T, Tobin JF, Lee SJ | display-authors = 6 | title = Myostatin mutation associated with gross muscle hypertrophy in a child | journal = The New England Journal of Medicine | volume = 350 | issue = 26 | pages = 2682–8 | date = June 2004 | pmid = 15215484 | doi = 10.1056/NEJMoa040933 | s2cid = 6010232 | doi-access = free }}
{{refend}}

{{Physical exercise}}
{{Strength training exercises}}
{{Authority control}}

[[Category:Muscular system]]
[[Category:Tissues (biology)]]
[[Category:Physiology]]
[[Category:Exercise physiology]]
[[Category:Bodybuilding]]

Pages transcluded onto the current version of this page (help):

Template:Ambox (view source) (template editor protected)
Template:Authority control (view source) (template editor protected)
Template:Category handler (view source) (protected)
Template:Citation (view source) (protected)
Template:Citation needed (view source) (protected)
Template:Cite book (view source) (protected)
Template:Cite journal (view source) (protected)
Template:Cite news (view source) (protected)
Template:Cite web (view source) (protected)
Template:DMCA (view source) (template editor protected)
Template:Dated maintenance category (view source) (template editor protected)
Template:Dated maintenance category (articles) (view source) (template editor protected)
Template:Delink (view source) (protected)
Template:Disputed (view source) (template editor protected)
Template:Div col (view source) (template editor protected)
Template:Div col/styles.css (view source) (template editor protected)
Template:Div col end (view source) (template editor protected)
Template:FULLROOTPAGENAME (view source) (template editor protected)
Template:Find sources mainspace (view source) (template editor protected)
Template:Fix (view source) (protected)
Template:Fix/category (view source) (protected)
Template:Hlist/styles.css (view source) (protected)
Template:Icon (view source) (template editor protected)
Template:Main (view source) (template editor protected)
Template:Main other (view source) (protected)
Template:More medical citations needed (view source) (semi-protected)
Template:Navbox (view source) (template editor protected)
Template:Ns has subpages (view source) (protected)
Template:Page needed (view source) (template editor protected)
Template:Pagetype (view source) (protected)
Template:Physical exercise (edit)
Template:Qualify evidence (edit)
Template:Refbegin (view source) (template editor protected)
Template:Refbegin/styles.css (view source) (template editor protected)
Template:Refend (view source) (template editor protected)
Template:Reflist (view source) (protected)
Template:Reflist/styles.css (view source) (protected)
Template:SDcat (view source) (protected)
Template:SfnRef (view source) (template editor protected)
Template:Sfnref (view source) (template editor protected)
Template:Short description (view source) (protected)
Template:Short description/lowercasecheck (view source) (protected)
Template:Strength training exercises (edit)
Template:Tooltip (view source) (template editor protected)
Template:Tooltip/styles.css (view source) (template editor protected)
Template:Use mdy dates (view source) (template editor protected)
Template:Yesno (view source) (protected)
Template:Yesno-no (view source) (template editor protected)
Template:Yesno-yes (view source) (template editor protected)
Module:Arguments (view source) (protected)
Module:Authority control (view source) (template editor protected)
Module:Authority control/config (view source) (template editor protected)
Module:Category handler (view source) (protected)
Module:Category handler/blacklist (view source) (protected)
Module:Category handler/config (view source) (protected)
Module:Category handler/data (view source) (protected)
Module:Category handler/shared (view source) (protected)
Module:Check for unknown parameters (view source) (protected)
Module:Citation/CS1 (view source) (protected)
Module:Citation/CS1/COinS (view source) (protected)
Module:Citation/CS1/Configuration (view source) (protected)
Module:Citation/CS1/Date validation (view source) (protected)
Module:Citation/CS1/Identifiers (view source) (protected)
Module:Citation/CS1/Utilities (view source) (protected)
Module:Citation/CS1/Whitelist (view source) (protected)
Module:Citation/CS1/styles.css (view source) (protected)
Module:Delink (view source) (protected)
Module:Disambiguation/templates (view source) (protected)
Module:EditAtWikidata (view source) (protected)
Module:Find sources (view source) (template editor protected)
Module:Find sources/config (view source) (template editor protected)
Module:Find sources/links (view source) (template editor protected)
Module:Find sources/templates/Find sources mainspace (view source) (template editor protected)
Module:Footnotes (view source) (template editor protected)
Module:Format link (view source) (template editor protected)
Module:Hatnote (view source) (template editor protected)
Module:Hatnote/styles.css (view source) (template editor protected)
Module:Hatnote list (view source) (template editor protected)
Module:Icon (view source) (template editor protected)
Module:Icon/data (view source) (template editor protected)
Module:Labelled list hatnote (view source) (template editor protected)
Module:Message box (view source) (protected)
Module:Message box/ambox.css (view source) (protected)
Module:Message box/configuration (view source) (protected)
Module:Namespace detect/config (view source) (protected)
Module:Namespace detect/data (view source) (protected)
Module:Navbar (view source) (protected)
Module:Navbar/configuration (view source) (protected)
Module:Navbar/styles.css (view source) (protected)
Module:Navbox (view source) (template editor protected)
Module:Navbox/configuration (view source) (template editor protected)
Module:Navbox/styles.css (view source) (template editor protected)
Module:Ns has subpages (view source) (protected)
Module:Pagetype (view source) (protected)
Module:Pagetype/config (view source) (protected)
Module:Pagetype/disambiguation (view source) (protected)
Module:Pagetype/rfd (view source) (protected)
Module:Pagetype/setindex (view source) (protected)
Module:Pagetype/softredirect (view source) (protected)
Module:SDcat (view source) (protected)
Module:String (view source) (protected)
Module:TableTools (view source) (protected)
Module:Unsubst (view source) (protected)
Module:Wikitext Parsing (view source) (protected)
Module:Yesno (view source) (protected)

Return to Muscle hypertrophy.

Retrieved from "https://en.wikipedia.org/wiki/Muscle_hypertrophy"