Editing Bodybuilding (section)

=== Performance-enhancing substances ===
Some bodybuilders use drugs such as [[anabolic steroid]]s and precursor substances such as [[prohormone]]s to increase [[muscle hypertrophy]]. Anabolic steroids cause [[hypertrophy]] of both types (I and II) of muscle fibers, likely caused by an increased synthesis of muscle proteins. They also provoke undesired side effects including [[hepatotoxicity]], [[gynecomastia]], [[acne]], the early onset of [[male pattern baldness]] and a decline in the body's own testosterone production, which can cause [[testicular atrophy]].<ref>{{cite journal | vauthors = Schroeder ET, Vallejo AF, Zheng L, Stewart Y, Flores C, Nakao S, Martinez C, Sattler FR | display-authors = 6 | title = Six-week improvements in muscle mass and strength during androgen therapy in older men | journal = The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences | volume = 60 | issue = 12 | pages = 1586–92 | date = December 2005 | pmid = 16424293 | doi = 10.1093/gerona/60.12.1586 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Grunfeld C, Kotler DP, Dobs A, Glesby M, Bhasin S | s2cid = 25911263 | title = Oxandrolone in the treatment of HIV-associated weight loss in men: a randomized, double-blind, placebo-controlled study | journal = Journal of Acquired Immune Deficiency Syndromes | volume = 41 | issue = 3 | pages = 304–14 | date = March 2006 | pmid = 16540931 | doi = 10.1097/01.qai.0000197546.56131.40 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Giorgi A, Weatherby RP, Murphy PW | title = Muscular strength, body composition and health responses to the use of testosterone enanthate: a double blind study | journal = Journal of Science and Medicine in Sport | volume = 2 | issue = 4 | pages = 341–55 | date = December 1999 | pmid = 10710012 | doi = 10.1016/S1440-2440(99)80007-3 }}</ref> Other performance-enhancing substances used by competitive bodybuilders include [[Growth hormone treatment|human growth hormone]] (HGH). HGH is also used by female bodybuilders to obtain bigger muscles "while maintaining a 'female appearance{{'"}}.<ref>{{cite book|url=https://books.google.com/books?id=9juCAgAAQBAJ|publisher=Routledge|title=Bodybuilding, Drugs and Risk|year=2002|author=Lee Monaghan|isbn=9781134588527|pages=145|access-date=June 30, 2020|archive-date=April 5, 2023|archive-url=https://web.archive.org/web/20230405222424/https://books.google.com/books?id=9juCAgAAQBAJ|url-status=live}}</ref>

Muscle growth is more difficult to achieve in older adults than younger adults because of [[biological aging]], which leads to many metabolic changes detrimental to muscle growth; for instance, by diminishing growth hormone and [[testosterone]] levels. Some recent clinical studies have shown that low-dose HGH treatment for adults with HGH deficiency changes the body composition by increasing muscle mass, decreasing fat mass, increasing [[bone density]] and muscle strength, improves [[cardiovascular]] parameters, and affects the quality of life without significant side effects.<ref>{{cite journal | vauthors = Alexopoulou O, Abs R, Maiter D | s2cid = 24874132 | title = Treatment of adult growth hormone deficiency: who, why and how? A review | journal = Acta Clinica Belgica | volume = 65 | issue = 1 | pages = 13–22 | year = 2010 | pmid = 20373593 | doi = 10.1179/acb.2010.002 }}</ref><ref>{{cite journal | vauthors = Ahmad AM, Hopkins MT, Thomas J, Ibrahim H, Fraser WD, Vora JP | title = Body composition and quality of life in adults with growth hormone deficiency; effects of low-dose growth hormone replacement | journal = Clinical Endocrinology | volume = 54 | issue = 6 | pages = 709–17 | date = June 2001 | pmid = 11422104 | doi = 10.1046/j.1365-2265.2001.01275.x | s2cid = 12681649 | doi-access = free }}</ref><ref name="pmid10971102">{{cite journal | vauthors = Savine R, Sönksen P | s2cid = 30263334 | title = Growth hormone - hormone replacement for the somatopause? | journal = Hormone Research | volume = 53 | issue = Suppl 3 | pages = 37–41 | year = 2000 | pmid = 10971102 | doi = 10.1159/000023531 }}</ref>

In rodents, knockdown of [[metallothionein]] gene expression results in activation of the [[Akt/PKB signaling pathway|Akt pathway]] and increases in [[myotube]] size, in [[myocyte|type IIb fiber]] hypertrophy, and ultimately in muscle strength.<ref>{{cite journal | vauthors = Summermatter S, Bouzan A, Pierrel E, Melly S, Stauffer D, Gutzwiller S, Nolin E, Dornelas C, Fryer C, Leighton-Davies J, Glass DJ, Fournier B | display-authors = 6 | title = Blockade of Metallothioneins 1 and 2 Increases Skeletal Muscle Mass and Strength | journal = Molecular and Cellular Biology | volume = 37 | issue = 5 | date = March 2017 | pmid = 27956698 | pmc = 5311239 | doi = 10.1128/MCB.00305-16 }}</ref> This has not been studied well in humans.

==== Injecting oil into muscles {{anchor|synthol}} ====
{{main|Site enhancement oil}}
Some bodybuilders inject oils or other compounds into their muscles (sometimes known as "synthol") to enhance their size or appearance. This practice can have serious health consequences and risks for humans.<ref>{{cite journal |last1=Sisti |first1=Andrea |last2=Huayllani |first2=Maria T. |last3=Restrepo |first3=David J. |last4=Boczar |first4=Daniel |last5=Manrique |first5=Oscar J. |last6=Broer |first6=Peter N. |last7=Shapiro |first7=Shane A. |last8=Forte |first8=Antonio J. |title=Oil injection for cosmetic enhancement of the upper extremities: a case report and review of literature |journal=Acta Bio Medica: Atenei Parmensis |date=2020 |volume=91 |issue=3 |pages=e2020082 |doi=10.23750/abm.v91i3.8533 |pmid=32921778 |pmc=7716972 |issn=0392-4203}}</ref>