Editing Bodybuilding (section)

== Muscle growth ==
Bodybuilders use three main strategies to maximize [[muscle hypertrophy]]:
* [[Strength training]] through weights or elastic/hydraulic resistance.
* Specialized nutrition, incorporating extra [[protein]] and supplements when necessary.
* Adequate rest, including [[sleep]] and [[Recuperation (recovery)|recuperation]] between workouts.<ref>{{Cite news|date=2017-03-01|title=9 things every athlete needs to know about sleep and recovery|url=https://www.mensjournal.com/health-fitness/9-things-every-athlete-needs-know-about-sleep-and-recovery/|access-date=2021-10-14|website=Men's Journal|language=en-US|archive-date=October 29, 2021|archive-url=https://web.archive.org/web/20211029171723/https://www.mensjournal.com/health-fitness/9-things-every-athlete-needs-know-about-sleep-and-recovery/|url-status=live}}</ref>

=== Weight training ===
{{Main|Weight training|Strength training}}
{{more medical citations needed|section|date=March 2022|This section covers medical topices, so [[WP:MEDRS]] should apply here.|talk=1}}
Intensive [[weight training]] causes micro-tears to the muscles being trained; this is generally known as [[microtrauma]]. These micro-tears in the muscle contribute to the soreness felt after exercise, called [[delayed onset muscle soreness]] (DOMS). It is the repair of these micro-traumas that results in [[muscle growth]]. Normally, this soreness becomes most apparent a day or two after a workout. However, as muscles become adapted to the exercises, soreness tends to decrease.<ref name="pmid7371625">{{cite journal | vauthors = MacDougall JD, Elder GC, Sale DG, Moroz JR, Sutton JR | s2cid = 28377940 | title = Effects of strength training and immobilization on human muscle fibres | journal = European Journal of Applied Physiology and Occupational Physiology | volume = 43 | issue = 1 | pages = 25–34 | date = February 1980 | pmid = 7371625 | doi = 10.1007/BF00421352 }}</ref>

Weight training aims to build muscle by prompting two different types of [[Muscle hypertrophy|hypertrophy]]: sarcoplasmic and myofibrillar. Sarcoplasmic hypertrophy leads to larger muscles and so is favored by bodybuilders more than myofibrillar hypertrophy, which builds athletic strength. Sarcoplasmic hypertrophy is triggered by increasing repetitions, whereas myofibrillar hypertrophy is triggered by lifting heavier weight.<ref name="mot">{{cite web|title=Weight Training Intensity or Volume for Bigger Muscles?|date=October 15, 2010 |url=http://www.motleyhealth.com/strength/weight-training-intensity-or-volume-for-bigger-muscles|access-date=February 24, 2012|archive-date=March 10, 2012|archive-url=https://web.archive.org/web/20120310092836/http://www.motleyhealth.com/strength/weight-training-intensity-or-volume-for-bigger-muscles|url-status=live}}</ref> In either case, there is an increase in both size and strength of the muscles (compared to what happens if that same individual does not lift weights at all), although the emphasis is different.<ref name=mot/>

=== Nutrition ===
The high levels of muscle growth and repair achieved by bodybuilders require a specialized diet. Generally speaking, bodybuilders require more [[Food energy|calories]] than the average person of the same weight to provide the protein and energy requirements needed to support their training and increase muscle mass. In preparation of a contest, a sub-maintenance level of food energy is combined with [[cardiovascular exercise]] to lose [[body fat]]. Proteins, [[carbohydrates]] and fats are the three major macronutrients that the human body needs to build muscle.<ref>{{cite web|title=Major Nutrients in Food|work=WebMD |url=http://www.webmd.com/a-to-z-guides/major-nutrients-in-food-topic-overview|access-date=August 27, 2013|archive-date=September 5, 2013|archive-url=https://web.archive.org/web/20130905081801/http://www.webmd.com/a-to-z-guides/major-nutrients-in-food-topic-overview|url-status=live}}</ref> The ratios of calories from carbohydrates, proteins, and fats vary depending on the goals of the bodybuilder.<ref>{{cite journal | vauthors = Manore MM, Thompson J, Russo M | title = Diet and exercise strategies of a world-class bodybuilder | journal = International Journal of Sport Nutrition | volume = 3 | issue = 1 | pages = 76–86 | date = March 1993 | pmid = 8499940 | doi = 10.1123/ijsn.3.1.76 | s2cid = 38151979 }}</ref>

==== Carbohydrates ====
[[Carbohydrate]]s play an important role for bodybuilders. They give the body energy to deal with the rigors of training and recovery. Carbohydrates also promote secretion of [[insulin]], a hormone enabling cells to get the [[glucose]] they need. Insulin also carries amino acids into cells and promotes [[protein synthesis]].<ref>{{cite magazine|last=Skinner|first=Rob | name-list-style = vanc |magazine=Scholastic Coach and Athletic Director |title=Nutrition for Muscle Mass|date=March 2002|volume=71|issue=8|page=3 |id={{ProQuest|208050071}} |department=Sidelines |issn=1077-5625}}</ref> Insulin has steroid-like effects in terms of muscle gains.<ref>{{cite journal | vauthors = Dimitriadis G, Mitrou P, Lambadiari V, Maratou E, Raptis SA | title = Insulin effects in muscle and adipose tissue | journal = Diabetes Research and Clinical Practice | volume = 93 | issue = Suppl 1 | pages = S52-9 | date = August 2011 | pmid = 21864752 | doi = 10.1016/S0168-8227(11)70014-6 }}</ref> It is impossible to promote protein synthesis without the existence of insulin, which means that without ingesting carbohydrates or protein—which also induces the release of insulin—it is impossible to add muscle mass.<ref>{{cite journal | vauthors = Miranda L, Horman S, De Potter I, Hue L, Jensen J, Rider MH | s2cid = 6649224 | title = Effects of contraction and insulin on protein synthesis, AMP-activated protein kinase and phosphorylation state of translation factors in rat skeletal muscle | journal = Pflügers Archiv | volume = 455 | issue = 6 | pages = 1129–40 | date = March 2008 | pmid = 17957382 | doi = 10.1007/s00424-007-0368-2 }}</ref> Bodybuilders seek out [[Glycemic index|low-glycemic]] [[polysaccharide]]s and other slowly digesting carbohydrates, which release energy in a more stable fashion than high-glycemic sugars and starches. This is important as high-glycemic carbohydrates cause a sharp insulin response, which places the body in a state where it is likely to store additional food energy as fat. However, bodybuilders frequently do ingest some quickly digesting sugars (often in form of pure [[Glucose|dextrose]] or [[maltodextrin]]) just before, during, and/or just after a workout. This may help to replenish [[glycogen]] stored within the muscle, and to stimulate muscle protein synthesis.<ref>{{cite web|last=King|first=Michael W.|name-list-style=vanc|title=Substrates for Gluconeogenesis|publisher=IU School of Medicine|url=http://web.indstate.edu/thcme/mwking/gluconeogenesis.html|access-date=March 11, 2007|archive-date=June 21, 2000|archive-url=https://web.archive.org/web/20000621005841/http://web.indstate.edu/thcme/mwking/gluconeogenesis.html|url-status=live}}</ref>

==== Protein ====
[[File:Protein_shake.jpg|thumb|Protein milkshakes, made from protein powder (center) and milk (left), are a common [[bodybuilding supplement|supplement]].]]
The motor proteins [[actin]] and [[myosin]] generate the forces exerted by contracting muscles. [[Cortisol]] decreases amino acid uptake by muscle and inhibits protein synthesis.<ref>{{cite book | vauthors = Manchester KL |chapter=Sites of Hormonal Regulation of Protein Metabolism|chapter-url=https://books.google.com/books?id=EgMwXpQRGQ8C&pg=PA229|pages=229–98 |veditors = Munro HN |year=2012|title=Mammalian Protein Metabolism, Volume 4|publisher=Elsevier |isbn=978-0-323-14257-1}}</ref> Current recommendations suggest that bodybuilders should consume 25–30% of protein per total [[calorie]] intake to further their goal of maintaining and improving their body composition.<ref name="LambertCP">{{cite journal | vauthors = Lambert CP, Frank LL, Evans WJ | s2cid = 17233384 | title = Macronutrient considerations for the sport of bodybuilding | journal = Sports Medicine | volume = 34 | issue = 5 | pages = 317–27 | year = 2004 | pmid = 15107010 | doi = 10.2165/00007256-200434050-00004 }}</ref> This is a widely debated topic, with many arguing that 1 gram of protein per pound of body weight per day is ideal, some suggesting that less is sufficient, while others recommending 1.5, 2, or more.<ref>{{Cite web|date=2004 | author= Samantha Heller|title=Protein: a guide to maximum muscle: confused? Let us separate the gristle from the meat.(Nutrition) |website= Men's Fitness |publisher=HighBeam Research|url=http://www.highbeam.com/doc/1G1-114819458.html|access-date=2023-02-08|archive-url=https://web.archive.org/web/20130703013711/http://www.highbeam.com/doc/1G1-114819458.html |archive-date=July 3, 2013 | url-status=usurped | url-access= subscription }}{{better source needed|date=July 2023| reason = subscription required to deadlinked site}}</ref> It is believed that protein needs to be consumed frequently throughout the day, especially during/after a workout, and before sleep.<ref>"Your nutrition problems solved; This month: pre- and postworkout nutrition, calculating protein intake and adding simple carbs".
''FLEX Magazine'', January 2005</ref> There is also some debate concerning the best type of protein to take. Chicken, turkey, beef, pork, fish, eggs and dairy foods are high in protein, as are some nuts, seeds, beans, and lentils. [[Casein]] or [[Whey protein|whey]] are often used to supplement the diet with additional protein. Whey is the type of protein contained in many popular brands of protein supplements and is preferred by many bodybuilders because of its high [[biological value]] (BV) and quick absorption rates. Whey protein also has a bigger effect than casein on insulin levels, triggering about double the amount of insulin release.<ref>{{cite journal | vauthors = Burd NA, Yang Y, Moore DR, Tang JE, Tarnopolsky MA, Phillips SM | title = Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men | journal = The British Journal of Nutrition | volume = 108 | issue = 6 | pages = 958–62 | date = September 2012 | pmid = 22289570 | doi = 10.1017/S0007114511006271 | doi-access = free }}</ref> That effect is somewhat overcome by combining casein and whey.

Bodybuilders were previously thought to require protein with a higher BV than that of [[soy]], which was additionally avoided due to its alleged [[estrogenic]] (female hormone) properties, though more recent studies have shown that soy actually contains [[phytoestrogens]] which compete with estrogens in the male body and can block estrogenic actions.<ref name="MikeFalcon">{{cite web|last=Falcon|first=Mike | name-list-style = vanc |url=http://www.maxmuscle.com/index.cfm?fa=article&doc_id=116&subcat=science|title=Estrogens, Testosterone & Phytoestrogens|url-status=dead|archive-url=https://web.archive.org/web/20061025023850/http://www.maxmuscle.com/index.cfm?fa=article&doc_id=116&subcat=science|archive-date=October 25, 2006|website=maxmuscle.com}}</ref> Soy, [[flax]], and other plant-based foods that contain phytoestrogens are also beneficial because they can inhibit some [[pituitary]] functions while stimulating the liver's P450 system (which eliminates hormones, drugs, and waste from the body) to more actively process and excrete excess estrogen.<ref name="TestosteroneSyndrome">{{cite book| first1 = Eugene | last1 = Shippen | first2 = William | last2 = Fryer | name-list-style = vanc |title=The testosterone syndrome: the critical factor for energy, health, and sexuality: reversing the male menopause|publisher=M. Evans|location=New York|year=1998|isbn=978-0-87131-829-9|url-access=registration|url=https://archive.org/details/testosteronesynd00euge}}{{page needed|date=May 2015}}</ref>

==== Meals ====
Some bodybuilders often split their food intake into 5 to 7 meals of equal nutritional content and eat at regular intervals (e.g., every 2 to 3 hours). This approach serves two purposes: to limit overindulging in the cutting phase, and to allow for the consumption of large volumes of food during the bulking phase. Eating more frequently does not increase [[Metabolic rate|basal metabolic rate]] when compared to 3 meals a day.<ref>{{cite journal | vauthors = Verboeket-van de Venne WP, Westerterp KR, Kester AD | title = Effect of the pattern of food intake on human energy metabolism | journal = The British Journal of Nutrition | volume = 70 | issue = 1 | pages = 103–15 | date = July 1993 | pmid = 8399092 | doi = 10.1079/BJN19930108 | doi-access = free }}</ref> While food does have a metabolic cost to digest, absorb, and store, called the [[thermic effect of food]], it depends on the quantity and type of food, not how the food is spread across the meals of the day. Well-controlled studies using whole-body calorimetry and [[doubly labeled water]] have demonstrated that there is no metabolic advantage to eating more frequently.<ref name="BellisleF">{{cite journal | vauthors = Bellisle F, McDevitt R, Prentice AM | title = Meal frequency and energy balance | journal = The British Journal of Nutrition | volume = 77 | issue = Suppl 1 | pages = S57-70 | date = April 1997 | pmid = 9155494 | doi = 10.1079/BJN19970104 | doi-access = free }}</ref><ref name="TaylorMA">{{cite journal | vauthors = Taylor MA, Garrow JS | s2cid = 19686244 | title = Compared with nibbling, neither gorging nor a morning fast affect short-term energy balance in obese patients in a chamber calorimeter | journal = International Journal of Obesity and Related Metabolic Disorders | volume = 25 | issue = 4 | pages = 519–28 | date = April 2001 | pmid = 11319656 | doi = 10.1038/sj.ijo.0801572 | doi-access =  }}</ref><ref name="pmid18053311">{{cite journal | vauthors = Smeets AJ, Westerterp-Plantenga MS | title = Acute effects on metabolism and appetite profile of one meal difference in the lower range of meal frequency | journal = The British Journal of Nutrition | volume = 99 | issue = 6 | pages = 1316–21 | date = June 2008 | pmid = 18053311 | doi = 10.1017/S0007114507877646 | doi-access = free }}</ref>

==== Dietary supplements ====
{{Main|Bodybuilding supplement}}
The important role of nutrition in building muscle and losing fat means bodybuilders may consume a wide variety of [[dietary supplements]].<ref>{{cite journal | vauthors = Philen RM, Ortiz DI, Auerbach SB, Falk H | title = Survey of advertising for nutritional supplements in health and bodybuilding magazines | journal = JAMA | volume = 268 | issue = 8 | pages = 1008–11 | date = August 1992 | pmid = 1501305 | doi = 10.1001/jama.268.8.1008 }}</ref> Various products are used in an attempt to augment muscle size, increase the rate of fat loss, improve joint health, increase natural testosterone production, enhance training performance and prevent potential nutrient deficiencies.

=== 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>

=== Rest ===
Although muscle ''stimulation'' occurs when lifting weights, muscle ''growth'' occurs during rest periods for up to 48 hours after the workout.<ref>{{Cite journal |last1=MacDougall |first1=J. Duncan |last2=Gibala |first2=Martin J. |last3=Tarnopolsky |first3=Mark A. |last4=MacDonald |first4=Jay R. |last5=Interisano |first5=Stephen A. |last6=Yarasheski |first6=Kevin E. |date=1995-12-01 |title=The Time Course for Elevated Muscle Protein Synthesis Following Heavy Resistance Exercise |url=http://www.nrcresearchpress.com/doi/10.1139/h95-038 |journal=Canadian Journal of Applied Physiology |language=en |volume=20 |issue=4 |pages=480–486 |doi=10.1139/h95-038 |pmid=8563679 |issn=1066-7814}}</ref><ref>{{cite web |last1=Braverman |first1=Jody |title=When Do Muscles Grow After Working Out With Weights? |url=https://www.livestrong.com/article/406021-when-do-muscles-grow-after-working-out-with-weights/ |website=livestrong |access-date=2 March 2024 |archive-url=https://web.archive.org/web/20230924094855/https://www.livestrong.com/article/406021-when-do-muscles-grow-after-working-out-with-weights/ |archive-date=24 September 2023 |language=en |date=10 April 2019 |quote=It's after you finish your workout…that your body is busy making new muscle protein. |url-status=live}}</ref> Some bodybuilders add a [[massage]] at the end of each workout to their routine as a method of recovering.<ref>{{cite book|last1=Shusterman|first1=Richard | name-list-style = vanc |title=Thinking Through the Body: Essays in Somaesthetics|date=2012|page=43|publisher=Cambridge University|isbn=978-1107019065}}</ref>

=== Overtraining ===
{{Main|Overtraining}}
Overtraining occurs when a bodybuilder has trained to the point where their workload exceeds their recovery capacity. There are many reasons why overtraining occurs, including lack of adequate nutrition, lack of recovery time between workouts, insufficient sleep, and training at a high intensity for too long (a lack of splitting apart workouts). Training at a high intensity too frequently also stimulates the [[central nervous system]] (CNS) and can result in a hyperadrenergic state that interferes with sleep patterns.<ref name="LonnieLowery_Overtraining">{{Cite web|date=2004| author = Lonnie Lowery | title= The Warrior Nerd: Overtraining or Undereating, part 1|work=TESTOSTERONE! NATION|url=http://www.t-nation.com/readTopic.do?id=459318|access-date=2023-02-08|archive-url=https://web.archive.org/web/20070927191307/http://www.t-nation.com/readTopic.do?id=459318 |archive-date=September 27, 2007 | url-status= dead }}</ref> To avoid overtraining, intense frequent training must be met with at least an equal amount of purposeful recovery. Timely provision of [[carbohydrate]]s, [[Protein (nutrient)|protein]]s, and various micronutrients such as [[vitamin]]s, [[Dietary mineral|minerals]], phytochemicals, even nutritional supplements are critical. A mental disorder, informally called [[bigorexia]] (by analogy with [[anorexia]]), may account for overtraining in some individuals. Sufferers feel as if they are never big enough or muscular enough, which forces them to overtrain to try to reach their goal physique.<ref>{{cite journal | vauthors = Mosley PE | title = Bigorexia: bodybuilding and muscle dysmorphia | journal = European Eating Disorders Review | volume = 17 | issue = 3 | pages = 191–8 | date = May 2009 | pmid = 18759381 | doi = 10.1002/erv.897 | s2cid = 20128770 }}</ref>

An article by ''[[Muscle & Fitness]]'' magazine, "Overtrain for Big Gains", claimed that overtraining for a brief period can be beneficial. Overtraining can be used advantageously, as when a bodybuilder is purposely overtrained for a brief period of time to super compensate during a regeneration phase. These are known as "shock micro-cycles" and were a key training technique used by Soviet athletes.<ref name="pmid14719980">{{cite journal | vauthors = Smith DJ | s2cid = 2021999 | title = A framework for understanding the training process leading to elite performance | journal = Sports Medicine | volume = 33 | issue = 15 | pages = 1103–26 | date = February 2003 | pmid = 14719980 | doi = 10.2165/00007256-200333150-00003 | url = http://www.pgedf.ufpr.br/Smith%20SpMed%202003%20%20SG%20%20DEspor%201.pdf | archive-url = https://web.archive.org/web/20170809052905/http://www.pgedf.ufpr.br/Smith%20SpMed%202003%20%20SG%20%20DEspor%201.pdf | archive-date = August 9, 2017 | url-status = live }}</ref>