Fytotherapie‎ > ‎

Sport

HISTORY OF HERBS IN SPORTS

Public disapproval of doping increases with each news report of an athlete’s failed drug test. The stance of official organizations reflects this, as WADA vowed to collect 5,000 samples in order to make the London Games the most tested and allegedly “cleanest” Olympics ever.1 Still, doping scandals continue and some might find themselves reminiscing about a time when all athletes performed their sports wholesomely and without any outside aid.
What many spectators do not realize, however, is that the practice of ingesting substances — often botanicals — with the hopes of enhancing sports performance has existed to some extent for thousands of years.2 In fact, athletes were never tested for performance-enhancing substances and illegal drugs until the 1960s, when the death of a Danish cyclist, who passed out while riding and had a severe crash, was attributed to an amphetamine overdose.2,3

The Ancient Greeks are reported to have ingested herbs and fungi for performance enhancement, as well as to have used honey to boost energy and carbohydrate levels.2 Physicians gave Olympic athletes bread prepared with spices and juices extracted from the poppy, and Roman gladiators allegedly ingested caffeine and the bitter alkaloid strychnine from the nux-vomica tree (Strychnos nux-vomica, Loganiaceae). The Roman naturalist Pliny the Younger (61 – 12 CE) recorded that runners would attempt to increase their muscle mass and strength by consuming a plant called mare’s tail (Hippuris vulgaris, Hippuridaceae).
According to John Riddle, PhD, a history and botany professor at North Carolina State University and an expert on the use of botanicals during ancient times through Classical Antiquity, the 1st century Greek physician Galen, who attended to Roman emperor Marcus Aurelius, got his start as a doctor for gladiators (email, July 18, 2012). Dr. Riddle’s 1997 book, Eve’s Herbs: A History of Contraception and Abortion in the West, reports that Galen wrote of “an athletic trainer [who] required his men to sleep on a botanical bed of chaste tree [Vitex agnus-castus, Lamiaceae],”4 which was a reputed male contraceptive and erectile function preventative, in order to preserve their energy.*

Centuries later, in the late 1800s, an American long-distance walking athlete reportedly chewed coca leaves during a trek of approximately 110 miles completed within 24 hours.5 Additional performance-enhancing substances during this period typically consisted of “sugar cubes dipped in ether, mixtures of brandy and cocaine, caffeine, cordials containing alcohol, and even nitroglycerine and strychnine.”6

During the 1950s, the Union of Soviet Socialist Republics (USSR) began to study adaptogenic substances, including many herbs, with the goal of enhancing performance and work output of athletes, soldiers, and government workers.7 According to the book Adaptogens: Herbs for Strength, Stamina, and Stress Relief(Healing Arts Press, 2007) by David Winston and Steven Maimes, “The Soviets’ pursuit of superior military strength, performance in the Olympic Games, political power, and the excellence of the well known Bolshoi Ballet mattered so much to them that whatever they could do to accomplish the goal of dominance was pursued.” Of the approximately 4,000 plants investigated, 12 herbs were considered adaptogens, including Siberian ginseng (now sold in the United States as “eleuthero”; Eleutherococcus senticosus, Araliaceae), rhodiola, and schisandra (Schisandra spp., Schisandraceae). Government scientists studied these herbs in Olympic athletes, miners, truck drivers, factory workers, and more, with results indicating improved physical performance and lower rates of sickness and fatigue, although the results published in Russian-language journals are difficult to access. One of the lead researchers of the Soviet adaptogens project, Israel I. Brekhman, created a multi-herb adaptogen product (sometimes marketed in the United States as “Prime One®”), which was reportedly used by more than 100 American athletes at the 1996 Atlanta Olympic Games.

 


References

1. Wilson S. 9 athletes suspended for doping in lead-up, 2 new procedures at ‘most tested’ Olympics ever. The Washington Post. July 25, 2012. Available at:www.washingtonpost.com/sports/9-athletes-suspended-for-doping-in-lead-up-2-new-procedures-at-most-tested-olympics-ever/2012/07/25/gJQAnMwW9W_story.html.
2. Papagelopoulos PJ, Mavrogenis AF, Soucacos PN. Doping in Ancient and Modern Olympic Games. Orthopedics. 2004;27(12). Available at:www.healio.com/orthopedics/journals/ORTHO/%7B938E8E86-5151-451A-BD36-CAB0E26D9746%7D/Doping-in-Ancient-and-Modern-Olympic-Games. Accessed July 25, 2012.
3. Aschwanden C. The top athletes looking for an edge and the scientists trying to stop them. Smithsonian magazine. July-August 2012. Available at:www.smithsonianmag.com/science-nature/The-Top-Athletes-Looking-for-an-Edge-and-the-Scientists-Trying-to-Stop-Them-160284335. html. Accessed July 26, 2012.
4. Riddle J. Eve’s Herbs: A History of Contraception and Abortion in the West. Cambridge, Massachusetts: Harvard University Press. 1997.
5. Heggie V. Sports doping, Victorian style. The Guardian. June 19, 2012. Available at: www.guardian.co.uk/science/blog/2012/jun/19/sports-doping-victorian-style. Accessed July 26, 2012.
6. Ravilious K. Barry Bonds steroid debate highlights history of drugs in sports. National Geographic News. June 22, 2007. Available at:http://news.nationalgeographic.com/news/2007/06/070622-barry-bonds.html. Accessed July 25, 2012.7. Winston D, Maimes S. Adaptogens: Herbs for Strength, Stamina, and Stress Relief. Rochester, Vermont : Healing Arts Press. 2007.



The Illegal and Legal Uses of Botanicals in Sports

Although the term doping carries a negative connotation, it does not always indicate that a substance is harmful. According to WADA, which publishes an annual document listing the substances banned in sports competitions worldwide, a substance will be prohibited if it meets at least 2 of the following criteria: “1) It has the potential to enhance or enhances sport performance, 2) It represents an actual or potential health risk to the athlete, or 3) It violates the spirit of sport.”26

Of the approximately 200 substances and methods on WADA’s 2012 Prohibited List, only one whole botanical is prohibited: cannabis (Cannabis spp., Cannabaceae). WADA additionally prohibits the use of several botanical derivatives and their synthetic counterparts, including the stimulants ephedrine, methylephedrine, and pseudoephedrine, all of which come from ephedra (Ephedra spp., Ephedraceae); the stimulant cocaine, which comes from coca (Erythroxylum coca, Erythroxylaceae); the stimulant cathine, which comes from the African medicinal plant khat (Catha edulis, Celastraceae); and morphine and diamorphine (heroin), which are derived from the opium poppy (Papaver somniferum, Papaveraceae) and considered by WADA to be narcotics. (All of the above are illegal in dietary supplements in the United States).

Instances in which botanicals are implicated in doping sometimes make headlines. Most recently, on August 6, 2012, an American judo fighter was sent home from the 2012 London Olympics after testing positive for cannabis, which he claimed was due to eating a cannabis brownie.27 Although it seems rather surprising that an athlete would consume the widely illegal substance, the Anti-Doping Database reveals that cannabis has been implicated in about 38 failed doping tests since 1997,28 likely due to its recreational popularity. Several cases document South American soccer players testing positive for cocaine and morphine and attributing it to drinking traditional Bolivian coca leaf tea and eating poppy seed bread, respectively.29 Again in 2011 — even after poppy seeds’ effects were made famous by an episode of the television comedy Seinfeld in which the sitcom’s character Elaine fails a drug test after eating poppy seed muffins — a New Zealand triathlete tested positive for morphine and argued that he had consumed poppy seed bread.30 Studies have confirmed that consuming the parent plant or parts of the parent plant can yield traces of these isolated substances, and sometimes officials sympathize with the athletes’ claims by reducing penalties or completely exonerating them.29,30 Still, these cases are seldom.

“Adequate information does not exist to support the view that sports doping with botanical materials is an issue,” said AHPA’s Dr. Dentali. “Ephedrine-containing products are not allowed in foods, including dietary supplements in the United States. Most everyone is aware that poppy seeds may trigger a positive drug test, and generally speaking athletes are smart enough to know that drinking coca leaf tea might produce the same result” (e-mail, July 30, 2012). (A peer reviewer of this article noted that in Canada, low-dose ephedrine hydrochloride [8 mg] as well as the herb ephedra are widely available for purchase as licensed natural health products [NHPs]. NHPs, which include vitamins, minerals, herbs, homeopathic preparations, and more, are regulated as a special class of drugs in Canada, not as the United States regulates dietary supplements, which are considered foods.)

Coca, ephedra, and khat are the only traditionally used herbs whose derivatives are explicitly prohibited in sports, and the testing of additional herbs or other medicinally active plants for performance-enhancing properties is not common nor easy due to their complex chemistry and pharmacology.31 Because different countries have a more accurate and detailed knowledge of culturally used herbs and substances, each can issue warnings for any botanical products suspected of affecting doping test results.

“There are many specialized, local botanical products used traditionally around the world, and monitoring them and their use is something left up to the local regulatory body,” said NSF’s Wyszumiala (email, July 20, 2012).

During the 2008 Beijing Olympics, for example, the Chinese Olympic Committee decided to forgo the use of traditional Chinese medicine (TCM) to treat athletes in order to avoid potential doping problems, and also banned products containing the herb Chinese angelica, or dong quai (Angelica sinensis, Apiaceae) for the same reasons.31

WADA previously prohibited the botanical stimulant caffeine,32 which is found in many common food plants including coffee (Coffea arabica, Rubiaceae), chocolate (Theobroma cacao, Sterculiaceae), and tea (Camellia sinensis, Theaceae), as well as the popular Argentinian herbal beverage yerba maté (Ilex paraguariensis, Aquifoliaceae), among others. During this ban, athletes could not have 12 mg or more of caffeine per liter of urine. This would be caused by drinking at least 5 cups of coffee, at least 6 cups of tea, or eating 2-3 chocolate bars shortly preceding the collection of urine samples.29 In 2004, WADA lifted its ban on caffeine, stating that it is “ubiquitous in beverages and food” and “metabolized at very different rates in individuals.”32 Caffeine remains on the organization’s monitoring list, and some WADA officials continue to express concerns for the stimulant, especially when formulated in high-dosage pills.33
“Herbal or plant-derived stimulants can be a very interesting dilemma,” said Oliver Catlin. “Some things like ephedrine are clearly banned, while other plant-derived stimulants like theobromine, which is in chocolate, are not considered banned. For an athlete, the pathway of determining what is or is not legal is challenging especially when the language in the stimulant section of the WADA Prohibited List includes, ‘and other substances with a similar chemical structure or similar biological effect(s).’ Determining what does or doesn’t qualify under this clause can be a difficult job, and a moving target.”
Even in regards to dietary and herbal supplements that are legal for use in sports, such as caffeine, many critics claim that athletes can receive all their nutritional and performance needs from diet and that there is no evidence these products actually work. In September 2012, for example, the Chief Medical Officer of Fédération Internationale de Football Association (FIFA) told the media that soccer players’ widespread usage of dietary supplements was “alarming” because it is “definitely not based upon the scientific evidence or literature.”34 He continued, “Scientists and nutritional specialists agree that a well-balanced diet will supply the body with the appropriate amount of nutrients it needs for top performance.”

WADA and IAAF take similar positions.
“Athletes do not necessarily need supplements,” said Dr. Dollé of IAAF . “As a question of principle, we never engaged in recommending or advising supplements. Firstly, because it would not be consistent with our consensus statement, secondly, because we do not have the resources to test the supplements.”

Some criticize anti-doping organizations for their one-way, hard-line stance against supplements.
“That mentality is certainly understandable as they don’t want athletes to get caught up with inadvertent positive tests,” said Catlin, “but is not in line with the reality that we face today, namely that athletes do take and will continue to take dietary supplements. The reality is that many supplements are indeed fine to take, while others can lead to positive drug tests and health complications. I really do appreciate [anti-doping organizations’] position and of course worked with them myself for many years. I just wish they could take a broader look at the supplement issue and accept the realities that athletes use them. I believe that if they did accept supplements and could help athletes find natural and safe alternatives to drugs that it would create trust and could help the anti-doping cause.”

It is also important to assess the accuracy of anti-doping groups’ claims of supplement inefficacy. A review of the evidence suggests some botanical supplementscan produce performance-enhancing effects. According to a 2012 article, “Herbs in Exercise and Sports,” published in the Journal of Physiological Anthropology, caffeine is documented as improving athletic performance in swimmers, endurance runners, and cyclists, as well as improving mental alertness.35 The International Society of Sports Nutrition’s (ISSN) 2010 recommendations for athletic supplements list caffeine as being “apparently effective,” which the authors define as, “supplements that help people meet general caloric needs and/or the majority of research studies in relevant populations show is effective and safe.”36 The authors continued, “Suggestions that there is no ergogenic value to caffeine supplementation [are] not supported by the preponderance of available scientific studies.”
ISSN recommended green tea extract as “possibly effective” (defined as “supplements with initial studies supporting the theoretical rationale but requiring more research to determine how the supplement may affect training and/or performance”) for its ability to increase energy expenditure in humans and possible use for weight loss.36

Ginseng, one of the most commonly marketed herbs for athletes, also has been referred to as the most studied herb for performance enhancement. Research has shown various species of ginseng, particularly Asian ginseng (P. ginseng), to increase exercise endurance, lower blood pressure, support oxygen consumption, abbreviate post-exercise recovery, enhance chest and leg strength, and reduce stress responses through its adaptogenic properties.35,37 Other studies, however, have found no significant effects on physical performance.38 (One review article suggested that many of the ginseng trials used a relatively low dosage level, i.e., usually those equivalent to about 8 mg total ginsenosides per day, compared to higher dosage levels used in traditional Chinese medicine.39)

The Australian Institute of Sport (AIS) lists beet (Beta vulgaris, Chenopodiaceae) root juice as a Class B supplement (“Considered for provision to AIS athletes under a research protocol”) presumably due to its nitrate contents and several studies showing that consuming beetroot juice prior to exercise can enhance performance.40 Furthermore, a 2010 double-blind, controlled clinical trial, published in the Journal of the International Society of Sports Nutrition, found that male weightlifters taking a fenugreek extract (Trigonella foenum-graecum, Fabaceae; Torabolic™, Indus Biotech) experienced significantly increased “upper- and lower-body strength and body composition in comparison to placebo” and had no side effects.41 Another study on TestoSurge®, a fenugreek extract, found that it increased testosterone levels and the bioavailability of testosterone when compared to placebo.42

According to 2 studies, ginger (Zingiber officinale, Zingiberaceae) root extract has been shown to improve pain and joint stiffness in osteoarthritic individuals after standing and walking.5 A study on rhodioloa (Rhodiola rosea, Crassulaceae) root extract, which is marketed for athletic-enhancing functions in the United States, reported that an acute dosage (200 mg) significantly increased endurance and somewhat increased oxygen intake in participants completing 17 minutes of cycling,5although this effect was no different than placebo after 4 weeks of taking the supplement.43 A small study examining the use of an extract made from the traditional Chinese herb astragalus (Astragalus membranaceus, Fabaceae) determined that it improved athletic endurance, though the study was criticized for its lack of standardization.5 A 1997 study on cayenne pepper (Capsicum spp., Solanaceae) taken by male long-distance runners found it increased “respiratory exchange ratio and blood lactate concentration both at rest and during exercise,” but that it had “no effect on oxygen consumption or energy expenditure.”38

Several additional herbs exhibit the ability to decrease pain, inflammation, and other conditions that can negatively affect athletic performance, but have not been studied specifically in athletic situations.5 Additional research has found no effect in athletic performance for some herbs, including cordyceps (Cordyceps sinensisand C. spp., Clavicipitaceae), yohimbe (Pausinystalia johimbe, Rubiaceae), puncture vine (Tribulus spp., Zygophyllaceae), and Eurycoma longifolia (Simaroubaceae) root, possibly due to short supplementation period and/or low concentration of E. longifolia.5,35,37 More studies are warranted to support the initial investigations into botanicals’ effects on sports and athletic performance.

According to Almada, most clinical trials performed on botanicals and other dietary supplements for sports performance “lack a key investigative, due diligence step” — testing the study’s products for banned substances.
“Is it not sufficiently inspiring to the crafty, unscrupulous marketer to have a ‘special batch’ made just for a study, adulterated with a ‘special ingredient’ since the university research lab invariably does not have the capability, nor intent, to analyze what is being studied for banned substances? Testing study products for banned substances, by an expert independent lab, should be standard protocol before undertaking the study.”

Conclusion
The relationship between professional athletes and dietary and herbal supplements is nothing less than complex. Despite the oft-negative representation and reputation of dietary supplements in and among mainstream media outlets as well as major sporting and anti-doping organizations, little hard evidence proves that herbal dietary supplements pose a risk in this context. Some evidence even suggests that various botanicals can have safe, beneficial effects on athletic performance. Still, evidence fails to exonerate all cases of potentially intentional adulteration by dietary supplement manufacturers. In order to progress toward resolving these issues, responsible parts of the dietary supplements industry, analysis labs, sports and anti-doping organizations, and the media must collaborate to support athletes through education, vigilance, and open-mindedness toward the reality of the situation.

*See feature article “New Research Supports Synthetic Origin of DMAA in Supplements” in HerbalGram 95 for more details on this topic.

References

1. Phelps sets record for Olympic medals. New York Daily News. July 31, 2012. Available at: http://articles.nydailynews.com/2012-07-31/news/32966485_1_michael-phelps-yannick-agnel-ricky-berens. Accessed September 14, 2012.
2. Tymn M. Mile trivia. Running Times Magazine. May 2004. Available at: http://runningtimes.com/Article.aspx?ArticleID=6385&PageNum=&CategoryID=. Accessed September 14, 2012.
3. Ross S. Douglas wins gold in gymnastics individual all-around. NBC News. August 2, 2012. Available at: www.nbcchicago.com/news/sports/Gabrielle-Douglas-and-Aly-Raisman-164740506.html. Accessed September 14, 2012.
4. Rise in supplement use by US adults. Natural Products Insider. April 13, 2011. Available at: www.naturalproductsinsider.com/articles/2011/04/rise-in-supplement-use-by-us-adults.aspx. Accessed September 14, 2012.
5. Kundrt S. Herbs and athletes. Gatorade Sports Science Institute. Sports Science Exchange 96. 2005;18(1). Available at: www.gssiweb.com/Article_Detail.aspx?articleid=704. Accessed September 14, 2012.
6. Aschwanden C. Athletes, stop taking supplements. Slate magazine. July 26, 2012. Available at:www.slate.com/articles/health_and_science/medical_examiner/2012/07/dietary_supplements_at_the_olympics_why_athletes_risk_false_drug_charges_.html. Accessed September 14, 2012.
7. Linford Christie. United Kingdom Athletics website. Available at: www.uka.org.uk/e-inspire/hall-of-fame-athletes/linford-christie/. Accessed August 22, 2012.
8. About WADA. World Anti-Doping Agency website. Available at: www.wada-ama.org/en/About-WADA/. Accessed June 25, 2012.
9. World Anti-Doping Code. World Anti-Doping Agency. 2009. Available at: www.wada-ama.org/Documents/World_Anti-Doping_Program/WADP-The-Code/WADA_Anti-Doping_CODE_2009_EN.pdf. Accessed September 14, 2012.
10. Questions & answers on strict liability in anti-doping. World Anti-Doping Agency website. Available at: www.wada-ama.org/en/Resources/Q-and-A/Strict-Liability-in-Anti-Doping/. Accessed July 26, 2012.
11. World Anti-Doping Agency (WADA) v. Jessica Hardy & United States Anti-Doping Agency (USADA). CAS 2009/A/1870. Arbitral Award delivered by the Court Of Arbitration For Sport.
12. Jessica Hardy events and results. London 2012 Olympic and Paralympic Games website. Available at: www.london2012.com/athlete/hardy-jessica-1134700/events/. Accessed September 14, 2012.
13. Abrahamson A. Jessica Hardy, AdvoCare file suit against each other. Swimming World Magazine. January 30, 2009. Available at:www.swimmingworldmagazine.com/lane9/news/20137.asp. Accessed September 14, 2012.
14. Burke L. Positive drug tests from supplements. SportsScience. 2000;4(3). Available at: http://www.sportsci.org/jour/0003/lmb.html. Accessed September 14, 2012.
15. Smith T. New research suggests synthetic origin of DMAA in supplements. HerbalGram. 2012; (95):46-49. Available at:http://cms.herbalgram.org/herbalgram/issue95/hg95-feat-dmaa.html.
16. Starling S. London Olympics 2012: DMAA responsible for 1 of 8 doping busts. NutraIngredients. August 14, 2012. Available at:www.nutraingredients.com/Regulation/London-Olympics-2012-DMAA-responsible-for-1-of-8-doping-violations. Accessed September 14, 2012.
17. Advanced search: methylhexaneamine. Anti-Doping Database website. Available at: www.dopinglist.com. Accessed August 17, 2012.
uilding.com execs fined for selling steroids. Natural Products Insider. August 2, 2012. Available at:www.naturalproductsinsider.com/news/2012/08/bodybuilding-com-execs-fined-for-selling-steroids.aspx. Accessed September 14, 2012.
19. Kim J, Chun Y-S, Kang S-K, Cho H-C. The use of herbal/traditional products supplementation and doping tests in elite athletes. Int J Appl Sports Sci. 2010;22(2):137-149.
20. Banned Substances Control Group website. Available at: www.bscg.org. Accessed September 14, 2012.
21. SPORT SAFE Testing Service website. Available at: www.sportsafe.com. Accessed September 14, 2012.
22. How to get certified. NSF Certified for Sport website. Available at: www.nsfsport.com/how_certified.asp. Accessed July 25, 2012.
23. Certified for Sport companies. NSF International website. Available at: www.nsf.org/Certified/consumer/listings_results.asp?KeyWords=&ProgramCode=BANNEDSUB&CompanyName=&ProductName=&SearchType=QUICK&prog_add=N&ShowCompany=N&p_special=ABS&p_abs=Y. Accessed July 25, 2012.
24. KeepSupplementsClean website. Available at www.keepsupplementsclean.org. Accessed September 14, 2012.
25. Sens. Hatch and Whitehouse introduce Anabolic Steroids Control Act; AHPA endorses legislation [press release]. Silver Spring, MD: American Herbal Products Association. July 25, 2012. Available at: www.ahpa.org/Default.aspx?tabid=69&aId=803.
26. The 2012 Prohibited List International Standard. The World Anti-Doping Code, World Anti-Doping Agency. August 24, 2011. Available at: www.wada-ama.org/Documents/World_Anti-Doping_Program/WADP-Prohibited-list/2012/WADA_Prohibited_List_2012_EN.pdf. Accessed October 3, 2012.
27. U.S. judoka expelled for marijuana. Reuters. August 6, 2012. Available at: http://www.nbcolympics.com/news-blogs/judo/u-s-judoka-expelled-for-marijuana.html. Accessed September 14, 2012.
28. Advanced search: cannabis and marijuana. Anti-Doping Database website. Available at: www.dopinglist.com. Accessed August 17, 2012.
29. Yonamine M, Garcia PR, de Moraes Moreau RL. Non-Intentional Doping in Sports. Sports Med. 2004;34(11):697-704.
30. Graham O’Grady blames poppy seeds for doping glitch. Triathlete.com. March 24, 2011. Available at: http://triathlon.competitor.com/2011/03/news/graham-ogrady-blames-poppy-seeds-for-doping-glitch_24598. Accessed July 26, 2012.
31. Stafford L. Concerns over use of African herbs during the 2010 World Cup. HerbalGram. 2010;(86):24-25. Available at:http://cms.herbalgram.org/herbalgram/issue86/article3520.html.
32. What is the status of caffeine? Questions and answers on 2012 Prohibited List. World Anti-Doping Agency website. Available at: www.wada-ama.org/en/Resources/Q-and-A/2012-Prohibited-List/. Accessed July 25, 2012.
33. Habashy A. AOC warns of caffeine use amid Stilnox ban. Yahoo!7 Sport. July 3, 2012. Available at: http://au.sports.yahoo.com/news/aoc-warns-caffeine-amid-stilnox-070548712.html. Accessed October 3, 2012.
34. Nieburg O. FIFA chief medical officer attacks food supplements. NutraIngredients. September 6, 2012. Available at: www.nutraingredients.com/Regulation/FIFA-chief-medical-officer-attacks-food-supplements. Accessed September 14, 2012.
35. Chen CK, Muhamad AS, Ooi FK. Herbs in exercise and sports. J Physio Anthropol. 2012;31(1):4. Available at: www.jphysiolanthropol.com/content/31/1/4. Accessed October 3, 2012.
36. Kreider R, Wilborn D, Taylor L, et al. ISSN exercise & sport nutrition review: research & recommendations. J Int Soc Sports Nutr. 2010;7(7). Available at:www.jissn.com/content/7/1/7. Accessed October 3, 2012.
37. Bucci L. Selected herbals and human exercise performance. Am J Clin Nutr. 2000;72(suppl):624S–36S.
38. Williams M. Dietary supplements and sports performance: herbals. J Int Soc Sports Nutr. 2006; 3(1):1-6.
39. Dharmananda S. The nature of ginseng: traditional use, modern research, and the question of dosage. HerbalGram. 2002;(54):34-51.
40. Beetroot juice/nitrate website fact sheet. Australian Institute of Sport. Australian Sports Commission. Available at:www.ausport.gov.au/__data/assets/pdf_file/0009/466029/Beetroot_juice_Nitrate_11-_website_fact_sheet.pdf. Accessed September 14, 2012.
41. Poole C, Bushey B, Foster C, et al. The effects of a commercially available botanical supplement on strength, body composition, power output, and hormonal profiles in resistance-trained males. J Int Soc Sports Nutr. 2010;7(34).
42. Wilborn C, Taylor L, Poole C, et al. Effects of a purported aromatase and 5 x-reductase inhibitor on hormone profiles in college-age men. Int J Sport Nutr Exerc Metab. 2010;20(6):457-465.
43. De Bock K, Eijnde BO, Ramaekers M, Hespel P. Acute Rhodiola rosea intake can improve endurance exercise performance. Int J Sport Nutr Exerc Metab. 2004 Jun;14(3):298-307.

Comments