Performance-enhancing substance
Performance-enhancing substances, also known as performance-enhancing drugs (PEDs),[1] are substances that are used to improve any form of activity performance in humans. A well-known example involves doping in sport, where banned physical performance-enhancing drugs are used by athletes and bodybuilders. Athletic performance-enhancing substances are sometimes referred to as ergogenic aids.[2][3] Cognitive performance-enhancing drugs, commonly called nootropics,[4] are sometimes used by students to improve academic performance. Performance-enhancing substances are also used by military personnel to enhance combat performance.[5]
The use of performance-enhancing drugs spans the categories of legitimate use and substance abuse.
Definition[edit]
The classifications of substances as performance-enhancing substances are not entirely clear-cut and objective. As in other types of categorization, certain prototype performance enhancers are universally classified as such (like anabolic steroids), whereas other substances (like vitamins and protein supplements) are virtually never classified as performance enhancers despite their effects on performance. As is usual with categorization, there are borderline cases; caffeine, for example, is considered a performance enhancer by some but not others.[6]
Types[edit]
The phrase has been used to refer to several distinct classes of drugs:
- Anabolic drugs build up muscle; examples include: steroids,[7] hormones, most notably human growth hormone, as well as some of their prodrugs,[8] selective androgen receptor modulators[9] and beta-2 agonists.[10][11]
- Stimulants improve focus and alertness. Low (therapeutic) doses of dopaminergic stimulants (e.g., reuptake inhibitors and releasing agents) also promote mental and athletic performance, as cognitive enhancers and ergogenic aids respectively, by improving muscle strength and endurance while decreasing reaction time and fatigue;[3][12][13] some examples of athletic performance-enhancing stimulants are caffeine,[2] ephedrine, methylphenidate and amphetamine.[3][12][13][14][15]
- Ergogenic aids, or athletic performance-enhancing substances, include a number of drugs with various effects on physical performance. Drugs such as amphetamine and methylphenidate increase power output at constant levels of perceived exertion and delay the onset of fatigue,[14][15][16] among other athletic-performance-enhancing effects;[3][12][13] bupropion also increases power output at constant levels of perceived exertion, but only during short term use.[16] Creatine, a nutritional supplement that is commonly used by athletes, increases high-intensity exercise capacity.[17]
- Human biomolecules – creatine and β-hydroxy β-methylbutyrate are naturally occurring compounds in humans that have well-established ergogenic effects and effects on body composition when supplemented.[18]
- Adaptogens are plants that support health through nonspecific effects, neutralize various environmental and physical stressors while being relatively safe and free of side effects.[19] As of 2008, the position of the European Medicines Agency was that "The principle of an adaptogenic action needs further clarification and studies in the pre-clinical and clinical area. As such, the term is not accepted in pharmacological and clinical terminology that is commonly used in the EU."[20]
- Nootropics, or "cognition enhancers", benefit overall cognition by improving memory (e.g., increasing working memory capacity or updating) or other aspects of cognitive control (e.g., inhibitory control, attentional control, attention span, etc.).[4][21]
- Painkillers allow performance beyond the usual pain threshold. Some painkillers raise blood pressure, increasing oxygen supply to muscle cells. Painkillers used by athletes range from common over-the-counter medicines such as NSAIDs (such as ibuprofen) to powerful prescription narcotics.
- Sedatives and anxiolytics are sometimes used in sports like archery which require steady hands and accurate aim, and also to overcome excessive nervousness or discomfort. Diazepam and propranolol are common examples; ethanol and cannabis are also used occasionally.
- Blood boosters (blood doping agents) increase the oxygen-carrying capacity of blood beyond the individual's natural capacity. They are used in endurance sports like long-distance running, cycling, and Nordic skiing. Recombinant human erythropoietin (rhEPO) is one of the most widely known drugs in this class.[18]
- Gene doping agents are a relatively recently described class of athletic performance-enhancing substances.[18] These drug therapies, which involve viral vector-mediated gene transfer, are not known to currently be in use as of April 2015[update].[18]
History[edit]
While the use of PEDs has expanded in recent times, the practice of using substances to improve performance has been around since the Ancient Olympic Games.[22] In the Olympic Games of 668 BC, Charmis had consumed a diet consisting of dried figs which was a significant factor in winning the 200-yard stade race.[23] Ancient Greek athletes at the time also incorporated stimulants such as wine and brandy into their training routines.[24] Stimulants derived from plants (e.g., Cola Nitida, Bufotein, etc.) were used by the Roman Gladiators to overcome injuries and fatigue.[25]
In the late 19th century as modern medicine and pharmacology were developing, PEDs saw an increase in use.[26] Supplements were now exclusively being used to enhance muscular work capacity.[26] The main stimulants being used included alcoholic drinks, caffeine, and mixtures created by the athletic trainers (e.g., strychnine tablets made of cocaine and brandy).[27] Testosterone was also a commonly taken stimulant, however, it was more difficult to obtain.[27] In 1889, a three-week program began where an athlete injected themselves with blood from the testicular veins, semen, and fluids from the testicles of a dog or guinea pig.[28] By 1895, it had been assessed that testicular extracts did in fact improve athletic performance by increasing muscular strength.[29]
In the 20th century, testosterone was isolated and characterized by scientists.[30] In 1941, the first record of synthesized testosterone use occurred when a horse was given testosterone which successfully improved its race performance.[28] Sports trainers soon after began advocating for testosterone use.[30] Images of bodybuilders with massive muscles began circulating which further perpetuated a desire among athletes to use testosterone.[28][30]
In the 1980s, the main PEDs were cortisone and anabolic steroids.[31] In 1988, the United States Congress establishes the Anti-Drug Abuse Act to criminalize the distribution and possession of non-medical anabolic steroids.[32] In 1999, the world anti-doping agency (WADA) was formed to address the escalating use of substances in sports, particularly after the 1998 doping scandal in cycling.[32]
Risk factors[edit]
Adolescents are the most vulnerable group when it comes to taking performance-enhancing substances.[33] This is in part due to the significance placed on physical appearance by this age group as well as feelings of invincibility combined with a lack of knowledge surrounding long-term consequences.[33] Studies have shown that the most common gendered risk factors include being an adolescent female dissatisfied with their body weight or an adolescent male who perceives larger body sizes as the ideal.[34] Having a negative body image or a history of depression can also be a significant risk factor.[34] These are further exacerbated by parental pressures surrounding appearance, media influence, and peer pressure.[33][35] Studies show that adolescent males who engage with fitness magazines are twice as likely to use performance-enhancing substances.[35] Adolescents who partake in competitive sports are at a particularly high risk, with those involved in football, basketball, wrestling, baseball, and gymnastics at the top.[35]
Usage in sport[edit]
In sports, the phrase performance-enhancing drugs is popularly used in reference to anabolic steroids or their precursors (hence the colloquial term "steroids"); anti-doping organizations apply the term broadly.[36] There are agencies such as WADA and USADA that try to prevent athletes from using these drugs by performing drug tests. WADA was founded on 10 November 1999, by Dick Pound. The World Anti-doping Agency focuses on establishing and enforcing rules and codes for all sports around the world. Their goal is to make all sports played fairly between all athletes in a doping free organization with the power to prevent athletes from using any form of performance-enhancing drugs. USADA started 1 October 2000, as non-profit and was composed of nine members. Five of which were former Olympic athletes with the other four elected from independent companies. This is the United States Anti-doping Agency and have the ability to test athletes across the nation.[37][38]
See also[edit]
- Ergogenic use of anabolic steroids
- List of doping cases in sport
- Steroid use in American football
- List of drugs used by militaries
- Positive psychology
References[edit]
- ^ "Effects of Performance-Enhancing Drugs | USADA". May 2019.
- ^ a b Pesta DH, Angadi SS, Burtscher M, Roberts CK (December 2013). "The effects of caffeine, nicotine, ethanol, and tetrahydrocannabinol on exercise performance". Nutrition & Metabolism. 10 (1): 71. doi:10.1186/1743-7075-10-71. PMC 3878772. PMID 24330705.
Caffeine-induced increases in performance have been observed in aerobic as well as anaerobic sports (for reviews, see [26,30,31]). Trained athletes seem to benefit from a moderate dose of 5 mg/kg [32], however, even lower doses of caffeine (1.0–2.0 mg/kg) may improve performance [33]. Some groups found significantly improved time trial performance [34] or maximal cycling power [35], most likely related to a greater reliance on fat metabolism and decreased neuromuscular fatigue, respectively. Theophylline, a metabolite of caffeine, seems to be even more effective in doing so [36]. The effect of caffeine on fat oxidation, however, may only be significant during lower exercise intensities and may be blocked at higher intensities [37]. ... For both caffeine-naïve as well as caffeine-habituated subjects, moderate to high doses of caffeine are ergogenic during prolonged moderate intensity exercise [61]. ... In summary, caffeine, even at physiological doses (3–6 mg/kg), as well as coffee are proven ergogenic aids and as such – in most exercise situations, especially in endurance-type events – clearly work-enhancing [26]. It most likely has a peripheral effect targeting skeletal muscle metabolism as well as a central effect targeting the brain to enhance performance, especially during endurance events (see Table 1). Also for anaerobic tasks, the effect of caffeine on the CNS might be most relevant. ... Muendel et al. [93] found a 17% improvement in time to exhaustion after nicotine patch application compared to a placebo without affecting cardiovascular and respiratory parameters or substrate metabolism. In this sense, nicotine seems to exert similar effects as caffeine by delaying the development of central fatigue as impaired central drive is an important factor contributing to fatigue during exercise. ... The physiological effects of the above mentioned substances are well established. However, the ergogenic effect of some of the discussed drugs may be questioned and one has to consider the cohort tested for every specific substance. However, only caffeine has enough strength of evidence to be considered an ergogenic aid.
- ^ a b c d Liddle DG, Connor DJ (June 2013). "Nutritional supplements and ergogenic AIDS". Primary Care. 40 (2): 487–505. doi:10.1016/j.pop.2013.02.009. PMID 23668655.
Amphetamines and caffeine are stimulants that increase alertness, improve focus, decrease reaction time, and delay fatigue, allowing for an increased intensity and duration of training ...
Physiologic and performance effects [of amphetamines]
• Amphetamines increase dopamine/norepinephrine release and inhibit their reuptake, leading to central nervous system (CNS) stimulation
• Amphetamines seem to enhance athletic performance in anaerobic conditions 39 40
• Improved reaction time
• Increased muscle strength and delayed muscle fatigue
• Increased acceleration
• Increased alertness and attention to task - ^ a b Frati P, Kyriakou C, Del Rio A, Marinelli E, Vergallo GM, Zaami S, Busardò FP (January 2015). "Smart drugs and synthetic androgens for cognitive and physical enhancement: revolving doors of cosmetic neurology". Current Neuropharmacology. 13 (1): 5–11. doi:10.2174/1570159X13666141210221750. PMC 4462043. PMID 26074739.
Cognitive enhancement can be defined as the use of drugs and/or other means with the aim to improve the cognitive functions of healthy subjects in particular memory, attention, creativity and intelligence in the absence of any medical indication. ... The first aim of this paper was to review current trends in the misuse of smart drugs (also known as Nootropics) presently available on the market focusing in detail on methylphenidate, trying to evaluate the potential risk in healthy individuals, especially teenagers and young adults.
- ^ Anon. Better Fighting Through Chemistry? The Role of FDA Regulation in Crafting the Warrior of the Future. Food and Drug Law: Final Paper. 8 March 2004.
- ^ "Caffeine and Sports Performance". Vanderbilt.edu. Retrieved 4 March 2012.
- ^ "What are anabolic steroids?". National Institute on Drug Abuse. August 2006. Retrieved 11 April 2016.
- ^ McKelvey VM. "Drugs in Sport". Archived from the original on 15 April 2013. Retrieved 15 April 2013.
- ^ Mohler ML, Bohl CE, Jones A, Coss CC, Narayanan R, He Y, et al. (June 2009). "Nonsteroidal selective androgen receptor modulators (SARMs): dissociating the anabolic and androgenic activities of the androgen receptor for therapeutic benefit". Journal of Medicinal Chemistry. 52 (12): 3597–3617. doi:10.1021/jm900280m. PMID 19432422.
- ^ "Clenbuterol" (PDF). Drug Enforcement Administration. November 2013. Archived from the original (PDF) on 17 October 2019.
- ^ Pluim BM, de Hon O, Staal JB, Limpens J, Kuipers H, Overbeek SE, et al. (January 2011). "β₂-Agonists and physical performance: a systematic review and meta-analysis of randomized controlled trials". Sports Medicine. 41 (1): 39–57. doi:10.2165/11537540-000000000-00000. PMID 21142283. S2CID 189906919.
- ^ a b c Parr JW (July 2011). "Attention-deficit hyperactivity disorder and the athlete: new advances and understanding". Clinics in Sports Medicine. 30 (3): 591–610. doi:10.1016/j.csm.2011.03.007. PMID 21658550.
In 1980, Chandler and Blair47 showed significant increases in knee extension strength, acceleration, anaerobic capacity, time to exhaustion during exercise, pre-exercise and maximum heart rates, and time to exhaustion during maximal oxygen consumption (VO2 max) testing after administration of 15 mg of dextroamphetamine versus placebo. Most of the information to answer this question has been obtained in the past decade through studies of fatigue rather than an attempt to systematically investigate the effect of ADHD drugs on exercise. ... In 2008, Roelands and colleagues53 studied the effect of reboxetine, a pure NE reuptake inhibitor, similar to atomoxetine, in 9 healthy, well-trained cyclists. They too exercised in both temperate and warm environments. They showed decreased power output and exercise performance at both 18 and 30 degrees centigrade. Their conclusion was that DA reuptake inhibition was the cause of the increased exercise performance seen with drugs that affect both DA and NE (MPH, amphetamine, and bupropion).
- ^ a b c Parker KL, Lamichhane D, Caetano MS, Narayanan NS (October 2013). "Executive dysfunction in Parkinson's disease and timing deficits". Frontiers in Integrative Neuroscience. 7: 75. doi:10.3389/fnint.2013.00075. PMC 3813949. PMID 24198770.
Manipulations of dopaminergic signaling profoundly influence interval timing, leading to the hypothesis that dopamine influences internal pacemaker, or "clock," activity. For instance, amphetamine, which increases concentrations of dopamine at the synaptic cleft advances the start of responding during interval timing, whereas antagonists of D2 type dopamine receptors typically slow timing;... Depletion of dopamine in healthy volunteers impairs timing, while amphetamine releases synaptic dopamine and speeds up timing.
- ^ a b Roelands B, de Koning J, Foster C, Hettinga F, Meeusen R (May 2013). "Neurophysiological determinants of theoretical concepts and mechanisms involved in pacing". Sports Medicine. 43 (5): 301–311. doi:10.1007/s40279-013-0030-4. PMID 23456493. S2CID 30392999.
- ^ a b Rattray B, Argus C, Martin K, Northey J, Driller M (March 2015). "Is it time to turn our attention toward central mechanisms for post-exertional recovery strategies and performance?". Frontiers in Physiology. 6: 79. doi:10.3389/fphys.2015.00079. PMC 4362407. PMID 25852568.
Aside from accounting for the reduced performance of mentally fatigued participants, this model rationalizes the reduced RPE and hence improved cycling time trial performance of athletes using a glucose mouthwash (Chambers et al., 2009) and the greater power output during a RPE matched cycling time trial following amphetamine ingestion (Swart, 2009). ... Dopamine stimulating drugs are known to enhance aspects of exercise performance (Roelands et al., 2008)
- ^ a b Roelands B, De Pauw K, Meeusen R (June 2015). "Neurophysiological effects of exercise in the heat". Scandinavian Journal of Medicine & Science in Sports. 25 (Suppl 1): 65–78. doi:10.1111/sms.12350. PMID 25943657. S2CID 22782401.
Physical fatigue has classically been attributed to peripheral factors within the muscle (Fitts, 1996), the depletion of muscle glycogen (Bergstrom & Hultman, 1967) or increased cardiovascular, metabolic, and thermoregulatory strain (Abbiss & Laursen, 2005; Meeusen et al., 2006b). In recent decennia however, it became clear that the central nervous system plays an important role in the onset of fatigue during prolonged exercise (Klass et al., 2008), certainly when ambient temperature is increased ... 5-HT, DA, and NA have all been implicated in the control of thermoregulation and are thought to mediate thermoregulatory responses, certainly since their neurons innervate the hypothalamus (Roelands & Meeusen, 2010). ... This indicates that subjects did not feel they were producing more power and consequently more heat. The authors concluded that the "safety switch" or the mechanisms existing in the body to prevent harmful effects are overridden by the drug administration (Roelands et al., 2008b). Taken together, these data indicate strong ergogenic effects of an increased DA concentration in the brain, without any change in the perception of effort. ... The combined effects of DA and NA on performance in the heat were studied by our research group on a number of occasions. ... the administration of bupropion (DA/NA reuptake inhibitor) significantly improved performance. Coinciding with this ergogenic effect, the authors observed core temperatures that were much higher compared with the placebo situation. Interestingly, this occurred without any change in the subjective feelings of thermal sensation or perceived exertion. Similar to the methylphenidate study (Roelands et al., 2008b), bupropion may dampen or override inhibitory signals arising from the central nervous system to cease exercise because of hyperthermia, and enable an individual to continue maintaining a high power output
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- ^ a b c d Momaya A, Fawal M, Estes R (April 2015). "Performance-enhancing substances in sports: a review of the literature". Sports Medicine. 45 (4): 517–531. doi:10.1007/s40279-015-0308-9. PMID 25663250. S2CID 45124293.
- ^ Koncic MZ, Tomczyk M (August 2013). "New insights into dietary supplements used in sport: active substances, pharmacological and side effects". Current Drug Targets. 14 (9): 1079–1092. doi:10.2174/1389450111314090016. PMID 23574283.
- ^ "Reflection Paper on the Adaptogenic Concept" (PDF). European Medicines Agency Committee on Herbal Medicinal Products. 8 May 2008.
- ^ Ilieva IP, Hook CJ, Farah MJ (June 2015). "Prescription Stimulants' Effects on Healthy Inhibitory Control, Working Memory, and Episodic Memory: A Meta-analysis". Journal of Cognitive Neuroscience. 27 (6): 1069–1089. doi:10.1162/jocn_a_00776. PMID 25591060. S2CID 15788121.
The present meta-analysis was conducted to estimate the magnitude of the effects of methylphenidate and amphetamine on cognitive functions central to academic and occupational functioning, including inhibitory control, working memory, short-term episodic memory, and delayed episodic memory. In addition, we examined the evidence for publication bias. Forty-eight studies (total of 1,409 participants) were included in the analyses. We found evidence for small but significant stimulant enhancement effects on inhibitory control and short-term episodic memory. Small effects on working memory reached significance, based on one of our two analytical approaches. Effects on delayed episodic memory were medium in size. However, because the effects on long-term and working memory were qualified by evidence for publication bias, we conclude that the effect of amphetamine and methylphenidate on the examined facets of healthy cognition is probably modest overall. In some situations, a small advantage may be valuable, although it is also possible that healthy users resort to stimulants to enhance their energy and motivation more than their cognition. ... Earlier research has failed to distinguish whether stimulants' effects are small or whether they are nonexistent (Ilieva et al., 2013; Smith & Farah, 2011). The present findings supported generally small effects of amphetamine and methylphenidate on executive function and memory. Specifically, in a set of experiments limited to high-quality designs, we found significant enhancement of several cognitive abilities. ...
The results of this meta-analysis cannot address the important issues of individual differences in stimulant effects or the role of motivational enhancement in helping perform academic or occupational tasks. However, they do confirm the reality of cognitive enhancing effects for normal healthy adults in general, while also indicating that these effects are modest in size. - ^ Prendergast HM, Bannen T, Erickson TB, Honore KR (March 2003). "The toxic torch of the modern Olympic Games". Veterinary and Human Toxicology. 45 (2): 97–102. PMID 12678299.
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External links[edit]
Media related to Ergogenic aids at Wikimedia Commons
