Performance-enhancing drugs are substances used to improve any form of activity performance in humans. 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.
Performance-enhancing drugs are used by athletes and bodybuilders. Use of cognitive performance enhancers by students is sometimes referred to as academic doping. They are also used by military personnel to enhance combat performance.
The phrase has been used to refer to several distinct classes of drugs:
- Ergogenic aids, or athletic performance-enhancing drugs, mainly include stimulants (see next bullet) and lean mass builders. Lean mass builders drive or amplify the growth of muscle and lean body mass, are also used to reduce body fat. They can also reduce the time it takes to recover from an injury. This class of drugs includes anabolic steroids, xenoandrogens, beta-2 agonists, selective androgen receptor modulators (SARMs), and various human hormones, most notably human growth hormone, as well as some of their prodrugs.
- Stimulants improve focus and alertness. Dopaminergic stimulants (e.g., reuptake inhibitors and releasing agents) also affect cognitive and athletic performance by improving muscle strength and endurance while decreasing reaction time and fatigue; some examples of ergogenic (athletic performance-enhancing) stimulants are caffeine, ephedrine, amphetamine, and methamphetamine.
- 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.).
- Adaptogens result in stabilization of physiological processes and promotion of homeostasis, an example being by decreased cellular sensitivity to stress.
- 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) 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. EPO is one of the most widely known drugs in this class.
The classifications of substances as performance-enhancing drugs 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.
- Ergogenic aid
- Ergogenic use of anabolic steroids
- List of doping cases in sport
- Steroid use in American football
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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
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The neurotransmitter dopamine is released from projections originating in the midbrain. Manipulations of dopaminergic signaling profoundly influence interval timing, leading to the hypothesis that dopamine influences internal pacemaker, or “clock,” activity (Maricq and Church, 1983; Buhusi and Meck, 2005, 2009; Lake and Meck, 2013). For instance, amphetamine, which increases concentrations of dopamine at the synaptic cleft (Maricq and Church, 1983; Zetterström et al., 1983) advances the start of responding during interval timing (Taylor et al., 2007), whereas antagonists of D2 type dopamine receptors typically slow timing (Drew et al., 2003; Lake and Meck, 2013). ... Depletion of dopamine in healthy volunteers impairs timing (Coull et al., 2012), while amphetamine releases synaptic dopamine and speeds up timing (Taylor et al., 2007).
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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.
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Mild dopaminergic stimulation of the prefrontal cortex enhances working memory. ...
Therapeutic (relatively low) doses of psychostimulants, such as methylphenidate and amphetamine, improve performance on working memory tasks both in in normal subjects and those with ADHD. Positron emission tomography (PET) demonstrates that methylphenidate decreases regional cerebral blood flow in the doroslateral prefrontal cortex and posterior parietal cortex while improving performance of a spacial working memory task. This suggests that cortical networks that normally process spatial working memory become more efficient in response to the drug. ... [It] is now believed that dopamine and norepinephrine, but not serotonin, produce the beneficial effects of stimulants on working memory. At abused (relatively high) doses, stimulants can interfere with working memory and cognitive control ... stimulants act not only on working memory function, but also on general levels of arousal and, within the nucleus accumbens, improve the saliency of tasks. Thus, stimulants improve performance on effortful but tedious tasks ... through indirect stimulation of dopamine and norepinephrine receptors.
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