The use of substances by athletes to enhance performance has been a feature of competitions since ancient times. Athletes took these substances to improve strength and overcome fatigue, a practice that continues today. Today these doping substances have become even more present in numerous sports. Some common examples of these substances are; steroids, erythropoietin, human growth hormone and stimulants. This essay will focus on stimulants. Stimulants have long been used in competitions, for example Thomas Hicks won the 1904 Olympic marathon after taking a combination of stimulants (strychnine and brandy) [1]. However, the use of performance-enhancing stimulants can have negative effects on your health. For example, Tommy Simpson collapsed and died during the 1967 Tour de France. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay The stimulants he was taking (alcohol and amphetamines) were partly blamed for his death [1]. Since then, stimulants have been on the prohibited list and their use during competitions has been banned [2]. Regardless, stimulants, whether legal or illegal, are consistently taken by athletes because they want to improve their performance to gain an advantage over others and win. Research has shown that the reason for the athlete's competitive gain is mainly due to stimulants that increase alertness, anaerobic performance, endurance and decrease fatigue [3]. Therefore, this essay will review the literature to see how different stimulants (e.g. amphetamines, ephedrine, caffeine, and cocaine) enhance sports performance to give an athlete a competitive advantage. Amphetamines Amphetamines were first synthesized in 1920 and were widely used during World War II to increase alertness and fatigue [4]. It stimulates the central nervous system (CNS) and causes the release of norepinephrine from sympathetic nerves mirroring sympathetic neural activity, as well as discharging dopamine from the brain [5]. Therefore, amphetamines cause an increase in these neurotransmitters (dopamine and norepinephrine), resulting in physiological consequences, such as increased heart rate and blood flow to the muscles [1]. Proposing the possibility that amphetamines may improve sports performance due to its stimulatory effects. Evidently, an article by Gene et al. [6] supports this, as it reveals that amphetamine significantly improved performance and athletes felt that this stimulant improved their strength, coordination and endurance. To add, Avis et al. [7] shows that the positive effects of amphetamines include higher levels of physical energy and mental attitude, along with those who consume them feeling more confident and efficient. Furthermore, in a randomized cross-over study of cycling at different intensities of RPE (hard or very hard), amphetamines allowed participants to endure higher work rates and levels of metabolic and cardio-respiratory activity for longer, while they perceived that the exercise was not that hard even when working on an RPE which represents very hard [8]. For example, exercise is prolonged by a stimulant that acts on the central nervous system [8]. Indicating that this stimulant is an ergogenic performance aid. However, continued use of this stimulant can have adverse health effects. For example, side effects associated with amphetamines are confusion, palpitations, rapid breathing, hypertension, tachycardia, and tremors[9]. Ephedrine Ephedrine is the purified form of an ephedra alkaloid, it is a sympathomimetic amine known for its stimulant properties [10]. These include action as a central nervous system stimulant and stimulation of alpha- and beta-adrenergic receptors [7]. Furthermore, this type of stimulant has been shown to help improve sports performance and weight loss [4]. For this reason they are used by athletes. Regarding weight loss, Shekelle et al. [11], meta-analysis reveals that ephedrine can promote moderate weight loss for up to 6 months, but there was no data on long-term weight loss. Regarding performance, a double-blind crossover study investigating the effect of 24 mg ephedrine on physical performance reports that ephedrine does indeed influence blood pressure and heart rate during exercise and recovery, but not improved none of the measures for physical work (strength, endurance, and power) [12]. On the other hand, Bell et al. [13] Study results reveal that ephedrine significantly improved power output during the initial phase of a cycling test (Wingate). Another study by Bell et al. [14] shows that a dose of 0.8 mg/kg ephedrine improved the running times of 12 athletes in a 10 km race from 46.9 ± 3.3 minutes to 45.5 ± 2.9 minutes. These results indicate that this stimulant can be used as an ergogenic aid for prolonged exercise such as long-distance running. The possible ergogenic effect shown by ephedrine could be due to the fact that this stimulant increases the release of monoamines such as dopamine at central and peripheral levels [10]. Caffeine Caffeine is consumed in various forms and enjoyed by millions of people, including athletes. The effect of caffeine is to reduce fatigue, increase alertness and wakefulness [15]. Research has shown that low to moderate doses of caffeine (3 to 9 mg/kg) have a significant impact on physical performance [16,17]. This is further supported by a double-blind crossover study [18]. The study found that varying amounts of caffeine consumed improved the performance of fifteen triathletes and cyclists during a 1-hour cycling time trial. Furthermore, a meta-analysis by Doherty and Smith [19], quantified the effect that caffeine had on different exercise protocols (short-term, high-intensity exercise, and time to exhaustion). They report that caffeine impacts whole-body exercise and has a greater effect on the time-to-exhaustion protocol (effect size = 0.63) than on the short-term protocol (effect size = 0 ,16). Overall, caffeine intake has been found to increase an individual's stamina levels [20]. Suggesting that athletes use caffeine due to its reported ergogenic benefits. The putative beneficial effects of caffeine on performance can be attributed to the fact that it exerts its effect through the intracellular oxidation of free fatty acids and acts as an adenosine receptor antagonist in the central nervous system [21]. However, its influence on performance is likely due to its role as an adenosine receptor antagonist [9]. In other words, caffeine's beneficial effect on performance is a result of its direct effect on the central nervous system. Next, caffeine also has potential side effects. For example, low doses cause anxiety, gastrointestinal disorders and inability to concentrate, while high doses can cause arrhythmias and mild hallucinations [22]. Cocaine Cocaine, similarly to the other stimulants mentioned, stimulates the central nervous system and the sympathetic nervous system [5]. So, he was coming."