The number of athletes, especially at top levels of competition, as well as the general population reported to be using stimulants, has markedly increased in recent years. The term stimulants covers a broad class of substances directly affecting the central nervous system (CNS). Many individuals use these drugs for various reasons, including performance enhancement, medical benefits, and recreational purposes. They may be legal or illegal. Since one of the primary mechanisms through which stimulants exert their effects is increased blood flow and heart rate, cardiac dysfunction is one of the main concerns associated with their use, along with other adverse effects that will be discussed later. Therefore, in the following article, you will find information about the main stimulant classes and their way of action, the constitutional rules around their use, the negative effects regarding their use, contraindications, and finally, a short overview of the most popular ones.
According to the International Olympic Committee (IOC), stimulants are classified as sympathomimetic amines, psychomotor stimulants, and central nervous system (CNS) stimulants. Sympathomimetic amines mimic or potentiate the effects of the sympathetic nervous system (SNS) through the neurotransmitter norepinephrine. Psychomotor stimulants, such as amphetamines, cocaine, and caffeine, have several effects related to mental function and behavior, including excitement and euphoria, motor activity increase, and fatigue mitigation. CNS stimulants increase the activity of the CNS’s respiratory and vasomotor centers and reflexes.
Stimulant usage by athletes
Stimulants exert multiple effects pursued by elite and professional athletes. For example, athletes competing in aesthetic sports, such as artistic gymnastics, or in sports with specific weight classes, such as wrestling, may seek stimulant prescriptions for a weight loss advantage. Other athletes competing in team sports, like basketball and football, seek stimulants for increased alertness as well as reduced and delayed fatigue. Other athletes not only use stimulants for performance-enhancing but for recreational purposes as well.
Rules around stimulant use
The primary method of administration for stimulants is oral intake. Recreational administration of stimulants also occurs by intramuscular and/or intravascular injection, smoking, and intranasal administration. Stimulants can be found in their pure form or over-the-counter sports products, such as pre-workout supplements. In any case, since there is confusion around the rules and recommendations for stimulant use by athletes, the World Anti-Doping Agency (WADA) only permits athletes to take stimulants if deemed necessary by their physicians for therapeutic use. Therapeutic use of stimulants includes attention deficit hyperactivity disorder (ADHD), narcolepsy, asthma, and nasal and sinus congestion, among others. In this case, elite athletes who compete internationally and whose physicians feel they should continue stimulant use must obtain a Therapeutic Use Exemption (TUE) from WADA.
The adverse effects of stimulants
Given the harmful effects of stimulants, the existence of an organization like WADA is deemed necessary. Therefore, banned stimulants include amphetamines, methamphetamines, ephedrine, pseudoephedrine, cocaine, and other substances with similar chemical structures and biological effects. Regarding permitted stimulants, they can still induce a broad range of short-term and long-term adverse effects and may be physically dangerous when used by athletes who are pushing their bodies to extremes. Specifically, long-term stimulant use can result in decreased appetite and weight loss, headaches, anxiety, insomnia, and shortness of breath. More severe health effects include psychosis, paranoia, stroke, hypertension or hypotension, arrhythmias, myocardial infarction and sudden cardiac death, seizures, and coma. The major factors influencing these outcomes are the user’s body weight, the specific stimulant used, the dose of the agent taken, and tolerance.
There are also numerous relative contraindications to the use of stimulants, including individuals with established cardiovascular disease, severe hypertension, untreated hyperthyroidism, glaucoma, and cardiac arrhythmias. Younger athletes under the age of 12 and pregnant women should also avoid using stimulants.
The most known stimulants are shortly reviewed below.
It is the most commonly used stimulant in the world, employed for recreational as well as performance enhancement purposes. As the most commonly used stimulant, caffeine is found in various drinks and foods, such as tea, coffee, and chocolate. It is consumed habitually in many countries worldwide, given its mild to moderate stimulant effects, which promote alertness and increased energy levels. Caffeine is a relatively safe stimulant.
They exert multiple effects, including general and cognitive performance enhancement along with euphoric effects. Their general mechanism of action is the stimulation of catecholamines, specifically norepinephrine and dopamine. These catecholamines lead to increased energy levels, euphoria, increased libido, and higher cognition. Athletes use many medications related to the amphetamine class of drugs for physical performance enhancement, including increased strength, acceleration, anaerobic capacity, time to exhaustion, and maximum heart rates. Still, all these drugs fall under bans by WADA. Methamphetamine, a kind of amphetamine, is a widely trafficked and illegal drug mainly used for recreational purposes.
Ephedrine and pseudoephedrine
They belong to the sympathomimetic amines class of stimulants whose primary mechanism is increased norepinephrine activity at the adrenergic receptors. They are both used as nasal and sinus decongestants caused by the common cold. Athletes may use over-the-counter formulations containing these substances to improve lung function and lower body strength and power before exercise.
It belongs to the psychomotor stimulants and acts through the blockade of the dopamine transporter protein, resulting in increased dopamine levels. It can temporarily increase energy levels, focus, alertness, and confidence, effects pursued by professional athletes who use it. However, in the long term, cocaine can only harm athletic performance since its use is associated with sleep disruptions, fatigue, anxiety, mood swings, reduced focus, arrhythmias, and hypertension, among others. Cocaine is also used for recreational purposes.
Overall, any performance enhancement that an athlete may receive from taking a stimulant raises an important ethical concern. An essential value in sports is fair competition. Athletes should play by the same rules and perform without external influences that may favor them. At high levels of competition, a performance advantage of even one hundred of a second can make a significant difference in first place, opportunities, and financial earnings. Applying this argument to the professional sports field, no use of performance-enhancing substances is fair and, therefore, should be prohibited.
- Avois L, Robinson N, Saudan C, Baume N, Mangin P, Saugy M. Central nervous system stimulants and sport practice. Br J Sports Med. 2006;40(Suppl1):i16-i20. DOI: 10.1136/bjsm.2006.027557
- Berezanskaya J, Cade W, Best TM, Paultre K, Kienstra C. ADHD prescription medications and their effect on athletic performance: A systematic review and meta-analysis. Sports Med-Open. 2022;8(1):5. DOI: 10.1186/s40798-021-00374-y
- Farzam K, Faizy RM, Saadabadi A. Stimulants. In: StatPearls. StatPearls Publishing, Treasure Island (FL);2022. DOI: 30969718
- Garner AA, Hansen AA, Baxley C, Ross MJ. The use of stimulant medication to treat Attention-Deficit/Hyperactivity Disorder in elite athletes: A performance and health perspective. Sports Med. 2018;48(3):507-512. DOI: 10.1007/s40279-017-0829-5
- Reardon CL, Factor RM. Considerations in the use of stimulants in sport. Sports Med. 2016;46(5):611-617. DOI: 10.1007/s40279-015-0456-y