"Stimulants are a class of performance-enhancing substances some bodybuilders use to increase focus, alertness, and energy during their workouts. Some of the most commonly used stimulants in bodybuilding include amphetamines, caffeine, ephedrine, and clenbuterol. These substances are believed to enhance mental and physical performance, reduce fatigue, and improve endurance [25]. While stimulants can provide short-term benefits, their misuse can have serious health consequences. For instance, using stimulants can cause an increase in heart rate and blood pressure, leading to cardiovascular problems such as heart attack, stroke, and arrhythmia. Additionally, the misuse of stimulants can lead to addiction and withdrawal symptoms, including anxiety, depression, and insomnia [26].

"Caffeine, found in many beverages and dietary supplements, is the most widely used stimulant in bodybuilding. While caffeine is generally safe in moderation, excessive use can lead to negative side effects, including restlessness, nervousness, and insomnia. Caffeine can also increase heart rate and blood pressure and cause gastrointestinal problems such as nausea and diarrhea [27]. Ephedrine and clenbuterol are also commonly used stimulants in bodybuilding. Ephedrine is a central nervous system stimulant known to increase metabolic rate and fat burning. Still, its use has been associated with serious health risks such as high blood pressure, heart attack, and stroke. Similarly, clenbuterol, often used to promote weight loss, has been linked to heart problems and muscle tremors [28]."

Source

Mantri S, Agarwal S, Jaiswal A, Yelne S, Prasad R, Wanjari MB. Bodybuilding: A Comprehensive Review of Performance-Enhancing Substance Use and Public Health Implications. Cureus. 2023 Jul 9;15(7):e41600. doi: 10.7759/cureus.41600. PMID: 37559855; PMCID: PMC10409494.