Yes. Caffeine is the most studied and most validated ergogenic (performance-enhancing) substance available without a prescription. Research consistently shows it improves strength, power, endurance, reaction time, and perceived effort across nearly every type of exercise. The effective dose is 3-6mg per kilogram of bodyweight, taken 30-60 minutes before training. The source matters less than the dose — but natural caffeine from coffee bean offers a smoother profile than synthetic caffeine anhydrous. The effects are real, the research is overwhelming, and if you're training without caffeine, you're leaving measurable performance on the table.