Caffeine impacts exercise performance by enhancing endurance and reducing perceived effort. As a stimulant, caffeine can boost alertness and concentration, helping athletes push through fatigue during workouts. Research suggests that it may improve performance in both endurance activities, like running, and high-intensity sports by allowing individuals to maintain intensity for longer periods. However, tolerance levels and individual responses to caffeine vary, so it’s essential to consider personal sensitivity and timing when incorporating caffeine into pre-workout routines to maximize its benefits.