The threshold for caffeine to have an ergogenic benefit is _________.

Caffeine is widely recognized for its potential ergogenic benefits in enhancing athletic performance, particularly in endurance sports. Research indicates that the threshold at which caffeine begins to demonstrate these beneficial effects is around 3 mg/kg of body weight.

At this dosage, caffeine can improve endurance, increase alertness, and potentially reduce the perception of effort during exercise. The mechanism behind this involves the stimulation of the central nervous system, which can lead to improved reaction time, reduced fatigue, and increased overall performance.

Higher doses may provide additional effects, but they can also lead to increased risk of side effects such as jitteriness, gastrointestinal discomfort, and insomnia. Thus, while a range of 3-6 mg/kg is often cited for performance benefits, 3 mg/kg is generally recognized as the minimum effective dose, making it the correct answer to the question.