While this question is often asked for athletes involved in endurance events, it was the first time I had heard it posed for anaerobes. Since then, the question has been posed with increasing frequency and seriousness. Frequent coffee drinkers, for instance, may reach that level with eight cups of coffee. It's difficult to tell how tea might contribute to urinary caffeine levels, since different teas have different levels of caffeine. You should be advised, however, that some teas may contribute more to caffeine levels than coffee.
Many sodas also have caffeine.
How Caffeine May Impact Performance Most of the studies on caffeine have been performed on endurance athletes, and some of these studies indicate that ingesting caffeine before exercise may improve endurance. The improvements seen in endurance are not fully understood. Part of the difficulty in understanding caffeine's effects is that there is a reduced dose response and adaptation to caffeine ingestion. Therefore, subjects accustomed to consuming foods that contain caffeine may experience no effect on performance with an added caffeine dose, while those who are unaccustomed to consuming caffeine may experience an endurance benefit. In this latter group, recent studies on endurance athletes indicate that caffeine consumed at levels below the IOC limit do impart an ergogenic benefit.