This article comes from Taylor Maid Coffee in the States:

Q: Dear Taylor Maid,
I have heard that coffee can help sports performance, What do you know about that?
-Todd Mezzullo, Sebastopol, CA.
A: Dear Todd,
Usually when one begins a workout of any kind, they find that they feel quite "rusty" in the beginning and slowly "loosen up", feeling better, stronger and faster. This is due to the fuel that the body chooses to access. Usually when we begin our run, ride, or swim, we use our carbohydrates as fuel. This fuel is similar to a low-grade gasoline; it will get you there, but you will never feel like you're going smooth and fast. As the body warms up, your choice in fuel changes. The body accesses it's fat reserves, a high quality fuel source. Fat burning is linked to "runners high", a feeling of invincibility and euphoria. You no longer feel sore, tired, or fatigued when accessing your fat reserves.
Recent studies have shown that if coffee is ingested 20 minutes before a workout, the body will access its fat reserves much earlier than normal. On top of that, you will burn more fat, increasing the overall payoff of your workout.