It’s good to read this, which is a side product of the excellent Just One Thing podcast.

I currently drink a couple of cups of coffee per (working) day — one at around 10:00 and the other at about 14:30. Given I often exercise in the middle of the day, this actually works out pretty well!

Studies have shown that coffee improves almost every aspect of sports performance, whether it's strength, explosive speed, endurance or skill.. Dr James Betts, Professor of Metabolic Physiology at the University of Bath, says: “I would put caffeine on top of the list of supplements that boost physical performance – both for the size of effect that you get, and the breadth.”

One way that coffee boosts performance is by blocking the action of adenosine. Adenosine is a chemical messenger in your brain which makes you feel tired. Caffeine blocks the action of adenosine, helping you go on for longer without getting tired. “You could do worse than imagining adenosine to be like a brake that’s going to slow down your neural activity. Caffeine essentially hits the same receptors to prevent sleepiness,” explains Prof Betts.

Another way coffee works to boost exercise performance is by raising your levels of adrenaline, which can reduce pain and delay fatigue. It could also have effects on your fat and muscles.

Source: Can coffee make you fitter? | BBC Radio 4 - Just One Thing