Follow your curiosity

What discovery has been shared with you?

FACTREE gives you something interesting to discover every day — and something worth talking about together.

Start with one fact. Explore it, go deeper, then follow whichever branch catches your imagination.

Choose subjects for a surprise

Exploring any topic

Begin your discovery

Your next discovery is one click away.

Choose one or more subjects above, or leave Any Topic selected and let curiosity decide.

Biology

Energy Systems

Quick fact

The phosphagen system can regenerate ATP at a rate nearly 100 times faster than aerobic metabolism, but it only lasts about 10 seconds.

Why this is interesting

You know that feeling when you sprint and your legs burn after just 10 seconds? That's one of your energy systems hitting its limit – and there are three distinct systems at work inside you, each with a different role.