What is Oxygen extraction fraction (OEF)?

Oxygen extraction fraction (OEF) is like how much juice you squeeze out of a lemon when you press it, it shows how hard your body is working to get oxygen from the blood.

Imagine your body is like a big fruit machine. When you're running or playing, your muscles need more oxygen to keep going. The blood brings this oxygen to your muscles, and OEF tells us how much of that oxygen gets used up by the muscles, like how much juice comes out when you squeeze a lemon hard.

Think of your blood as a delivery truck carrying oxygen. When you're sitting still, the truck doesn’t need to deliver too much. But when you're running around like crazy, the truck brings more oxygen, and your muscles use almost all of it, that’s a high OEF.

If your body is really working hard, the OEF number gets bigger, just like how you get more juice from a squeezed lemon than from one that's only gently pressed.