Question: why is the heart the size of your fist?

Laura Schofield answered on 19 Nov 2014:

Actually when you’re an adult its about the size of 2 fists! That’s because it is a huge muscle that has to work really hard to pump about 5.5 litres of blood around your body! Even when you’re resting your heart muscle is working twice as hard as your leg muscles do when you’re sprinting! If your heart is enlarged though it can cause you all sorts of problems like dizziness or swelling of your hands and feet or shortness of breath…the list goes on! So over many thousands of years, we have evolved to have the perfect sized heart, one that is big enough to do all that work, without becoming enlarged and making us ill!