Why Do You Shiver on a Cold Day?
If the surface of your skin gets too chilly, skin receptors send signals to the brain, which sets into motion a series of warming tricks. Shivering is one such tactic, in which your muscles contract and expand in speedy bursts. Shivering helps to make you feel warmer.
When you are cold, your brain sends messages to certain muscles to make you shiver. These muscles tighten and relax very quickly, over and over – without your thinking about them working. Your body shakes, and your teeth may chatter.
The working muscles burn up more fuel than usual, and produce extra heat in order to maintain body temperature. If you run or play a lot on a cold day, you won’t shiver. By exercising, you are already making your muscles work hard. The exercise warms you up.