Help real quick
After reading & the video, in your own words, explain how a muscle contracts​

Muscle contraction occurs when the thin actin and thick myosin filaments slide past each other. It is generally assumed that this process is driven by cross-bridges which extend from the myosin filaments and cyclically interact with the actin filaments as ATP is hydrolysed.

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.