Why do we do that?
The Warm Up
Warming your body it makes it more pliable. In other words it can stretch more. Your muscles are created to stretch about 150%. Just like many other substances, warming muscles up makes them more pliable so they can achieve their maximum lengthening without any damage to the muscle fibers. Stretching is best when the muscles are warm, not cold.
Your joints are may be the most important thing to warm up. Especially as you age. Like me. The synovial fluid inside of your joints, when heated, becomes thinner and thereby creates a better coating for your joints to move. That fluid is important because it reduces the friction not only on your bones, but on your soft tissues within the joint. The breakdown of cartilage is a huge contributor to joint problems and synovial fluid reduces the friction and therefore, the wear on the tissue.
Warming up also increases blood flow to your entire body and thus increases your temperature and metabolism. Increased blood flow also means you are oxygenating your system at a higher rate. This is a good thing for many reasons. It also prepares the body to rid itself of lactic acid (think of lactic acid like the exhaust of your energy usage), and allows you to clear it from your body at a higher rate. That translates into more endurance during exercise and a higher lactic threshold (that point where your body can’t get rid of enough lactic acid and you have to slow down).
When the nervous system is prepared through warm up exercises, it communicates better with your body. Your movements are more coordinated after your warm up, which means you perform better. Not only the nervous system, but the brain itself is prepared and has more clarity and focus.
Warming up also changes your hormone levels so your body can adjust to the change in energy demands. Hormones play an essential role in triggering the release of glycogen and other chemicals used in energy production and carbohydrate usage for energy demands.
Finally, warming up and raising your heart rate prepares your body to increase the heart rate in the future. In other words, instead of going from 0-60, you are warming up to 30 and then going from 30-60. It creates less of an initial stress. It makes it easier on the cardiovascular system to meet the demands of an intense workout.
And that my friends, is why we warm up.