The importance of Warm-up and Cool-down!

It used to be that I didn't really warm-up before exercising, but usually did a cool-down and stretched. I guess I had the mentality that I just didn't have time to warm-up or that I just wanted to get to the meat of my workout and get it done. Anyway I know better now and have for quite some time now, but I though I would share the 'rhyme and reason' behind why one should.
Warm-up and Cool-down periods are essential to any exercise session, not just aerobic. Warming-up brings about important physiologic changes that reduce the risk of injury, as well as make the exercise session more comfortable. First it causes an actual increase in the temperature of the muscle and connective tissue, thereby reducing the risk of soft tissue injury. Second, it allows the cardiovascular system to effectively adjust blood flow from the abdominal area to the active muscles where the need for oxygen is increasing in response to the exercise, while maintaining adequate venous return. This blood shunt is accomplished by constriction in arteries that supply blood to the gut, and dilation in arteries that deliver blood to the active muscles. Heart rate will quickly rise to near maximum in an attempt to supply adequate oxygen if the necessary three to five minutes of warm-up are not performed, especially if an intense pace is attempted too soon. Cool-down to 18 to 20 beats per 10 seconds (108 to 120 bpm) to allow the system to reverse the blood shunt. So in closing, adequate warm-up and cool-down periods not only reduce the potential for fatigue, but they also reduce the risk of exercise-related injuries.
TO YOUR HEALTH!