Girls/Boys
For most athletes, a 10-minute warm-up is fine. In cool weather, with an outdoor activity, your warm-up should be longer. Warming-up should increase your breathing and heart rate.
Cool-down at the end of activity is important. It can consist of activities from the warm-up, but at a slower pace. Stretching is good, hold each stretch 10-30 seconds.
Juniors/Seniors
A good warm-up dilates blood vessels, thus your muscles are well supplied with oxygen. The temperature raises in your muscles, so they have flexibility and work efficiently. A good warm-up should take 10-15 minutes. Stretching, hold each stretch 10-30 seconds, increases range of motion and eases stress on joints and tendons. A warm-up should also have activities that increase your breathing and heart rate.
Cool-down can consist of some of the warm-up activities, but at a slower pace. Stretching after a work-out can help reduce the build up of lactic acid, which could result in cramping and stiffness.