Why we need to warm up and cool down ?

Warmups and cool-downs generally involve doing your activity at a slower pace and reduced intensity.

 Warming up helps prepare your body for aerobic activity. A warmup gradually revs up your cardiovascular system by raising your body temperature and increasing blood flow to your muscles. Warming up may also help reduce muscle soreness and lessen your risk of injury.

 Cooling down after your workout allows for a gradual recovery of preexercise heart rate and blood pressure. Cooling down may be most important for competitive endurance athletes, such as marathoners, because it helps regulate blood flow. Cooling down doesn't appear to help reduce muscle stiffness and soreness after exercise, but more research is needed.