Why do we need to warm up before workout?

Warm-up is a pre-workout session which helps in increasing the heart rate and the body temperature which basically prepares for the workout activities. It comprises of cardio workout, warming up the muscles  and stretching exercises. Warm -up  is very much necessary in order to avoid injuries to the muscles. It helps in increasing the blood flow to the heart, thus stabilizing the blood pressure. It provides enough oxygen to the muscles . It also increases up the blood temperature which helps while performing long time workout. It lubricates the joints, to work out for longer period with out pain.Warm-up should last between 15-20 minutes.
 Make sure that you warm up the same muscles which you will going to work out after the warm-up session. Higher the body temperature better the contraction and expansion of the muscles. Warm up also helps for mental preparation, meaning it will be easier to train the parts when you are going for high intensity workouts.
Often people misunderstand the difference between warm up exercise and stretching exercise. Warm up is basically used to warm up the muscles which will going to be trained in the next workout. Where as stretching exercise stretches the muscles in order to have a smooth and painless workout.
There are 2 types of warm up exercises:Full body warm-up:Here we will be warming up the whole body. It means the temperature of the entire body muscles is increasing. For instance running, jogging or swimming are the best full body warm-up exercises. It pumps the blood to each and every muscles of the body and giving them the required oxygen that they need.Spot warm-up:Spot warm-up  helps in increasing the blood flow rate and the oxygen to that particular muscle. It doesn’t warm-up the whole body meaning it is specific to particular kind of muscle. For instance if you want to train for your legs , you can choose to go for squats. This is a very good spot warm-up exercise for legs.Cool down or Warm down:Warm down is very important as like warm up, it helps in recovering back the muscles after a strained workout. This includes some stretching exercises and a 5 minutes walk . It basically helps the body to come back to its original state.The main motto of cool down period is:•It brings the heart rate back to its normal state.•It brings back the blood that has been stored in the muscles back to the heart.You should always go for cool down  after the post work out along with stretching exercises. It helps in overall range of motion smoothly.  Stretching is as important as warm down. Stretching  relaxes the muscles and makes less prone to pain.
In order to conclude finally, it is most important to have warm up and warm down exercises with every workout which helps you stay healthy and fit always.