1. Blood pooling
When the body goes from actively moving to moving slowly, the squeezing action provided by the working muscles is greatly diminished. When exercise is stopped abruptly, this can cause the blood to pool in the lower extremities and slow its return back to the heart and, subsequently, the brain.
This can lead to lightheadedness, dizziness and fainting.
2. Delayed onset muscle soreness (DOMS)
DOMS occurs 24 to 48 hours after exercise due to microtears in the muscle fibers. This is a normal part of the exercise and some soreness is to be expected.
DOMS that hang around for more than 2-3 days may also be a sign of overtraining or illness. The cool-down allows for increased blood flow to the exercised muscle, which in return minimizes the DOMS effect.
3. Stress relief
Exercise triggers the brain to release endorphins, the “feel good” hormones. The cool-down plays an important part in this process.
When you slow down exercise and allow your body to come back to resting, a.k.a. balance state (homeostasis), you can get the full euphoric effect these neurochemicals
have on your body. Take a few extra moments to stretch and breathe and allow your body to feel refreshed.
4. Injury prevention
At the end of a workout, your muscles are warm and flexible. This is why static stretching added to the cool-down process can be very effective in improving overall flexibility. Static flexing involves stretching a muscle to near its furthest point and then holding it for 20 seconds.
After intense exercise, your body has lactic acid build-up. The cool-down process helps to start clearing this byproduct of exercise. A cool-down should consist of the last 5-15 minutes of your workout and should be focused on the muscle groups that were just worked.
So, while it might be just as easy to skip out early, remember that a 10-minute cool-down can be the difference between you and your fitness goals.