Static stretches are a part of "effective cool down" because they help to increase range of motion.
Also, it helps to improve performance and decrease blood flow.
EXPLANATION:
Static stretches are exercises that are done at the end of a work-out as they help to decrease the blood flow to the tissues and thereby cool down the muscles.
Static stretches also improve the flexibility of muscles and therefore increases the range of motion of muscles.
Static stretches also help in improving performance as it decreases the possibility of injury and leads to flexibility of muscles.
