What's the difference between turtle breath and fetal breath? What are the benefits of separation?

Turtle breathing is as slow as tortoise breathing, mainly because the slow breathing rhythm slows down the body's metabolism. The slow metabolism of the body is essentially delaying aging, which can slow down the pain and blood loss when the body is injured. Fetal breath refers to the breath of the fetus in the mother, which is not only the "innate qi", but also the closed breathing that does not provide oxygen for the body through the nose and mouth. Theoretically speaking, if we only rely on the interest of the fetus, the body can survive in a vacuum environment without other energy losses. But there is no way to achieve it in reality, so it has no practical significance after birth. It is worth noting that both Qigong in China and Yoga in India are using various pranayama methods to make the body infinitely close to fetal interest.