This is the classic "KO" of the body. You do not count to ten; you watch the person turn purple, then white, and slowly gasp back to life. In a combat scenario, the fight is over. You cannot defend yourself when your lungs refuse to work.
Q: Is the deep belly punch a safe technique? A: The deep belly punch can be a safe technique if practiced properly and with caution. However, it carries several risks, including injury to vital organs and concussion. deep belly punch
I learned this from a combat sports physio. Lie on your back. Knees bent. Take three slow, deep belly breaths. Then, using a soft fist or a rubber massage ball, you gently press—then release —into the soft spot just below the sternum (the solar plexus). This is the classic "KO" of the body