Why people stricken with polio could no longer breathe on their own?

People stricken with polio often experienced paralysis due to the poliovirus attacking motor neurons in the spinal cord and brainstem. This paralysis could affect the respiratory muscles, including the diaphragm, which is crucial for breathing. When these muscles become weak or paralyzed, individuals can no longer breathe independently, leading to respiratory failure and the need for mechanical ventilation or other forms of respiratory support.