Final answer:
Prolonged sympathetic nervous system activation inhibits digestion by contracting digestive tract sphincters, decreasing propulsion, and reducing gastrointestinal secretion and motility.
Step-by-step explanation:
Prolonged action of the sympathetic nervous system would most likely affect digestion by inhibiting digestion. This occurs because the sympathetic system is responsible for the fight-or-flight response, which redirects energy away from non-essential functions, like digestion, during times of stress. In contrast, the parasympathetic system enhances digestion during restful periods by increasing gastrointestinal secretion and motility. However, when the sympathetic system is activated, it causes sphincters in the digestive tract to contract, reducing digestive propulsion and leading to decreased gastrointestinal motility and secretion.