Running is risky – if they were to trip and fall, then they would be of no help to the person who needed them, and they would probably become a patient themselves. Running prevents them from surveying a scene thoroughly, and they might overlook a hazard like a protective dog, a weapon in the room, downed power lines, or similar. Running also elevates their own heart rate and respirations, which does not create a sense of calm for their patients, and makes it difficult for them to think clearly and act deliberately.