What is the sentence from that paragraph that directly states the main idea made about jogging?
But jogging is more than exercise. Jogging causes the body to produce a group of hormones called endorphins. These hormones may then release natural painkillers that can reduce suffering from arthritis, allergies, or other ailments. Jogging might actually trigger relief from pain and help ward off the common cold.
I’d go with the last one: “Jogging might actually trigger relief from pain and help ward off the common cold.”; it seems to be the summarizing sentence, which briefly explains the main idea.