The key is saving your high-intensity effort until the end of the race. “A marathon is supposed to be harder than your easy run, conversational pace,” Rockey says. “But it’s still just an aerobic workout. When you get anaerobic, that’s when you stop being able to talk.”

This past weekend was the Boston Marathon, where thousands of runners put their endurance to the test. John Korir won the event with a time of 2:01:52, breaking the course record in the process. That averages out to a 4 minute 39 second mile.

From booking elite athletes and hotels to deciding on bonus payments, this Sunday's London Marathon has been months in the planning.

Sabastian Sawe ran his way to the top of the men’s list on Sunday.