6 Mistakes That Could Sabotage Your Marathon

Marathon Mistake No. 3: Not Doing Your Homework

Nothing like getting into a nice groove in a race only to be met with a monster of a hill that you had no idea was coming, which totally throws you off your game. Avoid any surprises by studying the course map—especially the elevation charts—and visualizing yourself on every twist, turn, and climb (if you have time, running portions of the course is ideal.) "By knowing the terrain and race route, there won't be any surprises," says Chabner Thompson.

Same goes for checking—and rechecking—your race's website to find out what type of fuel will be served on the course. "That way, you can choose whether to supplement with the fuel on course or carry a different product of their choice," says Mayer. "You don't want to be stuck with a sports drink or gel that you haven't trained with. Products have different ingredients, and you'll have to find the one that works best for you."

More: 10 Mistakes to Avoid at Your Next Marathon

Marathon Mistake No. 4: Racing With a Partner

From early-morning meetups to Sunday long runs, you and your running buddy have taken nearly every step together in your journey to the marathon. So you're definitely running the race side-by-side too, right? Don't plan on it, warns veteran marathoner Elizabeth Chabner Thompson of Scarsdale, New York. "Running with someone is often a comfort, but it can also lead to one person holding the other back because of injury or a bad day," she says, adding that she once ran 24 miles of a marathon with a friend from her training group before he suddenly pulled up with a cramp. "There was no way I could make his cramp go away, so I went on to PR and he finished 10 minutes behind me. Loyalty wins you no points."

Bottom line? Run your own race

More: 4 Tips for Running With a Partner