Because running is the last leg of the race, your training goal is to build muscle endurance so you'll be able to finish strong when you're spent from swimming and biking. "Since you have to bang out only a few miles on race day, your running training focuses on boosting your body's VO2 max, or its efficiency in using oxygen, to get you through all three legs," says McCall. "And the best way to do that is by running shorter distances at higher intensities. In other words, intervals."
Shorten your stride. Reducing your stride lessens the impact on your body, which cuts your injury risk and also keeps your feet happy because they're spending less time on the ground. Count the number of steps you take per minute and aim for 180 (or three steps per second) as your goal.
Run relaxed. Bend your elbows to form 90-degree angles and make sure your fists aren't clenched. Keep your jaw loose and your shoulders down. During easy runs, you should be able to carry on a conversation. If you can't, slow down.
Start the first month with 20-minute runs twice a week, increasing time or distance by no more than 10 percent each week. Smacks of slacking off? You're really not: Thanks to your bike and swim cardio, 20 minutes is all you need right now to stay fit, says Shepley. Adding two-minute speed intervals will strengthen your legs and build the power you'll need to finish strong on race day.
Before you dash, warm up your running muscles with the three plyometrics moves below. Do each one for 10 to 15 steps, rest for 30 seconds, and repeat once.
Walking lunges: Step forward with your right foot and lower your body until both knees are bent 90 degrees, keeping your right knee behind your toes. Push off your front foot and switch legs, moving forward.
Butt kicks: Run forward, kicking your feet directly behind your body so that your heels touch your butt.
Bounding: Run with an exaggerated stride length, lifting your front knee high with each bound.