This workout adds circuits of 400 meter sprints, pushups, and crunches to your training. These circuits will help improve your muscular endurance under greater pressure. Sprint training also brings a "mental" component to your 5K training preparation. Forcing yourself to go all out for 400 meters and repeat it will force you to reach exhaustion and prepare your mind and body for race day when you hit the 2 mile mark and have to kick it into high gear. If you live near a hill, perform this week's sprints on a hill. Running hills requires a greater leg drive and arm pump and will prepare you for hills on your 5K course.