Some exercises we have included we have one basic category like sit ups, even though there are many different types of sit ups you can do. We’ve included the lunges separately as they work different muscles. Look at these links on forward lunges. If you are new to exercise pay particular attention to how to lunge to make sure you are working the right muscles safely.
http://www.sparkpeople.com/resource/exercises.asp?exercise=22
http://www.acefitness.org/exercise-library-details/0/94/
http://www.shape.com/fitness/workouts/know-your-basics-how-do-lunge