In this 12th video of the series, fitness instructor Danielle demonstrates how to use your doorway pull up bar for sit ups. By placing your pull up bar at the bottom of the door frame, you can place your toes beneath the bar to ensure you are using proper form for your sit ups. The bar should not lift when doing sit ups. It it does, you are using your leg muscles too much for momentum, and not using your abs effectively.
Danielle explains proper form for sit ups, which is important for avoiding injury, and for maximizing the benefits of your sit ups. This same method can be employed for crunches as well. Ensure that your lower back and shoulder blades are making contact with the ground, and make sure you are using a fluid motion.
Watch the following video as Danielle demonstrates proper form for the most effective sit ups and crunches.

Fitness instructor Danielle demonstrates how to perform push ups using your doorway pull up bar.  It is important to have a variety of exercises in your workout plan to ensure that one muscle group does not get overworked, giving you an unbalanced appearance.  Danielle demonstrates and explains how narrow grip push ups and wide grip push ups will target different muscles giving you the balanced appearance you are after.

Watch the video below:

In the last video segment, Danielle demonstrated how to hanging knee lifts and hanging leg lifts from your doorway pull up bar.  These are very beneficial to your abs.  In the video below, Danielle elaborates on some of the added benefits of this exercise.

Hanging knee lifts and hanging leg lifts are an excellent abdominal workout that can be performed with your doorway pull up bar. Watch the following video as Danielle demonstrates and explains the benefits.

In this video, Danielle talks about pull ups and the importance of using proper form. Poor form can result in unwanted injuries. Watch the video for a demonstration.

Pull ups and chin ups are similar in nature, but differ in the hand grip and the muscles that they target. Chin ups are typically easier to do than pull ups, because you get assistance from the biceps. Pull ups target more of your back muscles and get less assistance from the bicep.

Watch the following video where Danielle explains the differences between pull ups and chin ups, and the muscles that they target.

Hanging a P90X Pull Up Bar on your door frame is simple. Danielle demonstrates this in the second video of the instructional series. This pull up bar will fit up to a 32" door frame and trim is required. See the video below.