Pullups are used to test muscular strength and endurance. Doing pullups requires a lot of work from many different muscles. Not only are you holding yourself up on the bar using your arms, you must support every muscle in between. Your body uses major muscles to perform pullups, as well as stabilizers to ensure you maintain proper form throughout the exercise.
When performing pullups, the main muscles being used are in back. These muscles are used the most throughout the duration of a pullup. Not only do you use these muscles to pull yourself up, you also use these muscles while lowering yourself.
Secondary muscles are those that are used to assist major muscles in performing an exercise. The secondary muscles used in pullups include your arms, upper back, abs and obliques. These muscles engage throughout the duration of a pullup and are very important. These muscles ensure that you have proper form throughout the duration of the pullup. These muscles are in isometric contraction because they are not moving like those in the back.
Ab Workout During Pullups
Your abs are used throughout the duration of a pullup. Whether you are at the beginning, middle or ending phase of the exercise, your abs are engaged. The abs are stabilizing your body to ensure you have good form during the exercise. Your abs are contracted the entire time and therefore receive a good workout during pullups.
Due to your abs being used as stabilizers during pullups there is a good possibility that they will become sore. Stabilizer muscles do not necessarily move, but remain contracted throughout an exercise. The abs are also in an isometric contraction which means that they are being contracted but not moving. Performing pullups not only works the muscle in your back and arms but utilizes many other muscles including the abs. The main reason your abs hurt during and after a set of pullups is due to the fact that you are using them.
Your abs may also be sore if you aren't following proper form. If your arms and back aren't strong enough to lift your entire body, you may be bending at the waist, or swinging and using the momentum to complete the pullup. Your body should remain vertical as you grip the pullup bar. Cross your legs to help your body remain stable. Lift yourself by using your arm, shoulder and back muscles. Tighten your abs and breath steadily as you lift yourself up. When your chin reaches the bar, pause, then slowly lower yourself. If you aren't ready to do full pullups yet, consider using a counter-weight machine to build up your muscles slowly.