When it comes to searching for ab exercises it’s easy to find ones that involve crunching in a short range of motion.

Crunches, sit ups, leg raises, bicycles all involve partial ranges of motion where the spine flexes from a neutral position.

While these could help to build abdominal muscle, there is one often overlooked exercise that could be more effective and beneficial. This exercise involves stretching the abs first and then contracting them through the full range of motion.

In doing so this also creates mobility in the thoracic spine. The exercise is sometimes referred to as a myotatic crunch or a thoracic extension crunch. 

How it’s done

The movement is best performed with a foam roller, Bosu ball, stability ball, or any surface that lets you arch through the upper spine while keeping your back supported.

The intention is to keep tension on the abs while lowering slowly into a stretch with an arched upper back. You stop lowering when the abs are in a fully stretched position before pausing and coming back up.

For good form and getting the deepest stretch, the chin should be kept tucked and the pelvis should be flexing upwards through the movement.

Arms closer to the body will have less resistance than arms outstretched overhead so the movement can be adjusted for difficulty even while mid movement.

Also weight can be added easily for extra difficulty. Typically it’s best to set up with the knees above hip level to protect the lower back. If lower back pain is felt at any point, the range of motion should be shortened so the movement is pain free. 

Stronger core contraction

Since the exercise puts you in a full stretched position under load it sends a powerful signal to the body for building muscle.

Loaded stretching has been reported to work on a number of physiological factors beneficial to muscle growth. The movement is also going through a much larger range of motion which has the advantage of recruiting more muscle mass.

What’s often noted in this exercise is the feeling of the lower abs contracting hard to pull from the stretched position. Most conventional ab exercises don’t target this area effectively.

Benefits to the spine

One of the biggest benefits to this movement is that it mobilizes the thoracic spine. This area often gets very stiff and tight which can lead to back pain.

Having adequate mobility there helps to more evenly distribute force throughout the spine and often helps to take stress off the low back.

There have also been studies that show thoracic spine mobilization helps to alleviate back pain. This tends to be an area where a lot of people carry stress and creating movement there can help to relieve some of that stress. 

Benefits to the hips

Another benefit of this movement is that it minimizes the use of the hip flexors in performing it. Often hip flexors can get stiff and tight from being in a shortened position due to long periods of sitting.

A lot of conventional ab exercises involve heavy recruitment of the hip flexors in a shortened position which can exacerbate this problem. Since the movement is mainly isolated to the abdominal muscle it minimizes the use of hip flexors. 

Overall the movement can be very effective to start seeing higher levels of definition in the abdominal region with added benefits of spinal mobility.

Tim Ferris, author of “The 4 Hour Body” included this as one of the exercises that helped him achieve a 6 pack where other exercises failed. For best results increase repetitions, set, load, or frequency over time.