Tuck Crunch: Benefits, Muscles Worked, and More

published by: Debbie Luna
Last Updated:
January 19, 2023

Exercise routines have traditionally consisted of the abdominal crunch and its many iterations. Most individuals, regardless of whether they are serious athletes or go to the gym on occasion, have a set series of crunches that they do to enhance both their looks and the power of their core muscles. One of these variants, the tuck crunch, has gained popularity because of its simplicity and convenience.

The tuck crunch may be performed on almost any flat surface and requires the individual to flex their spine repeatedly. One may vary the resistance of the exercise by positioning the hands on the body in various ways. For example, the hands can be placed behind the head, across the chest, or on the sides of the body. The easiest variation would be hands on the sides of the body, as it provides the least resistance for the exercise.

Even though crunches are very effective exercises for developing the abdominal muscles, in recent years, they have come under a lot of flak due to evidence from studies indicating that they have a detrimental effect on spinal health. However, these studies were conducted ex-vivo, meaning they were conducted away from a live organism; hence, the precise risk-to-benefit ratio remains to be determined.

What is a Tuck Crunch?

A tuck crunch is performed on any flat surface using a repetitive crunching motion. A crunch is an exercise to strengthen the abdominal muscles by contracting them to flex the spine and pull the upper torso off the surface.

tuck crunch

The exercise is executed by lying supine on a surface with the thigh perpendicular to the floor and the knees bent at a 90° angle. One may vary the resistance for this exercise with different hand placements. However, putting the hands behind the back provides the most significant resistance for this exercise.

How to Perform a Tuck Crunch

To perform this exercise, lie supine on the floor, preferably with a mat. Bend the knees at a 90-degree angle and lift the thighs by bending at the hips until they are perpendicular to the floor. Place the hands across the chest and take a deep breath before flexing the spine.

When bending the trunk, the principle of proper breathing is to exhale when there is a muscular contraction and then inhale when the muscle relaxes. Inhale through the nose, and then exhale through the mouth. Next, engage the core and lift the upper back off the mat, bringing the chest closer to the knees. Exhale during this phase of the movement, then return to the starting position.

Muscles Worked in a Tuck Crunch

The muscle that runs horizontally across the front of the abdomen is called the rectus abdominis, more often referred to simply as the abs. This muscle is responsible for the six-pack in lean individuals. The main functions of this muscle are to bend the spine and compress the abdominal cavity. As a result, this abdominal muscle works the hardest throughout the workout.

tuck crunch muscles

A weightlifting belt is an excellent comparison of how the transverse abdominis muscle wraps around the waist. It supports the spine by creating pressure inside the abdominal cavity, which helps hold the entire core. The transverse abdominis is engaged when the core is braced.

Both the internal and external oblique muscles act to facilitate the rotation of the spine and lateral flexion of the trunk. During a tuck crunch, the obliques serve as stabilizers to prevent unintended movement.

Benefits of the Tuck Crunch

Better Isolation

A complete sit-up engages several groups of muscles, including the abdominals, hip flexors, and the muscles of the lower back. The abdominal crunch is better than full sit-ups for strengthening the rectus abdominis because it is more focused and doesn't use the hip flexors.

The rectus abdominis is the primary muscle that is worked in a crunch, which essentially makes the tuck crunch an isolation exercise. Sit-ups are great for targeting several muscular groups, but crunches will help to define the abs for that desired six-pack.

Easier than Sit-ups

Crunches can be easier to perform for some people. Sit-ups require a greater range of motion and can be difficult for people with limited mobility in their hips or lower back.

A full sit up is pictured below:

full sit up

Crunches, on the other hand, can be modified to be performed with bent knees or with the feet anchored to a stable surface, which can make them more accessible for people with mobility issues.

sit up

Better Engagement of the Upper Abs

Crunches can be more effective for targeting the upper abs as compared to sit-ups. Sit-ups require a greater range of motion, especially from the hip joint, making them a better exercise for the lower abdominals. In contrast, crunches involve a smaller range of motion focused on the trunk, which allows for more targeted activation of the upper abs.

Safer for the Lower Back

Some individuals have lower back discomfort when they do full sit-ups. They can put more strain on the lower back, which increases the risk of injury for people with existing lower back issues. On the other hand, because the lower back is never lifted off the floor while doing crunches, it reduces the risk of lower back injury and makes the tuck crunch more suited for those who suffer from lumbar pain and stiffness.

Controversy Over Crunches

The crunch has become a topic of contention among sports coaches, personal trainers, and fitness buffs. The concern is that high volumes of repetitive spine flexion may speed up spinal disc deterioration, as shown in studies using an ex-vivo porcine model. In addition, studies by Drake et al., Tampier et al., and Callaghan et al. have demonstrated that repeated flexion and extension motions contribute to intervertebral disc herniation.

Their studies subjected the porcine spine to high-volume cycles of flexion and extension with resistance similar to that in crunches. The porcine model was subjected to 4,000 to 85,000 cycles of repetitive flexion and extension, resulting in most of the discs showing complete or partial herniation.

Although these should be a cause for concern, keep in mind that the porcine model in these studies may not function precisely the same in normal movements as the muscles and other surrounding tissues were removed from the spine. Another thing to consider is that the porcine spine has a much smaller range of motion than the human spine during flexion and extension, as shown in a study by Alini et al.

The number of flexion and extension cycles used in the studies showing intervertebral disc herniations is also different from a normal exercise program, which usually only has a few tens of repetitions per set rather than thousands. In addition, most exercise programs have a few days of rest between hundreds of reps, allowing for adaptation and tissue recovery.

Physical exercise strengthens both the vertebrae and the discs, according to research conducted by Porter et al. A high degree of activity might cause vertebral strength to outnumber disc strength. It is also essential to bear in mind that the spinal tissue of live individuals adjusts to the strain of progressive training by growing stronger and, as a result, can tolerate higher amounts of pressure over time.

It is important to note that the crunch is a movement with a restricted range that does not operate the spine anywhere near its end-range flexion potential. As a consequence, the crunch places far less stress on the discs. However, it is safer to perform static exercises like planks if one feels pain or discomfort when performing crunches.

Final Thoughts

Overall, crunches can be a useful exercise for strengthening and toning the abs, especially for people who want to focus on the upper abs or who have mobility or lower back issues.

However, it is important to remember that no single exercise is a magic bullet for developing strong, defined abs. A well-rounded fitness routine that includes a variety of exercises for the abs, as well as the rest of the body, is likely to be most effective for achieving overall fitness and wellness goals.

References

1. Drake JD, Callaghan JP. Intervertebral neural foramina deformation due to two types of repetitive combined loading. Clin Biomech (Bristol, Avon). 2009;24(1):1-6. doi:10.1016/j.clinbiomech.2008.09.010

2. Tampier C, Drake JD, Callaghan JP, McGill SM. Progressive disc herniation: an investigation of the mechanism using radiologic, histochemical, and microscopic dissection techniques on a porcine model. Spine (Phila Pa 1976). 2007;32(25):2869-2874. doi:10.1097/BRS.0b013e31815b64f5

3. Callaghan JP, McGill SM. Intervertebral disc herniation: Studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. Clin Biomech (Bristol, Avon). 2001;16(1):28-37. doi:10.1016/s0268-0033(00)00063-2

4. Drake JD, Aultman CD, McGill SM, Callaghan JP. The influence of static axial torque in combined loading on intervertebral joint failure mechanics using a porcine model. Clin Biomech (Bristol, Avon). 2005;20(10):1038-1045. doi:10.1016/j.clinbiomech.2005.06.007

5. Alini M, Eisenstein SM, Ito K, et al. Are animal models useful for studying human disc disorders/degeneration? Eur Spine J. 2008;17(1):2-19. doi:10.1007/s00586-007-0414-y

6. Porter RW, Adams MA, Hutton WC. Physical activity and the strength of the lumbar spine. Spine (Phila Pa 1976). 1989;14(2):201-203. doi:10.1097/00007632-198902000-00009

Debbie (Deb) started powerlifting and Olympic lifting in High School as part of her track team's programming; She continues to train in order to remain athletic. Inspire US allows Deb to share information related to training, lifting, biomechanics, and more.
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