Dr. Taylor Ferguson
Why Crunches Just Won’t Cut It.
In my opinion, crunches and sit-ups are one movement that we could completely do away with. Harsh, I know. Hear me out here, there are reasons as to why I feel this way.
To start, let's break down what a crunch is. For all intents and purposes, I am referring to a traditional crunch where a person would be laying on the ground, face-up, knees bent, feet flat on the floor, while attempting to elevate their shoulders/torso off of the ground and towards their knees. It should also be mentioned, that throughout this post I am using the words crunch, crunches, and sit-ups interchangeably. When these movements are performed, the main muscle that is targeted is the rectus abdominis. This is the most superficial of our four core muscles.
The rectus abdominis is the muscle that creates the appearance of a “six-pack”, on one’s abdomen. This muscle is partially responsible for the flexion of our spines. I say partially, because there are other muscles that can also assist with this movement. Simply put, this is the muscle that allows you to actively bend at your waist. Therefore, as one is trying to elevate their torso during a sit-up, they are primarily recruiting the rectus abdominis muscle.
The other muscles that comprise our core are the internal and external obliques, as well as the transverse abdominis. The internal and external obliques and the transverse abdominis all have a connection to the lumbar spine, which allows these muscles to have a direct impact on the lumbar spine. Whereas, the rectus abdominis only attaches to the lower ribs, the pelvis, and the other abdominal muscles. Therefore, the effect that the rectus abdominis muscle has on the spine is much less than the effect that the engagement of the three other muscles has. Are you starting to see why crunches may not be the best exercise to strengthen your core? If you had a team of 4 players, would you only want one of those players to be conditioned at strong?
Let us continue, internal and external obliques are responsible for creating rotation within the lumbar spine and also resisting rotation in the lumbar spine. The transverse abdominis is our deepest core muscle and also the only core muscle that directly attaches to the lumbar spine. As a result, this muscle primarily acts as a lumbar spine stabilizer. Therefore, in order for a core exercise to have an effect on lumbar spine stabilization, it needs to recruit the transverse abdominis muscle. The transverse abdominis and the obliques are primarily targeted during movements that challenge our balance or require a static hold. Not during a sit-up or crunch.
Ok, so having a six-pack does not equate to having a strong core, but why is having a strong core so desirable anyway? Creating a strong core creates a window of opportunity. It improves our ability to maintain balance, which protects individuals from falling, potentially causing greater injury, especially in an older population. A strong core also has the potential to prevent the onset of lower back pain or the re-aggravation of one’s previously injured lower back.
How do you know if you should be strengthening your core? The simple answer is that everyone can benefit from having a stronger core. But also, one can determine the strength of their core by testing it functionally, i.e. how is your balance, how long can you hold a plank, how often do you experience lower back pain. It should be evaluated functionally as opposed to being based on the appearance of defined abs. As we discussed above, the presence of a six-pack is simply evidence of a well-defined rectus abdominis and a low body fat percentage. It does not reflect the strength of the other three core muscles or the functionality of one’s core. In order to have a strong and well-developed core, one should be working to strengthen the four core muscles as a team as opposed to simply focusing on the most superficial of the four. Exercises like a plank, glute bridges, side planks, Pallof presses, etc. are all movements that utilize the core as a whole.
While the return on investment from crunches and sit-ups is minimal from a strength and a functional perspective, this next section will show that it is maybe even worse than a minimal return on investment, but potentially damaging to your body. What if I told you that doing crunches or sit-ups regularly has the potential to actually cause harm?
It’s true. Crunches are not only not beneficial for strengthening your core, but they have the potential to cause injury and pain. The two areas that are susceptible to injury as a result of performing sit-ups and crunches are your lower back and your neck.
How is that possible, you may be wondering. For starters, when crunches and sit-ups are performed they are often done with our hands behind our head. This forces our chin towards our chest and actually reverses the curve of our cervical spine. A good core exercise maintains spinal neutrality. With the curve of our necks reversed, we are absolutely not maintaining a neutral spine. This in-it-of-itself has the potential to cause wear and tear but also, injury.
Additionally, when we are lying face up and trying to elevate our torso’s we often engage the muscles of our neck when trying to initiate the movement, as an assistant to our rectus abdominis muscle. When this occurs repeatedly we are putting ourselves at risk for developing a sprain or a strain of the ligaments/muscles of our cervical spine. We absolutely could perform crunches and sit-ups with a neutral cervical spine and without cervical muscular engagement, however, the likelihood that people of average strength and training could do so is very low. Even if we could do it, we would most likely not be able to perform this movement correctly for consecutive repetitions.
If you aren’t convinced yet, keep reading. The lower back is more often negatively affected by sit-ups and crunches than the cervical spine. The biggest reason for this is because crunches and sit-ups are repetitive movements. Similar to our cervical spine, this repetitive motion is away from our spine's neutral position and even worse, it is also reversing the curve of our lumbar spine. Due to the positioning, your lower back is under more stress during a crunch than your cervical spine. When doing this type of movement repetitively with force, you run the risk of injuring a lumbar disc. This can be a very painful experience and one that can take time to heal. Therefore, training our rectus abdominis through crunches and sit-ups and exposing ourselves to the potential for lower back pain, makes crunches and sti-ups the antithesis of core strengthening.
If you have an interest in strengthening your core properly or learning exercises to replace sit-ups and crunches in your routine, please email me, email@example.com. I will be happy to help you strengthen your core more effectively and safely!