If you’ve come here wondering, “How many sit ups should I do,” it’s likely because sit ups have made a regular appearance in workout regimens for years. Fitness gurus throw around claims that sit ups will burn belly fat and get you chiseled abs. Instead of following blindly, it’s time we critically assess–do sit ups give you abs? At Functional Patterns, we use a first-principles approach, to see how these claims align with reality. Let’s take this style of approach to see–are sit ups good for abs?
Why do humans have abs?
A first principles approach breaks down this complicated topic into its basic elements. To understand whether sit ups burn belly fat and give you abs, consider first why abs evolved to exist as part of the human body. Anthropologists agree that the human body evolved to allow humans to stand, walk, run, and throw as primary movements (Rodman and McHenry 1980; McGeer 1993; Skoyles 2006; Leisman, Moustafa, Shafir 2016; Webb 2018). This means that abs are one piece in a system that is designed to produce these four functions. If abs evolved to produce these four main functions, it follows that the best way to train and develop your abs would be methods that orient around optimizing the systems that make you stand, walk, run, and throw.
What function do sit-ups train?
In a standard sit up, the rectus abdominis (think your 6-pack abs) is typically isolated, flexing the spine forward. While this might make your abs sore and give you a feeling of accomplishment that you pushed through the pain, it’s unlikely to lead to the outcome you desire. This movement seems to train the abs to function in an isolated range of motion that does not show up in the systems the body should engage to stand, walk, run, or throw in the most optimal way.
It’s true that in these movements, you will see the abs flex the spine into a forward curvature. However, there are a couple key differences:
1. Training the spine to be supported from the front and back vs. just the front
When walking, running, and throwing optimally, the spine will be pulled into flexion by the abs, but once reaching a point of maximum flexion, it will be actively extended by chains of muscle and fascia running along the back side of your body, pulling the spine out of flexion. This is contrary to the sit up where after reaching the point of maximum flexion, the spine is straightened out by gravity as the upper body returns to the ground. Instead of training the spine to recoil from a flexed position, the sit up trains the spine to remain flexed or go limp after flexion. The most efficient movement cannot happen when the spine remains flexed or goes limp. Further, consider how this could impact posture. By not training the spine to extend, you are more likely to default to a flexed spine position while sitting and standing. It seems sit ups could contribute to the hunched over posture exhibited by so many humans today.
2. Isolation vs. Integration
The sit up predominantly engages the upper body without regard for how the lower body should engage to support the upper in that context. Chains of muscles and fascia run from the tips of our toes to the top of our head. The rectus abdominis is part of the Superficial Front Line, identified by Anatomy Trains (see image to the right). Instead of training the whole chain to contract, the sit up trains the abs to work independently from the rest of your body. Optimal movement requires all parts of the body to work together as a system–not as individual parts in isolation. Compare this to a steering wheel and a rudder on a boat. Even if the wheel spins and the rudder swings side to side, the captain will not be able to change direction unless the wheel and rudder are integrated.
As such, we can conclude that sit ups are not the most effective method to give you abs, and further, they will likely be detrimental to your ability to develop abs in a way that aligns with your body’s ideal physiology.
What about belly fat?
Again, let’s take a first-principles approach to understand–do sit ups burn belly fat. First, consider what is the main cause of the body to add on fat. When more calories are consumed than are used up, the body stores these excess calories as fat. This means that you can get rid of belly fat by either decreasing your calorie intake or using up more calories through exercise. How many sit ups should I do–will 100 sit-ups a day do anything? The additional calories you burn with sit ups may help to some extent, but we must also think about the negative effects described above that come along with that activity. The human body does not hand out participation trophies. This is to say, all activity is not necessarily good when examined holistically. Additionally, we at Functional Patterns have observed that fat seems to get stored in areas of the body where muscles are not integrated with the systems the body is designed to use to produce effective movement. When the muscle cannot support an area of the body effectively, the body relies on fat as a means of support. All told, the negative side effects of sit ups far outweigh the slight benefit.
So what should I do?
Let’s recap what we’ve learned from our first-principles analysis:
Are sit ups good for abs? Not really. The best way to stimulate natural development of any muscle is to use it in the movements it was primarily involved with over the course of human evolution. The motion that happens in a sit up does not tie back to those primary movements. Functional Patterns has developed a proprietary procedure for doing a “sit up”-like motion that does tie back to the primary movements. You can find that procedure within the Functional Training System online course.
Do sit ups burn belly fat? Only from the standpoint of the small number of calories burned from the movement. The things that have the greatest impact on belly fat are calorie intake and usage in addition to moving your body in ways that respect the human body’s primary evolutionary functions.
How many sit ups should I do? In the standard way they are performed, none. Remember, the outcome you desire is not based primarily on the quantity of exercises you do, but rather whether the exercise is contributing to your ability to stand and move better.
If you are looking for the easiest exercise to give you a flat stomach, it is going to be those that help you stand, walk, run, and throw most efficiently. At Functional Patterns, our method prioritizes these functions for this reason. Paired with thoughtful control of the calories you consume, the Functional Patterns training methodology sets you on the path to burning away stubborn belly fat and giving you abs that both look attractive and function well. As we’ve learned today, attractive looks and optimal function go hand in hand.
Leisman, G., A. A. Moustafa, and T. Shafir. 2016. Thinking, walking, talking: Integratory motor and cognitive brain function. Frontiers in Public Health 4: 94.
McGeer, T. 1993. Dynamics and control of bipedal locomotion. Journal of Theoretical Biology 163 (3): 277–314.
Rodman, P. S., and H. M. McHenry. 1980. Bioenergetics and the origin of hominid bipedalism. American Journal of Physical Anthropology 52 (1): 103–106.
Skoyles, J. R. 2006. Human balance, the evolution of bipedalism and dysequilibrium syndrome. Medical Hypotheses 66 (6): 1060–1068.
Webb, N. 2018. "The Upright Battle: Morphological Trends of the Bipedal Pelvis." PhD diss., City University of New York. CUNY Academic Works.