One of the most common questions that I get asked as a Certified Personal Trainer is, “How many sit-ups a day should I do to get abs?”
This ends up getting into a much deeper discussion about “getting abs“ and what that means in terms of modifying your diet and exercise routine to optimize your body composition and decrease your body fat.
It also transitions into a conversation about how doing sit-ups is not the most effective way to strengthen your abdominal muscles or improve functional core strength.1Escamilla, R. F., Lewis, C., Bell, D., Bramblet, G., Daffron, J., Lambert, S., Pecson, A., Imamura, R., Paulos, L., & Andrews, J. R. (2010). Core Muscle Activation During Swiss Ball and Traditional Abdominal Exercises. Journal of Orthopaedic & Sports Physical Therapy, 40(5), 265–276. https://doi.org/10.2519/jospt.2010.3073
That said, there can be some benefits of sit-ups, and if you want to perform sit-ups in your ab workouts, you likely have the following question: “How many sit-ups should I do a day or how many sit-ups should I do based on my fitness level?”
In this guide, we will discuss how to perform sit-ups properly, what muscles are worked by sit-ups, more effective alternatives to sit-ups for your ab workout routine, and ultimately answer your question, how many sit-ups should I do based on my fitness goal and training level?
Let’s jump in!
How Do You Do Sit-Ups?
Before we look at how many reps of sit-ups you should do a day or per workout based on your fitness goals, let’s cover how to perform sit-ups.
The key to ensuring that sit-ups are both safe and effective in terms of actually engaging the muscles targeted by sit-ups is contingent upon performing them properly.
Here are the steps for how to do a sit-up:
How To Perform A Sit-Up
- Lie on your back with your knees bent and your feet on the floor. Ensure your feet are shoulder-width apart and your toes are pointed straight ahead.
- Try to press your lower back into the ground.
- Cross your arms over your chest or place your hands behind your ears, gently cradling your head.
- Inhale, engaging your abs to lift your shoulder blades and torso all the way up off the ground until your torso is fully upright, perpendicular to the floor. Lift slowly using your muscles, not propelling your body up with momentum.
- Slowly lower your torso back to the starting position, not allowing gravity to take over and do all of the work.
Are Sit-Ups Good for Abs?
A sit-up is a bodyweight exercise that primarily strengthens your abdominal muscles, namely the rectus abdominis.
This is the “six-pack“ ab muscles that run down the center of your torso, allowing for flexion of the stomach area.
Sit-ups also work your hip flexors, which refer to a group of muscles along the front of the hip and pelvis on either side of your groin that help flex the leg or bring the leg up towards the trunk.
Other muscles worked by sit-ups include the internal and external obliques, which are the muscles on the sides of your abs, and the transversus abdominis, a deep core muscle that encircles your entire trunk.
The obliques contract isometrically to prevent lateral bending and rotation of your trunk as you lift your torso off of the ground and the transversus abdominis contracts to increase intra-abdominal pressure for spinal stability.
Although both sit-ups and crunches are performed lying on your back with your knees bent and feet flat on the floor, a full sit-up involves lifting your entire trunk off the floor into an upright sitting position.
Crunches only involve raising your shoulder blades off of the ground, which largely eliminates the engagement of the hip flexors, particularly if your feet are not held down.2Burden, A. M., & G. Redmond, C. (2013). Abdominal and Hip Flexor Muscle Activity During 2 Minutes of Sit-Ups and Curl-Ups. Journal of Strength and Conditioning Research, 27(8), 2119–2128. https://doi.org/10.1519/jsc.0b013e318278f0ac
For this reason, as long as you do not have contraindications to spinal flexion, crunches are generally better than sit-ups if your goal is to strengthen your abs.3Andersson, E. A., Nilsson, J., Ma, Z., & Thorstensson, A. (1997). Abdominal and hip flexor muscle activation during various training exercises. European Journal of Applied Physiology, 75(2), 115–123. https://doi.org/10.1007/s004210050135
This is because crunches isolate the abs. In contrast, both the rectus abdominis abs and the hip flexors are the prime movers in the sit-up exercise.
That said, neither crunches nor sit-ups are particularly effective at strengthening the abs in a functional way and both exercises can put excessive pressure on the neck and spine.
Alternatives to Sit-Ups
Although sit-ups are generally a beginner-friendly calisthenics exercise and sit-ups can help strengthen your abdominal muscles, for certain populations, performing any type of crunch or sit-up exercise is contraindicated because of the flexion imposed on the spine.4Sasaki, S., Tsuda, E., Yamamoto, Y., Maeda, S., Kimura, Y., Fujita, Y., & Ishibashi, Y. (2019). Core-Muscle Training and Neuromuscular Control of the Lower Limb and Trunk. Journal of Athletic Training, 54(9), 959–969. https://doi.org/10.4085/1062-6050-113-17
It’s important to note this because even though sit-ups are supposed to involve keeping your spine straight the whole time, most people do experience some flexion of the spine with sit-ups.
If you suffer from osteoporosis, have degenerative joint disease in your spine, spinal stenosis, or herniated discs, doing sit-ups can increase your risk of further damage to your spine, such as causing vertebral compression fractures or exacerbating narrowing between your vertebrae.
Women who are pregnant or men who are dealing with diastasis recti5Hall, H., & Sanjaghsaz, H. (2022). Diastasis Recti Rehabilitation. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK573063/ should also avoid doing sit-ups because of the increased intra-abdominal pressure and positioning inflicted by the movement pattern.6Escamilla, R. F., Lewis, C., Pecson, A., Imamura, R., & Andrews, J. R. (2016). Muscle Activation Among Supine, Prone, and Side Position Exercises With and Without a Swiss Ball. Sports Health, 8(4), 372–379. https://doi.org/10.1177/1941738116653931
Alternative core exercises that do not require spinal flexion (or increase the likelihood of spinal flexion) are recommended in all of these cases.
Additionally, most people use momentum, gravity, and/or their hip flexors rather than really engaging the abs in a functional way.7Sullivan, W., Gardin, F. A., Bellon, C. R., & Leigh, S. (2015). Effect of Traditional vs. Modified Bent-Knee Sit-Up on Abdominal and Hip Flexor Muscle Electromyographic Activity. Journal of Strength and Conditioning Research, 29(12), 3472–3479. https://doi.org/10.1519/jsc.0000000000001006
Therefore, if you are prone to hip flexor strains, you should not perform sit-ups, especially if you are going to have someone or something hold down your feet while you do sit-ups.
This is because doing sit-ups with your feet anchored down increases the reliance on the hip flexors and tends to cause people to use more momentum, all of which can increase the risk of hip flexor strains with sit-ups.
Here are some more effective alternatives to sit-ups that target the same muscles in a more functional, effective, and safe manner:
- Planks
- Pallof presses
- Bicycle crunches
- Reverse crunches
- Turkish get-ups
- Hanging leg raises
- V-ups
- Medicine ball chops
- Bird dogs
- Bear holds with shoulder taps
- Stability ball or suspension strap tucks
- Dying bugs
- Russian twist
- Cable machine crunches
How Many Sit-Ups Should I Do A Day?
Remember, using proper form and technique when performing sit-ups is essential for ensuring that this exercise is not only effective at strengthening your abs, but is also safe for your back, neck, and hip flexors.
If you decide you still want to do sit-ups in your ab workouts, the number of sit-ups you should do depends on your fitness level, training goals, and the other exercises you are performing for the muscles worked by sit-ups.
Here are a couple of guidelines for how many sit-ups you should do:
How Many Sit-Ups Should I Do If I’m A Beginner?
For beginners, a good starting place is 2-3 sets of 10 to 12 sit-ups. Build up to three sets of 10 to 20 reps.
Remember to focus on the quality not the quantity of sit-up reps; move slowly and with control. Don’t use gravity or momentum.
How Many Sit-Ups Should I Do to Build Strength?
As you get stronger, progress your sit-ups by holding a weight plate against your chest and performing sit-ups on an incline bench or slant bench with your feet above your head so that you have to work against gravity.
Perform 3-5 sets of 10-15 reps to build strength and muscle.
It’s better to add more resistance and perform fewer sit-ups per set to increase ab strength and build muscle.
Slow down the movement as much as possible.
However, make sure you can safely handle the weight and you’re not straining your abs, hip flexors, or spine.
How Many Sit-Ups Should I Do to Increase Muscle Endurance?
A good starting place for the number of sit-ups you should do for muscle endurance is 3-5 sets of 15-25 or more reps.
With any strength goal or fitness level, it is best to perform a variety of core exercises so that you have a well-rounded core strengthening routine.
This becomes even more crucial with sit-ups.
Remember, sit-ups are not going to give you the best “bang for your buck” in terms of strengthening the abs.
Even the US Army, which used to require sit-ups as part of the Army Physical Fitness Test, abandoned this exercise in 20208Brooks, D. (n.d.). Army to introduce new PT test in 2020. The Fayetteville Observer. Retrieved November 15, 2023, from https://www.fayobserver.com/story/news/military/2018/07/14/no-more-sit-ups-army-to-introduce-new-pt-test-in-2020/11508228007/ in the updated Army Combat Fitness Test.
Therefore, focus on some of the alternatives to sit-ups that were mentioned and consider only training with sit-ups in your core workouts if you are specifically doing a fitness assessment that requires this particular ab exercise.
For more great workout ideas, check out some other stability ball exercises here.
