The differences between crunches vs sit ups

Crunches vs Sit Ups: Which Is Better for Your Abs? And Why?

Chances are, you’ve heard the debate of crunches vs. sit ups. 

Which is the best exercise for a stronger core? Which one is the best ab exercise overall?

They’re both effective, popular exercises that target your abdominal area. People sometimes even use the terms interchangeably. 

So is there a difference?

Yes. Yes, there is. 

The main difference is that crunches target and isolate your core while sit-ups require the activation of more muscles in your body.

In addition to the core, it engages your transverse abdominis and lower back muscles. 

They’re each great in their own ways and you should consider adding both to your workout routine. They are also great for good posture

But remember, if you’re looking to burn belly fat or a lean stomach, you’ll need both a healthy diet and exercise. 

It’s essential to pay attention to calories and perform cardio and strength training. 

Let’s concentrate on both abs exercises covering what each is and their function. That followed by the target core muscles, proper form, and variations. 

Then we will compare the crunch vs sit up!

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What Is a Crunch?

What is a crunch exercise?
Crunch exercise

Crunches are a no equipment core exercise that targets your abs and are great for beginners! It’s an isolated exercise where your upper abdominal muscles contract to lift your head, neck, and shoulders. 

To perform the crunch exercise, lie on your back with your knees bent, feet shoulder-width distance apart, and firmly planted on the floor. 

Stack your hands behind your head, do not interlace your fingers. Hand placement is important. You don’t want to pull on your neck so consider placing your hands closer to the base. It’s all up to individual preference.

On an exhale, use your core to lift your thoracic spine (head, neck, and shoulders) off of the ground, crunching through your midsection.

Inhale, slowly lower back down to the starting position.

Note that there is a risk of injury with this exercise. It can place a lot of strain on your neck muscles and back. If that happens, place your arms across your chest instead. (1)

The downside to the crunch is that it only targets your upper and middle abdominals. You’ll have to add other exercises to your exercise routine (such as planks) to hit your obliques and lower abs.

Crunches are sometimes referred to as partial sit ups.

Types of Crunches

Types of Crunches: bicycle crunches, reverse crunches
Different types of crunches
  • Basic crunch: As described above, it is performed by lifting your upper back (to your shoulder blades) off of the mat.
  • Bicycle crunch: Add a twist! Set yourself up in the basic crunch position. Lift both legs at 90-degree angles. (Ultram) Your shins are parallel to the ground and your knees are stacked over your hips. Lift your head, neck, and shoulders. Engage your core. On an exhale, twist, connecting your right elbow to your left knee as you straighten your right leg. Inhale and release to the starting position. Repeat on the opposite side.
  • Reverse crunch: Flip your crunch around with the reverse crunch. Start by lying on your back, arms by your sides. Your legs are at 90-degree angles, knees stacked over your hips. On an exhale, engage your lower abdominals as you lift your knees towards your chest, raising your hips off the floor. Hold and release.
  • Crunch on a ball: You can also perform the basic crunch on an exercise ball! This is easier on your back and can add an extra challenge of stability.

What Is a Sit Up?

What is a Sit up?
Woman doing sit-up exercise

While similar to the crunch, the sit ups require you to lift your torso all the way up to your lumbar spine. In this core body workout, your whole torso is off the floor.

Because of this, situps activate more muscles than just your upper abdominals to perform. They engage your rectus abdominis, internal and external obliques (your side abs), hip flexors, iliopsoas, and your rectus femoris. (2)

You can even work your lower leg muscles by hooking your feet under a stable object such as a couch or bed.

With greater muscle engagement comes a greater risk of injury, especially on the spine. Use proper form and control to avoid straining your neck or back, especially your lower back muscles.

To perform, use the same setup as the basic crunch. Start with your feet firmly planted on the floor.

For added resistance, plant your feet under a secure object for lower leg engagement. Bring your hands behind your head.

On an exhale, lift your entire torso including your lower back muscles off the mat. In the same movement, curl your spine towards your knees. 

Inhale and with control, slowly lower back to the starting position. Repeat for your desired number of repetitions.

Types of Sit Ups

Types of sit-ups: V-ups
Woman doing V-ups sit-up
  • Basic sit up: As described above, this is done by lifting your spine off of the floor.
  • Frog leg sit ups: In this variation, bring the soles of your feet together into a diamond shape. 
  • Running Man sit up: This is a fun twist option! Lie on your back with your legs straight. As you lift your upper half off the floor, connect your right elbow to your left knee. Repeat on the other side. 
  • V-ups: The V-up is a more advanced move. Lie on your back with your legs straight. On an exhale, lift as you reach your fingertips towards your toes. Your body will create a “V” shape.

The Key Differences Between Sit ups vs Crunches

Differences Between Sit ups vs Crunches
Differences between sit ups vs crunches

As you can see, situps and crunches are very similar. The most notable difference is muscle isolation. But let’s dig a little deeper.

  • Range of motion: In crunches, you’re lifting your thoracic spine off of the mat. In a full sit-up, you are lifting your entire back upright.
  • Control: Crunches require less range of movement. You have more control to build abdominal strength compared to the situp. 
  • Suitability: Crunches are great for beginners. They provide intense muscle isolation. But if you’re looking to build strength, sit ups are better suited.
  • Muscle groups focus: The crunch allows you to focus on your upper abs. Situps allow you to focus on multiple muscle groups such as your hip flexors and obliques.
  • Spinal stress: Crunches place less stress on your spine due to a limited movement and more controlled compared to the sit up. Situps require a curve in your back as you lift and return. This may put too much pressure on your spine or cause neck pain.

Sit Ups vs Crunches: Which Is Better?

So which abdominal exercise is better?

The conclusion: it depends on your goals! The difference between sit-ups and crunches is mobility. The crunch requires less involvement of the back.

If you’re looking to work your upper abdominal muscles, crunches are your best bet. If you’re looking for a larger range of motion and rectus abdominis /oblique work, situps are your best choice.

In fact, it’s a great idea to incorporate both into your workout routine. This is especially so if your goal is weight loss, a lean stomach, or better posture!

Final Word On Crunches vs Sit Ups

In the sit-up vs crunch debate, choosing which effective core exercise is best for you depends entirely on your goals and fitness level.

If you’re a beginner, start with the crunch. Learn good form and control to avoid injury. 

If your goal is to build strength, go with the situp. It’s a larger range of motion (lifting your entire torso) than crunches. It also targets more than just your abdominal muscles.

Regardless of which you choose, be sure to work your entire core! Balance is key. In addition to these, add a side plank or plank to your training session.

As your endurance improves, you can add resistance or weights to your routine to further reach your goals.

For many people, a strong core is a goal. Consult a personal trainer for advice or to create a personalized exercise program.


  1. Nunez, Kristen. “How to Do Crunches and Other Exercises for Toned Abs”. Healthline. 26 Sept. 2019.
  2. Rice, Jeffery. “What Muscle is Used to Do Situps?”. Livestrong. 3 July 2019.

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