Life Style

Crunches vs. Sit-Ups: Which Are Better for Your Routine?

Woman doing abdominal exercises on a yoga mat outdoors.

If there are two exercises that nearly anyone who has ever exercised has done, it’s sit-ups and crunches. They’re simple, mainstay workout moves that require nothing but your body and a little bit of floor space. They can be done safely by people at any fitness level, and they can help you strengthen and sculpt your abs. But is one of them better than the other?

We looked into the benefits of both sit-ups and crunches, focusing specifically on the muscles in your body that perform them and how effective, or not, they are as part of your fitness routine. To help us discern whether sit-ups or crunches reign supreme on any given abs day, we spoke with two certified personal trainers to get their professional thoughts and opinions. Ahead, everything you need to know about these dueling abs exercises.


What Are Sit-Ups?

You probably already know what a sit-up is, but you might not realize that in order for the move to actually count as a full sit-up, you have to perform it from start to finish. Trainer Torra Wolf says that “sit-ups are the full range of motion as you lie on your back with bent knees, hands behind your head, and raise your upper body to your legs using your core.” Trainer Ray Cook notes that sit-ups “are an abdominal exercise that many people run to when they are first starting out with training to build endurance and definition of the rectus abdominis muscle, the six-pack.” He adds that “the basic performance of the movement starts with the exerciser lying on their back, lifting the torso up toward the knees, and returning to the ground.”

Now that you’re clear as can be on what sit-ups are, let’s look at what they can do for you.

Benefits of Sit-Ups

  • Improve strength throughout your entire core
  • Strengthen your muscles for everyday tasks, like getting out of bed
  • May help increase abs definition
  • Increase abs endurance, if performing many of them

Muscles Targeted During Sit-Ups

Though it may seem like sit-ups only target your abs, they actually do target the bulk of the muscles in your core. Wolf tells us that sit-ups work your rectus abdominis, obliques, and transverse abdominis. She adds that “as you lift your whole torso off the ground, the hip and neck flexors are contracted as well.” Cook says that sit-ups also utilize your hip flexors, which are an important muscle group that is often missed in strength training.

What Are Crunches?

Where sit-ups are a motion that takes you from laying on the floor on your back to fully seated with your chest completely off the ground, crunches require much less range of motion. And unlike sit-ups, which are a straightforward move with few variations, crunches have many.

To perform a crunch, Wolf instructs us that we should be “lying flat on the floor with legs bent.” She continues that from this position, you will “squeeze your abdominal muscles till your shoulder blades have lifted slightly off the ground. Done properly, the lower back should not move, only the chest. It is your choice whether to keep your hands behind your head to support your neck, or straight out in front of you.”

Cook notes that “crunches, when performed correctly, are known for their great core isolation and burn. The slight back and forth movement keeps the core contracted the whole time. With no breaks, it can really tighten those core muscles and strengthen the abdominal muscles.”

Benefits of Crunches

  • Simplicity: Wolf says that this move is an excellent one for learning how to activate your abs, because it is so simple
  • Increase abs strength
  • May enhance abs muscle definition
  • No strain on your spinal cord, which sit-ups might cause

Muscles Targeted During Crunches

As a slight, small motion that is heavily abs-focused, crunches predominantly work your rectus abdominis, as well as your obliques and transverse abdominis to a lesser extent. Unlike sit-ups, crunches do not work your hip flexors.

Sit-Ups vs. Crunches

So far, it may seem like sit-ups and crunches are pretty even when it comes to their benefits. However, after digging deeper, we discovered that isn’t actually the case. Crunches actually reign superior to sit-ups, according to our trainers.

First, because sit-ups involve a much greater range of motion through your back, they may not be ideal for your spine. Specifically, Wolf says that “crunches are found to cause less strain on the spinal cord and target the abdominal muscles. In recent studies, sit-ups have been found to be more damaging to the spine due to excess strain and pressure. Although crunches still curl the spine, they do not cause as much pressure as fully lifting the torso off the ground.” Cook adds that “sit-ups have greater implications on the lower back as well as an overreliance on the hip flexor muscle group during execution. Additionally, crunches do not need the assistance of an anchor or another person to be properly executed.”

The other reason that crunches are a better choice for your routine over sit-ups is that they may be more impactful for your abs, as they isolate those muscles more. Wolf tells us that “it is common for sit-ups to contract other muscles, such as the hip and neck flexors. With a full range of motion, more muscles work together. Therefore, when trying to isolate the abdominal muscles, crunches are the superior choice.”

Lastly, crunches are better for beginners who are learning how to properly use their core muscles. Wolf says that “a common mistake in abdominal workouts is pushing your abs outward as you crunch. With my clients, I take them back to the basics, teach them to pull their belly button in toward their spine, which helps to draw in their core and activate the muscles properly.” And Cook makes a point of letting us know that neither exercise should be considered the be-all, end-all for those who are looking to achieve a six-pack. He says that “fostering a sustainable lifestyle, and developing a healthy relationship with fitness and mindful eating, will reap greater benefits than any one movement.”

The Final Takeaway

Sit-ups and crunches are two simple, basic exercises. They both work your abs, but sit-ups also work your hip flexors. Sit-ups require a wider range of motion, while crunches are done with a much more limited range of motion.

When it comes to which is better, trainers say that crunches are. That’s because sit-ups can hurt your back and be hard on your neck and hip flexors, while crunches isolate your abs more completely. Because of that isolation, they are superior in terms of potential results, too. Crunches are better for beginners who are learning to activate their core, and for more experienced exercisers, they’re better because they are a more focused and isolating move, and will reap stronger rewards. So which exercise should you add to your routine? Crunches. They’re safer for your back and will give better results.

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