Crunches Vs Sit-Ups: Which Is Better?

Core strength isn’t just about having abs, it’s about supporting your posture, protecting your back from injury, improving your balance and stability, and making all other exercises and daily movements a whole lot easier. 

Building your core strength will be a key focus of any great workout routine, but what movements should you turn to? Crunches and sit-ups are two of the most well-known core exercises, but despite looking very similar or even referred to interchangeably, there are some significant differences between them that it pays to know about. After all, crunches and sit-ups are not the same thing. When it comes to comparing crunches vs sit-ups, here’s what you need to know.

Crunches

How to do a crunch

Start by lying flat on your back on a yoga mat with your knees bent and feet flat on the mat, roughly hip-width apart. Placing your hands behind your head or by your ears, tuck your chin into your chest and think about drawing your belly button towards your spine to engage your core. 

Then, use your abdominal muscles to lift your head, shoulder blades and upper back off the mat. Lower your head and shoulders gently to return to the starting position, then repeat for the specified number of repetitions. Throughout the exercise, your lower back should remain connected to the floor.

What muscles do crunches work?

Because crunches focus on lifting your shoulders and upper back off the floor, rather than your entire torso, they focus mostly on your abdominal muscles, particularly those in the mid and upper area. Crunches are a great example of an isolation exercise, meaning they target one specific muscle or area of the body. 

Sit-ups

How to do a sit-up

Start by lying flat on your back on a yoga mat with your knees bent and feet flat on the floor about hip-width apart. Place your fingertips by your ears and engage your abdominal muscles by thinking about drawing your belly button in towards your spine. 

Slowly lift your head, shoulder blades, and torso fully off the floor until you are sitting up tall. Slowly lower your torso, shoulder blades and head to the mat to return to the starting position. Repeat for the specified number of repetitions.

What muscles do sit-ups work? 

Unlike crunches, which almost exclusively work your abdominal muscles, sit-ups are a more intense and difficult exercise as they work a broader range of muscle groups such as your chest, lower back, hip flexors, chest and even muscles in your legs. 

Are sit-ups better than crunches?

Although working more muscles is a plus, it doesn’t automatically mean sit-ups are better than crunches. Sit-ups come with a higher risk of injury if they’re not performed correctly or if you already have back issues, due to the spinal flexion and extension involved in each rep. The best core exercises for you will depend on your unique body and training goals!

2011 research highlighted that some fitness professionals have questioned the safety and effectiveness of performing flexion-based spinal exercises like crunches, based on the belief that the spine has a finite number of bending cycles and exceeding this limit can lead to the early onset of disc damage. Whether or not this is true, these exercises can definitely cause back pain or discomfort for some people. 

Overworking your hip flexors can also lead to increased tightness in this area if you’re not prioritising recovery, stretching or foam rolling.

Which is best for YOU? 

Go for crunches if…

• If you have back problems or performing sit-ups hurts your back (or opt for another core exercise altogether!)

• If you’re a beginner or are coming back from a break or injury

• If you want to target your abs 

Go for sit-ups if…

• You can perform them correctly and don’t experience any back pain 

• You want to target a wider range of muscles 

• You want a challenge or a more intense exercise 

• You want to work on your mobility at the same time

Crunch and sit-up variations for a challenge

Wanting to squeeze even more out of your crunches? You can make crunches more difficult by adding a double pulse at the top of the movement, trying bicycle crunches, oblique crunches or toe tap crunches. 

To level up your sit-ups, try a sit-up with a twist, straight leg sit-ups, or hold a dumbbell or medicine ball for extra resistance.

Or skip these moves altogether

If you find crunches or sit-ups just don’t feel great for your body or you don’t enjoy them, don’t feel like they’re an essential exercise. There are so many other ways to build your core strength, especially if you’re wanting to avoid flexion and extension of your spine. Instead, you could opt for planks (or any plank variation), Russian twists or glute bridges.

Many functional strength exercises also work on your core strength, even if they don’t seem like ab exercises. Squats, deadlifts, hip thrusts and pull-ups are all great examples.

Core strength doesn’t start and end with crunches and sit-ups, but when you’re tossing up between these two exercises, it helps to know what sets them apart from each other and which is the better option for you. 

And if they’re not right for you, don’t be afraid to substitute another exercise if crunches or sit-ups appear in your Sweat program or On Demand workouts. Your body will thank you for it!