Sit Ups Are a Classic Core Exercise that Everyone Should Master—Here’s How

While you may love to dabble in complex core workouts like dragonfly or L-sit pull ups, the OG core crushers (think: planks and bird dogs) remain an effective way to work your midsection and improve your overall fitness. Sit ups are an example of a fitness move that truly never gets old, but it’s important to perform them the right way to avoid injury and make the most of your limited exercise time. If you have questions about how to sit up properly, you’re in the right place. 

What Is a Sit Up?

“A sit up is a commonly used core move where you start lying down with your knees bent and your feet on the floor,” says Peloton instructor Olivia Amato. “The goal is to lift your upper body off the mat using your core muscles while keeping your feet flat on the ground.” As you lower back down to the ground, you stay in full control of the movement and keep your lower back pressed firmly onto the ground. “Your hands can be crossed to opposite shoulders or behind your ears. Just make sure you aren’t pulling on your neck,” adds Olivia. 

Why Sit Ups Are a Great Core Exercise

While sit ups seem basic at first glance (sit up, lower down), Olivia says they offer plenty of benefits for beginner, intermediate, and advanced exercisers alike. 

First and foremost, sit ups strengthen your core, the general term used to refer to the midsection (or the group of muscles in your lower back, pelvis, stomach, and hips). Having a strong core helps you perform functional movements that are necessary for your everyday life, such as standing up and sitting down, lifting grocery bags, or reaching for items in your pantry. “Strengthening your core also helps improve your posture and just improve your overall fitness,” says Olivia. 

“Sit ups also improve your stability,” says Olivia. “This, in turn, will help strengthen your back, which is important if you have lower back pain.” For all these reasons, Olivia loves to add sit ups to her Peloton classes. “I do incorporate sit ups into my own routine and into classes. They are so hard and a good fundamental basic to come back to. Keeping your feet down is the hardest part,” she says. 

What Muscles Do Sit Ups Work?

When you’re performing a sit up correctly, you’ll probably feel it in most areas of your body, but Olivia says four muscle groups receive the most benefits from this exercise. “All of these muscles are important for improving core strength and stability, helping to prevent lower back pain, and helping to improve athletic performance overall,” says Olivia. 

Rectus abdominis: This is the top layer of the abdominal muscles that are colloquially referred to as “the abs.” 

Obliques: The obliques are the muscles on either side of the abdomen.

Transverse abdominals: This is the deepest of the six abdominal muscles, aka the deep core. It stretches from the ribs to the pelvis. 

Hip flexors: The hips flexors are a group of muscles located on the front of the hip, near the upper thigh. As the name suggests, they help your hip flex as you perform everyday movements like sitting or bending over. 

Sit Up Form and Safety Tips

When you’re ready to start your core workout, you need to keep a few key form and safety tips in mind. Below, Olivia breaks down exactly what trainers look for in the perfect sit up.

Control your movement on the way down: To reap the most rewards from your sit ups, think about slowly lowering yourself to the ground. This challenges your muscles to stay engaged for a few seconds longer, which can seriously boost your core strength in the long run. 

Moving with intention: You shouldn’t just go slow as you lower down. Try your best to perform the whole movement in a slow and controlled manner to make the most of your reps.

Keep your neck in a neutral position: Cranking your neck up towards your knees can result in pain in your neck and shoulders. Gently align your neck with the rest of your spine and remind yourself to relax your upper body and let your core do the work. 

Make sure your core is doing the work: As you perform the movement, tell yourself to let the movement come from your abdominals. Otherwise, your back will try to take over and make the exercise easier.

How to Do a Sit Up Correctly

Step 1: Setting Up 

Come down on to the floor or a yoga mat. Place your feet on the ground so your legs form a 90-degree angle. Press your lower back into the ground to engage your core. Cross your arms over your chest or place your hands gently behind your neck. 

Step 2: Sit Up 

Engage your abs to lift your upper body without using momentum. You want your chest to land on or near your thighs. 

Step 3: Lower Down

Slowly lower back down to the ground. Keep your tailbone tucked and your core engaged. Touch down and, when you’re ready, begin the move again. 

What’s The Difference Between Crunches and Sit Ups?

Sit ups and crunches may look similar, but they have a key distinction, according to Olivia. “With crunches, you aren’t fully sitting up. It’s a smaller movement with a smaller range of motion. With crunches you are engaging your core muscles to lift just your head, neck and shoulders off the floor instead of lifting your entire upper body off the floor as you would in a sit up,” she explains. 

In short: While performing sit ups, you are sitting all the way up; when performing crunches, you only come up part way. 

Sit Ups: Variations and Modifications

If you’re ready to revamp classic sit ups, you’re in luck: There are so many sit up variations that allow you to challenge different areas of your body. Below, we walk you through four of them. 

Assisted Sit Ups

If normal sit ups feel a bit too challenging, ask someone to hold down your feet as you sit up. If you’re alone, place your feet under the handles of heavy dumbbells to keep your feet from lifting up.

Butterfly Sit Ups

For a hip-opening, hip flexor-challenging variation, try bringing the soles of your feet together in butterfly pose. From there, you’ll just sit up as usual, reaching your fingers out and past your toes. 

V-Sit Ups

For this more challenging variation, you’ll begin lying flat on the ground with your arms extended straight overhead. Use your abs to bring your body upward, legs straight, upper body straight, so you look like a “V.” With control, lower down to the ground. 

Weighted Sit Up

If you’re ready to challenge your sit up abilities, grab a weighted plate or dumbbell. You’ll lie down on the ground just as you would during a classic sit up. Holding the weight or plate overhead, sit up and press the weight over your head. Your back should remain straight throughout the entire exercise. 

The Bottom Line

If you’re stumped about what core exercise to add to the mix today, sit ups are an easy and effective option. This simple workout move—which basically just involves sitting up and slowly lying back down—works four major muscle groups in your mid-body: the rectus abdominis, obliques, transverse abdominals, and hip flexors. And, fortunately, whenever classic sit ups start to feel a bit stale, there are countless variations you can throw into the mix.