In the battle of crunches vs. sit-ups, it’s hard to say which workout is the ab-solute best. But don’t sweat it. We’re here to break down the pros and cons of each. We also have terrific tips to help you make you the master of your midsection.

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The main difference between crunches and sit-ups is the range of motion. With sit-ups, you lift your torso up to bent knees with your feet flat on the floor. Crunches involve less effort. So, sit-ups activate more muscles but carry a greater chance of injury.

Sit-ups are one of the most popular ab exercises around. Some peeps think they’re basic AF, but sit-ups are actually hella effective. They target the rectus abdominis muscle that runs vertically down the front of your abdomen. They also work the hip flexors that extend from the thighs to your lower back.

Keep in mind, even though sit-ups aren’t crazy complicated, it’s still a good idea to be careful. You can put too much pressure on your spine as you lift yourself off the floor. Also, if your hip flexors tighten, it can trigger lower back or sciatica pain.

How to do sit-ups

GIF by Dima Bazak

Here’s how to slay some sit-ups like a pro:

  1. Lie flat on your back.
  2. Bend your knees 90 degrees and plant your feet flat into the floor.
  3. Place your hands either behind your head or crossed over your chest.
  4. Exhale while slowly curling your upper body forward until your chest almost meets your thighs. You should feel your ab muscles engaged.
  5. Inhale and return to the starting position.
  6. Repeat the sit-ups.

It’s pretty easy to incorporate sit-ups into your strength training workouts by adding sets after you lift and before or after squats. Aim for 3 or 4 sets of 15 sit-ups, 2 or 3 times weekly. This can maximize the results without exhausting your muscles.

Pro tip: Try to move smoothly and slowly. Be sure to use the correct technique to reduce your chance of injury.


There are lots of reasons why you may want to add sit-ups to your regular fitness routine. They can help:

  • improve posture
  • increase muscle mass
  • give your abs more definition
  • boost core and back strength
  • improve balance and stability
  • increase mobility and flexibility

P.S. A small 2010 study found that sit-ups helped increase diaphragm strength and overall respiratory function. But we def need more large-scale studies to prove all the perks.

Think of crunches as sit-ups’ more chill cousin. Yes, crunches work the abs, but they have a smaller range of motion. Only the shoulders come off the ground and your lower back stays on the floor. So, they might be a safer bet if you’re prone to back pain or injury.

Crunches give your rectus abdominis and obliques a solid workout. And according to a 2015 study, you may not need to crunch it up on the daily to see results. Researchers found that high school students with zero previous training who did one weekly session of crunches for 6 weeks had better abdominal endurance.

How to do crunches

GIF by Dima Bazak

Here’s how to get your basic crunch on:

  1. Lie on your back.
  2. Bend your knees and plant your feet flat on the floor.
  3. Place your arms across your chest.
  4. Inhale and tighten your abs.
  5. Exhale and slowly lift your shoulders off the floor to about a 30-degree angle.
  6. Hold for a second and feel your abs engage.
  7. Inhale and return to the starting position.
  8. Repeat the exercise.

Aim for a slow, controlled movement that engages the correct muscles. And don’t forget to use your core to raise the upper body to avoid head or neck strain.

Pro tip: As with sit-ups, you can add crunches to your strength training workouts a couple of times a week. Most folks aim for 3 sets of 15 reps. But you can switch it up based on your goals.


Doing crunches can help:

Psst. Another major perk is that they’re great for folks of all fitness levels, including beginners.

If sit-ups and crunches aren’t your fave — or if you want to switch things up a bit — here are some f-ab-ulous alternatives.

Bird dog exercise

This intermediate move targets abs and the muscles in your butt, hips, and back. Since it’s done on all fours, can be a top-notch option if you have back pain on the brain.

GIF by Dima Bazak

How to do the bird dog:

  1. Get on all fours with your hands shoulder-width apart and knees hip-width apart.
  2. Engage your core and inhale.
  3. Exhale and straighten your right leg behind you at hip level.
  4. At the same time, extend your left arm ahead at shoulder level.
  5. Hold the pose for 1–2 seconds.
  6. Return to the starting position.
  7. Repeat the exercise on the other side.

Mountain climber

The mountain climber is a full-body move that targets your core, hips, butt, arms, and thighs. Like the bird dog, it’s done on all fours, so it can help you avoid spinal stress.

GIF by Dima Bazak

How to do mountain climbers:

  1. Get into a push-up position with your hands shoulder-width apart and knees hip-width apart. Be sure to plant your palms evenly on the ground and curl your toes.
  2. Engage your core and move your right knee into your chest.
  3. Straighten your left leg behind you and curl your toes.
  4. Keep your arms in the same position, switch legs, and repeat, so you’re running your knees in and out at a comfortable speed.
  5. Continue for your desired duration.

Side plank rotation

Side plank rotations work your abs, obliques, and shoulders while helping hone your balance skills.

GIF by Dima Bazak

How to do it:

  1. Start in a side plank position with your right forearm on the floor. Your shoulder should be directly above your elbow with your feet stacked and hips off the ground.
  2. Raise your left arm to the ceiling and stretch your body from head to toe.
  3. As you exhale, reach your left arm around and underneath your torso. You should feel your obliques engaging as they help you rotate.
  4. Inhale and unwind your body to reach your left arm back to the ceiling.
  5. Keep your core and glutes engaged, helping you maintain stability and balance.

PSA: Side plank rotations are pretty advanced. So, you might want to master the OG side plank first.

Need a modification? No problem. We know this one is pretty intense, so here’s how you can make it a little less challenging.

  1. Get into a seated position and lower yourself down until your weight is supported by your right hip.
  2. Plant your right forearm into the ground at a 90-degree angle.
  3. Place your right foot over your left leg and plant your right foot into the ground.
  4. Press your weight into your forearm and lift your body off the ground.
  5. Keep your right foot pressed into the ground and your left leg straightened.
  6. Align your right hip with your right shoulder and engage your core.
  7. Rest your top arm by your side, stretch it straight into the air, or place it on your hip.
  8. Hold for up to 1 minute (or as long as you’re able to).
  9. Switch sides.
  10. Try to add a few extra seconds each time you practice this position.

Sit-ups and crunches are both valuable additions to a workout routine. Each exercise can help you build and maintain core strength and can also increase ab definition.

As for the sit-ups versus crunches debate, it really depends on your vibe. Some people prefer crunches because they effectively isolate the abs and have a lower chance of injury. But in general, sit-ups require a bigger range of motion and target the hip flexors more.