A PT Explains How to Do Crunches So They Actually Work Your Abs

Whether you're a frequent or infrequent gym-goer, there's a good chance you've done crunches. Crunches are a classic core-strengthening exercise. But while they may seem ubiquitous — heck, they're even part of the dreaded Presidential Fitness Test — they aren't the only way to strengthen your abs.

Like all exercises, crunches work best — and make you the least susceptible to injury — when they're done with proper form. POPSUGAR spoke with Grace Taylor, PT, DPT at H&D Physical Therapy, to learn everything you need to know about this classic core move, including whether it's actually worth your time, how to do crunches correctly, and plenty of crunch exercise variations that work your abs in different ways.

The Benefits of Crunches

Crunches utilize and strengthen your rectus abdominis (the ab muscle along the front of your stomach), internal and external obliques (which wrap around the sides of your stomach), transverse abdominis (your deepest, corset-like ab muscle), and hip flexors, Taylor says. The muscles utilized during crunches are important stabilizing muscles in the body. Better stability means better balance, lifting, postural control, and power production, plus minimized aches and pains, particularly in the lower back. Overall, a strong core supports just about every movement you do.

And the crunch movement does show up in your everyday life — think about how you get out of bed in the morning or get up from a couch or lying on the floor. Strengthening the muscles involved in this movement pattern will help you continue to execute it safely in your day-to-day.

Crunches Form Tips

There are two common positions for your hands while performing crunches, and Taylor has a preference. You can either place your hands behind your head, or you can cross your arms over your chest.

Placing your hands behind your head creates a longer lever arm and requires more intense core work. However, with this added challenge, it's easier to use momentum, rather than strength, to complete your crunches. This can place a lot of pressure on the spinal segments in the neck and upper back. If you use this variation, ensure your arms remain inactive throughout the entire exercise, so you're not pulling on your neck.

Placing your hands on your chest makes it easier to round your midback during the crunch, which can place more pressure on your spine and decrease your core use. However, this position is less likely to strain your spine than placing your hands behind your head, which is why Taylor recommends it.

To keep good form, Taylor recommends that you avoid tucking your chin toward your chest. A good way to avoid this is by finding a spot on the ceiling to keep your eyes on. Additionally, making sure you keep your low back flush with the ground is key. Sitting up too much can put a lot of strain on your spine and hips — if your back comes off the ground, know that you've gone too far. (That move is generally considered a "sit-up" rather than a crunch.)

Also, oftentimes when crunches are done absentmindedly, your hip flexors take over and pull on your lower-back muscles, which may cause spinal issues down the road, says Glo trainer Ridge Davis. And when they take over, they disengage your abs, making the crunch exercise far less effective as a core move. "It's all about awareness when performing crunches — or any exercise for that matter," Ridge says.

How to Do Crunches

With that in mind, it's worth it to learn how to do crunches correctly. "My philosophy is that there is not a bad exercise but a poorly executed one," Davis says. For a visual, watch Pilates instructor Isa Welly do this move properly, or follow the specific steps on how to do a crunch below.

  • Lie on the floor with your back flat, both knees bent, and feet planted on the floor about shoulder-width apart. Cross your arms, and place your hands on your chest.
  • Inhale, then exhale and activate your core muscles to lift your shoulder blades off the ground.
  • Hold for a second, then inhale while slowly lowering your shoulder blades to the floor. That's one rep.

Crunch Cautions and Modifications

Taylor confirmed what you may have already heard, that crunches are a heavily debated exercise. Like burpees, they can be beneficial if done property, but they can also put a lot of strain on your spine. Taylor doesn't recommend crunches to people with a history of neck or back pain and recommends choosing a different core exercise if you have pain during, immediately after, or the day after you do crunches. The good news? We have some ideas for you right here.

Keep reading for some crunch exercise variations that target different parts of your core and can be better choices depending on your exercise history and ability.

— Additional reporting by Lauren Mazzo, Nicole Yi, and Chandler Plante

Double-Leg Stretch
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Double-Leg Stretch

This classic Pilates ab move and crunch variation is perfect for working both your upper and lower abs. The goal is to feel a deep scoop in your abs, keeping your core strong and stable, while your extremities move.

  • Start lying on your back with your hips and knees bent to 90 degrees in a tabletop position. Lift your upper back and head off the mat, reaching your fingers toward your toes.
  • Lengthen your legs away from your center (at about a 45-degree angle to the floor) as you lower your upper body, reaching your arms overhead. Keep your low back pressing into the floor.
  • Bend your legs back into tabletop position as you lift your upper body off the floor and reach your hands toward your toes. That's one rep.
Bicycle Crunch
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Bicycle Crunch

Bicycle crunches are a great way to target your rectus abdominis and obliques in one easy exercise. Speed is not the name of the game here; go slowly to focus on your form and breathing. Also note: it's not necessary to touch your elbows to your knees, as this could strain your neck.

  • Lie flat on the floor with your lower back pressed to the ground (pull your abs down to also target your deep abs). Interlace your fingers, and put your hands behind your head.
  • Bring your knees in toward your chest, and lift your shoulder blades off the ground.
  • Straighten your right leg out to about a 45-degree angle to the ground while turning your upper body to the left, bringing your right elbow toward your left knee. Make sure your rib cage is moving and not just your elbows.
  • Now switch sides, and do the same motion on the other side to complete one rep (and to create the "pedaling" motion).
Pilates Scissor
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Pilates Scissor

Another Pilates mainstay, scissors demand the same core stability as the double-leg stretch, but when extending one leg at a time.

  • Lie on your back, and engage your core to lift your upper body off the floor so your shoulder blades hover.
  • Lift your left leg to hover off the floor, then bring it up toward the ceiling, gently holding your right shin.
  • Keep your upper body lifted as you switch legs. That's one rep.
Oblique Crunch
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Oblique Crunch

This simple — and literal — twist on the crunch exercise places more demand on your obliques, the muscles that wrap around the sides of your torso. Depending on your spinal mobility, you may not be able to place your legs flat on the floor — that's OK.

  • Start lying face-up on a mat with your knees bent and your feet flat on the mat. Your heels should be about a foot away from your hips. From this position, lower both legs to the right. Your right leg should be on the ground, and your left leg should be stacked on top of the right. Your upper back and shoulders should be flat on the mat.
  • With your hands behind your head or crossed in front of your chest, engage your core (gently brace your abdominal muscles) and slowly lift your shoulders off the ground, performing a crunch.
  • With control, lower your body back down to the starting position. That's one rep.
  • Try 10 reps on each side. Do a total of three sets.
Seated Knee Tuck
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Seated Knee Tuck

This advanced crunch variation can be a little hard on your hip flexors and lower back; if you experience any pain, stop doing this exercise and rest or try a different move.

  • Start seated on the ground with your feet on the floor in front of you, knees bent. Place your hands about an inch behind your back with your fingers facing forward. Lift both feet up off of the ground, and balance on your glutes.
  • Extend both legs to hover just off the floor as you simultaneously lower your upper body a few inches.
  • Using your abs, bring your legs back to your chest. That's one rep.
Overhead Reach With Leg Lower
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Overhead Reach With Leg Lower

This move challenges both your lower and upper abs to maintain torso stability while your arms and legs move away from your center. If you don't have a dumbbell, you can do this move with just bodyweight, too.

  • Lie on your back with your arms reaching toward the ceiling, holding one weight with both hands. With your left leg bent and right leg out long, bring your right toes toward the ceiling. This is your starting position.
  • Lower your arms and leg toward the floor, keeping your lower back touching the mat.
  • Lift your arms and leg to return to the starting position. That's one rep.
Leg Lift
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Leg Lift

Taylor says these leg lifts, also called reverse crunches, are one of her favorite crunch variations. Here's how to do them.

  • Lying on your back, lift your legs in the air with your knees bent at about 90 degrees. Place your hands on the floor beside your hips.
  • Without momentum, use your lower abs to slowly curl your hips off the floor and into your chest. Slowly lower them back to the starting position.
  • That's one rep.
Hollow Body Hold
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Hollow Body Hold

This hollow body hold challenges you to find stillness (easier said than done). The move is simple enough, but you'll definitely feel the burn.

  • Start on the floor, with your legs straight and your arms extended overhead.
  • Press your lower back into the floor and inhale to slowly lift your shoulders, arms, and legs off the floor, engaging your core and keeping your lower back pressed down.
  • Hold for 30-60 seconds. You can also bend your knees if it's too hard to keep your legs straight.
Standing Ab March
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Standing Ab March

If you're not a fan of the floor, the standing ab march will help strengthen your core just as well as crunches. Standing ab work is also good for mobility, stability and coordination. This ab march is just one variation to try out:

  • Start in a neutral standing position with your arms by your side.
  • Engaging your abs, bend your knee and raise it up to your torso. Pause at the top of the position, and lower back down to the ground, repeating on the other side.
  • Aim to march for 30 seconds. For an additional challenge, you can also hold a dumbbell overhead as you march.
The Hundred
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The Hundred

Think of this as an elongated crunch. In Pilates, the hundred is used to activate the core and build some heat. "This [classic Pilates move] is great because it engages your entire core," certified Pilates and barre instructor Tracy Green previously told PS. "Focus on the percussive breathing here — it's five sharp, quick breaths in, then five strong, quick exhales." The breathing is a big part of what engages your core.

  • Start lying on your back with your legs in tabletop position. Engage your abs and round your lower spine into the floor.
  • Exhale and lift your upper back off the floor, until the bottom tips of your shoulder blades are just touching the floor. Straighten your legs to a 45-degree angle, making sure your low back is staying connected to the floor. Reach your arms toward your feet, about two inches off the floor.
  • Pump your arms up and down with a small range of motion, keeping your elbows straight. Inhale for five arm pumps, and exhale for five pumps. That's one rep. Over time, try to work your way up to 10.
Dead Bug
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Dead Bug

Don't let the name fool you. The dead bug exercise feels a bit like a crunch, but it's more of a functional movement, targeting deep core muscles in the transverse abdominis and rectus abdominis, while also strengthening your obliques and pelvic floor.

  • Start on the floor, lying on your back. Lift your legs up to tabletop position, with your knees bent at 90 degrees and your shins parallel to the floor (make sure your knees are directly over your hips). Extend your arms toward the ceiling, stacking directly over your shoulders with your palms facing each other. From this position, flatten your back to the floor by tilting your pelvis slightly upward. This is your starting position.
  • Exhale to slowly extend one arm behind your head while simultaneously extending your opposite leg until it's straight, hovering just off the floor. Try not to let your lower back lift off the floor in the process.
  • Hold for one second, then inhale to lift both your arm and leg back to the starting position.
  • Repeat on the other side. That's one rep.

Lauren Mazzo was the senior fitness editor at POPSUGAR. She is a certified personal trainer and fitness nutrition specialist through the American Council on Exercise. Prior to joining POPSUGAR, she worked for six years as a writer and editor for Shape Magazine covering health, fitness, nutrition, mental health, sex and relationships, beauty, and astrology.



Chandler Plante is an assistant editor for POPSUGAR Health & Fitness. Previously, she worked as an editorial assistant for People magazine and contributed to Ladygunn, Millie, and Bustle Digital Group. In her free time, she overshares on the internet, creating content about chronic illness, beauty, and disability.