Which Classic Core Move Is Best — Sit-Ups vs. Crunches?

Experts weigh in on the age-old debate of which go-to abs exercise is best for your core strength.

Situps vs Crunches
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Some polarizing topics are meant to be debated forever: which Taylor Swift album reigns supreme, are dogs or cats better pets, and were Ross and Rachel really on a break, for example. And when it comes to working out, gym veterans and fitness newbies alike have often argued over which core exercise — sit-ups vs. crunches — is best for building abdominal strength. After all, they appear pretty similar in practice: Both involve laying on the ground with knees bent and feet flat on the floor, and both require you to use your core muscles to lift your torso off the ground. A sit-up, however, requires you to lift your entire torso off the floor so your chest comes toward your knees, while a crunch involves only rolling your shoulder blades and upper back off the ground for a much smaller range of motion.

Each move has its benefits, but you might not be clear on which abs exercise to prioritize if you want to build core strength (which is essential for enabling your everyday movements, supporting your spine for better posture, and preventing injury, BTW). Here, learn more about the benefits of sit-ups and crunches, plus which core exercise is best for your specific goals and needs.

Benefits of Sit-Ups

If you were ever subjected to the Presidential Physical Fitness Test in elementary school, you might already know that the sit-up is considered a foundational exercise in developing core strength and measuring overall endurance. Here's how to do a sit-up correctly for building core strength, plus the main benefits of sit-ups.

How to Do a Sit-Up

The sit-up sounds basic, but there are a few key techniques that ensure you're doing the move correctly, as Kayla Jeter, an NASM-certified personal trainer and certified functional strength coach, demonstrates below. First, lay down on the floor with knees bent and feet flat. Your hands can be behind your head, across your chest, or wherever feels comfortable. On an exhale, engage your core and squeeze your glutes as you life your entire torso (hips to head) off the ground toward your thighs. Try your best to keep your feet glued to the ground as you come up. Inhale as you slowly lower back down (without flopping to the floor — this helps develop core control).

Now that you know how to nail the sit-up for core strength, learn more about the benefits of sit-ups that have made them a staple in many exercise routines.

Works Multiple Muscle Groups

News flash: Your core involves multiple muscle groups beyond the front of your stomach. For example, your core consists of the rectus abdominis, transverse abdominis, obliques, serratus, erector spinae, and even your pelvic floor. And a benefit of the sit-up is that it works several muscle groups at once with one efficient move, says Jeter. "Several muscle groups are necessary when performing the movement to maintain proper form — abdominals, hip flexors, back, and neck, for example," she says.

Improves Functional Movement

Whether or not you realize it, you likely already do several sit-ups per day, even without going to the gym. "Sit-ups are a functional movement," says Francine Delgado-Lugo, an NCSF-certified personal trainer and co-founder of FORM Fitness Brooklyn. "We sit up every time we get out of bed or come out of a lying down position." So by practicing the sit-up regularly, you're strengthening the muscles that you use in your everyday life — which improves your functional strength as you age and helps prevent injuries. Think: You'll be less likely to wake up with a twinge in your low back after sleeping awkwardly.

Relieves Lower Back Pain and Hip Pain

If you have an office job or work from home, you've probably had one of those days where you look up from an engrossing task and realize you haven't moved in... (checks watch) three hours. Yikes. Being this sedentary means that your hip flexors and erector spinae (aka the muscles that support your spine so that you can stand upright) don't get as much love as they need, says Delgado-Lugo. "These muscles don’t get to lengthen and contract very much, due to our sedentary lifestyles," she explains. "The lack of use is often what leads to pain in these areas, so sit-ups, if done properly and as part of an appropriate strength program, can actually help to alleviate or prevent lower back or hip pain." So sit-ups — in addition to standing up regularly and doing exercise snacks for movement breaks — can help counteract a sedentary lifestyle.

Benefits of Crunches

While similar to sit-ups, crunches have their own distinct advantages as a core-strengthening move. But first, here's a quick refresher on how to do crunches correctly.

How to Do a Crunch

Unlike a sit-up, a crunch involves a small curl of your shoulders to lift your shoulders, neck, and head off the floor, as Jeter demonstrates below. Lay down on the floor with your knees bent and feet flat on the floor, while pressing the small of your back into the ground (that prevents arching in the low back, FYI). Hold your fingertips lightly behind your head and exhale as you engage your core muscles to lift your upper shoulders, neck, and head off the ground. Inhale as you lower back down — that's one rep.

Now that you know how to do a crunch with proper form, here's what to know about the benefits of crunches.

Isolates Rectus Abdominus

While sit-ups are more of a full-body movement that engages your glutes and hip flexors in addition to the core, crunches are more focused, says Delgado-Lugo. "Crunches isolate abdominal muscles, specifically the rectus abdominus, providing more concentrated work in the muscles targeted," she explains. The rectus abdominus muscles, FYI, are a pair of long, straight muscles that run down the middle of your abdomen. They're responsible for trunk flexion (that is, your ability to bend forward and come back to standing).

Requires a Smaller Range of Motion

While sit-ups entail going from a laying-down position to sitting upright, crunches are a much tinier, more subtle movement with a smaller range of motion — just curling your shoulder blades up off the ground. That smaller range of motion packs a one-two punch: It makes crunches more accessible to beginners, and it reduces the risk of injury, says Jeter. "Crunches require a smaller range of motion where only your shoulders raise and your lower back stays grounded, putting less pressure on your spine," she explains. With such minimal movement, you're less likely to injure yourself.

Builds the Foundation for Other Core Movements

"The crunch is the initial movement to a sit-up," explains Mallory Fry, ACSM-CEP, master coach for Row House. By focusing on lifting your shoulders, neck, and head off the ground, you're prepping your muscles to progress to a full sit-up down the line (if that's your goal, of course). The crunch can also be a helpful foundation for other core movements, such as hollow body holds and dead bugs.

How to Choose Between Sit-Ups vs. Crunches

Sit-ups and crunches look similar to the untrained eye. However, if you have specific core-strengthening goals or need certain modifications, here's how to decide between sit-ups vs. crunches.

If you have low back pain: Crunches

"Most people are challenged by sit-ups because they can exacerbate low back pain and/or neck and shoulder pain," says Delgado-Lugo. After all, low back pain is incredibly common; in fact, around four out of five people experience low back pain at some point in their lives, according to the Cleveland Clinic. If that's you, crunches are a better alternative for core strength than sit-ups, says Jeter. That's because "the pressure put on your spine from fully sitting up is alleviated with crunches," she explains.

If you want to build functional strength: Sit-ups

From getting up off the couch to lifting your torso off the floor so you can better pet your dog, sit-ups are already a movement you do naturally in your everyday life. If you're already thinking about how you can move well and without pain as you age, sit-ups are key for developing your functional strength (aka strength training that supports your performance of daily activities). "Sit-ups are a more transferrable exercise [than crunches] in everyday life," adds Jeter.

For overall core strength: Sit-ups

While sit-ups and crunches are beneficial for core strengthening, sit-ups work more muscle groups than crunches do, notes Delgado-Lugo. "All of the muscles involved [rectus abdominus, the obliques, spinal erectors, hip flexors, and diaphragm] must work together as a system to lift the torso up," she says. So for the most efficient core exercise to strengthen a multitude of abs muscles, the sit-up is your go-to.

For targeting upper abdominals: Crunches

While sit-ups may work more muscle groups than crunches, crunches offer a more targeted, isolated abs exercise. "Crunches specifically target the upper abdominals, strengthening our ability to lift our head, neck, and shoulders," says Fry.

For core stability and improving overall core function: Neither

While the debate between sit-ups vs. crunches continues, it takes more than these two exercises to truly improve your overall core strength. "Exercises that really strengthen the core are planks, farmers carries, and rotation and anti-rotation exercises because these exercises target functions of the core in your bodies — stability, bracing and stiffness, rotating under load, and resisting rotation against load," explains Delgado-Lugo. "A truly effective workout would include these in addition to sit-ups and crunches."

And TBH, focusing on only sit-ups and crunches for core exercises is an outdated way of training, says Jeter. "The old school of thought on 'core' exercises focuses primarily on aesthetics, targeting and isolating abdominals, and not necessarily improving overall function and strengthening of the lumbopelvic–hip complex," she explains. (FYI, the lumbopelvic hip complex, aka the pillar system, is another way of referring to your shoulders, core, and hips — the pillar of your body.) "Pillar exercises include plank holds, plank shoulder taps, plank kettlebell pull-throughs, bear holds, bear crawls, payoff press, kettlebell off-set marches, and more."

So while sit-ups and crunches might be one part of a well-rounded core exercise regimen, your core training should go beyond these two moves in order to fully support your body's movement patterns (such as pushing, pulling, lifting, carrying, hinging, and squatting). "None of [these movements] really occur in isolation on the floor so let’s do more core off the floor," advises Jeter.

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