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Are Sit-Ups and Crunches Bad for You?

Sit-ups and crunches are popular exercises for the abdominal muscles, but could they be doing more harm than good? Get-Fit Guy, Dr. Jonathan Su, gives you the scoop on who can safely perform and who should avoid sit-ups and crunches. 

By
Dr. Jonathan Su, DPT, CSCS, TSAC-F, C-IAYT
6-minute read
Episode #548
The Quick And Dirty

Some folks can perform sit-ups and crunches without issues if they're done in moderation, while others should completely avoid them, or hold off until core strength has been developed using safer alternatives.

Sit-ups and crunches are popular exercises for working the abdominal muscles. They’re the go-to for most people who want to strengthen their core or develop six-pack abs. However, sit-ups and crunches have come under increased scrutiny over the last several years as potentially dangerous movements that should be avoided. Are these exercises really as bad as some say they are? If so, what makes sit-ups and crunches so dangerous and what exercises should we be doing instead? 

The sit-up controversy: too much bending is harmful 

Let’s start by looking at where the idea that sit-ups and crunches are potentially dangerous comes from. This idea is based on studies showing that repetitive bending of the trunk, like the motions used in sit-ups and crunches, damages the discs of the lower back. These studies provide useful insights into how disc herniations (also called bulged, slipped, or ruptured discs) can happen. But the findings of these studies should be interpreted with a fair amount of skepticism. Why? Because they’re all based on research using the dissected spine of dead pigs that were continuously taken into sit-up or crunch-like motions from 4,400 to more than 86,000 times using a machine in a laboratory setting. Based on these studies, well-meaning rehab and fitness researchers began touting sit-ups and crunches as dangerous movements that should be avoided by most people. 

The body has an incredible ability to repair itself and most cases of painful disc herniations are able to heal within a few weeks.

I prefer a pragmatic approach when weighing in on these issues by considering both the research as well as the reality. We are, of course, living and breathing humans, not dead pig spines placed in bending machines for countless hours without pause. What we can take away from this line of research is that too much of the type of bending used in sit-ups and crunches does lead to damage of the spinal discs. But in reality, how many people do you know actually perform anywhere near the number of sit-ups or crunches used in the studies? Some researchers may point out that it’s the cumulative effect of these types of bending motions over a lifetime that causes problems. In other words, there’s a limit to the number of times you can bend the spine, and exceeding this limit ultimately leads to disc damage. 

But we can make the argument that research also shows that exercises involving bending of the trunk bring nutrients to the spinal discs that are important for keeping them healthy. It’s also known that the body has an incredible ability to repair itself and that most cases of painful disc herniations are able to heal within a few weeks. So are sit-ups and crunches okay if done in moderation? What do we make of all this? 

Should we avoid sit-ups and crunches?

The answer to whether sit-ups and crunches should be avoided is more nuanced than a simple yes or no. I do believe that certain people should completely avoid these exercises. Others should hold off on them until after a stronger foundation of core strength has been developed using safer exercises. Still, others could perform sit-ups and crunches without short-term or long-term issues if they’re done in moderation. 

Who should completely avoid sit-ups and crunches

Based on the research showing that too much bending is harmful, it would be prudent for us to identify certain groups of people who should completely avoid sit-ups and crunches. These would include: 

  1. People with back pain or a history of back pain: Sit-ups and crunches are known to exacerbate back pain and studies show a connection between back pain, disc herniation, and weakness in the core muscles of the back. 

  2. People with vulnerabilities of the spine: Sit-ups and crunches can cause compression fractures in people with osteoporosis so should be avoided by anyone with this diagnosis. Also, those with more than a couple of immediate or extended family members with serious back issues requiring surgery may have a genetic vulnerability and should avoid these exercises. 

  3. People who are older than 65: Aging brings about changes to our bodies, often in ways we don’t like. Case studies have reported strokes resulting from sit-ups and older adults would be wise to avoid sit-ups and crunches. Some fitness professionals would understandably argue that sit-ups are important for older adults because this motion is useful in daily life activities. Interestingly, research shows that there are safer alternatives to high repetitions of sit-ups that are actually more effective at training for sit-ups than sit-ups themselves!

Who should hold off until the core is stronger

If you don’t have any of the issues just mentioned, you don't have to completely avoid sit-ups and crunches. However, I do recommend holding off on these exercises if you’re out of shape or haven’t exercised in a while. I mentioned earlier that there’s a connection between back pain, disc herniation, and weakness in the core muscles of the back. I’ve seen too many people who are excited to get back in shape who perform too much, too soon, and are stricken with painful back injuries. My advice is to hold off on sit-ups and crunches for a few months and focus on developing a strong and balanced core using exercises such as the bird dog, the front plank, and the side plank.

Who can safely perform sit-ups and crunches

There’s no reason you should avoid sit-ups or crunches if you’re in shape and you don’t have any of the issues just mentioned. If you enjoy these exercises and want to do them, go for it! There are two suggestions I’d like to make though, just so you don’t end up in the group that should completely avoid these exercises down the road. 

First, please perform sit-ups and crunches in moderation. Remember, the body has an incredible ability to repair itself, but only if you give your body that opportunity. So avoid doing a hundred sit-ups and then a hundred crunches and then a hundred decline sit-ups and then a hundred twisting crunches every single day. You think I’m joking, but I bet I’ve just described some of your abdominal workouts. Instead, pick one or two exercises to do and then take a rest day away from these types of high-volume bending movements before going back to them again. 

Second, do your best to develop a balanced core by working all sides of your core. Focusing too much on the abdominal muscles with sit-ups and crunches creates imbalances that lead to bad posture and back pain. Yes, an overemphasis on the abdominal muscles can lead to bad posture because it will overly shorten the muscles in the front of the body and cause the spine to round forward. This persistent rounding of the spine puts undue stress on the low back, which results in back pain. 

Sit-ups and crunches aren’t really necessary for strengthening the core or developing six-pack abs because there are safer and more effective exercises that can get the job done.

Better alternatives to sit-ups and crunches

As you can see, my recommendation on whether sit-ups and crunches should be avoided is a little more nuanced. Certain people should completely avoid these exercises while others should hold off on them until after a stronger foundation of core strength has been developed using safer alternatives. Others could perform sit-ups and crunches without short-term or long-term issues if they’re done in moderation. Overall, sit-ups and crunches aren’t really necessary for strengthening the core or developing six-pack abs because there are safer and more effective exercises that can get the job done. 

Here are a few alternatives to sit-ups and crunches:

  • Front Plank: Face down on the ground with your elbows under your shoulders, hands flat on the floor, and feet hip-width apart. Tighten your core and raise your body upward until your back is parallel to the floor. Hold this position for up to 60 seconds.

  • Abs Rollout: Kneel on the ground with an ab roller, barbell, or dumbells in your hands directly underneath your shoulders and with your elbows straight. Tighten your core and roll forward as far as you can go without your body sagging and then return to the starting position. Repeat this motion 15-20 times with control. 

  • Leg Lift and Hold: Lie on your back with your hips and knees bent 90-degrees and your feet off the floor. Tighten your core, keeping your lower back pressed into the floor, and hold this position for up to 60 seconds. Straighten and lower your legs for more advanced core work, but only as low as you can go without your lower back lifting off the floor.

5-Day Core Strength Challenge

It’s time to put this knowledge into motion and you know what that means. Yes, a 5-day core strength challenge where you hit pause on sit-ups and crunches and perform the front plank, the abs rollout, and the leg lift and hold instead. Be sure to check out my YouTube videos for instructions on performing these exercises. Try to do each for 30-60 seconds or 15-20 repetitions on non-consecutive days (it’s okay to skip the ones you can’t do). Give it a try and let me know how you feel.

All content here is for informational purposes only. This content does not replace the professional judgment of your own health provider. Please consult a licensed health professional for all individual questions and issues.

About the Author

Dr. Jonathan Su, DPT, CSCS, TSAC-F, C-IAYT

Dr. Jonathan Su is the host of the Get-Fit Guy podcast. He is a physical therapist and fitness expert whose mission is to make fitness accessible for everyone. Dr. Su is a former U.S. Army officer responsible for injury prevention, rehabilitation, and performance optimization for soldiers in the field. He is also the author of the bestseller Six-Minute Fitness at 60+.

Got a question for Dr. Su? You can email him at getfitguy@quickanddirtytips.com or leave him a message at the Get-Fit Guy voicemail line at (510) 353-3104.