Ask most people what exercises they do to strengthen their abdominal muscles and they’ll likely mention crunches, and for some people, crunches might be the only exercise they do when training their abs. To do a standard crunch, you lie on your back and lift your upper body off the mat toward your bent knees. This movement activates the two large rectus abdominis muscles that give your midsection definition. However, some fitness experts believe that overdoing crunches is harmful to the back and spine, though research is conflicting about this.
Why might doing too many crunches harm your back? When you crunch, you flex your spine repeatedly. According to Stuart McGill, Ph.D., an expert and a professor of spinal biomechanics, crunches place up to 749 pounds of compressive force on your spine each time you crunch. Over time, repeated spinal flexion may place enough stress on the back and spine to herniate a disc.
That doesn’t mean you shouldn’t do crunches at all but suggests you shouldn’t do hundreds of them every time you train either. However, there’s another crunch variation that works your abdominal muscles differently. It’s called a reverse crunch and it targets your abs too. Do reverse crunches place excess strain on your back too?
In case you’re not familiar with the reverse crunch, here’s how to do one:
- Lie on a mat with your knees bent at 90 degrees, arms out to your sides, and feet flat on the floor.
- With your knees bent at a 90-degree angle, raise your legs until your thighs are perpendicular to the floor. Exhale as you raise hips off the floor and toward your chest. Your hips should rise up off the mat while your abs remain tight.
- Hold at the top for a second and reverse the movement as you slowly bring your feet back down to the mat. When you land on the mat, your knees should still be at a 90-degree angle and your knees should be over your hips.
- Keep repeating using slow, controlled movements.
Why Would You Want to Do Reverse Crunches?
The most important reason people do crunch is to strengthen and hypertrophy their abdominal muscles. The reverse crunch is designed to do that too. People often think reverse crunches isolate the lower abdominals better, but you can’t target your lower abdominal muscles in isolation. However, you’ll feel the movement more in the lower portion of your abs when you do a reverse crunch.
Another way reverse crunches are helpful is they work the external obliques, muscles that help pull your pelvis posteriorly. That’s important if you sit much of the day and develop anterior pelvic tilt from long periods spent perched in a chair. Anterior pelvic tilt is where your pelvic tilts forward too much and you develop an inward curvature of your spine. It can lead to back, hip, and knee pain if you don’t correct it. The reverse crunch, by strengthening the external obliques will help you fight anterior pelvic tilt.
How Safe Are Reverse Crunches for Your Back?
If you do reverse crunches with good form and a slower tempo, this crunch variation places less stress on the lumbar spine than a traditional crunch. When you do a reverse crunch, the movement comes from your thoracic spine rather than your lumbar spine, as with a standard crunch. But if you do the exercise too quickly by letting your knees drop down to the floor too fast, you can get some lumbar hyperextension that isn’t healthy for your back.
Slowing the tempo of reverse crunches has other benefits too. When you reverse crunch in a controlled manner and slowly bring your knees down, you increase the tension in your rectus abdominis muscles and that can lead to greater strength and hypertrophy gains. When you move too quickly and let your knees drop, you use momentum and taking tension off of your abdominal muscles.
Make Reverse Crunches Harder
If you do enough reverse crunches, you’ll eventually reach a point where a reverse crunch feels too easy. Don’t worry! You can make them more challenging by doing the exercise on an incline bench. Doing reverse crunches on a bench at a 60-degree incline will force your rectus abdominis muscles to work harder and that can lead to greater strength and hypertrophy gains.
The Bottom Line
Reverse crunches are somewhat safer for your back than standard crunches if you do them with a slow tempo and good form. There are also potential benefits to doing reverse crunches in moderation. You may be rewarded with stronger abs and more muscle definition. Who wouldn’t want those benefits? However, reverse crunches alone won’t give you six-pack abs. For that, you need exercises that isolate the abs and core, such as planks, and compound exercises that burn more calories and work the abdominal muscles indirectly.
Don’t forget that exercise alone won’t give you a six-pack tummy. The biggest problem women have with developing defined abdominal muscles is they carry too much body fat in the abdominal region and that covers up muscle definition. Most women won’t have ab definition unless they get to a body fat percentage of 14 to 20%. However, you’ll still build abdominal strength, even if you don’t achieve a visible six-pack.
Also, striving for six-pack abs might not be best for your health either. If you lower your body fat percentage too low to get your ab muscles to “pop,” you risk developing other problems, like infertility, irregular periods, and bone loss. Strive for strength rather than a certain aesthetics. Strength training will make you stronger and healthier, regardless of whether you have striations on your abs and rock a midriff top. Aim for better health and strength and be proud of the body you’ve achieved!
References:
- com. “Crunches Are Bad For Your Back — Here Are 10 Ab Exercises to Do Instead”
- com. “Why The Reverse Crunch Is Your Shortcut to Six-Pack Abs”
- org. “Reverse Ab Crunch”
- com. “Body Fat Percentage for Abs: What’s the Magic Number?”
Related Articles by Cathe:
Are Abdominal Crunches on a Stability Ball More Effective?
Are You Working Your Core Muscles Properly?
What’s the Best Rep Speed for Building Abdominal Definition?
Abdominal Exercises: Are You Doing Too Many Reps?
Abdominal Training: Are Ab Crunches Damaging to Your Back?
The Most Effective Ab Exercises Revealed
Ab Training: Can the Quest to Get Defined Abdominals Lead to Back Pain?
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