But that’s only when you do them right. And a lot of people don’t.
Bad sit-ups are bad for you
There are just a ton of ways people can hurt themselves performing crunches and sit-ups improperly. They’ll clasp their hands behind their necks and yank upwards to help them sit up, they keep their legs too straight, risking hyperextending their lower back and they bend their backs, straining the lumbar spine. Ouch.
Improper form can lead to stomach pain, muscle strain, hernias, and spinal injuries. Not fun.
Still, I don’t want to scare you off away from them. They’re great exercises to tone your abdominals. It’s just a matter of doing them right.
So what’s the difference between a crunch and a sit-up anyways?
It’s all in the name. The crunch focuses specifically on the abdominals, tensing and working your abs, while a sit-up targets not just your abs, but also your back, shoulders and occasionally your hip flexors
Crunches and sit-ups generally begin from a flat position, lying back on the floor with legs bent, feet flat against the ground.
So how do you do a sit-up or crunch correctly?
Are you lying down? Okay, cool; let’s begin.
With a crunch, you’re targeting the rectus abdominus muscles only. With your hands crossed on your chest, lift your head and shoulders up, squeezing and contracting your stomach muscles, exhaling as you rise. Hold for a second or two, and then release, lowering your head to the ground, inhaling. Then repeat.
With a sit-up, you’re targeting the rectus abdominus, as well as your back and shoulders. Contract your stomach muscles, and lift your head, shoulders and torsos off the ground until you are completely sitting up. Then lower yourself down. Again, exhale as you rise, inhale as you lower. Then repeat.
Keeping your hands crossed along your chest will minimize the risk of neck strain. If you do want your hands behind your head, be sure to keep your elbows pointing outwards, and don’t clasp your fingers together—keep them loose, so as to support the neck, and not force it to work to lift you. That’s your abs’ job. Lifting your chin, rather than keeping it tucked in, also reduces pressure on the neck.
It’s easy to damage to your neck and spine in these kinds of exercises. When you’re lifting your torso off the ground, you should be using your stomach muscles to do those—that’s what the exercise is for, after all. Don’t use your neck to help you, and don’t ‘help out’ your crunch by pulling your neck or head forward with your hands. Note—for both sit-ups and crunches, your knees should be bent at a 90 degree angle.
And go slowly—it’s all about the muscle contraction, not speed.
Got all that? Good, because you’re going to have to do a lot of these, and after sixty or so, they start to get hard.
How many reps should you do?
Used in conjunction with other aerobic exercises, you should go with three sets of 10-15 exercises.
Sit-ups and crunches used as part of a full aerobic regimen are extremely effective at toning and working your abdominals, even if they don’t mean you’ll get a magic six pack.
Hey, wait a minute! How do you get rock-hard abs, then?
A good-looking six-pack is tough to achieve, my friend, and the fact of the matter is, you’ll probably have to drop down to 10% body fat to get them to show.
Core exercises like crunches and sit-ups are perfect for toning those muscles, but it’s the stomach fat lining them that hides them from the world. Only with a combination of rigorous exercise, a good diet, and stomach muscle toning will you get those abs.
But keep at it—toned and developed abdominals keep you healthier and stronger, so work at them.
But do it safely.