How to do perfect crunches every time

Crunches are perfect core exercises that will not only help you to develop your core strength but will also help you to build tone around your midriff. We’ve seen way too many people doing crunches wrong to let that go on any further so have decided to put this article together to help you get them right every time.

What is a crunch?

As the name suggests, abdominal crunches (to give them their full name) are designed to work on the muscles at the front of your abdomen that connect the sternum to the pubis (known as the rectus abdominis) and your obliques abdominal muscles. They can be done on their own or as part of a high-intensity intermittent training plan along with other core exercises. Crunches are very simple and easy to do but at the same time are probably the exercise that more people get wrong more often.

What’s the difference between sit-ups and crunches?

Both sit-ups and crunches are abdominal exercises that also work your core. The main difference is the muscle groups they work. While crunches concentrate mainly on your rectus abdominis and obliques muscles, sit-ups work your abdominal muscles as well as your neck, chest, hip flexors and lower back. Crunches are better for tightening and strengthen your abdominal muscles whereas sit-ups will focus more on your arms, back and buttocks.

How do I perform a crunch?

Start by lying on your back with your feet flat on the ground, your knees bent and your hands secured behind your head. With you arms open keep your hands behind your head start to tighten your abs. As you do this lift your shoulders and upper back so that your shoulders are completely off of the ground. It’s important to make sure you don’t use your arms to lift yourself but instead use your abdominal muscles. Hold this for a few seconds then return to the start before repeating.

How do I get it right every time?

Crunches are all about technique and once you’ve got that right it’s pretty easy to do it right every time as long as you don’t start rushing. Make sure you take the same time and care with every crunch. The most important thing about crunches is to make sure you’re not lifting yourself up. This is where a lot people go wrong and is actually the most common mistake that people make when doing crunches. Instead of using their abdominal muscles to lift themselves they either use their arms or secure their feet and use that to pull themselves upwards. Instead make sure you use your abdominal muscles and every crunch you do will be perfect.

What are crunches good for?

As a core exercise crunches are a very good way to strengthen your inner core muscles. Because of the muscle groups used to preform crunches they’ll also help you to improve your posture, mobility and flexibility. Contrary to what a lot of people think crunches won’t help you lose belly fat on their own. They’ll help you to tone your muscles but need to be done in conjunction with other exercises if you want to lose fat.

If I want to lose belly fat what should I do?

Crunches on their own won’t help you to lose any fat. To do so you should be combining them with some sort of full-body or aerobic exercise such as burpees or a HIIT workout. This will help get your heart rate up which in turn will help you to burn the calories, the crunches will then help to tone your belly.

What are the different crunch variations?

There are a variety of different crunches and you can even make up your own but every crunch is actually a variation on the basic crunch. You can read about more crunches in our article about losing belly fat but we’ve included a few of the more popular ones below:

Twist crunch
  • Twist crunch – Start with your back on the floor with your hands by your ears and you legs raised and knees bent to create a right angle. Contract your abs and bring your left elbow towards your right knee. Again hold this for around five seconds before returning to the start and repeating with the other arm and leg.
  • On the ball – For this you should sit on a Swiss ball with your feet on the floor. Lay yourself back on the ball, making sure your back is parallel with the ground. It should feel like your back is curved around the ball. Hold your arms upwards towards the ceiling and use your abs to raise your chest until the middle of your back is off of the ball, hold for up to five seconds then lower yourself and repeat.
  • Knee tuck – With a knee tuck you start by sitting on the floor with your hands behind you (creating a 45 degree angle) and your legs raise to a 45 degree angle. Keeping you abdomen tensed bend your knees to a 90 degree angle and raise your upper legs towards your chest.
Russian plank
  • Russian – Start on a declined bench with your legs held under the pads and your arms crossed over your chest. Make sure your feet don’t move and then lean back until your back is flat and your knees are bent at a 90 degree angle. Next crunch your abdominal muscles and twist your abdomen to the left, right, left then right again, making sure you keep your feet flat and don’t move them or your hips.
  • Wood chop – To start with lie on the floor with your legs raised and knees bent at a 90 degree angle (creating a ‘table top’). Raise your arms up towards the ceiling while holding a dumbbell in each. Open your arms and lower them to the floor before returning them back towards the ceiling. Then continue to perform a normal crunch but keeping your arms straight and twist them so they go to the side of your legs. Repeat the whole thing but this time twisting to the other side. Make sure that you keep your legs in the same position throughout.
Jackknife plank
  • Jackknife – Start by lying flat on the ground with both your arms and legs extended, make sure that your lower back is flat and isn’t arched at all. Tighten your abdominal muscles and then raise your arms and legs until they’re almost together and around 35-35 degree angle to the floor. Make sure you keep your head up and in a line with your back. The jackknife crunch is sometimes referred to as a V crunch and should be held for around 3 seconds.
  • Side Jackknife – This is similar to the jackknife but instead of lying on your back you lie on your side, put your hand behind your head and bend your arm. Tense your abs and then bring your shoulder and hip together as you lift your leg. Again hold this for around 3 seconds before returning to the start and repeating on the other side.

Common mistakes and how to avoid them

The most common mistake is instead of using your abdominal muscles to lift your shoulders you either lift with your arms or use pressure against your feet to lift yourself. To prevent this don’t prop your feet under anything but instead place them flat on the floor and make sure your arms are relaxed. To start with it can be difficult to not lift with your arms but a good way of doing it is to not grip your hands together, if they’re just resting behind your head then you’re less likely to use them to lift yourself. Whereas if your hands are held behind your head it’s easy to hold your hands tighter which in turn will give you a bit of lift.

Another mistake is you rise too high, crunches aren’t sit-ups so you should only lift your shoulders and lower back until they off the floor and not bring your body right up. It can often help to do crunches in front of a mirror to make sure you’re lifting to the right level. If you do use a mirror though make sure your not twisting your body to look, instead just glance without turning your head too much.

This might sound silly to say but you’d be surprised how many people concentrate on an exercise so much that they’re not actually breathing. Be honest we’ve all done it, you’re thinking about what you doing then suddenly realise you’re not breathing. It’s easy to do but just as easy to not do, before you start take a few deep breathes, paying particular attention to each breathe. This will help keep your mind on breathing then as you start to perform a crunch you’ll find you’re breathing without needing to think about it.

It’s also very important to keep your movements constant. There’s no point tensing your muscles as you raise your back but relax as you return to the start. Using your muscles to lower yourself back is just as important as it is at the start. It’s the whole fluid movement and the contracting of the muscles throughout that’s important. 

Can crunches give me a hernia?

Also long you don’t over do it when you first start, crunches can actually help prevent you getting a sports hernia. Any abdominal exercise will tone and strengthen your muscles, it’s this increased strength than can help to prevent hernias. If you’ve already had a hernia that has been repaired then crunches can help avoid a recurrence.

Can I do crunches while I’m pregnant?

It may surprise you to know that this is one of the most commonly asked questions on Google when it comes to crunches. In the early stages, usually the first trimester, you can do crunches but they should be avoided as soon as your bump starts to show. The reason for this is that the expansion of the belly causes the rectus abdominis to separate, doing crunches at this stage will put unnecessary strain on the muscles.

Can I do crunches with a bad back?

As you’re curling your spine and therefore putting a strain on your back and spine you should be cautious while doing crunches. There are so many reasons for back pain that it’s not possible to give any one definitely answer to whether you can or can’t do crunches with a bad back. Some doctors will say to do gentle crunches while other will advise that you should avoid them altogether if you have any lower back pain. What is crucially important though is that if you do do crunches with a bad back you listen to your back, if you get any extra pain or twinges stop immediately.


While crunches are very good for building and toning muscle they’re best used in combination with a high-intensity interval training plan if you’re looking to lose weight. If you’re interested in learning more about other exercises and workout plans then check out the other articles in our how to do series.